LA-7488-MS

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Outer Geosciences

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LOS ALAMOS SCIENTIFIC LABORATORYPost Office Box 1663 Los Alamos. New Mexico 87545

WSM LA-7488-MSInformal IRtportSptcial DiitributionIssued: Junt 1979

Outer Geosciences

Richard L. Blake

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CONTENTS

ABSTRACT 1

I. SUMMARY 1

II. INTRODUCTION 3

III. ATMOSPHERIC/SOLAR-TERRESTRIAL SYSTEM 4

A. The Sun 4B. Interplanetary Medium 7C. Magnetosphere, Radiation Belts, and Plasmasphere 7D. Earth Atmosphere/Ionosphere •. 10E. Climate and Weather 16F. Interactions of Possible Significance 19

IV. RELEVANCE OF OUTER GEOSCIENCES TO DOE MISSIONS ANDNATIONAL INTERESTS 22A. General Case for DOE 22B. Specific Clases of National Interest 23

V. OUTER GEOSCIENCES AREAS OF EMPHASIS FOk DOE 32

ACKNOWLEDGMENTS 34

REFERENCES 34

APPENDIX A. OUTLINE OF AN OUTER GEOSCIENCES PROGRAM WITHSUGGESTED FRACTIONAL SUPPORT 35

APPENDIX B. EXISTING PROGRAMS IN GOVERNMENT AGENCIES 38

IV

OUTER GEOSCIENCES

by

Richard L. Blake

ABSTRACT

This report presents an objective discussion of the importance of theatmospheric/solar-terrestrial system to national energy programs. A briefsketch is given of the solar-terrestrial environment, extending from theearth's surface to the sun. Processes in this natural system influenceseveral energy activities directly or indirectly, and some present and poten-tial energy activities can influence the natural system. It is not yet possibleto assess the two-way interactions quantitatively or to evaluate theeconomic impact. We suggest that an investment by the Department ofEnergy (DOE) in a long-range basic research program is an important partof the department's mission. Existing programs by other agencies in thisarea of research are reviewed and a compatible DOE program is outlined.

I. SUMMARY

When new technologies are developed, questionsinevitably arise whose answers depend upon thestate of understanding in the fundamental sciencesbehind the technologies. The sciences relevant todemand, sources, and production of energy on earthsurely include the solar system sciences—how thesun and earth evolve and how their components in-teract. We demonstrate herein that appropriate ac-tivities by the Department of Energy (DOE) will in-clude support for basic research on theatmospheric/solar-terrestrial system, which we havelabelled the "Outer Geosciences" and in which areincluded the sun, interplanetary medium,magnetosphere, ionosphere, and upper atmosphere.By acting now with foresight to augment theknowledge base of the atmospheric/solar-terrestrialsystem we may well preclude future misfortune from

unpredicted interactions between energytechnologies and the environment.

At a time when this nation has become keenlyaware of the adverse effects of energy andtechnology on the environment, DOE has beengiven the task of developing the technologies ofenergy supply. To carry out its task for the good ofmankind, DOE has a three-phase assessmentprogram in the areas of environment, technology,and resources. When such assessments are at-tempted, it immediately becomes clear that the "en-vironment" is not just the atmosphere and solidearth volume near an energy installation but ratherthe totality of solid earth, water systems, biologicaland chemical systems, and the atmosphere—allparts of a complex, interacting global systemsometimes called the biosphere. The need to con-sider the global aspects of this system has becomeclear in recent years and has prompted this report.

Our national energy, transportation, and industrialsectors will necessarily be with us throughout ourfuture and will have significant influence on theworldwide environmental system, as we have learn-ed from radioactivity, smog, and ozone hazards.

In recent years we have learned that importantvariations in the earth's biosphere arise from in-teractions of the near-surface components with a farlarger system extending to the sun and also ariseirom man-produced factors. Not only does solarradiation drive the circulation of the lower at-mosphere with its weather patterns, but the short-wavelength (ultraviolet or uv) portion and particlesare largely responsible for conditions in the higheratmosphere well above the weather-dominatedlayer. These higher portions contain trace con-stituents whose importance far exceeds their frac-tional concentration; a prime example is ozone. Theconcentrations and changes in these trace con-stituents caused by fluctuations in solar radiationsmust be assessed as a base line to compare withchanges caused by energy-related technologies andother man-made injections.

Solar emissions related to the 11-year solar ac-tivity cycle cause major changes in the earth'smagnetic field, plasmasphere, ionosphere, and at-mosphere. In turn, these changes induce effects atearth's surface with significant socioeconomic con-sequences. Examples (some of which are illustratedin Fig. 1) include

(a) interruptions in long-distance power trans-mission owing to geomagnetic induction,

(b) interference in oil and gas pipeline monitors,(c) disruption of long-distance radio and

telephone communications,(d) severe interference with magnetometer

signals obtained for geophysical explorationfor minerals and petroleum, and

(e) modulation of both climate and weather.Recently, evidence for the last example has becomestronger. In particular, drought conditions in theU.S. high plains and other parts of the world haveoccurred in association with the 22-year double solaractivity cycle regularly since the mid 1800's andwith longer term solar activity minima for the past5000 years (where comparison has been possible).Changes in average rainfall and average pressuretrack the solar activity in different ways at differentgeographic locations.

VARIATIONS OF SOlAH " *EMISSIONS CAUSE IONOSPHERICAND GEOMAGNETIC DISTURBANCES

HADIATION AND PARTICLE FLUKES AND GEOMAGNETICDISTURBANCES CAUSE NUMEROUS EFFECTS ON TECHNOLOGICALSYSTEMS ON EARTH

f l fCTHlCAL POWERTRANSMISSION LINE

DISRUPTION

Fig. I.A sketch to illustrate how solar activity causesvariations in the earth's outer environment,which in turn cause undesirable effects nearthe earth's surface. More examples are given inthe text, including effects on weather andclimate.

Man-produced factors known to affect the naturalsolar-terrestrial system include the following.

(a) Harmonics of 60- and 50-Hz power systemsmay be a dominant cause of electron lossesfrom the magnetosphere into the ionosphere.

(b) Increasing carbon dioxide levels from fossilfuel consumption cause atmosphere warmingand climate changes.

(c) Injections of chemical or radioactive speciesinto the atmosphere from weapons tests, in-dustrial processes, energy technologies, trans-portation, and other human activities mayalter not only the total radiation balance thatcontrols climate directly but also the radia-tion balance in nonvisible spectral regions,such as the uv, producing human medicalconsequences. In addition, the atmosphericelectrical state may be altered with possiblemeteorological consequences.

(d) The space power systems discussed so far cansignificantly modify the ionosphere locallyand, when used for long periods and in largenumbers, globally.

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Fig. 2.A sketch of the earth's atmosphere andionosphere (not to scale) to illustrate the globalscale of a few activities relevant to DOE. Thefigure depicts how activities both at the sur-face and in space can influence the global en-vironment of earth. Space power systems andnuclear debris from spacecraft reactors orweapons tests in the upper atmosphere arepotential future problems whose consequencescan only be deduced from knowledge of theOuter Geosciences environment.

Figure 2 indicates very generally the global natureof the atmosphere and ionosphere. Vertical andhorizontal transport can occur in several ways, withthe result that perturbations in the atmosphere orionosphere do not always remain localized.

At present there is insufficient basic knowledge ofclimate, the atmosphere, magnetosphere, and sunas an interacting system to permit definitive conclu-sions on cause-effect relationships. Therefore, partof DOE's responsibilities must be support of basicscientific research to expand the knowledge baseabout this total system, so that realistic assessmentscan be made about consequences to the natural en-vironment from man's energy systems and viceversa.

The goals of the Outer Geosciences Programsuggested here are

(1) to provide detailed characterization of thestructure, natural variability, and dynamics

of the atmospheric/solar-terrestrial systemand

(2) to provide a basis for reliable prediction andassessment of the effects of energy andnational security activities on that systemand vice versa.

Because we arc- concerned about basic research,the support actn ity logically belongs in the Divisionof Basic Energy Sciences (BES), where it will com-plement existing applied research projects in otherDOE divisions. In BES the basic research inatmospheric/solar-terrestrial areas can be im-plemented by expansion of the Geosciences to in-clude more outer atmospheric and solar-terrestrialstudies (that is, the Outer Geosciences).

Other agencies that have been contacted have ex-tended considerable encouragement for DOE toemphasize basic research to improve our base-lineknowledge in specific areas including

(a) sun-climate relations,(b) sun-weather relations,(c) upper atmosphere physics and chemistry,(d) magnetospheric physics (especially coupling

to the ionosphere and atmosphere), and(e) solar physics (especially the activity cycle and

radiative output).More understanding is needed in these areas beforethe effects noted above can be assessed adequately.Only when the important variables have beenisolated and their interrelations defined can realisticassessments be made. A consensus on the need forfundamental research on components of the sun-earth system in all its varieties of interactions and aconsensus that modeling of parts as well as thewhole system should be encouraged to keep up withobservational developments were readily apparent.

Coordination with the National AtmosphericSciences Program and the National ClimateProgram would follow naturally because DOE isalready engaged in the former and it has been in-volved in planning the latter.

II. INTRODUCTION

As DOE's responsibility in recent years has shift-ed from purely nu< lear matters in the AEC to theentire spectrum of energy systems, the interactionsbetween energy systems and the environment havetaken on increasing importance. At present we are

far too ignorant of the natural environment to an-ticipate accurately the long-term global conse-quences of most energy technologies. What we doknow is that "environment" certainly includes morethan the immediate surroundings of an energy in-stallation. Existing programs in DOE that aregeared to this "local" concept of the biosphere are es-?ential to DOE's mission, but we believe they arenot sufficient. Our reasons will be outlined in thisreport.

There are projects under way in DOE to improveour knowledge of the local system at the interface ofearth and atmosphere. The Division of Biomedicaland Environmental Research has numerousresearch projects in this area and other divisionscontribute to them. Surface geophysical scienceshave been included in the basic research program ofthe Division of Physical Research for a decade. AGeosciences Working Group (GSWG) with mem-bers from all DOE divisions has been effective incoordinating geosciences-related research. GSWGrecently has become aware of the need for improvedknowledge of the extended atmosphere and sun-earth phenomena. The natural environment is beingviewed increasingly on a global scale as an evolvingset of interacting components including the solidearth, water systems, biological and chemicalsystems, the atmosphere, the geomagnetic field, andincident solar radiation and particle fluxes.

This report responds to the question, raisedwithin the GWSG and by outside scientists and per-sonnel in other agencies, of why DOE has notbecome more active in support of research in theOuter Geosciences including the outer atmosphere,magnetosphere, interplanetary medium, and thesun. A small but very productive activity in thisarea has been supported by the GeosciencesProgram and the Division of Military Application(DMA), but the long-term socioeconomic impor-tance seems so great that more coordinated supportseems appropriate and timely. In what follows wereview the reasons why the Outer Geosciences arerelevant to DOE's mission, the existing programs inall agencies, and the significant areas that should besupported by modest expansion of the presentGeosciences Program.

Outer Geosciences will be our shorthand todescribe the totality of the atmosphere, ionosphere,magnetosphere, interplanetary medium, and the

sun—all parts of an interacting system with directpresent and future influence on mankind.

HI. ATMOSPHERIC/SOLAR-TERRESTRIALSYSTEM

Our earth is part of the solar system and inex-tricably bound to participate in the system's evolu-tion. We are concerned here with several facts aboutthe sun's energy output and its effects on earth.Over eons the solar output has been responsible forthe existence of fossil fuels. On a daily basis thesun's visible radiation output is the driving force forearth's atmospheric circulation, which is what wecall weather after including the interaction of thisatmospheric circulation with land masses, oceans,polar ice, and other influences. Intermediate be-tween these extremes are many earth responses tosolar outputs other than visible light. The effects ofthese earth responses on human endeavors are oftenindirect and subtle; nevertheless they are impor-tant. In this section, we illustrate the generalfeatures of the system with emphasis on inter-mediate interactions, which we lump together in abroadly defined discipline called atmospheric/solar-terrestrial processes or Outer Geosciences. We pre-sent the descriptive information working inwardfrom the sun to the earth's surface.

A. The Sun

As innocent and constant as the sun appears inour daily lives, the nonscientist often thinks of it asimmutable, a fixed object in the heavens to be ad-mired for its beauty and life-giving power. When weinquire as to the source of its energy, we learn thatnuclear reactions going on in the solar interior overbillions of years have created the energy that dif-fuses outward to the solar surface and is emittedinto space. Most of the energy from our sun is emit-ted as visible light (Fig. 3).

Solar processes are linked by the nature of thesun's structure from the deep interior to the outeratmosphere. The earth's climate and environment,extending from surface phenomena through the at-mosphere and into the ionosphere andmagnetosphere, are determined by the evolution of

Fig. 8.An image of a portion of the solar photospherein visible light, which contains most of theenergy output of the sun and drives the cir-culation of the earth's atmosphere. Here, theappearance of a large group of dark sunspotsbreaks the symmetry and uniformity that haveled people for centuries to think of the sun as aconstant and "perfect" sphere of hot gas. Solaractivity is concentrated around these sunspots,which usually cover only a small fraction of thesun's surface (Sac Peak-AURA photograph).

earth and sun as an interacting system. Solar radia-tion produces and controls our natural environment,which indeed has undergone drastic change overgeological time and which is susceptible to short-term modifications, as we have come to realize in re-cent years. Life on earth evolved in consonance withthe solar visible light output and the existence ofearth's atmosphere and water. Fossil fuels extractedfor energy today originated in the changes that haveoccurred on earth and perhaps also in the solar out-put over the long time periods. Therefore, solarresearch must become one of our national priorities,not only to harness solar energy for conversion touseful power but also to understand solar processesand how they influence solar-terrestrial relations.

Radiation emitted as visible light from the sun'ssurface, the photosphere, starts out as x-radiationdeep in the core where the temperature is millions ofdegrees (see Fig. 4). There the radiation is liberatedas the by-product of thermonuclear reactions, bywhich the plentiful hydrogen is converted intohelium and a small amount of helium is convertedfurther into heavier elements. Theoretical models ofthe sun have led us to believe this process will go onin a practically constant manner for several billionyears, generating radiation of high energy (shortwavelength), which gradually is degraded to lowerenergy as it diffuses out toward the surface andeventually is released into space as visible light.Just beneath the photosphere it is difficult for theradiation to pass through by this diffusive processand some of the energy is carried up by convection, aprocess analogous to water boiling in a pot. Some ofthe convection bubbles are carried past the visiblesurface into the lower density chromosphere andcorona above, heating these higher layers.

The convection cells are also probably related tothe existence and distribution of magnetic fields onthe sun. These fields become intensified in the ac-tive regions, which are areas of the solar atmospher';characterized by photospheric sunspots, brightchromospheric "plages," arches of very hot plasmain the corona, and the strong magnetic fields linkingthese features. Figures 5-8 show how solar magneticfields and gas combine to form remarkably complexfeatures, A continuous wind of ionized solar gasflows in varying intensity from different poitions ofthe sun, eventually encounters the earth's magneticfield, and flows around the earth on into inter-planetary space (see Fig. 9). Some gas finds its wayinside the magnetic sheath surrounding the earth, isaccelerated to high energies, and is stored in the VanAllen radiation belts.

Occasionally violent storms called flares occur inthe solar active regions with consequent spewinginto space of enormous quantities of high-energyradiation and particles (see Fig. 5). The radiationcauses sudden changes in the earth's ionosphere andimmediate disruption of short-wave radio com-munications. A day or two later, the swept-outmagnetic field and particles cause auroral stormsand sudden changes in the magnetosphere andradiation belts. These solar emissions are shown inFig. 10.

Fig. 4.This cross-sectional view of the sun illustrates the present concept of solar structure. Radia-tion generated by thermonuclear processes in the core streams outward until, near the sur-face, it merges with bubbling convection cells that assist in transferring energy outward.Bubbles overshooting the thin visible atmosphere (Fig. 3) are in part responsible for thechromosphere, transition region, and corona, all of which actually merge in a complexcauldron of hot gases and magnetic fields.

Recently established facts and problems call intoquestion the adequacy of solar structure theory fortwo critical regimes, the core and the convectionlayer. Predicted levels of neutrino emission from thecore have not been confirmed by measurement.Whether the core is rotating remains a question asdo both the possible existence of large-scale convec-tion between the interior and surface and the possi-ble variability with time in core properties. The con-

vection layer is believed to be critical to the ex-istence of the chromosphere, the corona, and the 11-year activity cycle of magnetic fields and energeticphenomena. The activity cycle is correlated withterrestrial phenomena, including climate, althoughwe do not yet know the interaction mechanism. Ithas now been established that this cycle of activitydisappeared for several cycles in the late 17th cen-tury and that the disappearance coincided with a

Fig. 5.Solar activity has many manifestations. Herewe see some of the remarkable complexity ofthe solar chromosphere as viewed in themonochromatized light of hydrogen (Ha). Thewhite patch is a flare in progress. Ejection ofsolar gas into space is seen at the limb near thetop, but this photograph cannot show thesimultaneous emission of huge amounts ofhigh-energy particles and electromagneticradiations ranging from the radio region to thegamma-ray region thai are aho emitted duringflares. (Sac Peak-A LIRA photograph.)

low-temperature period on earth (the "Little IceAge"). This correlation shows that conditions at thetop of the convection layer are subject to variation,which in turn suggests that the spectral distributionof solar radiation has similar variation. On a longertime scale, variation in total solar radiation possiblycontributes to the major changes in the earth'sclimate deduced from the paleontological record.

Thus we must reckon with the possibility thatboth the total solar radiation and its spectral dis-

tribution vary with time. Although the suspectedrange of variation may be insignificant in terms ofpower to be generated from sunlight, it may haveprofound effects on climate and environment.Clearly, we should strive to understand theprocesses controlling production of and variation insolar spectral emissions and the interactions bywhich the earth's total atmosphere responds to solarirradiations.

B. Interplanetary Medium

Together, the solar wind and the portions of thelocalized solar magnetic fields that are carried outby the solar wind dominate the interplanetarymedium. There is also an interplanetary magneticfield that remains relatively steady as the sunrotates, This field is the extension of the generalpoloidal solar magnetic field. Galactic cosmic raysand occasional solar cosmic rays pervade the inter-planetary medium. There is a low-concentrationpopulation of particles at energies intermediatebetween solar wind and cosmic rays. Finally, there isdust from the debr is of comets andasteroids.

The interplanetary medium is important in theOuter Geosciences because solar-terrestrialprocesses are linked between sun and earth throughthis medium and because plasma and waveprocesses in this medium have theoretical applica-tions to controlled fusion energy technologies.

C. Magnetosphere, Radiation Belts, andPlasma sphere

Because the earth has a magnetic field, inside ofwhich is the ionosphere and outside of which is thesolar wind, there exists an extensive region of verycomplex fields and ionized gas around the earth.This region contains the magnetosphere, withinwhich are the plasmasphere and radiation belts.

To a person located in space some distance fromearth, the three-dimensional environment could bevisualized like Fig. 11. The solar wind ions and elec-trons are diverted when they encounter the earth'smagnetic field at 10 to 15 earth radii on the sunwardside. Because these ionized particles can flow easilyalong magnetic field lines but cannot flow across

rifi. a.One has to resort to rockets or satellites to view the sun in euv U/iht. The results are certainlyworth the effort, tis revealed by this phvloffraph in the monochromatized liffht of ionizedhelium (fie II .KM A). A nreat deal of structure is anain evident, but it. looks different fromthe structures in Fin. •"» because this emission comes from the transition roffion betweenchromosphere and corona, which is higher. Here, we see a tfreat prominence of solar daslifting off from the sun. As this n»s mooes away from the sun it produces a transient disrup-tion in the solar ctironu and interplanetary medium. If it is ejected in the direction of earth, itwill affect the maf>nct.ospherc. Fast ejections cause mannatic storms and associatedphenomena. (NHL photograph from NASA Skylab.)

them, the resultant How pattern takes on the ap-|M>arnnce shown. A sharp demarcation line calledthe "bow shock front" is set up. Most of the solarwind flows around the Mirth between the bow shookfront and the magnetopause, but some of it leaks in-side by a variety of processes and becomes the

magnetosphcric plasma, '('he streamlines of flowlook somewhat like u comet tail.

The magnetnpausc is another demarcation line.Within it, the earth's magnetic field and themagnetosphere plasma maintain the reasonablywell-defined geometry depicted by the streamlines

Fig. 7.The shock it are associated with u fust coronaltransient ejection is evident at upper left inthis photograph, taken in white light by a co-ronagraph in span-. For this image the visibledisk of the photosphere must be blocked out byan occulting aperture in the telescope. Well-formed corona streamers can be seen in themiddle right side (compare Fig. 4). (HAOphotograph from NASA Sky lab.)

in Fig. II. Between the magnctopause and howshock front is the magnetosheath, a region of tur-bulent plasma and fields. The polar cusp is a conse-quence of the electrodynamic interactions of thissystem; it is a region of weak field strength ex-tending from the magnetosheath down into thepolar ionosphere on the sunward side. It is filledwith magnetosheath plasma and represents onepathway for interaction between solar wind,magnetosphere, and the earth's upper atmosphere.Another pathway is through the magnetotail, whichcontains a thin region of generally zero field strength(the neutral sheet) surrounded by a plasma sheet.Interactions in the magnetotail are responsible foraccelerating some of the particles that form theradiation belts as well as for magnetic substormevents.

The radiation belts art- regions of high-energy par-ticles inside the magnetosphere; their boundariesare defined by the regions where magnetic field linesform closed loops. By a combination of wave-particle and other interactions the electrons andprotons in the radiation belts are accelerated to highenergies. If we imagine the magnetic field lines to beloops of rope with the ends touching the earth's sur-face in the polar and auroral latitudes (60° to 90°),the high-energy ions move along these ropes andsimultaneously spiral around them. The ends of thelines converge in the polar and auroral zones.Because of this convergence (field gradient), theions are reflected in the opposite direction and con-tinue to bounce back and forth between northernand soul hern hemispheres, generally moving alongthe field lines. Consequently, the radiation belts areroughly doughnut-shaped shells around the earth'smagnet kequat or.

In (he same region of space with the radiationbelts there is a low-energy plasma of electrons andprotons, most of which probably leaks from theionosphere below. This plasma constitutes theplasmasphcre. The high- and low-energy particlesrarely collide because their densities are so low.Collisions do occur in the auroral and polar zones,where some of the particles travel down toward theatmosphere far enough to experience a collisionbefore they are reflected by the converging fieldlines. The particles that collide and remain in theatmosphere are said to have been precipitated.Other loss processes also occur.

Replenishment of magnetospheric particles thatprecipitate out is determined in part by cosmic raysand in part by the solar wind and its interactionwith the magnetosphere. Since the solar windoriginates at the sun in preferred longitudes aroundthe solar circumference, the magnetosphere is buf-feted alternately by strong and weak streams. Thesestreams tend to alternate not only in density andspeed but also in magnetic polarity carried out fromthe sun. This combination of solar wind conditionsis called ths sector structure.

In addition to the solar wind there are occasionalburst-like ejections of matter from the sun, usuallyassociated with solar flares. Strong bursts causegeomagnetic storms and substorms. The marvelousvariety of interactions within this magnetosphericregion is more than just a subject for scientific

Fig. 8.To view the hot corona without an occulting disk, we can use an x-ray telescope. Because thecoronal temperature is .several million degrees, it emits radiation in the x-ray region of thespectrum. This photograph reveals that the outer range of the solar atmosphere has a struc-ture different from the regions seen in the preceding figures. By viewing the sun in theseseveral spectral regions, and hence different regions of the solar atmosphere, we hope to un-ravel the complex processes that constitute solar activity. The very bright patches are abovesunspot active regions. A large coronal hole runs from above center to the bottom as a darkpatch. Magnetic loops are revealed by the thin bright lines of emission near the center andalong the 4 o'clock radius. (AS&Ephotograph from NASA Skylab.)

curiosity. In Sec. IV we show that significant effectsoccur at the earth's surface.

D. Earth Atmosphere/Ionosphere

The density of the earth's atmosphere falls offvery rapidly with distance above the surface until it

reaches only a few atoms per cubic centimeter in in-terplanetary space. In between there are manylayers where important natural phenomena occur.Most notable to us at the surface is the weatherlayer or troposphere, shown at the bottom of Fig. 12.This figure is drawn with a variable vertical scale topermit a better illustration of layers andphenomena. Figure 13 shows that the temperature

10

HELIOCENTRIC DISTANCE (AU)

Fig. ftEven when there is no flare in progress, the sunemits streams of matter into space, This is thesolar wind, It tends to be emitted continuouslybut shows enhancements in preferred solarlongitudes. One such preferred longitude is il-lustrated here, liecause the sun rotates, the gastakes the form of a spiral (the garden sprinklereffect} as it moves out from the sun into space.Eventually it reaches earth and mostly flowsaround the magnetosphere, although some of itenters the magnetosphere and contributes tothe earth's plasmasphere and radiation beltsafter some interaction processes. The spiralcurve does not become very pronounced for en-counters as close as the earth, which is at 1-A Uheliocentric distance in this illustration.

has peaks and valleys related to the absorption ofsolar uv and x-ray radiation.

The traditional way to subdivide the atmosphereis to consider it as having a number of layers andboundaries where sharp changes occur in the ver-tical temperature profile, as shown in Fig. 13. Thetroposphere is often designated as the lower at-mosphere, whose depth varies with latitude andlocal weather conditions. The stratosphere, or themiddle atmosphere, is roughly 30 km deep and ex-tends to 50 km, which is the maximum altitudemeteorological balloons can reach. The tropopauseis a shallow layer that separates the troposphere andstratosphere, two layers of markedly different tem-perature gradients. Its height above the ground at a

given time and place is quite variable. For example,the tropopause in equatorial latitudes may be ashigh as 18 km, whereas in polar latitudes it may beas low as 6 to 8 km.

The upper atmosphere (as distinct from thestratosphere) extends from 50 km to as high as 1000km and includes the mesosphere, mesopause, andthe thermosphere. The upper atmosphere includesthe ionosphere, where the concentration of free elec-trons and ions becomes significant. The ionosphereis divided into three regons: D (50-59 km), E (90-160km), and F (above 160km).

Atmospheric density decreases approximately ex-ponentially with altitude; half of the atmospherelies below 6 km, 99% below 30 km, and 99.9% below50 km. The dominant species below 100 km arenitrogen molecules (~78.1%), oxygen molecules(~20.9%), and argon atoms (>0.9%). Althoughthese three species make up about 99.96% of the at-mosphere below 100 km, the remaining 0,04% is thekey to atmospheric behavior. Above 100 km, atomicoxygen is a major constituent. The entire system ispowered by solar energy extending over a very broadspectrum from hard x rays to radio frequencies. Thesolar spectrum intensity is relatively constant above2000-A wavelength but is strongly dependent onsolar activity at shorter wavelengths. The earth's or-bital and rotational motions modulate the energyinput, each in a characteristic way. Some energypasses through the atmosphu." to the earth (thevisible and rf windows), but a large portion is ab-sorbed by the atmospheric gases. The rotational mo-tion accounts for diurnal changes in the weather,wind velocity, cloudiness, etc., and the orbital mo-tion is associated with seasonal changes.

The altitude dependence of density, temperature,and energy absorption produces a strong altitudedependence of fundamental processes and observ-able phenomena. The earth's motion and magneticfield further complicate the system. Energy absorp-tion produces a great variety of minor constituentseither directly by photoionizaton, photodissocia-tion, and photoexcitation (and related higher energyparticle processes) or indirectly by subsequent par-ticle interactions, to provide the final 0.04%. Thereactive species of importance include electrons,atoms (O,N,...), positive ions (O,*, N,+ , NO+, O+,NO,+,...), negative ions (Or , O,", CO,-, NO,",NOr,. , .) , derived molecular species (O§, NO,HiO,,...), free radicals (OH, HO,,,..), excited states

11

Fig. 10.Artist's concept of some of the solar emissions responsible for terrestrial effects. The geyser-like stream depicts (in an oversimplified way) how some solar flares hurl a storm cloud ofcharged particles and electromagnetic radiations into space. If the charged particle cloud isdirected toward the earth, it causes the glowing aurora borealis and various geomagnetic dis-turbances. The euv and x-ray emissions cause sudden changes in the ionospheric electronconcentration; in turn, radio propagation around the earth by ionospheric reflection isdisrupted.

of atoms and molecules fO('D), O,(Uf), N,v,...],

and complexes [Or, N«+, (H,O)n> H+,...). Trace

amounts of water and carbon dioxide also play im-portant roles.

Both the composition and the dynamics of the up-per atmosphere are affected by natural and man-made perturbations. Among natural perturbationsare the solar wind, x-ray and >-ray pulses, and

cosmic rays from outer space (all of which excite andionize atoms and molecules in the upper at-mosphere); cosmic dust from meteoritic showers inthe upper atmosphere; and volcanic eruptions thatinject particulate matter and various chemicalspecies (often in copious amounts) in thetroposphere and the stratosphere.

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Fig. 11.Earth's magnetosphere as shown here is shaped on the outside like a comet. The solar windpressure pushes the earth's magnetic field into a slightly flattened shape on the sunward sideend stretches it out into a long tail on the side away from the sun. Several interactionprocesses are responsible for the plasma and magnetic field conditions inside the magneto-sphere, including the plasma sheet, polar cusp, and high-energy particle radiation belts.

The sources of man-made perturbations are powergeneration and consumption, weather modification,and nuclear weapons testing. The 1963 test bantreaty prohibits nuclear weapons tests or any othernuclear explosion in the atmosphere, in outer space,or under water. However, the treaty has not beensigned by France or by the People's Republic ofChina. Clearly, power generation and consumptionare the most significant man-made causes of at-mospheric perturbations. Fossil fuels contribute ex-tensive amounts of chemical and particulate pollu-tants to the environment, primarily in thetroposphere. The advent of the supersonic trans-port and the National Aeronautics and Space Ad-ministration's (NASA) future use of the space shut-tle system have extended the perturbation domainwell into the stratosphere.

Although naturally occurring atmospheric pertur-bations affect primarily the upper atmosphere andthe stratosphere, whereas artificial perturbations oc-cur generally in tropospheric altitudes, recently dis-covered cyclic processes have helped focus attentionon the coupling that exists between the lower andthe upper atmospheres. In particular, a 14-day cyclehas been discovered in the circulation pattern be-tween the troposphere and the stratosphere over thenorthern hemisphere. The cycle was first theorized 8years ago, and its existence now has been partiallyconfirmed by National Oceanic and AtmosphericAdministration (NOAA) scientists. The troposphereand the stratosphere are thus coupled by a verticalexchange of energy from the troposphere into eddiesin the lower stratosphere.

13

Fig. 12.A vertical profile of the earth's atmosphere and ionosphere showing some of the manyphenomena that are part of the Outer Geosciences. The vertical scale is broken in places andnonlinear.

400

EXOSPHERE

300

Jisoo

no-.:

TEMPERATURE (K) noo

Fig. 13.Temperature of the earth's atmosphere as afunction of height above the surface. The tem-perature distribution through the atmosphereprovides a basis for dividing the atmosphereinto layers or spheres. The tropospheregenerates weather phenomena. Thestratosphere is the location of the ozone layer.The exosphere is the outermost portion of theatmosphere, where the gas is so rarefied thatcollisions between gas particles occur onlyrarely, causing the temperature distributionthere to be isothermal with height.

14

Visible sunlight penetrates the atmosphere withvery little absorption. Therefore the troposphericlayer is heated by contact, with the surface and byabsorption of infrared radiation from the surface.Because all this heat input comes from the bottom,the temperature decreases with distance above thesurface, as may be verified when one goes from avalley to a high mountain. The rate at which thetemperature drops with altitude leads to an un-stable situation. Convection sets in and the at-mosphere constantly mixes itself as cells of gas cir-culate in (he well-known manner where warm airrises and cooler air from above descends to take itsplace.

At the level of the tropopause the water vapor hascondensed out, thus removing the major source ofinfrared ahsorption from below. Hence the overlyingatmosphere is largely in radiative equilibrium withthe solar radiation from above providing the heating(uv, euv, and x rays). The higher levels of thestratosphere contain ozone and are heated by thesolar uv. This heating from above causes a tem-perature inversion in the stratosphere between thetropopause and the peak ozone layer (~25 km),which makes the stratosphere stable against convec-tive mixing.

The temperature rise caused by ozone absorptionpeaks out at about 50 km and then falls again toabout 80 km. This band is the mesosphere, anotherregion of falling temperature that is unstableagainst convection. At still greater altitudes solar uvbelow 100 A is absorbed, and another temperaturerise occurs in thermosphere (~80 to 700 km). Above1000 km the temperature approaches a constantboundary value (~ 1000 K).

The two convection regions, together with oc-casional overshots into the neighboring stableregions, lead to a complete mixing of the at-mosphere up to about 120 km. At greater heights theindividual gas species take up different distribu-tions with altitude, depending on their molecularweights, by a process called diffusive separation.

In the ~80- to 200-km range, solar euv and x-radiations are absorbed predominantly by ionizingthe atmospheric gases. Thus the solar flux is respon-sible both for heating the upper atmosphere and forcreating the ionosphere. The ionosphere extendsfrom ~60 to ~300 km, above which the ionizationdensity falls off and the ionosphere merges with the

plasmasphere. The energy absorbed through ioniza-tion by solar radiation during daytime is convertedby gas reactions into gas kinetic energy (heat). Theheat input is conducted downward until equilibriumis reached. Above 250 km so little solar energy is ab-sorbed that a negligible temperature gradient isneeded to conduct heat downward; thus ther-mosphere temperature tends to be nearly constantabove 250 km. It relaxes fast enough, however, thatthe temperature drops at night when the sun is notproviding heat input. Similarly, both ionization andtemperature of the upper atmosphere vary over thesolar cycle, because the incoming solar x rays andeuv fluxes vary with solar activity.

Figure 12 shows how the ionosphere is used toreflect radio waves. A given frequency is reflectedfrom a specific electron density layer. Consequently,any process that changes the electron density willperturb certain communication frequencies. Pertur-bations arise from winds and tides in the upper at-mosphere and from variations in solar flux. Majorchanges occur during solar flares because a suddenburst of harder x rays penetrates into the 30- to 80-km region and creates momentary excess D-regionionization. In the 5- to 60-km region, the dominantsource of ionization (except during solar flares) iscosmic rays. Near ground level, ionization of the at-mosphere is due mostly to natural radioactivity ofthe surface. Thus the atmosphere has some elec-trical conductivity at all levels, which for severalreasons varies with solar activity. The variable at-mospheric conductivity is one hypothesizedmechanism by which weather may be related tosolar activity.

Figures 14 and 15 illustrate how the solar visibleradiation output drives the circulation of the earth'stroposphere on a global scale. These depictions,however, are highly idealized as a pattern averagedover the globe and over years of observation. At anyone time the pattern could look quite different andin the mid latitudes the illustrations are not fullyconsistent, Both figures emphasize the north-southcomponent of circulation along a meridional slice.

Incoming sunlight penetrates the atmosphere tothe surface where some is reflected (albedo) and therest is absorbed. The surface in turn emits infraredradiation, which is absorbed by the atmosphere andheats it up. The heating rate at the surface is greaternear the equator than in the polar regions, but the

15

HllAll I.I | (',

I l l

1

Nil 1

1 .MlI.IUN

/

i i / i mm

> ^i>n

\

J , M A N n i

lAtlllllll 0

»————

TKEIIMf.Ar,iu

Fig. 14.A section through the earth along a meridianplane showing the general circulation of the at-mosphere as driven by the unequal solarheating between poles and equator. The sur-face trade winds and polar easterlies find ex-planation in the deflection of circulating airmasses by the earth's rotation. The prevailingmid-latitude westerlies probably owe their ex-istence primarily to large-scale frictional forcesbetween the surface and "wave regime" circula-tion at these latitudes. The lower portion has alittle more detail to emphasize Palmen's modelof the interchange between troposphere andstratosphere.

cooling to space is about the same as from near thetropopause where water condenses out. The dif-ference in heating is what causes the atmosphere tocirculate, on the average in giant cells as depicted.Warm air rises in the equatorial region and movestoward the poles. On the way it is deflected by theearth's rotation, which prevents the circulation cellsfrom extending all the way to the poles. Instead, thecirculation returns equatorward along the surface,

giving rise to the tropical trade winds. Similar airdeflection in the polar cells gives rise to the polareasterlies. At the intersection of cells from the polarand tropical zones the atmosphere responds to theclash of warm and cold air masses by setting upstrong winds in a generally east-west direction alongthe boundary (the jet stream at high altitudes). Theundulation of this boundary around the earth iscalled the circumpolar vortex. On the surface, localsegments of the circumpolar vortex produce warmand cold fronts preceded or followed by high- or low-pressure "cells." Thus in mid latitudes we speak ofthe "wave regime" of circulation to describe the flowwith a large-amplitude horizontal wave motion athigher altitudes (as seen on the 500-mbar maps onTV) and the breakup into eddies about high and lowpressures at lower altitudes (the surface weathermap on TV). Figures 15 and 16 are attempts to il-lustrate these general atmospheric circulation pat-terns in three dimensions. The north-south compo-nent is emphasized in Fig. 15, whereas Fig. 16 showshow the strong east-west component causes theFerrel and polar cells to take on the appearance ofgiant cells of predominantly horizontal circulation.The prevailing patterns depend not only on theseason but also on the geography of land masses andoceans. NOAA scientists believe a slight warming ofthe mid Pacific ocean caused the high-pressurebulge seen along the west coast of North America.This ridge in combination with the unusual highcentered over the North Pole caused the severe win-ter of 1976-77 in the eastern United States. Thepolar high-pressure cell may have been influencedby the minimum of solar activity.

E. Climate and Weather

Usually, we do not think of climate and weatheras related to solar-terrestrial processes. Yet we havejust shown how solar radiation drives the at-mosphere at all levels. Details of weather andclimate (the long-term average weather) depend onadditional parameters, particularly on the couplingbetween atmosphere and oceans, land masses, andice and snow masses. Figure 17 illustrates the com-ponents of the climate-weather system. Modelsmust take account of all these components, as far aspossible. The primary influences that are external to

16

SOLAR RADIATION m*y ffcktror v*ry. jurt u tuntpgfe antfU l v ftwgnrtnni fluctmU. Butw far. inrtrum«tU haw no*dvtietari «ny ngulw ch*nf» Int h t a U t t h

Fig. /5.A three-dimensional view of the general circulation ofthe earth's atmosphere emphasizing the latitudinalmotion in "cells" and the jet stream formation at the

upper-level boundaries of cells with differenttemperature air masses. Figure 14 would be a slice outof this figure along a meridian plane. (Illustrationwith the permission of National Geographic Society.)

IN winds blowinabadwHitepI O O H N U AROUND a mnr low-pressure sys-L c m in Ike North Pacinc i r i » M and deHniilw• « a hM*-pct*«« rid* along North America'swest coast, the earllrarcliMt jet rfream and iL<arcumprwiiw nMeriies wen di»trttd to A b d uin a pattern unbroken for mod of the winter of1976-;; Turnout back lo the south, and acceler-ated bv a sMft of U K nonna! Canadian low lo thesuvOwatt over Newfoundland, the winds—nowbearing a frtitiM of Arctic air—funneled slnifht« N of the northwest into the United Stales. Andthe duMter was bom.

Same xieMijU boll lo the oceans and theirvan nook of warm and cold water wa fe r left)far ke>* to kmn-mMie prediction of such radicalshuts in wind rkcutaUun. Thowrh experts wreethat sea*surface temperatures are innuenced bythe atincupkere. which ki return is affected b> themore heat-relentiiT watar, the)- datier on the im-IJOrtiKe of ocean feedback to continental weather.ChamKS in the Peru Current, for numpk. areseen by some as symptoms, not causes, of ilniantweather patterns.

« 26.A three-dimensional perspective view of general cir-culation in the northern latitudes, emphasizing thetendency for horizontal motion to predominate at mid

to high latitudes and showing the anomalous patternassociated with the unusual winter of 1976-77. (Il-lustration with the permission of NationalGeographic Society.)

CHANGES OF LAND FEATURESOROGRAPHY. VEGETATION.*

ALBEDO. U C .

Fig. 17.Components of the climate-weather system.Full arrows ( *•) are examples of externalprocesses, and open arrows (•**—» are exam-ples of internal processes. Components with a *can be modified by man's energy programs.

Fig. 18.A flow chart for some processes that must beincluded in models of the climate-weathersystem. Although solar visible radiationpredominates in thermal forcing of the atmo-spheric circulation, the other thermal-forcingfactors and the coupling functions determinethe details of weather and climate.

the system are (1) the solar radiation, which drivesthe system; (2) solar activity, which somehowthrough solar-terrestrial processes modulates thesystem; and (3) man's activities, which can becomesignificant in future years and may already besignificant regarding carbon dioxide and ozone.

Figure 18 shows in a rudimentary way how tomodel the weather-climate system. We have seenthat the difference in net solar heating with latitude

provides the primary thermal forcing function of at-mospheric circulation. However, the actual circula-tion is also influenced by the water content of the at-mosphere and the interaction of the atmospherewith land masses, oceans, ice and snow masses, andwith man's technologies. When all these factorshave been included and the computed circulationhas been averaged over intervals long enough tosmooth out small-scale eddies, the model representsthe climate. Variations in climate can arise fromchanges in the direct forcing functions or in thecoupling functions. The double-ended vertical arrowat the right-hand side of Fig. 18 indicates that avariability range exists in climate from all causes.

Climate data exist from historical records over thepast few hundred years, from tree rings extendingback as much as 10 000 years, and over longerperiods from cores taken from the ocean bottom andland sediments and from polar ice packs. Thesedata indicate external causes of climate variabilityas well as causes that are part of the system. Overperiods of years to hundreds of years, significant ex-ternally forced climate variability can be caused byvolcanic events, solar variability, and human im-pacts. A large effort is under way to monitor humanimpacts, but the first two factors are both difficultto evaluate and not studied systematically atpresent.

F. Interactions of Possible Significance

We have defined the relevance of OuterGeosciences to DOE interests primarily in terms ofprocesses that occur on a global scale, implying aconcern for interaction processes that link the loweratmosphere and earth surface to the upper at-mosphere and magnetosphere. Global processes im-portant to control of the atmospheric/solar-terrestrial system dynamics include circulation,waves, electric and magnetic fields, currentsystems, chemical reactions, and radiation trans-fer. The following are a few global-scale interactionprocesses.

(1) Electric currents provide an important energytransfer mechanism between the magneto-sphere and ionosphere; perhaps also to thetroposphere.

19

(2) Any circulation changes (convection) in themagnetosphere require the flow of currentsinto and out of the auroral zone.

l.'i) Convection of the solar wind is the dominantsource of energy input to the polar region up-per atmosphere.

(4> Waves and circulatory motions in the at-mosphere are influenced by the geomagneticfield.

(5) Magnetospheric storms produced by out-bursts from the sun cause a wide variety ofglobal effects both at high altitudes and onthe earth's surface.

(6) Energy transport by gravity waves and tidalmotions connects the troposphere to the up-per atmosphere at very high levels wheredirect convective circulation cannot reach.Gravity waves also carry energy from auroralregions to lower latitudes.

(7) The many trace molecular constituents in-troduced into the atmosphere by man-madeand natural sources have important control-ling effects on numerous global chemical reac-tion cycles.

(8) The chemical balance of the upper at-mosphere is affected by the large-scale cir-culations, which can enhance or degrade somespecies at particular global locations (usuallyrelated to seasons but not restricted to thiscase).

(9) Stratospheric transport of energy andchemical processes involves both diffusionand a broad spectrum of atmospheric waveswhose periods range from minutes to weeks,and probably to longer periods, and whosedistance scales extend from meters to the cir-cumference of the earth.

(10) Tropospheric thunderstorms provide pathsfor currents between the lower and upper at-mosphere.

Interaction processes most worthy of immediatestudy and support over the next few years includethe following.

In solar physics the entire complex of plasma-magnetic field interactions has potential relevanceto understanding processes in the earth's magneto-sphere and atmosphere. In addition, many of theprocesses are similar to processes in controlled

magnetic fusion and laser fusion systems. Importantinteraction processes include plasma instabilities,wave-particle interactions, magnetic merging, con-vection, generation or magnetic fields (dynamoprocesses), and conversion of magnetic energy intoheat energy. Nuclear interactions in the solar in-terior and their observable consequences in neutrinoemission and solar structure are relevant to our un-derstanding of how to apply the basic laws ofphysics.

In the solar wind-magnetosphere regime,magnetic merging must be studied to gain a betterunderstanding of how electromagnetic energy is con-verted to particle energy. In both the magneto-sphere and the sun, nature seems to haveremarkably efficient ways to move ionized gasacross magnetic field lines and to accelerate the gasparticles to high energies. Magnetic merging is oneof the most likely acceleration mechanisms. Particlediffusion across a magnetic boundary, especiallycollisionless diffusion, needs more study in com-parison to plasma-magnetic field configurationsthat permit hulk transport of the plasma across thefield. The collisionless shock wave is important inthe magnetosphere and solar wind as well as inmany laboratory plasma confinement experiments,yet it is poorly understood theoretically. Thevarieties of magnetic, particle, and wave interac-tions involved in magnetic storms and substormsmust be sorted out and understood, especiallybecause of the practical need to anticipate oc-currence times and the resultant disruption of powertransmissions and communications and because oftheir contributions to the energy budget of theneutral upper atmosphere. Precipitation ofmagnetospheric particles into the atmosphere is notwell understood, but the growth of instabilities in-volving wave-particle interactions is of central im-portance. Recent experiments have given goodevidence that harmonics of earth power systems ac-tually couple to magnetospheric particles and causeprecipitation. Much progress has been made recen-tly on delineation of convection in the magneto-sphere; this subject needs further detailed studybecause magnetospheric convection couples to theionosphere and neutral upper atmosphere by way ofion drag.

20

Among interactions of importance in the upperatmosphere that seem in need of improved un-derstanding, the most urgent probably are the large-and small-scale dynamic processes occurring withinthe thermosphere, at the thermosphere-magnetosphere boundary, and between themesosphere and stratosphere. Next in importance isprobably the investigation of the exchange ofenergy, momentum, charge, and mass within theionosphere-thermosphere-magnetosphere systemduring auroral processes. Finally, the chemistry andexchange transport of minor constituents betweenthe thermosphere and mesophere needs furtherelucidation, with simultaneous consideration of theeffects of upward propagating planetary, tidal, andgravity waves. The search for processes to explainthe influence of solar activity on weather andclimate may require global transport models in-cluding each of the above interactions.

The atmospheric distribution of nitric oxide isparticularly important. Nitric oxide has a strong in-fluence on ozone concentrations in the stratosphereand its NO+ ion may control the ion-chemical in-teractions that produce hydrated ions at highaltitudes. Ion-induced nucleation may be importantboth to the growth of particulates in the upper at-mosphere and to the sun-weather connection.

We do not have an adequate concept on which tobuild models of Outer Geosciences phenomena thataffect weather and climate. By implementing theNational Climate Plan, we hope to obtain improveddata from the climate- and weather-controlling fac-tors shown in Fig. 18. However, the plan wasgenerated before the significance of solar-terrestrialprocesses to climate modulation was appreciatedfully, and this report can be considered an adden-dum to the National Climate Plan, wherein weempha-ise the role of solar-terrestrial processes.

How could processes high above the tropospherehave anything to do with events within thetroposphere? There must be some interchangemechanism between the upper and lower at-mosphere, and the mechanism must be sensitive tothe variations of solar activity. Possible propagatorsof the solar influence include the following.

(1) Some portions of the solar wind find their waythrough the magnetosheath and the polar cuspsdirectly into the upper atmosphere in polarlatitudes. Other portions are modified in energy,

stored in the radiation belts, and eventuallyprecipitated into the atmosphere, mostly in aurorallatitudes.

(2) Solar uv, euv, and x rays are absorbed from thetropopause up to thermosphere levels and areresponsible for both the existence of the ionosphereand the heating of the upper atmosphere. Recentdiscoveries show that higher than expected concen-trations of atmospheric gases have reachedmagnetospheric levels, by processes not yetelucidated. Similarly, there is interchange betweenthe troposphere and upper atmosphere, at least inpart through the general circulation and differencesin tropical and polar tropopause levels as depictedin Fig. 14. These interchanges between atmosphereand magnetosphere and between troposphere andstratosphere may be important to the sun-climatecoupling.

(3) Solar cosmic rays penetrate to stratosphericlevels in the the earth's atmosphere during somevery energetic flares. Cosmic rays from outside thesolar system can reach the lower stratosphere andupper troposphere, where they are the principalsource of ionization. Their intensity varies withsolar activity, which modulates the shielding effectof the interplanetary magnetic field. Near groundlevel, ionization of the atmosphere is due mostly tonatural surface radioactivity. Thus the atmospherehas some conductivity at all levels above the sur-face. The distribution in height of this conductivitydepends on solar activity and the circulation of theatmosphere.

(4) Other possible propagators of a solar in-fluence on the earth's atmosphere are variations intotal solar visible radiation, infrared radiation, orthe extended solar magnetic field. The last isalready included in the solar wind category. Varia-tions in visible solar radiation over periods up to adecade are

which the solar propagator modulates the complexinteractions between atmospheric composition,photochemistry, dynamics, and radiative transfer.Some potentially viable interchange mechanismsthat have been suggested include the following.

(1) Convection in thunderstorms can providedirect interchange of energy and compositionbetween troposphere and stratosphere.

(2) Electric currents through thunderstorms cancouple the troposphere to the entire upper at-mosphere including the ionosphere. At leastone hypothetical model has been outlined formodulation of cloudiness and rainfall bysolar-flare-induced changes in conductivity ofthe atmosphere.

(3) Winds and wave motions pervade the entireatmosphere and provide a transport processfor energy and composition.

(4) Transport also occurs by molecular and eddydiffusion through all levels of the atmosphere.

(5) Radiation transfer in the atmosphere is par-ticularly important in the ir and uv ranges.Changes in atmospheric composition, even ofsome very minor trace constitutents, can havea major effect on radiation transport.

The coupling between solar propagators and at-mosphere processes usually will be changed whenunusual species are injected into the atmosphere.Such injections arise from volcanic eruptions,nuclear explosions, high-altitude aircraft and spacevehicle exhausts, debris and effluents from space ac-tivities, and man's activities at the surface.

There are more interactions between sun andearth than the few mentioned here. The variety andcomplexity of known solar-terrestrial phenomenahave increased substantially since the advent of thespace age. However, we don't have to decipher everyminute detail of every solar and terrestrialphenomenon to meet national goals of energyproduction and environmental protection. Instead,the scientists must accumulate in a coherent wayenough knowledge of solar and terrestrial processesto permit recognition of what is essential to ourgoals. Not only should we store up facts, but also wemust abstract and simplify an increasingly complexset of facts to the point where we can developtheories that explain and predict phenomena. Thusthe key to progress is knowing what measurementsshould be made and formulating the results into

theories that represent the essential features of thereal sun and real earth on time scales important tohuman beings.

IV. RELEVANCE OF OUTER GEOSCIENCESTO DOE MISSIONS AND NATIONALINTERESTS

A. General Case for DOE

DOE must address the following basic question.How will energy production, transmission, and con-trol be influenced by and influence the natural en-vironment over both short and long periods? By law,every DOE division must answer this question. For-mulation of a satisfactory answer depends criticallyon existing knowledge of solid earth, oceans, the ex-tended atmosphere, and the sun as parts of an in-teracting and evolving system. Thus, DOE has acompelling self-interest in fostering expansion offundamental knowledge of the total system.

In response to the legally imposed requirement,DOE has an Environmental and Resource Assess-ment Program charged with assessments in threebasic categories—environment, technology, andresources (ETR). The ETR assessments requiregeophysical, atmospheric, and solar data. From along-term perspective we must consider both theevolution of the natural environment and man's ef-fects on it. Thus the data base for resource assess-ment is time dependent, and all three ETR assess-ments are interdependent. DOE's task is complex,requiring considerable scientific knowledge,sometimes not available. For example, it was notpossible to draw firm conclusions about the effectsof SST exhausts on the ozone layer becauseknowledge of the stratosphere was inadequate.Shmiarly, we cannot forecast future energy needsfor a model world accurately because there is neitheradequate knowledge of the many factors (solar flux,volcanic dust, transportation and industrial emis-sions, etc.) that control the climate nor the climatefeedback that must influence decisions on energyproduction.

Virtually all environmental impact statementsformulated by DOE or received by DOE have beenlimited to the present "inner environment." Asimilar situation exists regarding technology and

22

resource assessments, "Environmental impact" isusually taken to mean pollutants and health,ecological, socioeconomic, and long-term effects.Long-term effects have largely been neglected orignored in environmental impact statements todate. We argue that long-term and global effectsneed serious consideration now. If DOE is to meetits responsibilities to develop energy technologieswhile protecting the environment, all assessmentstatements must be formulated to look ahead to thelong-range evolution of the atmospheric/solar-terrestrial system, that is, the Outer Geosciences do-main. Problems posed by SST exhausts andfluorocarbon releases have dramatized the impor-tance of this outer system to such assessments. Inthis section we list additional specific interactionsbetween man's activities and solar-terrestrialprocesses. Two points are clear from the known in-teractions. Our understanding of the natural systemis inadequate, and the outer geosciences are impor-tant to our understanding of the biosphere. Accor-dingly, any basic research role assumed by DOEmust include both surface and outer geosciences.

Like other agencies DOE has recognized the im-portance of supporting basic research in areas rele-vant to its mission. Relevant basic research shouldbe supported both to augment the base of fun-damental knowledge required to make quantitativeassessments of the consequences of activities in theagency's mission and to foster a community ofscholars whose expertise can be used to make tech-nical evaluations. Also, basic research must precedeapplied research for technological development. InDOE's National Plan,1 there is clear recognition of"a real responsibility to identify available energyalternatives and to improve knowledge of their en-vironmental implications. Extensive research mustbe conducted if the public is to be informed of thetrue nature of the trade-offs and the implications ofthe various choices." Furthermore, "Environmentplanning and implementation must therefore ensuresupport for long-term environmental R&D in theface of pressures to turn full attention to near-termdemands." Withdrawal from basic research insystems known to influence man's activities is an in-vitation to decay for a modern society. We maintainhere and in the following sections that the outergeosciences must not be neglected.

B. Specific Cases of National Interest

In this section we briefly describe some knownsituations where atmospheric/solar-terrestrialprocesses interact with human activities. Each in-teraction is of major socioeconomic concern to thenation, and some of them are directly related to theDOE mission (marked *). Table I summarizes someof the activities and solar-terrestrial phenomena.

1. "Climate and Weather. No quality of ourpresent-day terrestrial environment is more crucialthan the state of weather and climate. The energythat the sun radiates toward our planet is the mostimportant energy source sustaining global-scale at-mospheric motions and fueling daily weather.

Weather and climate are ever changing. Just asno 2 days of world weather patterns are alike, so no 2years, no 2 centuries, no 2 geological epochs are

.identical in their climatic conditions.Weather and climate are perpetually variable for

many reasons. We know that weather and climateare shaped through complex physical interactionsbetween the atmosphere, the oceans, the snow andice in polar regions, and other environmental condi-tions. To a large extent, the variability of weatherand climate is likely to be self-stimulated by theseinteractions. Also in part the variability of the at-mospheric processes arises from the random natureof turbulence in a gaseous medium. There areseveral indications, however, that part of theweather and climate variability is governed by ex-ternal influences, in particular by changing condi-tions on the sun, whose coupling to the atmospherewe do not yet understand.

Over the past 100 years, and especially since 1950,many correlations of the earth's weather andclimate with the sun or solar-induced phenomenahave been reported. Rainfall, temperature,pressure, thunderstorms, influx of stratospheric airinto the troposphere, vorticity area, and othermeterologicai phenomena have been correlated withsunspot number, the 27-day solar rotation, solarflares, and both the quiescent and the disturbedgeomagnetic field. Usually the effects are too smallto have practical significance within our present un-derstanding of weather and climate. But in some

TABLE I

HUMAN ACTIVITIES INTERACTING WITH SOI.AH-TKHHKSTHIAI. PROCESSES

Activity

Civilian Application Areai

'Kleclric power cumpanies(energy transmission)

"Space power systems

'Pipelines*I)OK ciimmunication (prospective)

•(Jeophysical exploration

•Knergy production, complexagriculture, and interactiontransportation sequences

1/mR-ttTW u-V'phone KtwiTnvmirortinnCivilian hf communication

(lenoral Services AdministrationVoice of AmericaCoast (iuiirdCommercial companiesVarious s

Civilian satellite communication

Commercial aviationMid-latitude communication (VHF)NaviRolion (VLH)

HiRh-latitude communication (VHK)

High-altitude polar tlinht radiationhazard

Solar-Terre«tri«l ProceM

Magnetic storms

IonosphereMagnetosphereGeomagnetic activityMagnetic stormsX-ray and uv flare emissionMagnetic storms

Magnetic stormsSubstitrmsClimate

weather, andsolar activity

MaRnetic stwmsX-ray and uv emissionMagnetic stormsSubsiormsPolar cap absorption

Magnetic stormsSubstormsIonospheric irregularities

Solar tlare radio emissionMagnetic stormsI'olar cap absorptionMagnetic stormsSunstormsPolar cap absorptionProton events

Military Application Areas

•DOD hf communication

*DOD reconnaisance (radar, nth, saO

"Spacecraft survival(radiation damage and charging)

DOD SATOOM communication

DOD navigation

X-ray emissionuv emissionIonospheric structurePolar cap absorptionMagnetic stormsSubstormsPolar cap absorptionMagnetic stormsProtonsMagnetosphere and ionosphereCharged particlesMagnetic stormsSubstormsProtonsIonospheric irregularitiesX-ray emissionuv emissionMagnetic stormsPolar cap absorption

24

cases, especially rainfall modulation at somegeographic locations, the effects can be up to 50%and can have major significance. Both the recentdrought in the Western United States high plainsand the past severe winters in the East fit the pat-tern of the predicted solar cycle modulation.

A one-to-one correlation does not exist, in thesense that a specific change in weather or climatewill always follow a specific solar change. On theother hand, the reality of solar-induced modulationof atmospheric processes is becoming well es-tablished as more data accumulate and are subjec-ted to critical tests of significance. The modulationof large-scale atmospheric processes is such thatpressure, temperature, and precipitation are affec-ted differently at different global locations andtimes. Early skepticism is now being replaced by agenuine concern to find explanations by way of in-teraction mechanisms. The explanations clearly arean essential research goal at present because theymust precede any attempt to incorporate solar-terrestrial effects into global climate and weathermodels for prediction.

Ultimately the decision to support research on in-teractions between climate and weather and solar-induced phenomena must rest on whether the ef-fects are significant. Recently three strong pieces ofevidence have been added to the many correlationsfound in the literature.

(a) The magnetically reversing solar wind boun-daries that sweep by the earth every severaldays are followed by small, systematicchanges of atmospheric flow.

(b) The 22-year magnetic cycle on the sun ap-pears to modulate the geographical scale ofmajor droughts that afflict the Western andCentral United States.

(c) Long-term variations of the mean solar ac-tivity level, from one century to another, ap-pear to have stimulated equally long-termchanges of terrestrial climate, such as thoseassociated with the Little Ice Age in the 15thto 19th centuries.

DOE's interest in atmospheric/solar-terrestrial research cannot be tied simply toeffects on weathet, because no meaningfulalterations of energy policy or planning can betied to factors varying over periods of less thana month. The effects on climate and its global

variations over years, on the contrary, are ger-mane to DOE's mission of fostering energyproduction, distribution, and conservation.

2. *Energy Transmission Lines. The waves andcurrent systems of the ionosphere and magneto-sphere produce undesired effects on long conductorsby inducing currents in the conductors.

Geomagnetic storms, which are intense worldwidechanges in the earth's surface magnetic field inresponse to plasma bursts from the sun, can disturbpower distribution systems severely. Numerouspower outages have been traced to this cause since1940. Sometimes the problem is erratic inducedoperation of differential relays, sometimes trippingof circuit breakers, and sometimes the completefailure of a power transformer, such as the failure atthe British Columbia Hydro and Power Authorityfollowing the August 1972 solar flare activity.

One cause of such disruptions is the induction ofvoltages on transmission lines with large separationsbetween ground points. Induced 10 V/km voltagesare sufficient to cause disruptions and these levelsare sometimes generated in magnetic storms. Amore serious effect is the current induced in thewindings of power transformers. Such a current canreach 100 A and saturate a transformer core causingthermal degradation and decreased transformerlifetime. Lifetime affects the cost of power and thusinfluences everyday usage. Major disruptions are in-frequent but devastating in their consequences.

Administrators under pressure to solve immediateproblems might argue that further basic research isunnecessary, that we should design around theproblems. To some extent this is possible now.However, had the argument been accepted years agoand had we not found the correct explanation, wecould have entered an era of major power distribu-tion systems with incorrect system designs and withdisastrous results. Basic research on the solar-terrestrial system, in this case the magnetosphere-ionosphere regime, will continue to provide usefulnew understanding to power system designers.

3. 'Geophysical Explorations for Minerals andPetroleum. In exploration geophysics, magneticsurveys are conducted to obtain information aboutsubsurface rocks and minerals. Most surveys in-volve measurements of the total intensity of the

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earth's magnetic field across the survey area. Ofnecessity, the measurements include time fluctua-tions of the field, and one problem that must bedealt with is separation of the unwanted time varia-tions from the desired spatial variations. The natureand seriousness of the problem, and its solution, de-pend on the nature of the geophysical survey.

Most magnetic surveys are made with airbornemagnetometers, and probably more than onemillion line-kilometers are flown every year all overthe world. The most common survey objectives areto assist with geological mapping and mineral ex-ploration. Another type of survey is common overthe oceans, where the structure of the oceanic crustis revealed by the magnetic anomaly patterns recor-ded in data obtained by towing magnetometersbehind ships and sometimes from near the oceanbottom. Finally, there are ground magnetometersurveys, usually restricted today to local detailing ofindividual mineral prospects.

Various methods of separating geomagnetic timevariations from the desired surface spatial varia-tions have met with limited success. Because ex-ploration and budget flows cannot be modified to fitthe sunspot cycle, a large fraction of such explora-tion surveys can be wasted effort or can lead to falseconclusions about mineral or petroleum deposits.

Although geomagnetic variations may seriouslyhamper exploration for minerals and oil, they canalso be used to advantage, particularly to determineresistivities of sedimentary rocks in the earth's crustto lO'-km depths. Useful geomagnetic variations in-clude pulsations (periods of up to a few minutes),substorms (15-150 minutes), storms, the daily varia-tion dynamo, and the ionospherical ring currentdecay fields (periods of hours to days). Study resultsare useful in determining the composition and struc-ture of the earth's crust.

4. 'Pipelines. The Alaskan oil pipeline and theproposed Al-Can line have dramatized the use ofpipelines to distribute oil and natural gas over con-tinental distances. Less dramatic but still impor-tant to the public is the fact that this method ofenergy distribution is influenced by solar-terrestrialphysics processes. The influence is exerted in theform of electrical currents induced in the metalpipes by geomagnetic variations and the consequentenhanced corrosion rate of the pipes. At low and mid

latitudes the corrosion rate is negligible, but anuisance effect exists from the induced-current in-terference with normal pipeline corrosion surveyengineering work. This problem has caused im-plementation of a regular NOAA service forpredicting induced-current activity.

At auroral zone latitudes (~ 60-70°) the inducedcurrents from magnetospheric and ionosphericchanges are much more frequent and stronger. Theirinterference can be a severe problem during corro-sion survey engineering studies and for the pipelinemonitoring and control electronics.

5. ^Communications. Fluctuations of radio fre-quency signals propagated through the ionospherehave long been a concern to designers of civilian andmilitary communication systems. The fluctuationsoccur at all frequencies, from vlf « 3 MHz) to hf (3-30 MHz) and up. It was believed that if microwavefrequencies (GHz and higher) and increased com-munication bandwidth were used, the ionospherewould no longer be a problem because it is essen-tially nonabaorbing at such frequencies. For com-munication by way of orbiting spacecraft, this modehas removed much of the fluctuation associatedwith time scales from seconds to years.

However, since initial implementation of the IN-TELSAT network (using 4 and 6 GHz), signal am-plitude scintillations (with peak-to-peak excursionsranging from 1 to 10 dB) have been reported fre-quently from some earth stations located at lowlatitudes. Studies of the fluctuation characteristicsand patterns suggest that they are produced byirregularities in the ionosphere F-region (200-300km).

Almost always, the scintillations are observedshortly after local ionospheric sunset during themonths near equinox. As the number of sunspotsdecreases, the total number of days on which scin-tillation is observed decreases. Apparently, the diur-nal pattern does not change as the level of solar ac-tivity changes.

As yet no theory satisfactorily explains theproduction mechanism of the ionosphericirregularities producing the scintillations in this fre-quency range. In addition, there is little informationpertaining to the thickness and spatial distributionof these irregularities. Such information is necessaryfor the development of a theory to correlate vhf andGHz scintillations.

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Continued use of shortwave communications (3-30 MHz), which operate by reflection of the signalfrom the ionosphere, will require constant attentionto ionospheric changes induced by radiation andparticle fluxes from the sun and magnetosphere. Inrecent years we have learned that irregularities inthe ionosphere arise not only from direct solar-induced perturbations but also from a complex setof interactions between the neutral atmosphere,ionosphere, and magnetosphere, and man-causedeffects.

Telephone and telegraph cable communicationsare perturbed by solar-induced geomagnetic varia-tions. For example, unexplained outages of the BellSystem's L-4 long-haul cable system occurred on 24days between January 1969 and August 1971, Someof these outages probably were caused bygeomagnetic effects in this period near the solar ac-tivity maximum. A particular storm in August 1972was studied in detail from ground-based andsatellite data. The induced line voltage caused bythe sudden compression of the geomagnetic fieldwas more than sufficient to shut down the system.

Exactly what mechanism produced the large sur-face magnetic variations in August 1972 is notknown, but it appears they were associated wHhlarge asymmetric distortions of the earth's mag-netosphere and hence were magnetopause currents,rather than classic ionospheric currents. This in-vestigation is relatively undeveloped at present and,if pursued vigorously, should increase un-derstanding of solar wind-magnetospheric interac-tion processes and should help to reduce cable com-munications difficulties.

Reliable communications are important to all sec-tors of our government and society, but especially toour national security sector, represented in DOE bythe Office of Military Application.

6. '"Effects of Space Radiation on Systems inSpace. Looking toward the future, we see an enor-mous expansion in the number of space systemsdesigned to serve terrestrial applications and ter-restrial customers. The investment in such spacesystems is Hkely to run into tens of billions of dollars.Even savings of fractions of a per cent, derived as aresult of better information regarding the energeticradiation, translate directly into savings that runinto tens of millions of dollars.

The radiation environment at the synchronous or-bit, where most earth application spacecraft will belocated, consists primarily of electrons and protons.Order-of-magnitude changes in intensity are verycommon. The fluxes of low-energy particles, elec-trons and protons with energies

generally will assume a negative electrostatic poten-tial with respect to the undisturbed plasma. Themagnitude of this potential is of the order of theelectron temperature expressed in electron volts.Thus, potentials of a few volts are commonlyobserved on spacecraft in the plasmasphere, butpotentials >10 000 V can be seen on spacecraft inthe plasma sheet or in plasma cloud regions of themagnetosphere.

A spacecraft's overall charge state probably hasminimal effect on operations. If the vehicle ischarged negatively for long periods, some increasedsurface degradation owing to ion bombardment willbe noticed. The major operational effect arises fromdifferential charging. Nearly all spacecraft exteriorsconsist of various insulators. This type of outer sur-face usually is needed for thermal control. However,the charge stored on different parts of the spacecraftcan cause differential potentials of thousands ofvolts between insulating surfaces.

Discharges from external vacuum-depositedaluminum (VDA) can remove the outer surface andthus degrade thermal properties. Similarly, theouter surfaces of optical elements can be affectedseriously. More serious is the now convincingevidence that several different classes of spacecraftoperating in synchronous orbit experience operatinganomolies caused by discharges produced by elec-trostatic charging. Noise on the spacecraft com-mand lines often gives false commands. In at leastone case, total loss of an Air Force spacecraftprobably occurred because of extreme differentialcharging prolonged by an intense geomagnetic sub-storm.

Theoretical and experimental studies to under-stand and control spacecraft charging are currentlyunder way under sponsorship of several agencies.The level of understanding needed varies with theuser. Scientifically, some investigators want to un-derstand the phenomenon completely as an in-teresting plasma physics problem with far-reachingcosmological implications. Magnetosphericphysicists want to measure uncontaminated naturalplasmas. Practically, many systems offices are try-ing to run operational spacecraft, and they simplywant to fix the problem of extraneous commandswith as little redesign of existing vehicles as possi-ble. For many operational and future spacecraft, thequestion becomes one of probability and economics,topics that interest all agencies involved in space ac-

tivities, including DOE. What construction tech-niques will have the highest expected return (for in-stance, communications, weather observations, orspace power systems) for the lowest price? Ananswer to that question requires better un-derstanding of the earth's radiation environmentand consequent materials response before specificrecommendations can be made to the spacecraftdesigner.

8. People in High-Altitude Flight or in Space.Astronauts in space need protection from cosmicrays, especially during major solar flares. Now thatspace stations are being considered for habitationover long time periods, we must know the spaceradiation environment in great detail so that peoplein space may be protected from overdosage. There isalso a potential radiation hazard to pilots of high-altitude jet aircraft flying repeatedly over the polarregions or at very high altitudes in mid latitudes.Although the particle flux at energy high enough topenetrate an aircraft skin is small, the pilots areconcerned about both the particle and secondary x-ray dosage accumulated over many flying hours. Inrare events that may occur once per solar cycle, evenpassengers may be exposed to the dosage near themaximum permissible dose during a single 2-hourflight.

Both pilots and passengers in commercial jetshave encountered the problem of ozone irritation.Exposure to concentrations above 0.3 ppm causesirritation to the eyes, mouth, and throat, decrease innight vision, shortness of breath, coughing, andchest pains. Evasive action, such as flying at loweraltitudes or on the poleward side of the jet stream,often can be taken, because a great deal has beenlearned in recent years about the daily, seasonal,and geographic distribution of ozone in the at-mosphere. However, abnormally high ozone concen-trations may occur and persist for short periods atcertain geographic locations and altitudes near andabove the tropopause. The reasons for these oc-currences are not known at present. Ozone of coursehas a beneficial effect in that it absorbs the solar uvradiation that otherwise would be a human healthhazard. Ozone is one component of theatmospheric/solar-terrestrial system that must bewell understood to keep its advantages but avoid itsdisadvantages.

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The hazard to people in space will be especiallyimportant to DOE if space power systems are to beconstructed.

All the above interactions involve an influence ex-erted on human activities by solar-terrestrialprocesses. Below we list some interactions wherehuman ac t iv i t i e s change the na tu ra latmospheric/solar-terrestrial system.

9. *Space Power Systems. Among the prospectsfor meeting our country's energy needs in the 21stcentury, perhaps the boldest, and certainly the mostexciting, are space power systems. As currently en-visioned, huge power stations, each capable of serv-ing a large city, would orbit at geosynchronousaltitude and would transmit space-generatedmicrowave power to earth. The power would be ob-tained by collecting solar radiation and converting itto microwaves, We are not speaking for or againstspace power systems, but we point out the need CorOuter Geosciences information in their evaluationand implementation.

The impact of space power systems on theionosphere needs careful consideration. Themicrowave spectral region was selected for powertransmission largely because of the atmosphere'stransparency to such frequencies. Thus, interac-tions between the beam and the medium should beof little or no consequence. Preliminary systemsstudies, however, have identified potentialionospheric problems related to microwave trans-mission and space-vehicle exhaust products.Because such problems could affect communica-tions systems and other microwave transmissions,they must be considered in space power systemdesign and development. Because the problems canbe evaluated only within the limits of our knowledgeof the natural ionosphere and its coupling to theneutral atmosphere, we must continue improvingour knowledge of these pa r t s of theatmospheric/solar-terrestrial system.

Base-line designs of power satellites call for anaverage flux through the atmosphere of ~100 W/mJ

in a beam ~7 km in diameter. Only ~0.001% of theenergy in the beam will be absorbed in theionosphere, and thus there will be virtually no im-pact on the transmitted power level. On the otherhand, 0.001% corresponds to 1 mW/m*, which is ofthe same order of magnitude as the solar energy con-

tained in wavelengths shorter than 1000 A, or euv.This solar energy represents the major source of heatand ionization in thermosphere and ionosphere. Acomparison of solar euv and microwave energ