Report Satellite oceanography: a new tool for marine policy makers Remote sensing oceanography is a powerful new fool available to the marine policy maker. The extensive global archive of satellite thermal infrared data exfending over the past six years, the sparser collection of visible data useful in chlorophyll-a estimates, the dramatic decrease in computer costs and the emergence of comprehensive satellite data handling software have all contributed in making this possible. Three recent applications show the potential of these data in research and applied oceanographic problems as well as the processing capability of existing facilities.

Technological advances in ocean- related industries ~ both existing ones such as fisheries and petroleum pro- duction and new ones such as ocean incineration and deep-sea mining - are increasingly stressing the marine en- vironment. At the same time, these advances threaten conflicts between the various uses and depletion of existing resources to the detriment of all.

Careful management at the inter- national, regional and local levels is required such that mankind benefits optimally from this exploitation with- out giving rise to conflicts and without irrecoverably damaging the ocean for future generations. Management structures capable of achieving such objectives will require precise oceanographic data dense in both space and time. preferentially on the upper 100 m or so of the water column or near the seafloor, the regions most affected by the bulk of the applica- tions and biologically the most fragile. Satellite-derived oceanographic data provide information on the upper water column, but rarely on the sea- floor and that only in shallow (< 10 m) waters.

Satellite-derived environmental data coupled with dramatic improve- ments in computational capabilities can, if properly applied, meet some of the data needs of marine policy mak- ers. The value of satellite data in addressing these needs stems from their synoptic (nearly instantaneous) coverage of large areas of the ocean’s surface at high repetition rates and

MARINE POLICY January 1986

from the extensive and rapidly grow- ing archive of high quality data cover- ing the globe. Another emerging advantage of satellite oceanography is that. as experience is gained at central archives in dealing with the substantial volumes of data involved, the time for public access to these data is decreas- ing and is now in the order of a few days to a month for a large part of the thermal infrared data. By contrast, public access to mooring data, XBT data, drifter data, etc is substantially longer than this and often data col- lected by researchers remain totally inaccessible to their colleagues.

Some basics

In general the spatial scales of oceanographic phenomena determine their time scales because currents in the open ocean rarely exceed a couple of knots (about lms). For example, if the process of interest is a perturba- tion of the edge of a strong current such as the Gulf Stream, with a wavelength and thus spatial scale of 100 km, following the evolution of this perturbation requires information on the edge of the Gulf Stream every few days. On the other hand, if one is interested in surface waves app- roaching the shoreline with wave- lengths of 100 m, observations sepa- rated by seconds are required for an adequate description of the wave.

This issue of relevant temporal and spatial scales becomes very important because of the tight technological con- straints placed on the rate at which

satellite data can be transmitted to ground receiving stations. Satellite- borne sensors collect information about pieces of the Earth’s surface called picture elements or pixels. The width of the path over which the satellite-borne sensor collects data de- fines the swath of the sensor. (The swath consists of adjacent rows of pixels.) As the spatial resolution of a sensor increases, ie the pixel size decreases, the area that the sensor covers must decrease if the data trans- mission rate is to remain approximate- ly constant, As the swath width de- creases, the time required to cover the Earth’s surface increases. The data rate constraints are such that daily global coverage is possible at a spatial resolution of 1 km or greater. Finer resolution results in greater time be-

tween repeat coverage. The oceano- graphic phenomena best matched to the capabilities of satellite-borne sen- sors are those with scales of tens of kilometres or larger. At these spatial scales the corresponding oceano- graphic time scales best match the repeat coverage possible at present data transmission rates. Satellite- derived data at smaller scales, eg those available from LANDSAT, are still of value, but their application is more restricted.

The important questions of data availability and the capability of pro- cessing these data must also be consi- dered. Over the past decade there have been dramatic advances in both these areas. In lY78. three satellites of great significance to oceanography were launched: SEASAT. NIMBUS-7 and TIROS-N. SEASAT was dedi- cated to oceanographic research and carried a number of active microwave sensors which measured sea surface roughness. Although it failed after 100 days due to an on-board power fail- ure, its data proved to be extremely valuable in designing new sensors. NIMBUS-7, also a research satellite, carried the Coastal Zone Color Scan- ner (CZCS), which collects data at l-km resolution in the visible portion of the spectrum. Visible data are of value in biological as well as physical studies of the ocean because of the near-surface biological and physical structures which they reveal. TIROS-N

57

was the first satellite in an oper-

ational series of meteorological satel- lites. High quality data from its prim- ary sensor, the Advanced Very High Resolution Radiometer (AVHRR) (l- km resolution) have been collected continuously since spring 1979 from the five satellites of the series laun-

At the same time that these data

ched thus far. Furthermore. the USA

were becoming available. several computer-based systems capable of

is committed to flying a similar sensor

processing them were being de- veloped. The system most widely used

into the 1990s. A more detailed de-

in the USA is that developed by Brown. Evans and Brown of the Uni-

scription of these satellites and of

versity of Miami.

future US plans is presented in the JOI report. ’

Three examples of remote sensing work are described: they were per- formed at the University of Rhode Island (URI) using the software de- veloped by the University of Miami group. These examples have been selected to show the wide range of oceanographic applications possible with satellite-derived data. The first two examples, real-time applications of satellite data in commercial and industrial ventures. also show the im- portance of feedback in new projects such as these as they evolve. The volume of data processed and ana- lysed for the third example, which focuses on a basic research applica- tion, provides a feeling for the capabil- ity of existing satellite data processing hardware and software.

Sea surface temperature charts for fishermen

As part of a pilot project to investigate the feasibility of using satellite-derived thermal infrared (IR) data for com- mercial fishing ventures, sea surface temperature (SST) charts were made available in near real time to fisher- men off the southern coast of New England (USA). The data received in Washington. DC (USA) were re- corded on tape and shipped via air express to URI’s Oceanographic Re- mote Sensing Laboratory. Within three hours of receiving the data at

URI (24 to 36 hours after the satellite overpass). the data were processed and a chart produced. This chart was mailed to over IS0 local fishermen who in general received it the follow- ing day (approximately 36 to 48 hours after the data were collected). Be-

The format of the chart remained the same over this period - a fixed geographic region with water masses

cause data were ordered and charts

of different SSTs depicted by different shades of grey, but, as a result of

mailed only on cloud-free or nearly

continuous interaction with the fishing community through workshops and

cloud-free days, and because of

questionnaires. two other charts were added toward the end of the study.

numerous problems with the Washing-

The fishermen found the basic chart

ton. DC to URI link, only about

useful because different species of fish arc found in waters of different

one chart per week was mailed over a

temperatures. but they also wanted to know where regions of steep tempera- ture gradients wcrc bccausc apex pre-

period of approximately IS months.

dators, such as swordfish, which are often of greater commercial value, are found at such water mass boundaries. In response to this interest, a chart covering the same geographic region and showing large SST gradients was added to the mailing. An area within the region was also of special interest to many of the fishermen; a blow-up of this area was therefore enclosed.

Despite the fairly infrequent mail- ings, a number of fishermen found the charts to be useful. The major difficul- ties associated with the project were acquiring the data in a reliable fashion at URI, and, once processed. distri- buting these charts to the fishermen. Many of the fishermen felt that data older than 24 to 36 hours wcrc of little use to them. In addition. the inability to make reasonably priced copies of all the information desired also proved to be a deficiency. Processing the data, however, was not a limitation: all the requests by fishermen with respect to processing were readily met. Despite these major difficulties, 60% of the fishermen responding to a questionnaire mailed at the end of the project felt that it saved them in excess

of $500 per year. (Over 30% res- ponded to the questionnaire.)

One of the more intriguing qucs- tions that has emerged from this and a similar study on the west coast of the USA’ is whether a commercial ven- ture selling such charts is viable. Spe- cifically. are the fishermen willing to pay for this product given the benefits which they themselves attribute to it? The answer - at least at present - appears to be no. In both studies, fishermen have insisted that such a service should be provided by the government at no or very low expense to the users because satellites acquir- ing the data are funded with tax dollars. It appears to be difficult to convince this independent group that there is a cost associated with produc- ing and distributing the charts that should bc borne by the user.

Warm-core ring tracking for offshore drilling operations

Satellite data were used when Shell Development drilled exploratory oil wells in the Baltimore Canyon off the cast coast of the USA. Thcsc wells were drilled in ocean depths of approximately 2000 m by the dynami- cally positioned drill ship Victory 7 Sens. During delicate operations, an unexpected change in a current of several knots can have costly conscqu- cnccs. Warm-core rings spun off by the Gulf Stream move through the area of the drill sites periodically and have currents on their periphery of several knots. These rings, which give rise to large changes in ocean currents in short times, have a strong SST signal and hence are easily tracked with satellite IR data.

Shell Development. as part of their programme to track warm-core rings in the area, contracted with URI to process and analyse cloud-free satel- lite IR data. At the outset. imagery was acquired and processed only im- mediately prior to cruises in which tracking instruments were deployed in rings while they were still several hundred kilomctrcs from the drill site. Because the tracking was intermittent. by contractual arrangement. and the cloud cover was heavy immediately prior to and during one of the first

58 MARINE POLICY January 1986

planned buoy deployment cruises, the location of the front for deploying the from the previous six years along with ring could not be located and the tracking buoy was mistakenly de- ployed in a weak eddy, not the ring of interest. This, coupled with heavy cloud cover for the next three weeks and a ring moving faster than normal, resulted in the drill ship being struck by the ring in the midst of a delicate operation, with adverse effects. At this point Shell negotiated a con-

moorings. In two subsequent cruises, satellite images will also be sent to sea to aid in a sampling programme undertaken in conjunction with the mooring work. Following the field programme, analysis of all the satellite IR data obtained will provide the context within which to interpret the results derived from the moorings.

the capability to process large vohrmes of data suggest that satellite-derived data can now make a major contribu- tion in such environmental baseline studies. For example, in one URI project on baseline work for the deep- sea mining programme, CZCS data were used to obtain a first estimate of the chlorophyll-a concentration in the Pacific Ocean east of Hawaii. Deep-

tinuous monitoring programme with Conclusions

sea mining, if undertaken in a produc- URI. Following this modification in tion mode, will very possibly result in the programme. no further problems These applications of satellite IR data significant volumes of sediment being were encountered. to oceanographic problems demon- dumped at the top of the water col-

strate clearly the potential of remote umn with possible adverse effects on

Basic oceanographic research sensing as a tool in dealing with the the biology in the resulting plume, ocean environment. Its growing hence the interest in chlorophyll-u. As

Satellite-derived IR data will be used acceptance by the oceanographic re- part of the same study the Applied in all phases - planning, field work, search community further attests to Physics Laboratory of Johns Hopkins and analysis - of a multi-million this potential. Our research has fo- University processed thermal infrared dollar air-sea interaction experiment cused on infrared satellite data be- data from the global archive for the planned for January 1986 in the Sar- cause of the relative ease of access to gasso Sea.’ A number of moorings

region. In another area the Environ- such data and their expected con- mental Protection Agency is consider-

with thermistors and current meters, tinued availability. Colour data (visi- ing the use of IR data for baseline and some with meteorological pack- ble light), from which a good estimate studies of ocean dumping at Deep

ages, will be deployed in deep water of chlorophyll-u is possible, are not as Water Dump Site 106 (106 miles from so as to span a strong oceanic front readily available. Furthermore, a New York City), as well as for their associated with the Subtropical Con- several-year gap in data collection is monitoring activities of upcoming vergence (STC). This is the first prog- expected prior to the launch of the ocean incinerator tests. ramme of this magnitude and diversity next generation of colour scanner into which satellite data have been (1989 or 1990). For these reasons, less carefully integrated from the outset. emnhasis has been ulaced on these

Practical tool

The planning-phase has involved pro- cessing and preliminary analysis of frontal locations in the STC in more than 5 000 satellite passes covering the area in a three-year period. During the field programme, satellite data will be acquired and processed in near real time (less than 24 h) at URI. The processed imagery will be sent to a

data in our research despite the excit- The advent of powerful, inexpensive ing biological data now being derived computers in conjunction with the from them.4 Since the bulk of biolo- algorithm developments and data gical activity occurs in the photic zone availability discussed above have (the upper 100 m or so of the water moved remote sensing oceanography column), the region sensed in the from a possibility envisioned by a few visible portion of the spectrum by only several years ago to a practical satellite-borne sensors, and because of oceanographic tool available to most the importance of biological data in major institutions today. To establish

minicomputer on the mooring- ocean management, colour data may a remote sensing facility capable of deployment vessel while at sea via the prove, in the long run, to be a more handling the problems discussed research satellite ATS-3. As part of important input to ocean. management above requires in the order of this programme, in May 1985 a com- systems than the infrared data. $150 000 in computer hardware. One plete 512 x 512-pixel, S-bit, processed year of AVHRR IR data covering a satellite image was successfully trans- mitted to a research ship (WV En-

deavor) at sea for analysis on a high- resolution display system. To the best of our knowledge this is the first successful transmission of full resolu- tion images to a civilian ship at sea.

The satellite-derived SST fields re- ceived on the ship will be integrated with the historical satellite data on the front location and recent ship-derived XBT data to determine the optimum

Environmental baseline

URI has been involved in several other recent studies in which both AVHRR and CZCS data have been used to construct an environmental baseline for a region facing new and potentially damaging industrial activ- ity. Such studies reveal one of the more important roles that satellite data will play in ocean management issues. The global archive of IR data

strip 3 000 km wide and circling the globe twice daily at 4-km resolution costs about $75 000. To process and analyse these data requires a staff of three - a computer manager, a remote sensing oceanographer and a techni- cian to load the 500 tapes involved and submit the jobs required for the analy- sis. Processing and analysing these data for a typical baseline study would not consume all the personnel or computational resources of such a

MARINE POLICY January 1986 59

Peter Cornillon Graduate School of Oceanography

Kingston, RI 02881, USA

‘Joint Oceanographic Institutions (JOI), A Research Strategy for the Decade 1985 - 7995, Washington, DC, 1985. ‘D.R. Montgomery, ‘SEASAT data ap- plications by commercial users’, Marine Geodesy, Vol 4. No 4, 1980, pp 387-416; L. Breaker and F. Jurick, ‘Providing near real-time sea surface temperatures to the

California north coast fishing fleet: An approach’, in Oceans ‘75 Proceedings, San Dlego, 1975, pp 794-796. %.A. Stage and R.A. Weller, ‘The Frontal Air-Sea Interaction Experiment (FASINEX)‘, submitted to the Bulletin of the American Meteorological Society, 1985. 40.B. Brown, R.H. Evans, J.W. Brown, H.R. Gordon, H.C. Smith and KSBaker, ‘Phytoplankton Blooming off the US East Coast: a satellite description’, Science, Vol 229, July 1985, pp 163-167; G. Fledman, D. Clark and D. Halpern, ‘Satellite color observations of the phytoplankton distribu- tion in the eastern equatorial Pacific during the 1982-83 El Nino’, Science, Vol 226, November 1984, pp 1069-1071.

Conference reports Heated exchange in Geneva Preparatory Commission for the International Seabed Authority (ISA)/

International Tribunal on the Law of the Sea (ITLOS), Geneva, Switzerland, 12

August - 4 September 1985

The resumed Geneva meeting of the

Prep:lratory Commission for the Inter-

nation:d Seabed Authority (ISA) and

the International Tribunal on the La\\

of the &:I (ITLOS) conformed more

to the holding pattern predicted at the

close of the spring meetin:! than to ;I

forward motion pattern (see Mtrrirlc,

Polic;v. October. IYX5. pp 34cL33.1).

During the 12 August to 3 Septemhei

meeting no progress occurred on in-

plrmentation of Resolution II eov-

erning the rights and obligations of

Pioneer Investors in deep-scahecl min-

ing. Chairman Joseph S. Warioba of

the United Republic of Tanzania indi-

cated that if by the second week of the

lYt(6 meeting of the Commission in

Jam:& (I7 March to I I April) no

understanding has hecn achieved on

iresolving overlaps among the pioneers

(a necessary prelude to their registra-

tion. he would place the matter before

tho Commission to determine ;I course

of action. The Commission must Aso

complete and adopt the rules to imple-

ment Resolution II, before ;IIIV

pioneers can be registered.

A somewhat heated exchange

occurred in Geneva over the adoption

by the Commission on 30 August of ;I

declaration sponsored by the (;roup of

60

77 thut condemns by reference the

national exploration licenccs for dccp-

seabed mining issued by the USA in

I%%. It does not refer to the UK

licence issued in Dcccmbcr I%%!. This

declaration supersedes the draft rc-

solution presented by the E%stern

European <iroup in 1YX-l attacking the

Provisional Underst:mding on Deep

Seabed Matters signed on 7 August

lYX4 by the Western mining states and

Japm. Adoption of the declaration

may caux the FR CJermany some

concern about issuing national mining

licences this year as planned. because

of that country’s interest in rrtaining

FIamburg as the site for the ITLOS.

Frustration

Delays in implcmcnting Resolution II

give rise to frustration in the Prepara-

tory Commission and suspicion that

the Convention regime may be eroded

by developments occurring outside the

Convention. This fuelled the adoption

of the declaration noted above and

contributed to increased politicization

of discussions in Special Commission .i

(SCN.3) on the Mining Code. Chair-

man Warioba sought to dampen these

reactions by expanding his consultz

tions on the problems affecting implc-

mentation of Resolution II to a broad-

er spectrum of Commission members

(see below). In the Informal Plenary

on the ISA he also deferred considera-

tion of ;I number of contentious issues

in the rules of proccdurc for the

Authority (see below).

Concrete results

Nevertheless, the Preparatory C‘om-

mission will huve to produce some

fairlv concrete results in the not too

distant future if it is to retain the

interest and support of all its members

and observers. It must meet the cm-

cer’n\ hoth of the nations eager to

breathe life into the Convention min-

ing regime and of those seeking proof

of the flexibility of the (‘ommission in

implementing ;I regime that facilitates

deep-scabcd mining by private and

state-owned entities along with the

Enterprise. Ad. mcc the rules for

registration of pioneer Lipplicants ;irc

completed ant1 the applicants arc rcg-

istcrcd. the <‘omniicsion will face

another challenge: to cnsurc that all

the states involved in waheci mining

continue to actively participate in the

Commission and contribute to the

tirvelopment of ;I viable mining code.

For if these states diminish their

efforts, the regime may yet turn out an

empty shell ~rnd its guarantees to

pioneers under Resolution II

meaningless.

Warioha held extensive consulta-

tions in <;enev~i with the existing

pioneer applicants - J~~pan. Fr;mce,

USSR and India ~ to facilitate their

findinp ;I solution to the overlapping

claims between the French and the

Soviets and the Japanese and the

Soviets. I Ie must find one that guaran-

tees to the Enterprise one viable mine

site as contemplated in Resolution II

from each applicant, but the substan-

tial French/Soviet overlap makes this

difficult (see Mrrriw I’nlic:r. October

IY115. pp 34(&313). Finding ;I solution

is further complicated by the explora-

tion licences issued by the LJS govern-

ment in lYt(3. some of which overlap

with the Soviet claim; neither the

Soviets nor the Enterprise w.ish to end

up with ;I mine site arca that conflicts

with the US licences. &spite protesta-

MARINE POLICY January 1986