Measuring ITM Variability:Missions Around Geospace-Part 2

Jan J SojkaCenter for Atmospheric and Space Sciences

Utah State University, Logan, Utah 84322

Heliophysics Summer School 9 : Boulder, Colorado 28th July to 4th August, 2015

WHAT DOES ITM STAND FOR?

IonosphereThermosphereMesosphere

ITM materials can be found in HSS Text books.

Robert Schunk and Andrew Nagy: their text “Ionospheres”, a Cambridge press Atmospheric and Space Science Series book.

Volume 1: Chapter 12: On the ionosphere and chromosphere: Fuller-Rowell and Schrijver

Volume 2: Chapter 12: Flares, coronal mass ejections, and atmospheric responses: Fuller-Rowell and Solomon

Volume 3: Chapter 13: Terrestrial Ionospheres: SolomonVolume 3: Chapter 14: Long-term evolution of the geospace climate: Sojka

THERMOSPHERE

IONOSPHERE

Neutral species Ionized species: PLASMA

THERMOSPHERE

IONOSPHEREWHERE OR WHAT IS LEO?

LOW EARTH ORBIT Period is about 90 minutesAbove 300km, or else short life!

What do we need to measure in the ITM?

What are outstanding science questions for the ITM? And who cares?

Question A: How does the thermospheric density respond to specific scale sizes and duration of energy deposition?Who Cares A: LEO satellite life time and collision avoidance between in excess of 10,000 LEO “projectiles”.

Question B: How does the ionospheric “roughness” arise and evolve from energy inputs and instability conditions of particular scale sizes?Who Cares B: Radio wave propagation using from VLF to GPS find the ionosphere to be a refractive medium that disrupts emergency “first responder” communications and geo-positioning information.

State variables and dynamics at multiple points simultaneously along with ITM drivers. Pretty much everything!

Measuring the Thermospheric density

CHAMP (CHAllenging Minisatellite Payload) July 2000 to Sept 2010, circular orbit at 460 km

What Instrument technique was used to measure neutral density?

Accelerometer to detect satellite de-acceleration.

Followed by a satellite called GRACE (Gravity Recovery And Climate Experiment. Same measurement technique.

What happens when you make measurements at lower heights?

GOCE (Gravity Recovery and Climate Experiment) Circular orbit at 250 km. March 2009 to November 2013

Six, 3 axis accelerometers Ion propulsion technology

Short Life Time

Swarm: ESA’s magnetic field mission, not an acronym!?

Three satellites, 2 at 460 km and 1 at 530km, different orbit planes

Why in different orbit planes?

AccelerometersMagnetometers: “evolution of Earths magnetic field”Novel use of Langmuir Probes to measure Electric fields.

Launch: November 2013

Horizontal gradients

TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics).

Launched December 2001, Polar Orbit, 625 km.

Instruments are all remote sensing optical spectrometers.

SABER (Sounding of the Atmosphere using Broadband Emission Radiometry)

GUVI (Global Ultraviolet Imager)

SEE (Solar Extreme ultraviolet Experiment)

TIDI (Timed Doppler Interferometer)

A natural coordinate for the atmosphere is the pressure level! (Zp)

A little more ITM Science

Energy state of the ITM system can be obtained by temperature measurements:

Thermosphere: Tn

Ionosphere ions: Ti

Ionosphere electrons: Te

What are the primary energy sources?

Magnetospheric Auroral, Electric Fields, and Currents

DMSP (Defense Meteorological Satellite Program)

Circular Orbit at 840km

Sun syncronous

A fleet maintained for over three decades.

Onboard environmental suite of instruments.

Plasma Ne, Te, Ti, Vi, magnetic field, currents, auroral particles

These environmental instruments provide the main ITM measurements!

Night time weather images contain aurora !

DMSP weather image! Space Weather

White light auroralDMSP image.

Eastcoast of the USA and Canada.

Have you used this mission? GPS (Global Positioning System)

How does GPS deliver an ITM science measurement?

1) The geolocation of a ground based radio receiver depends upon obtaining several very accurate line-of-sight distance and angle measurements between the ground and members of the GPS satellite fleet.2) The line-of-sight distance however involves radio waves passing through a refractive material, the ionosphere.3) Hence neither the time-of-flight nor the signal phase are simply dependent upon distance!!!4) Hence corrections need to be made for the ionosphere. The corrections are for time-of-flight, phase, and refraction. 5) GPS uses 2 different frequencies each has a different correction.

Resulting from this correction is a measure of how many electrons are along each path, the total electron content (TEC). TEC is the GPS users noise and the ITM science measurement.

COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate).

6 satellites in LEO using GPS to carry radio occultations

What ITM parameters does the radio occultation technique generate?

The Electron Density Profile (EDP) can be reconstructed from these occultation data.

AMPERE (Active Magnetosphere and Planetary Electrodynamics Response Experiment) on the Iridium 66 satellite communications fleet

Which non science grade house keeping instrument is used?

The satellite attitude determination magnetometer

Another outstanding ITM science and application issue.

Around the magnetic equator electric fields create the daytime Appleton CrestsPost sunset as the ionospheres bottom side gradients steepen instabilities are generated. These grow to form large scale “bubbles” causing radio wave scintillation and breakdown in communications.

C/NOFS (Communication/Navigation Outage Forecast System)

Equatorial, inclination of 13o, 405 km X 800 km orbit

VEFI: vector electric field inst.CINDI: coupled ion-neutral dynamics investigationCORISS: occultation receiver for ionospheric sensing and specificationDIDM: digital ion drift meterCERTO: coherent radio tomography experimentPLP: Planar Langmuir Probe

C/NOFS was launched in 2008

Will provide a unique few days of low altitude (extremely low) information as it re-enters the atmosphere this “November”

The uncertainty of exact time and place demonstrates the challenge of forecasting satellite drag.

Unique scientific measurements will be made below 250 km for two or three days.

Future ITM missions in the pipe-line in the USA

ICON (Ionospheric Connection Explorer)Launch date : June 2017 into LEO orbit MIGHTI: Michelson Interferometer, for neutral winds and temperaturesEUV: height and density of daytime ionosphereFUV: daytime atmospheric composition and night ionosphereIVM: plasma and electric fields

GOLD (Global-scale Observations of the Limb and Disk)

Launch date: 2017 in geosynchronous orbit on commercial communications satellite.

High resolution far ultraviolet imaging spectrometer

COSMIC-2: next generation of COSMIC-1

OPAL (Optical Profiling of the Atmospheric Limb)

This is a 3U CubeSat to be launched from ISS (International Space Station)

Why we still need measurements scientifically and why the space weather users need them in real time.

ITM observations has a very significant ground based component.

Which countries and agencies provided the ITM missions discussed in this presentation. It is a diverse and international distribution often having non ITM objectives.