Cluster and DEMETER Satellite Data. Fabien Darrouzet (Belgian Institute for Space Aeronomy (IASB-BIRA))

Transcription

1 Cluster and DEMETER Satellite Data Fabien Darrouzet (Belgian Institute for Space Aeronomy (IASB-BIRA)) 1

2 Outline Magnetosphere Plasmasphere Cluster Mission WHISPER Instrument and Data DEMETER Mission ISL Instrument and Data Get WHISPER Data Through ESPAS Get ISL Data Through ESPAS Summary - Conclusion 2

3 Magnetosphere 3 Magnetic field of the Earth (~ dipole) + Solar wind from the Sun Terrestrial Magnetosphere Compressed in direction of the Sun (dayside, 12:00 LT, ~10 R E ) Elongated in opposite direction (nightside, 00:00 LT, ~100 R E ) External boundary: Magnetopause Boundary regions: Ext.: Magnetosheath Int.: Ionosphere Several regions inside: Plasmasphere Radiation Belts Radiation Belts Solar Wind Bow Shock Cusp Magnetopause Auroral Zone Plasmasphere Magnetosheath Tail [Courtesy of ESA]

4 Plasmasphere 4 Region of the inner magnetosphere, in toroidal shape around the Earth (like a donut), in co-rotation with the Earth, populated by cold plasma coming mainly from ionosphere: Discovered in the late 50 s, early 60 s with ground-based data (whistlers waves) but also satellites data (Lunik-2 from Russia) Electrons and positive ions: Protons H + (90%) Helium He + Oxygen O + Properties: Energy few ev Density cm -3 Temperature ~10 4 K

5 Outline Magnetosphere Plasmasphere Cluster Mission WHISPER Instrument and Data DEMETER Mission ISL Instrument and Data Get WHISPER Data Through ESPAS Get ISL Data Through ESPAS Summary - Conclusion 5

6 Cluster Mission 4 identical satellites (summer 2000, ESA): Rumba (C1), Salsa (C2), Samba (C3), Tango (C4) Polar orbit (57 hours, 4 x 19.6 R E ), 2 crossings of the plasmasphere at perigee in both hemispheres ZGSE (RE) [Courtesy of ESA] Tetrahedral configuration changing along the orbit, with various spacecraft separation distances modified almost every year ( km) 11 instruments onboard, 1 used here, WHISPER 6 XGSE (RE)

7 WHISPER Instrument and Data (1) WHISPER, wave instrument measuring electric field: 1 receiver antenna (1 electric cable of 88 m and 2 probes at its ends) 1 wave transmitter and 1 receiver 1 acquisition and analysis system 2 modes of operation: Active: analyze of the pattern of resonances triggered in the medium by a radio pulse Characteristic frequencies of the medium Transmission at time t Reception at time t + D t Surroundingi onized gas CLUSTER Passive: the receiver monitors the natural plasma emissions in the frequency band 2 80 khz 7

8 WHISPER Instrument and Data (2) Typical electric field time-frequency spectrogram: Observation of the different regions and boundaries of the magnetosphere crossed by Cluster 4 during 10 hours in 2001 (typical trajectory shown on the right) Mode Passif Magnetopause Fpe Frequency (khz) Mode Actif Cusp Magnetosphere Bow Shock Magnetosheath Solar Wind 8 Time (UT) Identify the electron plasma frequency F pe related to the electron density N e by: F pe {khz} = 9 [N e {cm 3 }]1/2

9 Outline Magnetosphere Plasmasphere Cluster Mission WHISPER Instrument and Data DEMETER Mission ISL Instrument and Data Get WHISPER Data Through ESPAS Get ISL Data Through ESPAS Summary - Conclusion 9

10 DEMETER Mission 10 Satellite DEMETER = Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions Mission devoted to the investigation of Earth ionosphere disturbances due to seismic and volcanic activities. Micro-satellite (130 kg), Europe and France (CNES) Launch on 29 June 2004, alive until 9 December 2010 Orbit: 710 km altitude, 98.3 inclination, 14 orbits per day 6 instruments, including ISL (Instrument Sonde de Langmuir)

11 ISL Instrument and Data 11 ISL is a Langmuir probe that measures: Local electron density from 10 3 to 10 6 cm -3 (other data measured by instrument but not provided by ESPAS) 2 modes of operation: Survey: on board processing to reduce the transmitted flux (transferred data rate ~25 kbits / sec) Burst: scientific data transmitted with little or no processing. High rate mode mainly activated above seismic zones (maximal data rate ~1.7 Mbits / sec)

12 Outline Magnetosphere Plasmasphere Cluster Mission WHISPER Instrument and Data DEMETER Mission ISL Instrument and Data Get WHISPER Data Through ESPAS Get ISL Data Through ESPAS Summary - Conclusion 12

13 Get WHISPER Data Through ESPAS (1) Login on the ESPAS portal Click on «SEARCH» Select «Assets» (to acces WHISPER data) 13

14 Get WHISPER Data Through ESPAS (2) List all the assets proposed Choose 1 or several WHISPER instruments 14

15 Get WHISPER Data Through ESPAS (3) Click on «Time Period» button Fill in the time period needed Click on «Submit» button 15

16 Get WHISPER Data Through ESPAS (4) Observation collections (1 per satellite selected) Several observations files during short time intervals Click on «Download» button to get the results (files or values) 16

17 Get WHISPER Data Through ESPAS (5) Fill in a name for the request Agree with licences related to data selected Click on «Download» 17

18 Get WHISPER Data Through ESPAS (6) The process of selection of data is finished Close the window and go «My Account» 18

19 Get WHISPER Data Through ESPAS (7) Select «Dataset File» or «Data Values» to get the results of the request, 1 st «Dataset File» Download the data 19

20 Get WHISPER Data Through ESPAS (8) Select «Dataset File» or «Data Values» to get the results of the request, 2 nd «Data Values» Download the data (ASCII or 3 other formats) and plot it 20

21 Get WHISPER Data Through ESPAS (9) 21 Example of result file with density from Cluster/WHISPER: Header with lots of information:!---- CAA MERGED CEF FILE ( T18:32:22Z) ---- FILE_NAME = "C1_CP_WHI_ELECTRON_DENSITY _ _ _220000_V cef" FILE_FORMAT_VERSION = "CEF-2.0" END_OF_RECORD_MARKER = $... Format: Time, Uncertainty of time tags, Spectrum Type, Computation Method, External Data Used, Human Validation, Electron Density, Uncertainty, Contrast, Quality, $ Data: T11:55:31.844Z, ,"A","11", "-,"V", , , 0.54,3 $

22 Get ISL Data Through ESPAS All the steps are similar, except that «Data Values» access is not working yet!! Zip file with data files in binary format + ASCII report file Information given in the report file: Type of request Where to get the code to read the file 22

23 Outline Magnetosphere Plasmasphere Cluster Mission WHISPER Instrument and Data DEMETER Mission ISL Instrument and Data Get WHISPER Data Through ESPAS Get ISL Data Through ESPAS Summary - Conclusion 23

24 Summary - Conclusion Cluster is a magnetospheric mission, WHISPER is an instrument that determines the electron density DEMETER is a ionospheric mission, ISL is an instrument that determines the electron density Both datasets are accessible through the ESPAS portal Datasets easy to use and interesting for ionospheric and magnetospheric research Thank you!! 24 Vibration tests of electronic module of DEMETER Dancing Cluster satellites

25 Abstract 25 The ESPAS portal allows to retrieve density data from two European missions: Cluster and DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions). The Cluster mission consists of four identical satellites (C1, C2, C3, C4) launched in 2000 on similar elliptical polar orbits with an initial perigee at about 4 Re, an apogee at 19.6 Re and an orbital period of 57 hours. The spacecraft continue to investigate the Earth's magnetic environment and its interaction with the solar wind in three dimensions. The DEMETER mission has been launched in June 2004 into a quasi sun-synchronous circular orbit (inclination ) at 715 km altitude. The satellite operated until December 2010 and was devoted to the study of ionospheric disturbances related to seismic activity and pre- and post-seismic signatures, and to human-induced ionospheric effects. Both missions carried several scientific instruments, with some of them in particular allowing to determine the density at the position of the satellite. On Cluster, the WHISPER (Waves of HIgh frequency and Sounder for Probing Electron density by Relaxation) instrument measured electron density. On DEMETER, ISL (Instrument Sonde de Langmuir) measured the electron density and IAP (Instrument d'analyse du Plasma) the ion density. The missions, instruments and datasets will be described during this lecture, as well as how to access them through the ESPAS portal.