1. WHISPER Report Jean Gabriel Trotignon and WHISPER Team
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Laboratoire de Physique et Chimie de l'Environnement
3A, avenue de la Recherche Scientifique
F Orléans cedex 02, France
WHISPER Report
Jean Gabriel Trotignon and WHISPER Team
Final Review of the 1st Phase
of the CAA
ESA/ESTEC, Noordwijk,
The Netherlands
May 20, 2008
Phone: (33 2) ; Fax: (33 2) ;

2. Presentation Outline Whisper Data Products
Final Review of the 1st Phase of the CAA
ESA/ESTEC, Noordwijk, The Netherlands, May 20, 2008
Jean Gabriel TROTIGNON
Presentation Outline
I. Introduction
Whisper Data Products
Management Structure
II. Density Determination Methods
III. Cross-Calibration Activity
IV. Archiving Activity & Data Delivery
Schedule for the Extension
V. Conclusion
Téléphone: (33 2) Secrétariat: (33 2)
Télécopie (Fax): (33 2)

3. I. Introduction Whisper Data Products
1. Natural Waves Related Archives
2. Energy Related Archives
3. Sounding Related Archives
4. Electron Density Related Archives
Archives 1 to 3 are mass-produced (low-level products)
Come from a quasi-direct reading of decommuted Whisper archives, converted into physical units. Production by CNES, validation by LPCE.
Archives 4 require human intervention (high-level products)
different types of signature (resonances, cut offs, …)
different plasma regimes
no systematic signature
sometimes, no signature at all !

4. 1. Natural Waves Related Archives
Most of the time Whisper listens to natural waves
[2kHz, 80kHz] band
On one of the two EFW antenna pairs: Ey or Ez
Spectrum obtained by on-board FFT (163 Hz resolution), only amplitudes, phases are lost.

5. Two types of natural waves archives:
1. Natural Waves Related Archives (cont’d)
Two types of natural waves archives:
CP_WHI_NATURAL
Natural (accumulated) spectra
CT_WHI_NATURAL_EVENTS
Processing mode changes

6. CP_WHI_NATURAL CT_WHI_NATURAL_EVENTS TC mode Times: start & end times
Spectrum (central) time
Time uncertainty in s
[due to accumulation]
FFT size
Reception antenna
Spectrum values (in V2 m-2 Hz-1)
Frequencies (in kHz)
Overflow saturation flag
Average number
(Number of accumulated spectra)
Number of gain changes during
acquisition
Sizes of mantissa & exponent
of compressed data
CT_WHI_NATURAL_EVENTS
TC mode
Times: start & end times
of event
FFT size
Receiving antenna
Average number
Gain command
Spectrum selection rate
Indicates the ratio of accumulated spectra actually transmitted
Energy overflow averaging flag
Compression method required,
compressed data size
Information on compression method

7. 2. Energy Related Archives
In each natural spectrum acquisition/accumulation interval, total power energies are accumulated and transmitted
On-board compression from 32 to 8 bits
Two archives:
CP_WHI_WAVE_FORM_ENERGY
PP_WHI (raw estimate of density, energy in 3 freq. bandwidths)

8. 3. Sounding Related Archives
Max frequency resolution: 163Hz
Maximum frequency range: [4, 82] kHz
Current time resolution pattern

9. Six types of archives: 3. Sounding Related Archives (cont’d)
CP_WHI_ACTIVE
Sounding spectra
CP_WHI_PASSIVE_ACTIVE
Passive spectra
CP_WHI_ACTIVE_TO_PASSIVE_RATIO
Active to passive ratio (4 possible values for each bin)
CT_WHI_ACTIVE_EVENT
Sounding mode changes
CP_WHI_HK
Elementary sounding events, extracted from WEC housekeeping files
CP_WHI_SOUNDING_TIMES
simplified version of CP_WHI_ACTIVE files, only keeping sweep central sounding times

10. CP_WHI_ACTIVE 3. Sounding Related Archives (cont’d)
Spectrum (central) time
Time uncertainty (in s)
[due to acquisition and sweep]
Receiving antenna
Active spectrum values (in V2 m-2 Hz-1)
Frequencies (in kHz)
Scanned frequency table
gives swept frequencies and sweep order
Sounding interval (in ms)
Time between 2 successive emissions in a sweep
Emission/Reception delay
Time between emission and reception
Number of gain changes
Compression parameters: mantissa and exponent sizes

11. 4. Electron Density Related Archives
CP_WHI_ELECTRON_DENSITY
Central time of spectrum from which density is derived
Time uncertainty
Spectrum type (Active or Natural)
Computational method
Used algorithm code
External data used
E for EFW
Electron density (in cm-3)
Electron density uncertainty (in cm-3)
If available (depends on the algorithm)
Quality factor (between 0 and 1)
If available, based on the local contrast of the peak/cutoff

12. Introduction (cont’d)
Management Structure
LPCE– CETP / CNRS
J.-G. Trotignon: PI (from 09/2007)
To be hired: Archive Developer
P. Décréau: retired (PI until 08/2007)
P. Canu: Co-I, Data Handling
J.-L. Rauch: Co-I, Data Handling
S. Kougblénou: Software Engineer
A. Martinez: Software Engineer
Software development
Data decommutation
Validation of mass-produced archives
Production, validation, & delivery of Ne archives
CNES
M. Camps
F. Dériot
C. Miquel
Data decommutation
Production & delivery of mass-produced archives
CAA
A. Masson: Co-I
Production of sounding time archives & ASCII files
of Ne in the tail

13. Job advertisement for WHISPER CAA assistant
(English version
from
Hugo Alleyne)

14. II. Density Determination Methods
Different strategies are used to determine the density.
They take advantage of:
* large variety of resonances that are actually excited &
* large variety of natural wave behaviours,
that strongly depend on encountered plasma characteristics.

15. II. Density Determination Methods (cont’d)
Solar wind & magnetosheath
Only one strong resonance is observed at, or close to, plasma frequency fpe from which the density Ne is directly derived:
Ne [cm-3] = fpe² [kHz] / 81
In addition, lower cut-off of thermal noise recorded whenever WHISPER is used as a natural wave detector is also a valuable way to determine Ne. Cut-off indeed occurs very close to fpe.
Another way to give Ne is to combine WHISPER active observations with S/C potential measurements made by EFW and to adjust, at best, the two time series, interval by interval. Pattern recognition processes are therefore applied.

16. At the bottom, Ne inferred from: plasma resonances (crosses) and
Natural Waves
Plasma Resonances
Derived Densities
Earth’s magnetosheath measurements by WHISPER-1, when passive (top) and active (middle).
At the bottom, Ne inferred from:
plasma resonances (crosses) and
lower cut-off frequency of thermal noise recorded when passive (red curve).

17. Active WHISPER-1 spectrogram on 13 May 2002, from 15:50 to 17:40 UT.
S/C potentiel gives Ne variations versus time, but absolute values have to be calibrated using Whisper active measurements .
==> S/C potential variations may be combined with WHISPER observations
for Ne determination. Pattern recognition techniques are thus applied.
PLASMA
FREQUENCY
Solar Wind SW
MGN
Active WHISPER-1 spectrogram on 13 May 2002, from 15:50 to 17:40 UT.
Ne deduced from S/C potential is shown in white, while WHISPER-EFW processed density is plotted in red.

18. II. Density Determination Methods (cont’d)
In magnetosphere, resonances are first extracted from other signals with the help of image processing techniques and then identified.
Identification is possible, because in Hamelin’s diagram frequency locations of fqn are aligned.
==> Density of cold plasma component may then be read in abscissa.

19. Density Determination Methods (cont’d)
In magnetosphere, and in particular in plasmasphere, resonances arise at fce & harmonics, fpe, fuh, and fqn that correspond to electrostatic cyclotron waves whose group velocity vectors are close to zero.
From fpe, fuh = (fpe² + fce²)½ , and fqn, plasma parameters may be deduced and in particular the total plasma density.

20. Image Processing Techniques
Spectrograms are processed in order to:
improve the contrast,
reduce the noise,
smooth the image while preserving edges (Nagao filter), &
extract pics.

21. 1.0 0.5 0.0 1 5 N = 4 N = 5 N = 3 HAMELIN’S DIAGRAM (Fqn – nFce) / Fce
Fpe / Fce
N = 4
N = 5
Calculated Fpe
N = 3
Here, two fqn resonances are found between two successive gyroharmoniques. A series is actually aligned on a vertical line. The abcissae of the other series are decreasing.

22. Cold Ne (cm-3) Cold Ne / Total Ne (%)
WHISPER 2 SEPT 24, UT – 0830 UT
Cold Ne (cm-3)
Cold Ne / Total Ne (%)
Plasmasphere
Plasmapause
Magnetosphere
The density of cold electrons is given by the series of fqn that are aligned in the Hamelin’s diagram, while the total electron density comes from the observed fpe resonance.
The pourcentage of cold electrons appears to be 60 % in the magnetosphere and 95 % in the plasmasphere, as expected.

23. (Top) Natural wave spectrogram,
(Middle) Total electron density, in white, derived from lower cut-off frequency superimposed on natural wave spectrogram &
(Bottom) Active spectrogram.

24. Active Natural II. Density Determination Methods (cont’d)
Extraction methods available
Active
Natural

25. About Density Quality Factor
CLUSTER 1, WHISPER Spectrogram, March 16-17, 2001
20:20:00 – 20:50:00
Natural (passive)
11:10:00 – 11:30:00
Active and
Natural
06:05:00 – 06:25:00

26. C1, WHISPER Natural, March 16, 2001, 20:20 – 20:50 UT

27. 06:05:00 – 06:25:00
Natural (passive)

28. C1, WHISPER Natural, March 17, 2001, 06:05 – 06:25 UT

29. C1, WHISPER Active, March 17, 2001, 11:10 – 11:30 UT

30. C1, WHISPER Natural, March 17, 2001, 11:10 – 11:30 UT

31. C1, WHISPER Active, April 13, 2005, 15:00 – 22:00 UT

32. III. Cross-Calibration Activity
Participation in:
6th Cross Calibration Workshop, London, October 2007
7th Cross Calibration Workshop, Tenerife, 9 March 2007
Cross Calibration activities:
EDI/WHISPER: removal of EDI perturbations in WHISPER spectra
(Allows the density determination to be improved)
EDI/FGM/WHISPER: determination of B in plasmasphere
EFW/WHISPER: density extraction
(Refines density extraction / provides density estimates when no Whisper natural wave signatures can be used)

33. Archiving activity for the extension
IV. Archiving Activity & Data Delivery
Schedule for the Extension
Archiving activity for the extension
Process data from 2006 to 2009
Deliver data to CAA
Update processing software at LPCE
- Software for Tail data sets ingestion to be developed
- Tail data sets to be processed and converted
- Density quality to be fixed
Update documentation (ICD to be updated)
Participation in Cross-Calibration activities and CAA reviews

34. Data delivery schedule
IV. Archiving Activity & Data Delivery
Schedule for the Extension (cont’d)
Data delivery schedule
March 2008 – Feb 2009, delivery of:
mass production archive,
mid 2007 density products.
March 2009 – Feb 2010, delivery of:
mass production archive,
mid density products.
March 2010 – Nov 2010:
prepare data for final archive,
delivery of 2009 density products.
On case-by-case basis: providing of tail data sets.

35. Conclusion Archive production will start as soon as new
Final Review of the 1st Phase of the CAA
ESA/ESTEC, Noordwijk, The Netherlands, May 20, 2008
Jean Gabriel TROTIGNON
Conclusion
Archive production will start as soon as new
CAA assistant will be hired (job advertisement
has been distributed to scientific community);
Special effort on density extraction to be
continued & quality factor refined;
No major issue encountered or foreseen.
Téléphone: (33 2) Secrétariat: (33 2)
Télécopie (Fax): (33 2)