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-45071 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) 38 25 52 63; Fax: (33 2) 38 63 12 34; E-mail: Jean-Gabriel.Trotignon@cnrs-orleans.fr

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) 38 25 52 63 Secrétariat: (33 2) 38 25 52 64 Télécopie (Fax): (33 2) 38 63 12 34 E-mail: Jean-Gabriel.Trotignon@cnrs-orleans.fr

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 !

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.

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

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

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)

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

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

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

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

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

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

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.

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.

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).

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.

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.

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.

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.

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.

Cold Ne (cm-3) Cold Ne / Total Ne (%) WHISPER 2 SEPT 24, 2000 0630 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.

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

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

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

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

06:05:00 – 06:25:00 Natural (passive)

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

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

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

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

III. Cross-Calibration Activity Participation in: 6th Cross Calibration Workshop, London, 24-25 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)

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

Data delivery schedule IV. Archiving Activity & Data Delivery Schedule for the Extension (cont’d) Data delivery schedule March 2008 – Feb 2009, delivery of: 2006 + 2007 mass production archive, 2006 - mid 2007 density products. March 2009 – Feb 2010, delivery of: 2008 + 2009 mass production archive, mid 2007- 2008 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.

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) 38 25 52 63 Secrétariat: (33 2) 38 25 52 64 Télécopie (Fax): (33 2) 38 63 12 34 E-mail: Jean-Gabriel.Trotignon@cnrs-orleans.fr