Rutland Hotel, Sheffield, UK
Minutes by Anders.Eriksson@irfu.se
Mats André firstname.lastname@example.org
Stuart Bale email@example.com
Rico Behlke firstname.lastname@example.org
Jan Blecki email@example.com
Patrick Canu firstname.lastname@example.org
Tobia Carozzi email@example.com
Nicole Cornilleau-Wehrlin firstname.lastname@example.org
Chris Cully email@example.com
Anders Eriksson Anders.Eriksson@irfu.se
Andrew Fazakerley firstname.lastname@example.org
Michael Fehringer email@example.com
Rejean Grard firstname.lastname@example.org
Georg Gustafsson email@example.com
Jan Holtet firstname.lastname@example.org
Craig Kletzing email@example.com
Vladimir Krasnoselskikh firstname.lastname@example.org
Harri Laakso email@example.com
Per-Arne Lindqvist firstname.lastname@example.org
Elizabeth Lucek email@example.com
Björn Lybekk firstname.lastname@example.org
Milan Maksimovic email@example.com
Arnaud Masson Arnaud.Masson@esa.int
Olivier Moullard firstname.lastname@example.org
Forrest Mozer email@example.com
Kalevi Mursula KALEVI.MURSULA@OULU.FI
Kai Niskala KAI.NISKALA@OULU.FI
Arne Pedersen firstname.lastname@example.org
Anders Tjulin Anders.Tjulin@irfu.se
Andris Vaivads email@example.com
Claude de Villedary Claude.Devilledary@cetp.ipsl.fr
Simon Walker firstname.lastname@example.org
Ieuan Willis email@example.com
Keith Yearby firstname.lastname@example.org
1. Intro (Mats)
Mats welcomed everybody to this mainly technical meeting, the science issues being treated in the WEC meeting tomorrow as they are of interest to all the WEC community. Thanks to the dedicated work of the EFW team, not least by our former PI Georg Gustafsson, we now have four instruments performing excellently in space.
2. Cluster status (Mats)
Cluster works well, all instrument operational except ASPOC on SC1 and CIS on SC2. Commissioning review (Feb 1) succesfully ended commissioning, and we are now in the science phase of the mission. Extension of Cluster mission above the nominal two years lifetime may be possible, depending on the fuel consumption and hence on the operational scenarios.
3. EFW status
All OK, showed spin-fit data for full orbit and details of EFW and STAFF SA spectra to illustrate that large-scale as well as small-scale features can be studied using Cluster electric field data.
Spacecraft potential (Vsc): Comparison of CIS density to EFW Vsc. 40 V = 0.01 cm-3, 25 V = 0.1 cm-3, 10 V = 0.8 cm-3. Cannot use old relations for Vsc/density, need new relations for Cluster.
E-field: Showed offset tables for Ex and Ey for different probe pairs (derived from ground and on-board spin fits). Offsets generally constant and small (few tenths of mV/m). Plot of Ex and Ey from different probe pair spin fits show the pairs are equivalent. Shows consistency. To demonstrate absolute accuracy, he showed a plot of ExB velocity with s/c v removed (E.B = 0 assumed) showing the corotation velocity of the plasmasphere.
Comparison to ACE (and to some extent CIS) data very good:
short-circuiting effect of booms seem to be 10% or less, though further comparisons needed. Also showed integrated E (from spin fits and E.B = 0) using measured and model B in the Msphere - agrees perfectly.
Intro on s/c potential. Showed comparisons of Vsc to WHISPER and CIS (CSDS) data. WHISPER generally indicates higher density than CIS, though both gives higher density values for a given Vsc than expected from previous missions. Also, the probe-to-sc potential (which is what we measure) do not go so close to zero in high-density plasmas as could be expected from previous missions.
Vsc: Polar EFI/HYDRA comparison preliminary compares well with EFW/WHISPER comparison.
4. Interference (Anders, Arne, Forrest)
EDI: As yet, only I/F seen is lines at multiples of the square modulation frequency (multiples of 8/15 kHz) when looking at EFW internal burst data, and of course the slight change in Vsc due to the EDI current. The latter effect needs to be taken into account when using Vsc to study density.
WHISPER: The WHISPER synchronization in NM seems to work: not much WHISPER interference is seen in differential signals in NM sampling. We can see WHISPER when we have BM telemetry, where it contaminates the EFW data while transmitting. This creates no problems for spin fitted data, though it of course interferes with high resolution studies. Presently, WHISPER is transmitting every 7th spin in normal operations, and we certainly do not want more frequent transmissions.
ASPOC: When operating, ASPOC profoundly changes the electric field pattern in such a way that EFW cannot any longer measure the electric fields with any accuracy. The effect is worst in tenuous magneotspheric plasmas, where ASPOC operations completely disables our possibility of observing naturally occuring electric fields, but the problem is serious also in the magneotsheath and solar wind. Examples presented include complete shielding of the natural electric field in the magnetosphere, and enhanced sunward spurious field in the magnetosheath. The EFW team concludes that time sharing with ASPOC is necessary. The SDC manager may consider blanking E-field in CSDS prime parameters when ASPOC is on, and using SC1 (ASPOC not working) only for summary parameters.
5. Comparisons to EDI
Forrest: Not yet any good simultaneous EDI and EFW electric field data to compare, but expected to arrive soon.
6. Use of internal EFW burst memory
Ensure routine use of burst memory only within acquisition periods (as defined in the Master Science Plan, MSP). For explicit purposes, bursts can of course be taken also outside regular acquisition periods, but default should be to have them only within a period with NM1 or BM1 telemetry.
Nicole requests taking 2 E + 3 B at 9 ksamples/s with time-tagged bursts, so that we get full waveform data of the electromagnetic field up to 4 kHz simultaneously on all four s/c.
7. Special orbits
Andrew Fazakerley recapitulated the history of special orbits. Initial idea to put about 1/3 of all orbits as special orbits, where non-standard operations are suggested. The 1/3 disappeared very quickly, and now the number is about 1/8. PEACE maintains a web page with special orbit suggestions.
Special orbit suggestions:
b. Forrest interested in the burst-dump-burst-dump mode. This needs BM telemetry to get reasonable coverage, and preferably at least 22 kbit/s to EFW.
c. Langmuir mode use of two probes is not a special orbit issue, but an internal WEC discussion. STAFF SA likes to keep one satellite with all probes in E mode not to loose all information on despun E.
d. Bandpass filter orbit: Forrest suggests using the Hx telemetry for BP/BPC instead of V12/V34 in the solar wind, in order to get high resolution measurements of Langmuir wave packets. We plan to run this on orbit 111.
Policy on special orbits and non-standard operations of EFW:
Suggestions should be sent to Mats. We are happy to consider anything anybody suggests, as long as there is some reasonable scientific background and it is certain that the data actually will be analyzed.
Anders summarized present operations. We run all four probes in E-field mode, except for the bias voltage sweeps about once every two hours. In BM1 mode, we have as yet always had 15 kbit/s. Burst memory is dumped in BM3 as regulated in MSP.
Arne raised the point if they are too fast. Anders thinks no, as there is no hysteresis effect on the bias voltage sweeps, though current and voltage bias sweeps may be different in this respect.
Bias voltage sweeps will be extended on the positive side to get info on solar wind and magnetosheath plasma. Presently, we run sweeps about every two hours. We may sweep more often on particular orbits.
Per-Arne described the EFW CSDS parameters.
11. EFW associates and EFW science projects
Mats introduced the concept of EFW associates, which are people working with EFW data together with some EFW CoI without being CoIs themselves. Associates can be suggested at http://cluster.irfu.se, and are always associated with a particular CoI.
In order to encourage cooperation and to avoid confusion and duplication of work, ongoing science projects should also be reported to the PI using the same web page.
Uppsala to update documentation list, removing old references, including new, and having EFW docs available directly under EFW, not only via the Isdat page.
Uppsala also to put up publications and presentations list.
13. FGM data
Mats described the FGM data policy, as formulated by the FGM PI and verified by Elizabeth Lucek (email@example.com):
b. FGM as part of the physics (identifying boundaries, finding coordinates): co-operation and co-authorship from FGM.
c. FGM data make up the main physics: not authorized outside the FGM team.
14. Papers for the Annales Geophysicae special issue
Mats presented a list of the planned papers. Papers should not be published in other journals before the publication date of the Annales special issue, i.e. September 2001. After this date, publication is encouraged in all science journals.
15. Upcoming meetings
Tobia: ISDAT 2.7 released, with modules for all WEC instruments.
Requests to Tobia.Carozzi@irfu.se.
Forrest: SDT available to any EFW CoI who wants it. Requests to firstname.lastname@example.org.
17. Next meeting
We do not aim for any EFW team meeting in at least four
Late summer or early autumn may be good times.
Summary of actions: