PEACE moments Andrew Lahiff 29 November January January 2005

peacemoments - summary Cluster & Double Star PEACE moments: number density, velocity, pressure, heat flow vector, temperature Cluster & Double Star PEACE moments: number density, velocity, pressure, heat flow vector, temperature GSE or B-field aligned coordinate systems GSE or B-field aligned coordinate systems any distribution, any sensor combination any distribution, any sensor combination S/C potential corrections S/C potential corrections plain ASCII, CEF & CDF output files plain ASCII, CEF & CDF output files if you run it without thinking, i.e. looking at spectrograms, your results will probably be wrong - more on this later… if you run it without thinking, i.e. looking at spectrograms, your results will probably be wrong - more on this later…

peacemoments - GUI There are 3 pages: basic basic S/C potential S/C potential integration integration Note: there are help bubbles

peacemoments - GUI There are 3 pages: basic basic S/C potential S/C potential integration integration

peacemoments - GUI There are 3 pages: basic basic S/C potential S/C potential integration integration

peacemoments - recent changes v1.2 & below: v1.2 & below: - called exportIDFS, then Qtran: cdf  qft  read into peacemoments - temporary files were ASCII - this was very slow now peacemoments can read data directly from the IDFS archive; temporary files are binary now peacemoments can read data directly from the IDFS archive; temporary files are binary - this is much faster

peacemoments written in C/C++; GUI in Perl/Tk. Needs: written in C/C++; GUI in Perl/Tk. Needs: - SDDAS - Qtran for CDF output files - gnuplot for generating plots the latest versions use the latest versions use IDFS libraries (not in standard SDDAS installation) IDFS libraries (not in standard SDDAS installation) “cIDFSSource” code from Joey Mukherjee (SwRI) “cIDFSSource” code from Joey Mukherjee (SwRI) to promote & read data from the database available as an executable for Linux, Solaris & Mac OS X available as an executable for Linux, Solaris & Mac OS X

peacemoments LEEA 3D velocity  distribution function HEEA 3D velocity  distribution function sweep mode,  sun pulse times EFW PP potential  GSE spin-axis  angles FGM PP B-field  vector .mom file  moments.mom files gzipped and stored - used next time you calculate moments for the same time period (faster than getting data from database).  IDFS routines - promotion & reading data from the IDFS archive

PEACE - distributions 3D distributions: 3DR, 3DXP, 3DXE, 3DF; 2D: SPINPAD 3D distributions: 3DR, 3DXP, 3DXE, 3DF; 2D: SPINPAD LAR: Low Angular Resoution MAR: Medium Angular Resolution HAR: High Angular Resolution 3DF - highest resolution 15 degree polar res. 15 degree polar res degree azimuth res degree azimuth res. Double Star only has 3DF SPINPAD determined on the ground from PAD data

peacemoments - distributions SPINPAD SPINPAD 3DR 3DR 3DF 3DF 3DX1P, 3DX1E, 3DX1 3DX1P, 3DX1E, 3DX1 3DX1P + 3DX2P 3DX1P + 3DX2P 3DX1P + 3DR 3DX1P + 3DR 3DX1E + 3DR 3DX1E + 3DR also PEACE onboard (MOMS_L2), HIA PP, CODIF PP, WHISPER PP also PEACE onboard (MOMS_L2), HIA PP, CODIF PP, WHISPER PP

peacemoments - sensor combinations 1-sensor: 1-sensor: L1L2B, TH1H2, H1H2, L1L2 L1L2B, TH1H2, H1H2, L1L2 2-sensor: 2-sensor: TL1L2B, TH1H2B, TL1L2, H1H2B TL1L2B, TH1H2B, TL1L2, H1H2B normally use either normally use either TL1L2B or L1L2B TL1L2B or L1L2B (HEEA more likely to be (HEEA more likely to be saturated than LEEA) saturated than LEEA) usually like this (but not always)

Double Star - sweep option 1 26 keV 1 keV 34 eV 1 eV Spin 1,3,5,7,… Spin 2,4,6,8,…

Double Star - alternating sweeps 26 keV 1 keV 34 eV 1 eV Spin 1,3,5,7,… Spin 2,4,6,8,…

Double Star - alternating sweeps Top Overlap Bottom H L moments covering full energy range - time resolution 8-seconds Can have similar “sensor combinations” to Cluster, e.g. TL1L2B, L1L2, …

Double Star - sensor combinations use TL1L2B for alternating sweep mode use TL1L2B for alternating sweep mode don’t use TH1H2B (peacemoments won’t actually let you) don’t use TH1H2B (peacemoments won’t actually let you) - frequently the overlap part of the ”high sweep preset” sweeps aren’t transmitted sweep preset” sweeps aren’t transmitted  “H1H2” doesn’t exist  “H1H2” doesn’t exist

timetags 3 options: 3 options: PEACE interval averaged PEACE interval averaged PEACE sunpulse PEACE sunpulse CSDS interval averaged (same as PP’s) CSDS interval averaged (same as PP’s) t PP = t PEACE; sun + t duration (0.5 + (SPOS - 75/16)/1024) For CL, SPOS = 176 or 1200; for DS SPOS = Note: from v1.41, these timetags also apply to SPINPAD, PEACE onboard, HIA, CODIF & WHISPER

Available Data Listing - Cluster peacemoments has an “Available Data Listing” command (this uses CPMODES) peacemoments has an “Available Data Listing” command (this uses CPMODES) Example Output: 17th November 2002, CL-2 SPINPAD (LEEA) START: :00: STOP: :09: MAR 79 START: :10: STOP: :11: MAR 71 SPINPAD (HEEA) START: :00: STOP: :09: MAR 91 START: :10: STOP: :11: MAR 89 3DR (LEEA) START: :00: STOP: :09: DR (HEEA) START: :00: STOP: :09: DX1 (LEEA) START: :10: STOP: :09: [N] Note that each time interval listed has a single sweep mode and sweep preset.

Available Data Listing - Double Star Example Output: 13:20 to 14:20 11th March 2004, TC-1 3DF (HEEA) START: :20: STOP: :19: MAR 91 63

Output: GSE can select GSE or B-field aligned output can select GSE or B-field aligned output running the program with GSE output gives all of the following moments: running the program with GSE output gives all of the following moments: * n * v * P * Q * T plain ASCII, cef & cdf output files plain ASCII, cef & cdf output files

Output: B-field aligned running the program gives all of the following moments: running the program gives all of the following moments: * n * v para v perp * Q para Q perp * P para P perp P perp1 P perp2 * T para T perp T perp1 T perp2 P rotated so that the z-axis is parallel to the B-field P para = P zz P perp1 = P xx P perp2 = P yy P perp = (P perp1 + P perp2 )/2 P para = P zz P perp1 = P xx P perp2 = P yy P perp = (P perp1 + P perp2 )/2Also, T = P/(nk) T = P/(nk) where, e.g., v para = B (v.B)/(B.B) v para = B (v.B)/(B.B) v perp = v - v para v perp = v - v para B is the FGM PP B-field vector.

Configuration files can save/load configuration files can save/load configuration files - stores start & stop times & dates, distribution, sensor combination, S/C number, coordinate system, S/C potential offsets, etc. - preferences are not saved in these files (temperature units, timetag convention, etc) preferences can be saved preferences can be saved ‘Calculate All in Current Directory’ command ‘Calculate All in Current Directory’ command - calculates moments using all configuration files in the current directory

running from the command line peacemoment can be run from the command line - example: peacemoment can be run from the command line - example: peacemoments cl1_25Jan2005.cpm peacemoments_cmd CL1 3DR TL1L2B ON 1 2 bins NONE CSDS_AVERAGED eV

Restricting the integration ranges the energy, polar & azimuth integration ranges can be restricted the energy, polar & azimuth integration ranges can be restricted the lower & upper limits can be different for each spin if necessary the lower & upper limits can be different for each spin if necessary - useful if you want to isolate beams peacemoments reads in the limits from text files peacemoments reads in the limits from text files

Calculation of moments moments (relative to the bulk flow) of the velocity distribution function, e.g.: moments (relative to the bulk flow) of the velocity distribution function, e.g.: n = ∫ f(v).d 3 v nu = ∫ f(v).v.d 3 v p ij = m ∫ (v i - u i ).(v j - u j ).f(v).d 3 v q = (m/2) ∫ (v - u) 2.(v - u).f(v).d 3 v Integration is over the whole of velocity space.

Calculation of moments standard moments (these do standard moments (these do not contain the drift velocity): not contain the drift velocity): n = ∫ f(v).d 3 v nu = ∫ f(v).v.d 3 v P ij = m ∫ v i.v j. f(v).d 3 v Q = (m/2) ∫ v 2. v. f(v).d 3 v relative moments: relative moments: n = n u = u pij = Pij - m n u i u j q = Q - u Tr(P)/2 - u.P + m n u 2 u + m n u 2 u peacemoments calculates moments the same way as the on-board PEACE moments are calculated peacemoments calculates moments the same way as the on-board PEACE moments are calculated

Calculation of moments we only have 4 integrals to calculate: we only have 4 integrals to calculate: MOMENT i = ∫ f(v).M i (v)d 3 v where M 1 (v) = 1M 2 (v) = v M 3ij (v) = mv i v j M 4 (v) = (m/2) v 2 v Note:

Calculation of moments we know f(v) for a finite number of energy, polar & azimuth bins we know f(v) for a finite number of energy, polar & azimuth bins e.g. for 3DR e.g. for 3DR 15 energy bins covering E min to E max 6 polar bins covering degrees 16 azimuth bins covering degrees rewrite each integral as a sum over integrals for each bin, e.g. rewrite each integral as a sum over integrals for each bin, e.g.

Calculation of moments Therefore: Therefore:becomeswhere

Calculation of moments Assume f( , , v) doesn’t vary much inside each bin, therefore Assume f( , , v) doesn’t vary much inside each bin, thereforebecomes These integrals are carried out analytically. These integrals are carried out analytically. For more information see Extracting the Bulk Parameters of a Particle Distribution by R.A. Gowen & M.A. Birdseye For more information see Extracting the Bulk Parameters of a Particle Distribution by R.A. Gowen & M.A. Birdseye

Spacecraft potential corrections (1) when carrying out the energy integration: when carrying out the energy integration: - ignore any energy bins if V SC > E lower (here V SC is the S/C potential) This removes the photoelectrons. - remaining energy bins are rescaled E lower  E lower - V SC E upper  E upper - V SC This removes the acceleration of the electrons by the S/C potential.

Spacecraft potential corrections (2) can use EFW PP probe potential, or an ASCII file can use EFW PP probe potential, or an ASCII file two S/C potential offsets two S/C potential offsets - offset 1: difference between EFW probe and spacecraft potential (value from EFW team, typically 1 eV) V SC = V EFW + V offset 1 - offset 2: for removing photoelectrons above the EFW probe potential (either in bins or eV). Cuts off the integration at a higher energy. Important to set offset 2 correctly. Usually leave offset1 at default value. Important to set offset 2 correctly. Usually leave offset1 at default value. Increasing offset 1: Increases V SC Increasing offset 2: - removes more energy bins above V SC energy bins above V SC

User-defined S/C potential file if there’s no EFW data: if there’s no EFW data: ask someone from Cassini for help ask someone from Cassini for help look at spectrogram & determine the potential by eye look at spectrogram & determine the potential by eye if the potential for another S/C exists & is similar: if the potential for another S/C exists & is similar: efwgenerate :00: :00:00 CL1 generates an ASCII file containing EFW data

User-defined S/C potential file making your own S/C potential ASCII file: making your own S/C potential ASCII file: :00: :00: :00: :59: :00: :00: V 12:00:0010:00:00 V 12:00:0010:00:0011:00:00

Examples & removing photoelectrons

SPINPAD 2-sec resolution moments when HEEA and LEEA cover the same energy range when HEEA and LEEA cover the same energy range this has slightly better time resolution than 3DR! this has slightly better time resolution than 3DR!

It’s sometimes easy… (1) in this example (offset1 = 1 & offset2 = 0), i.e. V SC = V EFW + 1 in this example (offset1 = 1 & offset2 = 0), i.e. V SC = V EFW + 1 PEACEHIA

It’s sometimes easy… (3) PEACE (TH1H2B) PEACE (TL1L2B) HIA in this example (offset1 = 1 & offset2 = 0), i.e. V SC = V EFW + 1 in this example (offset1 = 1 & offset2 = 0), i.e. V SC = V EFW + 1

…but this is more common PEACEHIA

Comparisons with CIS If PEACE and CIS disagree: CIS might be in the wrong mode (look at the status bytes) CIS might be in the wrong mode (look at the status bytes) you need to adjust the S/C potential offset to ensure you need to adjust the S/C potential offset to ensure photoelectrons have been removed completely photoelectrons have been removed completely …

Importance of S/C potential corrections

Removing photoelectrons (1) removal of all photoelectrons (this can’t easily be automated) removal of all photoelectrons (this can’t easily be automated) an example spectrogram for < 100 eV using just EFW probe potential won’t remove all photoelectrons using just EFW probe potential won’t remove all photoelectrons offset 2 in peacemoments needs to be used to remove photoelectrons above offset 2 in peacemoments needs to be used to remove photoelectrons above the EFW probe potential the EFW probe potential need to be careful if there are cold electrons need to be careful if there are cold electrons

Removing photoelectrons (2) may need to use Steve Schwartz’ QTMC software to fill in the gap between the S/C potential and the lowest energy may need to use Steve Schwartz’ QTMC software to fill in the gap between the S/C potential and the lowest energy measured by peace measured by peace need to be careful if there are cold electrons need to be careful if there are cold electrons

Removing photoelectrons (2) Example 1: Example 1: Importance of setting offset 2 correctly green & blue cuvers overlap

Removing photoelectrons (4) Example 2: Example 2: Importance of setting offset 2 correctly

Removing photoelectrons (6) peacemoments can generate SpectroScalar layouts showing PEACE data & EFW potential peacemoments can generate SpectroScalar layouts showing PEACE data & EFW potential - meant to encourage users to look at spectrograms! - use “lower band edge” not “centre” energies!

Problems & interference from other instruments

Vz problem PEACEHIA CL-1CL-3 in 3D & on-board moments HEEAusually worse than LEEA

HEEA-LEEA velocity mirror effect PEACE (TH1H2B) PEACE (TL1L2B) HIA Vz problem also can be seen here!

HEEA saturation sometimes HEEA can be saturated sometimes HEEA can be saturated - use TL1L2B instead of TH1H2B - use TL1L2B instead of TH1H2B - use L1L2B instead of TH1H2 (if LEEA & HEEA cover same energy range) - use L1L2B instead of TH1H2 (if LEEA & HEEA cover same energy range) HEEALEEA

PEACE secondary electrons need to work out what to do about them… need to work out what to do about them…

PEACE internal electrons When the sun is within the field of view of the analyser, the influx of solar ultraviolet radiation produces low-energy photoelectrons.

WHISPER interference (1) sometimes moments have spikes at regular intervals: sometimes moments have spikes at regular intervals:

WHISPER interference (2)

WHISPER interference (3)

Problems caused by EDI in very low density plasmas there can sometimes be severe EDI-induced in very low density plasmas there can sometimes be severe EDI-induced spacecraft charging spacecraft charging

additional moments-related software

peaceplot Command-line program for instantly plotting moments comparisons (no endless menus and mouse-clicking) Command-line program for instantly plotting moments comparisons (no endless menus and mouse-clicking) plots: number density, speed, velocity, temperature, anisotropy, current density plots: number density, speed, velocity, temperature, anisotropy, current density PS or PDF output files PS or PDF output files All the moments plots in this talk were generated using peaceplot.

peaceplot - example peaceplot -date cl 4 -n

peacecurrent calculates current densities from peacemoments output files calculates current densities from peacemoments output files current density = electron charge x number density x velocity has ASCII and CDF output files has ASCII and CDF output files gives parallel & perpendicular currents from peacemoments B-field aligned output files gives parallel & perpendicular currents from peacemoments B-field aligned output files

peacetp Calculates transition parameters as described in Re-ordered Electron Data in the Low-Latitude Boundary Layer by M.A. Hapgood and D.A. Bryant Calculates transition parameters as described in Re-ordered Electron Data in the Low-Latitude Boundary Layer by M.A. Hapgood and D.A. Bryant The transition parameter (TP) indicates the range of progression between magnetosheath (TP = 0) and the magnetosphere (TP = 100) The transition parameter (TP) indicates the range of progression between magnetosheath (TP = 0) and the magnetosphere (TP = 100) fit polynomial to log[T e ] versus log[N e ]fit polynomial to log[T e ] versus log[N e ] project each data point onto the curveproject each data point onto the curve calculate distance from each projectedcalculate distance from each projected data point along the curve to an arbitrary data point along the curve to an arbitrary origin beyond the magnetosheath end origin beyond the magnetosheath end of the plot  raw TP of the plot  raw TP raw TP normalized to the range 0-100raw TP normalized to the range 0-100

peacetp needs a peacemoments ASCII output file or any ASCII file containing date, time, number density & temperature needs a peacemoments ASCII output file or any ASCII file containing date, time, number density & temperature generates an ASCII file containing timetags and transition parameters generates an ASCII file containing timetags and transition parameters

peacecdfcombine combines any number of cdf files, e.g. combines any number of cdf files, e.g. peacecdfcombine file1.cdf file2.cdf file3.cdf … uses the header from the first file and the data from all files uses the header from the first file and the data from all files

Other miscellaneous utilities

day-of-year  month & day to convert YYYY-MM-DD to YYYY-DOY to convert YYYY-MM-DD to YYYY-DOY daytodoy to convert YYYY-DOY to YYYY-MM-DD to convert YYYY-DOY to YYYY-MM-DD doytoday

ssledit command-line program for instantly making global changes to SpectroScalar layouts command-line program for instantly making global changes to SpectroScalar layouts Very useful when you have many spectrograms! (previously called peacess)

ssledit - examples change start & stop times change start & stop times ssledit layout.lay -st 12:00:00 -sp 15:00:00 change start time, date & S/C number change start time, date & S/C number ssledit layout.lay -st 10:00: sc 3 change y-axis limits change y-axis limits ssledit layout.lay -ymin 10 -ymax 1000 change colour scale change colour scale ssledit layout.lay -cmin 1e-06 -cmax also can change units, log  linear scales, etc. also can change units, log  linear scales, etc.

sslbatch for generating many spectrograms using the same layout, but different for generating many spectrograms using the same layout, but different - times & dates - S/C numbers gif & ps output options gif & ps output options Example: Example: sslbatch file.lay listfile where listfile is of the form: :00: :55: :30: :40: :30: :55:00 a batch interface to SpectroScalar

peacepromote For very easily promoting all data required to calculate moments onto e.g. a laptop For very easily promoting all data required to calculate moments onto e.g. a laptop peacepromote file.txt An example file.txt: TC1 FP MOM <- gets TC-1, 3DF + pitch angles, + everything for moments CL1 S <- gets CL-1, SPINPAD CL2 R MOM <- gets CL-2, 3DR, + everything for moments For Cluster, will promote : CPCGP, CPMODES, AUX, EFW & FGM For Double Star, will promote: DPGEN, AUX, & FGM batch promotion tool

moments in the IDFS archive

moments in the database MOMENTS MOMENTS - on-board moments with problems MOMS_L2 MOMS_L2 - on-board moments with corrections MOMS_L3 MOMS_L3 - current version of the “best” moments

status of MOMS_L2 do not use MOMENTS do not use MOMENTS MOMS_L2 : onboard moments but with MOMS_L2 : onboard moments but with - corrected geometric factors - corrected factor of 2 - available in GSE coordinates - (now) has correct pressure tensor & temperature MOMS_L2 currently available for 2001 to MOMS_L2 currently available for 2001 to

status of MOMS_L2 problems still in MOMS_L2: problems still in MOMS_L2: based on on-board moments which use on-board energy tables, efficiencies & response surfaces. Any errors in these parameters cannot be corrected in ground processing. based on on-board moments which use on-board energy tables, efficiencies & response surfaces. Any errors in these parameters cannot be corrected in ground processing.

status of MOMS_L3 currently corresponds to version 3 PEACE PP currently corresponds to version 3 PEACE PP - generated using MOMS_L2 moments - rules to decide which sensor combination to use depending on the S/C potential e.g. if B contains mostly photoelectrons, use TL1L2 (not TL1L2B) Example number density comparions with HIA Example number density comparions with HIA

the end