Documentation for ISEE 3 Solar Wind Data Set 78-079A-01S: One-Hour Averaged Solar Wind Electron Moments H. Kent Hills, May 15, 1995 Entered into NSSDC's Technical Reference File as #B44583. ---------------- DATA SET BRIEF DESCRIPTION: These hour-averaged data were generated at NSSDC from the ISEE 3 data set 78-079A-01O, which has a nominal 168-second resolution and is a data set of solar wind electron moments from the Los Alamos experiment. This hour-averaged data set contains date, hour, and the following averaged parameters: electron density; bulk flow speed; flow azimuth; Tperp; Tpar; azimuth of the temperature maximum; heat flux; and the heat flux azimuth. In addition, the standard deviation for each average and the number of values used in each average are also included. A data inventory file is also available, showing the hours of each day for which data exist. ---------------- USER DOCUMENTATION: This averaged data set was generated at NSSDC by Dr. H. Kent Hills from the nominally 168-second resolution ISEE 3 data set 78-079A-01O. The standard deviation for each average and the number of values used in each average are also included. If the calculated standard deviation of any of the three angles exceeded 9999.9, then the value was replaced with 9999.9 (this happened only a few times). There are many cases where the number of values is 1. Note that the standard deviations will be zero in these cases. Obviously this is only a reflection of the lack of scatter of values, and is an unrealistic measure of the reliability of the particular data value. The azimuth angles given in the input data were processed in a special way to avoid such problems as averaging +178 degrees and -178 degress to get 0 instead of 180 degrees. Each angle was assumed to represent a vector of unit magnitude. The vector was converted to rectangular components, then all of the x components and all of the y components were averaged to determine an averaged vector. From the two averaged components an averaged angle was computed. The magnitude of the averaged vector was also computed and included in the output (items 27-29 in the format description). When input angles are all nearly the same, this magnitude is very near 1. The Fortran source code for the program used to generate this data set from the input data is available for reference. During the hour-averaging process, it was discovered that numerous input files had duplicate segments of data, and some files had obvious errors in assigning the day at a few times very near midnight (the day number was changed in these cases). Also, in one case a few record times appeared twice with slightly different data values. All these problem files were corrected to eliminate all instances of duplication of record-time and all instances of record-times not being in increasing order. Software is available to read the data files and display each long record as a series of short records that can be displayed on any terminal screen. A data inventory file was generated from the actual data files, and it shows the hours of each day for which data exist, for all years of the data set. FORMAT DESCRIPTION: Record format: Variable length, maximum 188 bytes Record attributes: Fortran carriage control 1) date (YYMMDD) 2) hour (0 - 23) 3) average electron density (cm-3) 4) average bulk flow speed (relative to the spacecraft) (km/s) 5) average azimuth of the bulk flow (GSE+180 degrees) 6) average minimum total temperature (Tperp, deg K) 7) average maximum total temperature (Tpar, deg K) 8) average azimuth of angle of maximum temperature (degrees, 135=Parker spiral angle) 9) average heat flux (erg cm-2 sec-1) 10) average azimuth of the heat flux (degrees, 0=antisunward, 90=towards dawn) 11-18) standard deviation of items 3-10 19-26) number of values used to compute the averages in items 3-10 27-29) magnitude of the averaged vector for items 3, 8, and 10 All records are 188 bytes in length. The first record in each file provides ASCII labels for the columns of the data records that follow. The data records may be read with the following Fortran statements: read(7,2001)itime,ihour,parmavg,sigma,parmcount,rsq 2001 format(1x,I6,1x,I2,2E10.3,F6.1,2E10.3,F6.1,E10.3,F6.1, 2 2E10.3,F6.1,2E10.3,F6.1,E10.3,F6.1, 3 8I3,3F6.3) ============================================================================== PERTINENT DOCUMENTATION SELECTED FROM THE ORIGINAL HIGH-TIME-RESOLUTION DATA SET: These data have been supplied by Dr. J. T. Gosling, Los Alamos National Laboratory and contain high temporal resolution solar wind electron moments derived from measurements obtained by the Los Alamos electron experiment on the ISEE-3/ICE spacecraft. The ion instrument on ISEE-3 failed on 1980-Feb-26 so no proton data are available from this instrument after that date. The temporal resolution of these data is usually approximately 168 seconds. Each data record (2 lines) contains 1) the date (YYMMDD), 2) the time in seconds form start of day (SSSSS.S), 3) the UT time of day in HHMMSS>0, 4) the electron density (cm-3), 5) the bulk flow speed (km/s), 6) the bulk flow azimuth (GSE+180 degrees), 7) the minimum total temperature (Tperp, deg K), 8) the maximum total temperature (Tpar, deg K), 9) the angle of maximum temperature (degrees, 135=Parker spiral angle) 10) the heat flux (erg cm-2 sec-1), 11) the heat flux azimuth (degrees, 0=antisunward, 90=towards dawn) ---------- Bulk flow speed and azimuth (parameters 5 and 6) ------------------------------------------------ The plasma bulk flow speed is measured relative to the spacecraft and the bulk flow azimuth is measured positive from the (spacecraft-centered) solar ecliptic (SE) -X direction toward the SE -Y direction, i.e., 0 degrees corresponds to antisunward flow and positive flow angles correspond to flow towards dawn (+90 deg), and negative flow angles correspond to flow towards dusk (-90 deg). Thus, antisunward = 0 deg = -GSEX [ should be SEC?] toward dawn = +90 deg = -GSEY sunward flow= 180 deg = +GSEX toward dusk = -90 deg = +GSEY Z-axis = spacecraft spin axis direction, North The spacecraft spin axis was maintained within 0.5 degree of perpendicular to the ecliptic. T-max azimuth (parameter 9) --------------------------- The Tmax azimuth ranges from 0 to 180 degs with 0 and 180 degs corresponding to alignment with the sun-spacecraft line and 135 degs corresponding to the nominal Parker field spiral angle at 1 AU. The alignment of the maximum temperature angle with the magnetic field is usually within 15 degrees. The electron temperature maximum is aligned perpendicular to the field about 2% of the time in the solar wind. See papers by J.L. Phillips et al. in JGR 1989, 1990. Heat flux azimuth (parameter 11) -------------------------------- Plasma heat flux azimuth (where available) is similar to the velocity azimuth, but it is measured from 0 to 360 degrees, i.e., 0 and 360 degrees correspond to heat flux directed antisunward, 180 degrees corresponds to sunward heat flux, 90 degrees corresponds to a heat flux directed toward dawn, and 270 degrees corresponds to a heat flux directed toward dusk. Thus, antisunward = 0,360 deg = -GSEX [ should be SEC?] toward dawn = 90 deg = -GSEY sunward flux= 180 deg = +GSEX toward dusk = 270 deg = +GSEY ------------------------------------ For a description of the Los Alamos instrument on the ISEE-3/ICE spacecraft, see: Bame, S.J., J.R. Asbridge, H.E. Felthauser, J.P. Glore, H.L. Hawk, and J. Chavez, ISEE-C solar wind plasma experiment, IEEE Trans. Geosci. Electron., GE-16, 160-162, 1978. ------------------------------------------------------------ =============== From: NCF::SUMANT "Sumant Krishnaswamy, NSSDC" 2-MAY-1991 12:45:16.38 To: ESSDP1::073500 CC: SUMANT Subj: Error bars on ISEE data parameters Jack, Do you have any estimates of the uncertainties or error bars associated with the various electron and proton moments, flow angles, and other high time resolution parameters (solar wind), geotail, g-z) on the ISEE-1, 2, and -3 data tapes you have sent to us over the last couple of years? Are they discussed in any of your papers? Thanks. Sumant =============== From: ESSDP1::073500 "Jack Gosling" 3-MAY-1991 13:07:26.91 To: NCF::SUMANT CC: 073500 Subj: Error bars on ISEE data parameters Sumant, We do not have any error bars to provide you and I do not recall that they have ever been discussed in any of our publications. Jack Gosling ================= NSSDC note: For comments on intercomparison of data from different spacecraft, see also Russell and Petrinec, GRL, 19, No. 10, 961-963, May 22, 1992. =================