This file contains notes and pertinent emails used in the recomputation of TELEX 2004 MCASS data. Dean Lauritsen -- lauritsn@ucar.edu 22 July, 2004 -------------------------------------------------------------------------------------------------- Les Showell (NSSL) was the system operator for Missions 1, 2, 3 part1 and 3 part2. Ivy Apostolakopoulos (NSSL) was the system operator thereafter. Ivy compiled an excellent Excel spreadsheet summary of the MCASS soundings for this field program. The file name is: "TELEX_2004_Sonde_Tracking.xls" and should be included as a part of the final data set. -------------------------------------------------------------------------------------------------- The recomputed 'D' files have had their file names modified to indicate they've been reprocessed. Example 1: D20040513_015658.1 <-- the original data file taken in the field D20040513_015658_Rz.1 <-- the recomputed file; 'R'=recomputed, 'z'=final iteration Example 2: D20040524_232113.1 <-- the original data file taken in the field D20040524_232113_RMz.1 <-- the recomputed file; 'R'=recomputed, 'M'=Merged file*, 'z'=final iteration * a Merged file is a special case situation where the operator terminated a sounding, reaquired the signal at a later time and started re-tracking. The MCASS data acquisition software needs to download sonde specific sensor coefficients from each sonde prior to flight. After a sonde is launched it is not possible to access these coefficients, so the operators hit on the idea of loading coefficients from an unused sonde and continuing from there. All PTU data was erroneous in this second part of the sounding and needed to be recomputed with the correct coefficients and the resulting data 'merged' with the recomputed part 1 'D' file. There were two instances of this in TELEX 2004. -------------------------------------------------------------------------------------------------- A note about wind error flags in the 'D' prefix files. The Garmin GPS receiver in the MCASS sonde transmits two data sentences for each GPS measurement. The $GPGGA sentence has a UTC timstamp and Lat/Lon/Alt, satellites in track and other data. The $PGRMV has only X/Y/Z velocities. Each sentence ends with a checksum that is used to flag data as having telemetry bit errors. However, the 'D' file only has a single bit error/missing data flag value for BOTH the velocity and position data. This wind/position flag is the "1" of the "S01" data field in the 'D' data line. In the original 'D' file (data taken in the field) this flag is set if EITHER or BOTH of the raw GPS velocity and position lines have a bit error. For the TELEX 2004 post-processing, the recomputation keyed on the $GPGGA GPS Position sentence and only passed sentences without bit errors. Therefore, when a "1" wind flag is seen in the resulting 'D' files it means that the position data is without error but a velocity error was detected. The following example shows an example of this circumstance. In the resulting recomputed 'D' line, the position data can be trusted but the velocity data cannot. $GPGGA,002118,3556.3362,N,09813.3995,W,1,08,0.9,8066.4,M,-25.5,M,,*4C <-- GPS Position line; NO bit errors $PGRMV,18.2,1.5E <-- GPS Velocity line; it has bit errors The two data lines above produce the following GPS Velocity (wind) and GPS Position data: MCASS-T02 COM GMT GMT Air Air Rel Wind Wind Vert GPS GPS Geopoten GPS Sonde Sonde GPS Wind GPS MCASS-T02 COM Sonde Date Time Press Temp Humid Dir Spd Veloc Longitude Latitude Altitude Wnd RH1 RH2 Snd Error Altitude MCASS-T02 COM ID yymmdd hhmmss.ss (mb) (degC) (%) (deg) (m/s) (m/s) (deg) (deg) (m) Sat (%) (%) Sat (m/s) (m) MCASS-T02 COM --------- ------ --------- ------- ------ ------ ------ ------ ------ ----------- ---------- -------- --- ------ ------ --- ----- -------- MCASS-D02 S01 034745045 040530 002118.30 367.34 -25.22 75.53 265.29 18.26 0.00 -98.223325 35.938937 99999.00 8 75.53 69.47 8 0.90 8066.40 Dean -- 20 July, 2004 -------------------------------------------------------------------------------------------------- Hi, Dean - Here's my list: Case 1) 20040524_232113.1 and 20040525_003057.3 This is one where .1 (on sonde 152)was accidentally terminated, and Les started sonde 171 on channel 3, which gave the .3 file. So it seems like the .3 will need to be recalculated with the .1 coefficients, then appended to .1. Does that sound right? Case 2) 20040524_234941.2 and 20040525_000345.4 This one may be ok. The .2 file was sonde 171, which never acquired GPS in the time it was out, so it was pulled back in and didn't fly. Les did not terminate .2 - he just started sonde 058 on channel 4 on same frequency around 0003 UTC (you can see the new sonde appear in the .2 files at this time). But since this sounding was on a different channel, the .4 file should be just fine as far as coefficients go, right? If so, we can just junk the .2 file. I think recalculating .4 might still be a good idea, as from what I've seen in it there might be recoverable GPS positions that were wiped out from D and T due to channel 2 still running. Let me know what you think. Case 3) 20040603_023257.3 and 20040603_050108.3 I had sonde 171 running on channel 3 - thought it was down (completely ratty telem) so I terminated. EFM operator picked it up an hour later, so started sonde 125 on channel 3 at same frequency. Again, this seems like the latter .3 file needs to be recalculated using the former .3 coefficients, then appended. Sorry for all the confusion. We surely never intended these actions to be the cause of so much hassle. I'm still going through the flights one by one - I should have my spreadsheet about ready to go today or tomorrow, so I'll send that to you as a check against your original list. Thanks - Ivy ----- Original Message ----- From: Dean Lauritsen Date: Monday, July 12, 2004 4:08 pm Subject: MCASS 'Mixed Sonde' Soundings >> Hi Ivy, >> >> Any chance you've positively identified the three (you thought) >> 'mixed >> sonde' MCASS soundings? These are the ones that started with the >> correct sensor coeff's and ended with coeff's from another. I'd >> like to >> make a recomputation run on the entire MCASS group once these >> oddballs >> are identified. >> >> Thanks, >> Dean..... -------------------------------------------------------------------------------------------------- Dean - here's my input to your listing. In a few cases I added files you didn't have listed, just in case you go back and wonder what the others are. Ivy. Mission 1 (1 file; 1 sonde) D20040513_015658.1 - Flight 1 Mission 2 (3 files; 3 sondes) D20040513_183815.1 - Flight 2 (raw GPS timetag jump at 184354 to 184342 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040513_184851.2 - Flight 3 (raw GPS timetag jump at 185625 to 185613 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040513_185738.3 - Flight 4 Mission 3 part 1 (6 files; 3 sondes) D20040524_232113.1 - Flight 5 part 1 (raw GPS timetag jump at 232625 to 232613 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040524_234024.3 - Flight 6 (raw GPS timetag jump at 235125 to 235113 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040524_234941.2 - Flight 7 part 1 (NO LAUNCH -- dkl) D20040525_000345.4 - Flight 7 part 2 (raw GPS timetag jump at 001624 to 001612 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040525_003057.3 - Flight 5 part 2 D20040525_005742.1 - no flight, aborted on ground Mission 3 part 2 (4 files; 1 sonde) D20040525_025804.4 - test D20040525_033508.1 - test D20040525_035415.1 - Flight 8 D20040525_040643.2 - no flight, aborted on ground (would have been Flight 9) Mission 4 (6 files; 4 sondes) D20040526_215717.1 - Flight 10 (raw GPS timetag jump at 221854 to 221842 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040526_222001.2 - Flight 11 D20040526_224037.3 - Flight 12 (raw GPS timetag jump at 225624 to 225612 (acquired Almanac and corrected for Leap Seconds -- dkl)) D20040526_233023.4 - Flight 13 D20040527_000653.1 - Flight 14 first try - did not acquire GPS, tried new sonde (NO LAUNCH -- dkl) D20040527_002517.2 - Flight 14 second try - did not acquire GPS - flight aborted (NO LAUNCH -- dkl) Mission 5 (6 files; 3 sondes) D20040529_231352.1 - Flight 15 D20040529_233549.2 - Flight 16 D20040529_235943.3 - Flight 17 - EFM detached at launch; (GPS timetag problem? not sure -- dkl) D20040530_001817.4 - no flight D20040530_005828.1 - Flight 18 - bad pressure, tried new sonde (NO LAUNCH -- dkl) D20040530_010731.1 - comments are 'bad sonde' - doesn't say why - Flight 18 aborted Mission 6 (4 files; 3 sondes) D20040603_013614.1 - Flight 20 D20040603_021824.2 - Flight 21 D20040603_023257.3 - Flight 22 part 1 D20040603_050108.3 - Flight 22 part 2 Mission 7 (1 file; 1 sonde) D20040606_040153.1 - Flight 23 Mission 8 (1 file; 1 sonde) D20040617_064508.1 - Flight 24 (uses 2nd of 2 coeff groups: S20040617_064508.1.fix -- dkl) Mission 9 (3 files; 3 sondes) D20040618_055058.1 - Flight 25 D20040618_060423.2 - Flight 26 (uses 2nd of 2 coeff groups: S20040618_060423.2.fix -- dkl) D20040618_062912.3 - Flight 27 Mission 10 (8 files; 5 sondes) D20040619_123200.1 - Flight 28 D20040619_124349.2 - Flight 29 D20040619_125439.3 - prepped sonde for Flight 30, turned off during launch hold due to interference D20040619_130331.3 - Flight 30 D20040619_132650.4 - prepped sonde for Flight 31, did not acquire GPS, tried new sonde D20040619_133257.4 - prepped sonde for Flight 31, had funky pressure, tried new sonde D20040619_134036.4 - Flight 31 D20040619_143955.1 - Flight 32 Mission 11 (7 files; 4 sondes) D20040620_152510.1 - Flight 33 D20040620_153033.2 - Flight 34 D20040620_154710.3 - prepped sonde for Flight 35, turned off during launch hold due to interference D20040620_160837.3 - Flight 35 D20040620_161825.4 - prepped sonde for Flight 36, turned off during launch hold D20040620_162335.4 - Flight 36 D20040620_175732.1 - ground GPS test Mission 12 (7 files; 4 sondes) D20040622_053741.1 - Flight 37 D20040622_054542.2 - prepped sonde for Flight 38, turned off during launch hold D20040622_062158.2 - Flight 38 D20040622_063722.3 - prepped sonde for Flight 39, didn't acquire GPS, tried new sonde D20040622_064141.4 - prepped sonde for Flight 39, GPS wasn't happy, tried new sonde D20040622_065754.3 - Flight 39 D20040622_071230.4 - Flight 40 Mission 13 (1 file; 1 sonde) D20040629_001548.1 - Flight 41