Level 2 data available via the on-line data base is orbital format ice data records at the full data rate (10/sec for Seasat and Geosat, and 20/sec for ERS-1) which contain the time, precise location, altimeter height measurement, corrected precise surface elevation, atmospheric corrections, tidal values, retracking corrections, and AGC. This data is updated on-line as more precise orbits, corrections, and tide values become available.
IDR Header Record
| BYTES | TYPE | DESCRIPTION |
|---|---|---|
| 1-2 | C*2 | 'IH' for IDR header |
| 3-16 | C*14 | Name of rev access directory that corresponds to this file |
| 17-30 | C*14 | Name of georeferenced directory that corresponds to this file |
| 31-44 | C*14 | Name of bin/rev directory that corresponds to this file. |
| 45-48 | I*4 | Version No. of this data base - same as used in name |
| 49-52 | I*4 | Year month day of beg of file YYMMDD |
| 53-56 | I*4 | HHMMSS of beginning of file |
| 57-60 | I*4 | YYMMDD of end of file |
| 61-64 | I*4 | HHMMSS of end of file |
| 65-68 | I*4 | Satellite ID |
| 69-76 | C*8 | Continent or ocean covered by database |
| 77-100 | ??? | Spares |
IDR Processing Record
| Bytes | Type | Description |
|---|---|---|
| 1-2 | C*2 | 'IP' for IDR processing |
| 3-8 | C*6 | YYMMDD, year, month, day of processing |
| 9-26 | C*18 | name and version number of processing program (i.e. BINS8902) |
| 27-40 | C*14 | name of input file # 1 |
| 41-100 | C*14 | Names of other input files in C*14 variables |
IDR Rev Record
| Bytes | Type | Description |
|---|---|---|
| 1-4 | C*4 | 'IR ' for IDR Rev |
| 5-8 | I*4 | Rev number |
| 9-12 | I*4 | Date of first processed data rec in pass begin (MJD) |
| 13-16 | I*4 | Time of first processed data rec in pass (sec) |
| 17-20 | I*4 | Fractional seconds of time of first processed data rec in pass (microsec) |
| 21-24 | I*4 | Longitude of asc node (microdegrees) |
| 25-26 | I*2 | RMS of orbit adjustment in bytes 57-58 (mm) |
| 27-28 | I*2 | RMS of orbit adjustment in bytes 61-62 (mm) |
| 29-30 | I*2 | RMS of orbit adjustment in bytes 65-66 (mm) |
| 31-32 | I*2 | RMS of orbit adjustment in bytes 79-80 (mm) |
| 33-100 | ??? | Spares |
IDR Data Record
| BYTES | TYPE | DESCRIPTION |
|---|---|---|
| 1-2 | C*2 | File/record type 'ID' for IDR data |
| 3-4 | I*2 | Retracking status word part 1 |
| 5-8 | I*4 | Time since time on rev header record (microseconds) |
| 9-12 | I*4 | Latitude (Microdegrees N) |
| 13-16 | I*4 | Longitude (Microdegrees E) |
| 17-20 | I*4 | Surface height relative to the ellipsoid -- original orbits (D-PAF) (cm) |
| 21-24 | I*4 | WDR record number associated with this IDR record. |
| 25-28 | I*4 | Altimeter measurement (mm) |
| 29-32 | I*4 | Altimeter measurement status word |
| 33-36 | I*4 | Surface height status word |
| 37-38 | I*2 | Ionosphere correction (mm) |
| 39-40 | I*2 | Wet Troposhere correction #1 (mm) |
| 41-42 | I*2 | Dry Troposhere correction (mm) |
| 43-44 | I*2 | Geoid height (cm) |
| 45-46 | I*2 | Solid tides (mm) |
| 47-48 | I*2 | Ocean tides (mm) |
| 49-50 | I*2 | Slope correction (cm) |
| 51-52 | I*2 | Significant wave height (cm) |
| 53-54 | I*2 | AGC (.01 DB) |
| 55-56 | I*2 | Attitude (.01 deg) |
| 57-58 | I*2 | Reserved for future use. |
| 59-60 | I*2 | Increment to surface height for precision orbit #1 (cm) |
| 61-62 | I*2 | Reserved for future use. |
| 63-64 | I*2 | Increment to surface height for precision orbit #2 (cm) |
| 65-66 | I*2 | Reserved for future use. |
| 67-68 | I*2 | Increment to surface height for precision orbit #3 (cm) |
| 69-70 | I*2 | GSFC Retracking correction from 1st ramp (cm) |
| 71-72 | I*2 | GSFC Retracking correction from 2nd ramp (cm) |
| 73-74 | I*2 | Sigma of ramp 1 position (0.01 gates) |
| 75-76 | I*2 | Sigma of ramp 2 position (0.01 gates) |
| 77-78 | I*2 | Tangent of cross track slope (x10^5) |
| 79-80 | I*2 | Reserved for future use. |
| 81-82 | I*2 | Wet Troposhere correction (ATSR/M) (mm) |
data in 83-92 for GEOSAT and Seasat are set to 0 for ERS-1 they are defined as follows:
| 83-84 | I*2 | Mode ID status word |
| 85-86 | I*2 | Data Location status word |
| 87-88 | I*2 | Range, Sigma0, Hs combined status words |
| 89-90 | I*2 | Waveform error, Waveform shape, and Location error combined status words |
| 91-92 | I*2 | Low rate (1/sec) flag words |
| 93-94 | I*2 | 10% Threshold retracking correction (cm) |
| 95-96 | I*2 | 20%Threshold retracking correction (cm) |
| 97-98 | I*2 | 50%Threshold retracking correction (cm) |
| 99-100 | I*2 | Retracking status word part 2 |
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Curator: Jairo Santana NASA Official: Dr. H. Jay Zwally Last Updated: 12/11/2006 |