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Level 1 data available via the on-line data base is orbital format waveform data records at the full data rate (10/sec for Seasat and Geosat, and 20/sec for ERS-1) which contain the time, location altimeter return waveform, and retracking parameters.
WDR Header Record
| BYTES | TYPE | DESCRIPTION |
|---|---|---|
| 1-2 | C*2 | 'WH' for WDR header |
| 3-16 | C*14 | Name of rev access directory to use to read this file |
| 17-30 | C*14 | Name of georeference 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 DATA BASE |
| 77-184 | ??? | Spares |
WDR Processing Record
| Bytes | Type | Description |
|---|---|---|
| 1-2 | C*2 | 'WP' for WDR processing record |
| 3-8 | C*6 | YYMMDD - year, month, day of date processed |
| 8-26 | C*18 | Name and version number of processing program (i.e. BINS8902) |
| 27-40 | C*14 | Name of input file # 1 |
| 41-184 | ??? | Names of other input files in C*14 variables |
WDR Database Configuration Record
| Bytes | Type | Description |
|---|---|---|
| 1-4 | C*4 | 'WC ' - for WDR data base configuration |
| 5-8 | I*4 | latitude in .01 deg N of beg of data base |
| 9-12 | I*4 | latitude in .01 deg N of end of data base |
| 13-16 | I*4 | longitude in .01 deg E of beg of data base |
| 17-20 | I*4 | longitude in .01 deg E of end of data base |
| 21-184 | ??? | Spares |
WDR Row Descriptor Record
| Bytes | Type | Description |
|---|---|---|
| 1-4 | C*4 | 'WS ' - for WDR Row descriptor record giving latitude and longitude division sizes that pertain to these rows |
| 5-8 | I*4 | beg row number that information on this rec pertains to where row 1 corresponds to beg latitude |
| 9-12 | I*4 | end row number that information on this rec pertains to where row 1 corresponds to beg latitude |
| 13-16 | I*4 | size of latitude division between individual rows this pertains to,to the beg row through the end row -1 in .01 deg |
| 17-20 | I*4 | number of longitude divisions in each row |
| 21-184 | ??? | Spares |
There can be as many header records as required as long as they start with the letter 'C' and are placed in the header region of this file. The order of the header records is not important as long as they all precede the data records.
WDR Rev Record
| Bytes | Type | Description |
|---|---|---|
| 1-4 | C*4 | 'WR ' for WDR 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 ( microdeg) |
| 25-184 | ??? | Spares |
WDR data record
| BYTES | TYPE | DESCRIPTION |
|---|---|---|
| 1-2 | C*2 | File/Record type 'WD' for WDR data |
| 3-4 | I*2 | Retracking status word part 1 |
| 5-8 | I*4 | Time in microsec from time on pass header record |
| 9-12 | I*4 | Latitude in microdeg N |
| 13-16 | I*4 | Longitude in microdeg E |
| 17-20 | I*4 | Surface Height relative to the ellipsoid - original orbit (cm) |
| 21-24 | I*4 | Surface Height status word |
Bytes 25-42 contain the parameters describing the function used to fit the waveform for GSFC retracking.
| 25-26 | I*2 | þ(1) = Noise level in 0.1 counts |
| 27-28 | I*2 | þ(2) = Amplitude increment to top of erf for first ramp in counts |
| 29-30 | I*2 | þ(3) = Gate of midpoint of erf for first ramp in .01 gates |
| 31-32 | I*2 | þ(4) = Rise time of erf for first ramp in 0.1 gates |
| 33-34 | I*2 | þ(5) = Amplitude increment to top of erf for second ramp in counts |
| 35-36 | I*2 | þ(6) = Gate of midpoint of erf for second ramp in .01 gates |
| 37-38 | I*2 | þ(7) = Rise time of erf for second ramp in 0.1 gates |
| 39-40 | I*2 | þ(8) = Exponential decay factor for second ramp in (.0001/Gates) |
| 41-42 | I*2 | þ(9) = slope between first and second ramps in (.01/gate) |
| 43-44 | I*2 | Waveform Peakiness (x1000) |
| 45-46 | I*2 | Tracking gate (.01 gates) |
| 47-48 | I*2 | AGC in .01 dB |
| 49-50 | I*2 | H13 in cm |
| 51-178 | I*2 | Waveform 64 Gates in counts |
| 179-180 | I*2 | Sigma Naught in .01 dB !! Corrected 4/26/2001 by JPD |
| 181-182 | I*2 | Retracking status word part 2 |
| 183-184 | I*2 | spares |
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Curator: Jairo Santana NASA Official: Dr. H. Jay Zwally Last Updated: 12/11/2006 |