Crossover Height Differences Monitoring
Single cycle crossover height differences over the Antarctic and Greenland ice sheets (grounded ice of the BedMachine masks): the difference between the heights of the ascending and descending passes of the cycle where their ground tracks cross (ascending minus descending), interpolated between consecutive 20 Hz measurements of each track. Crossovers are found separately in LRM and SARin modes and for each retracker, using heights without the retracker's height error flag, along tracks of the measurement (POCA) locations. A pair of passes gives one crossover (the median of their crossings, as tracks of POCA locations can cross more than once). Over time intervals without surface change the differences measure the height precision of the altimeter and processing chain. Differences larger than 5 m are counted as outliers, but excluded from the statistics (the Valid column) and maps. The maps show the mean crossover difference within 20 km of each 10 km grid cell.
Retracker 3: measurements with the height_3_error bit (mask 4194304) of flag_prod_status_20_ku set are excluded. Only LRM mode measurements are used. Crossover differences larger than 5 m are outliers: counted, but not valid.
| Retracker | LRM | SARin |
|---|---|---|
| Retracker 1 height_1_20_ku | Ocean CFI retracker | UCL margins retracker |
| Retracker 2 height_2_20_ku | UCL land-ice retracker | N/A (not used) |
| Retracker 3 height_3_20_ku | OCOG retracker | N/A (not used) |
Baseline-F, cycle 194: 25-Aug-2026 to 23-Sep-2026 · 263 GDR-A files · data covers 18.1 of 30 days Partial cycle processed 11-Oct-2026 01:13 UTC
Crossover Height Differences: Retracker 3 (OCOG retracker), LRM mode: Maps (10 km grid, mean)
Crossover Height Differences: Retracker 3 (OCOG retracker), LRM mode: Cycle 194 Statistics
| Area | Crossovers | Valid | Mean (m) | Median (m) | Std Dev (m) | RMS (m) | Min (m) | Max (m) |
|---|---|---|---|---|---|---|---|---|
| Antarctic Ice Sheet | 22,060 | 21,862 (99.1%) | -0.02 | 0.00 | 0.48 | 0.48 | -4.93 | 4.99 |
| Greenland Ice Sheet | 162 | 162 (100.0%) | 0.03 | -0.01 | 0.40 | 0.40 | -0.68 | 4.20 |
Statistics use every crossover of the cycle within each area acquired in LRM mode. Std Dev is the population standard deviation, RMS the root mean square.
Crossover Height Differences: Retracker 3 (OCOG retracker), LRM mode: Trends
Click a point to show that cycle.
