CALIBRATION AND VALIDATION OF CRYOSAT-2 LOWRESOLUTION MODE DATA

摘要

Running ahead of the continuously growing need for operationalrnuse of sea level products, TUDelft started offrnthe Radar Altimeter Database System RADS many yearsrnago. This system attends to a global international sealevelrnservice. It supports, on one hand, science, like studiesrnon ocean circulation, El Nio, sea level change, andrnice topography, and on the other hand (offshore) operations,rnlike delivery of ocean current information, windandrnwave statistics, ice detection and ice classification.rnAt present, the database is used by a large scientific communityrnthroughout the world, and is daily maintained andrndeveloped by Altimetrics LLC, TUDelft and NOAA. Itrncontains all historic altimeter data, and now has to be updatedrnwith the data from ESAs ice mission CryoSat-2,rnwhich was launched successfully in April 2010. Thesernnew data are important to augment the data set and byrnthat to improve the estimates of sea level change andrnits contributors. For this the data have to be validatedrnand calibrated, necessary corrections added and improvedrn(including modelling of corrections that are not directlyrnavailable from the CryoSat-2 platform), and the orbit accuracyrnverified and if possible the orbits brushed up. Subsequently,rnvalue-added ocean and ice products need to berndeveloped in synergy with all the other satellite altimeterrndata. During the commissioning phase we primarilyrnlooked at the sanity of the available level-1b and level-2rnLow Resolution Mode (LRM) data. Here, for the 2011rnCryoSat Validation Workshop, we present the results ofrnour calibration and validation of LRM L2 data by internalrncomparison of CryoSat-2 and external comparison withrnother satellites. We have established a range bias of 3.77rn(measurement range too long) and a timing bias of 8.2msrn(measurement range too late).