Global calibration of SARAL/AltiKa using multi-mission sea surface height crossovers

Denise Dettmering (Deutsches Geodätisches Forschungsinstitut (DGFI), Germany)


Christian Schwatke (DGFI, Germany); Wolfgang Bosch (DGFI, Germany)

Event: 2014 SARAL/AltiKa workshop

Session: Calval over ocean / In situ Calval

Presentation type: Type Poster

In March 2014 SARAL/AltiKa completed its first year in orbit. We perform a comprehensive quality assessment based on the first 10 cycles of GDR-T 1 Hz data set by means of a global multi-mission crossover analysis. Within this approach, SARAL sea surface heights (SSH) are compared with data from other current missions, mainly Jason-2 and Cryosat-2, to reveal its accuracy and consistency with the other altimeter systems. Alongside with global mean range bias and instrumental drifts, investigations on geographically correlated errors as well as on the realization of the systems origin are performed. The study proves the high quality and reliability of SARAL. The mission shows only a small range bias of about 5 cm with respect to Jason-2 and neither significant time-tag bias nor instrumental drifts. With 1.3 cm the scatter of radial errors is in the same order of magnitude as for Cryosat-2 and Jason-1 geodetic mission phase and will probably further improve using an enhanced sea state bias (SSB) model. However, the wet tropospheric corrections from SARAL radiometer still show some systematic effects influencing the range bias as well as geographically correlated error patterns and the z-component of the origin. Improved inflight calibration will be necessary to overcome these effects.
Denise Dettmering
Deutsches Geodätisches Forschungsinstitut (DGFI)