Global Calibration and Validation of the Jason-2 and SARAL Geophysical Data Records

We present updated results on the global calibration and validation of the Jason-2 version D Geophysical Data Records (GDRs), and the first test release of SARAL/Altika GDRs. We focus in particular on temporal and geographically correlated errors, and the analysis of inter-satellite differences of various components of the two sea surface height measurement systems at ground-track crossing locations (crossovers). A valuable approach for evaluating geographically correlated errors is segregating the inter-satellite differences by quadrant, namely ascending and descending ground tracks in the northern and southern hemisphere. We also consider systematic differences in the altimeter measurements as a function of significant wave height and wind speed, noting that calibration of the backscatter coefficient, wind speed, and sea state bias is most likely needed for the SARAL/AltiKa measurements at this early stage of the mission. In doing so, one of our objectives is to develop an estimate for the overall sea surface height measurement system error budget for SARAL.