Global SARAL Data Quality Assessment of IGDR and GDR data

The SARAL mission was successfully launched on 2013-02-25, and cycle 1 started on 2013-03-14. SARAL has a single frequency altimeter (the first altimeter in Ka-band) and a dual-frequency radiometer on-board. It was expected that the Ka-band induces some changes, such as a reduced data availability due to higher sensitivity to rainy or cloudy conditions. About 6 months of OGDR and IGDR data products will be available, as well as at least 4 cycles of GDR products. Within the first months of the Altika mission, a first patch (P1) was developed to correct for some anomalies in the products and to account for the in-flight calibration data in the ground processing. This patch was applied for the GDR since cycle 1, and for the IGDR from cycle 4 pass 395 onwards.

Since the start of the IGDR data of SARAL, analyses of OGDR and IGDR were performed at CLS, as part of the CNES SALP (“Système d’Altimétrie et Localisation Précise”) project. GDR products are also analyzed as soon as the cycles are available.

Hereafter some results of these analyses are presented. A focus is done on the data availability and validity. Indeed the data availability is less impacted by rain events as previously expected. Furthermore the main altimeter and radiometer parameters are analyzed and compared to other altimeter missions such as OSTM/Jason-2. The system performance at mono-mission crossovers is analysed. Furthermore multi-mission crossovers (with Jason-2) are presented and large-scale regional biases analysed. Our analyses are focused on the data produced with the patch 1.