A demonstration of the potential of Cryosat-2 to contribute to mesoscale observation

Cryosat-2 was designed for its primary scientific objectives, i.e. for cryosphere science. As far as oceanography is concerned, various mission design choices make it less accurate than missions designed to comply with ocean surface topography requirements such as Jason-2 or ENVISAT. Cryosat-2-specific errors are equivalent to more than 50% of the sea surface height variability over 40% of the oceans. Cryosat-2's sampling pattern is also suboptimal for mesoscale observation because the satellite tracks from any consecutive period of 2 to 20 days (e.g. the most recent and most valuable data for near real time mesoscale observation) are aggregated in 500 km wide bands which are interleaved with 500 km wide observation gaps. Yet we merged Cryosat-2 data with other radar altimeters to improve the resolution of multi-mission gridded products (maps) of sea level anomalies in the Gulf Stream. Comparisons to independent data from the Jason tandem show a large improvement from mono-satellite (ENVISAT) observation. Qualitatively, the 2-satellite map using Cryosat-2 is more coherent with maps derived from the Jason tandem, or with sea surface temperature and ocean color composite maps. Quantitatively, interpolating Cryosat-2 + ENVISAT maps and ENVISAT maps on independent along-track measurements from the Jason tandem yields an average error reduction of 7 to 15 cm RMS, i.e. 25% to 50% of the regional variability of the sea surface topography. While Cryosat-2 is not an operational oceanography mission, it has the potential to contribute to mesoscale observation as a mission of opportunity, as well as the potential to mitigate the upcoming loss of ageing altimetry satellites (Jason-1, ENVISAT). Comparing maps derived from various combinations of 2 and 3 satellites to the best synoptic view available (map derived from 4 altimeters) shows that Cryosat-2 can capture 50% to 66% of the mesoscale variability observed with ENVISAT or Jason-1 in the area. (C) 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.