News

After a first announcement last month, the upgrade on meteo fields used for altimetry corrections is planned on May 3rd 2011. Some impacts are expected.

After a first announcement last month, we are pleased to announce an update of all altimetric processing chains, in order to bring the current spatial resolution of model-based atmospheric corrections, in line with the current native resolution of the ECMWF model used to derive them. The upgrade is planned to take place at ECMWF on May 3^rd around 12HUTC.

Since January 26^th 2010, the native resolution of the ECMWF atmospheric deterministic model used in the estimation of these corrections is of the order of 16 km. Interpolated grids down to 25 km have been used since in all operational altimetric processing chains.  

Impact studies have been carried out in the last few months for Jason-2 and Envisatproducts considering both resolutions, by looking specifically at the following parameters: wet tropospheric correction, dry tropospheric correction, U and V wind components, sea surface pressure and the Dynamic Atmospheric Correction.

For Jason-2, the results on OGDR products indicate differences on the order of only tens of cm/s RMS on wind speed components, and less than 1 mm RMS for the range corrections. On IGDR and GDR products, where the Dynamic Atmospheric Correction is applied, we have observed additionally range differences of 3 mm RMS in shallow water areas. No impact has been observed in significant wave height.  

In conclusion, the scientific impact of this upgrade on all altimetric products is quite negligible.

For Jason-2, the only expected impact for users is a delayed delivery of IGDR products on May 4^th.

Jason-1 and EnvisatIGDRs should be processed and delivered nominally.