4th bimonthly progress report (December 2009 - January 2010)

The work performed hithereto during the project, including this reporting period, was presented on the SeaSAR workshop in ESRIN 25-29 January. One presentation was given by Knut-Frode Dagestad about implementation and validation of a Bayesian SAR wind retrieval scheme. A second related presentation about direct 1-dimensional (SAR look direction) surface current retrieval and validation in the Northeast Atlantic was given by Morten W. Hansen. Two proceeding papers were also submitted, to appear in the workshop proceedings. Both presentations and papers are attached below.

The main conclusion about the Bayesian SAR wind retrieval is that the scheme works very well. It is particularly useful for challenging situations with variable wind direction. For the general case where traditional SAR retrieval is very accurate, we find that the Doppler can have a negative contribution, since the calibration uncertainties can add noise to the retrieval scheme. The challenge of calibrating the Doppler is also of discussed in the paper/presentation about direct current retrieval. It was reassuring to learn from the SeaSAR workshop that other teams, in particular including ESA, are working on improving the calibration of the Doppler Centroid, and that futher improved accuracy can be expected from Sentinel-1.

Promising new improvements of the Doppler calibration are under investigation at the moment, and good results will hopefully be presented in the next report. It will then be checked if this may improve the Bayesian scheme for the general case. The focus of this project will also gradually be shifted towards WP2 - consistent wind-wave-current inversion.