Sea Ice Monitoring Using Quikscat & Ascat Scatterometers during the Last 15-Year Period

Abstract:

Microwave sensors onboard polar orbit satellites are commonly used for sea ice monitoring at high latitude : radiometers are routinely used for this application and scatterometers have also shown they can contribute significantly to it.

Since 1991, numerous scatterometers data at C and Ku-bands are available since ERS-1 with NSCAT, QuikSCAT, OSCAT, HY, and ASCAT sensors. In this presentation, we will show how the recent QuikSCAT and ASCAT sensors could be used to build 15-year observation data time series for sea ice monitoring for both Arctic and Antarctic areas.

Backscatter data enable to discriminate sea ice from open ocean areas, in particular scatterometers are useful to detect new ice, even at the early stage of growth which is not possible using radiometers.

Backscatter data from scatterometer can also be used for sea ice type detection (first year from multi-year sea ice in the Arctic), results and differences between C-band and Ku-band sensors results will be presented.

Moreover, sea ice displacement maps can be built in central Arctic from backscatter data, examples will be shown using the merging of scatterometer and radiometer data. We will see in this presentation that Antarctic sea ice displacement maps can also be inferred. From these displacement maps, mean sea surface currents can be estimated.

In this presentation we will also focus on the benefit of the use of the two ASCAT sensors that are presently available (onboard MetOp-A -since 2007 and -B, since 2012), in particular for the Antarctic area.

This presentation will enhance i) the need of scatterometer data for sea ice application with many examples of the inferred parameters in particular from the U.S. QuikSCAT/SeaWinds and the E.U. MetOp/ASCATs scatterometers ii) the need of the continuity of scatterometers missions and iii) the benefit of the combination of sensors and datasets (scatterometers, scatterometers with radiometers) for a long-term observation of the polar areas.

These data are routinely processed at IFREMER/CERSAT and available for the scientific community. The ASCAT calibrated reprocessed data (2007-2014) will be soon available, added to the SeaWinds/QuikSCAT dataset (1999-2009), they will provide an exceptional basis for future analysis and synthesis of long-term variations of the sea ice in both Arctic and Antarctic polar areas.