For several years, the CERSAT has been providing sea ice data and maps from various scatterometers (microwave radar) and radiometers onboard earth observation satellites (ERS-1, ERS-2, ADEOS-1, QuikSCAT, SSM/I, AMSR-E). IFREMER/CERSAT provides continuous Arctic sea ice drift maps from 1992. This database will continue with ASCAT/MetOp data.

The scatterometer is initially designed to measure winds over ocean surface, but it can also be used to detect sea ice edge and sea ice type (first year, multi-year). Radiometer is commonly used for sea ice concentration. Using correlation technique between successive maps, sea ice drifts can be estimated from both of these sensors.

From 1992 until 1999, 3 and 6 day-lags drifts are estimated from SSM/I radiometer. Since 1999, drifts are estimated from the combination of QuikSCAT scatterometer and SSM/I radiometer (merged drift), this product has been validated over 5 winters. Since 2002, AMSR-E radiometer provides higher resolution data, adapted to regional studies; due to its resolution, drifts can be estimated at 2 day-lag. Monthly merged drift maps are also available.

In DAMOCLES project, the main activity at IFREMER has been to built ASCAT/MetOp scatterometer daily incidence-adjusted backscatter maps on sea ice areas. From these maps, sea ice drift maps were processed in order to continue the long time series of sea ice drifts.

 

Figure 1 : Arctic sea ice drift, 30th April-3rd May 2002, from the combination of SeaWinds/QuikSCAT scatterometer and SSM/I radiometer. Drifts less than one pixel are marked with a cross. In red : identical drift for QuikSCAT and the two SSM/I polarizations, in green : identical drift for two of the product ; in blue : selection of one product. Drifts are not estimated over grey areas. Blue areas are open-water areas. N.B. Vectors are not at the scale of the map.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2 : Monthly Arctic sea ice drift, 1st-March-1st April 2005, from the combination of SeaWinds/QuikSCAT scatterometer and SSM/I radiometer. Drifts less than one pixel are marked with a cross. Drifts are not estimated over grey areas. N.B. Vectors are not at the scale of the map.