Ice motion provides the advective component of the equations
governing the mass balance of the sea ice cover. Thus its routine observation would be of great value to the understanding ice and ocean behavior. We [Kwok et al., 1998] have demonstrated the feasibility of creating a global multi-decadal ice motion record from satellite passive microwave imagery . When the ice motion results are compared with contemporaneous buoy- and SAR-derived ice motions, the uncertainties in the displacement vectors, between 5 and 12 km, are better than the spatial resolution of the data. We are currently compiling two 20-year ice motion datasets:. The first is a
data set of ice motion from SMMR and SSM/I from 1978 to 1998.
The second is a blended data set of daily ice motion that combines motion data from these passive microwave imagers with motion data from buoys, AVHRR, ERS-1 SAR, RADARSAT. Each ice motion vector is computed by optimal weighting of all available ice motion observations resulting in enhanced motion estimates that are regularly gridded in time and space, free of temporal or spatial gaps. We include model velocities in the blended product to cover various gaps in the direct observations: throughout the summer in the passive microwave record, gaps from clouds in AVHRR and gaps during transition seasons in the relatively short SAR record. These data products and documentation will be made available to the user community through the World Wide Web. This work allows an important record of ice motion to be established for the duration of the SMMR, SSM/I, and future
microwave sensors, that is, from 1978 into the next millenium. NOAA, NASA, NSF and ONR are presently investing in improving the treatment
of sea ice in high latitude ocean models and GCMs. The passive
microwave ice motion data will provide an invaluable data source for testing sea ice behavior in these models. The blended product will provide a twenty-year record for analyses of the sea ice mass balance and its role in the global hydrologic balance.