A Climate Data Record of Global Sea-Ice Drift from the EUMETSAT OSI SAF

Sea-ice drift is a key variable for understanding sea ice in a changing climate, and an Essential Climate Variable (ECV) product for the Global Climate Observing System (GCOS). In the Arctic, sea ice has been reported to drift faster in recent years (e.g. Rampal et al., 2009), associated with its reduction in area, thinning, and loss of multiyear ice. In the Antarctic, trends in sea-ice drift have been linked to trends in wind patterns (e.g. Hollands and Kwok, 2012). 

In this contribution, we present a new 30-year Climate Data Record (CDR) of global, year-round sea-ice drift vectors covering 1991 to 2020. This uses the continuous maximum cross-correlation technique (CMCC) for measuring sea-ice drift from pairs of brightness temperature images of passive microwave satellite missions (Lavergne et al., 2010). During summer, this technique becomes less accurate due to surface melting and higher atmospheric humidity. We therefore employ a parametric free-drift model to fill the data gaps in the summer. This model calculates the ice drift based on wind vectors from the ERA5 wind reanalysis, under the assumption that the internal stresses of the ice can be neglected. We describe the algorithm baseline for the new CDR as well as results of validation against the sparse network of on-ice buoy trajectories. We finally describe the merits and known limitations of the new data record. This CDR was created in the context of the EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF) and is readily available at https://doi.org/10.15770/EUM_SAF_OSI_0012.

References:

Holland, P., Kwok, R. Wind-driven trends in Antarctic sea-ice drift. Nature Geosci 5, 872–875 (2012). https://doi.org/10.1038/ngeo1627

Lavergne, T., Eastwood, S., Teffah, Z., Schyberg, H., and Breivik, L.-A. (2010), Sea ice motion from low-resolution satellite sensors: An alternative method and its validation in the Arctic, J. Geophys. Res., 115, C10032, doi:10.1029/2009JC005958.

Rampal, P., Weiss, J., and Marsan, D. (2009), Positive trend in the mean speed and deformation rate of Arctic sea ice, 1979–2007, J. Geophys. Res., 114, C05013, doi:10.1029/2008JC005066.