Daily Arctic and Antarctic sea ice extents and normalized backscatter
Product status: -
The sea ice extent and normalized backscatter from the ERS, Quikscat and ASCAT
scatterometers result from the Bayesian discrimination of measured backscatter
distances to prescribed ocean wind and sea ice geophysical model functions. The
sea ice product contains the Bayesian sea ice probability and a proxy age of sea
ice mapped onto 12.5 km polar stereographic grids. The sea ice extent is formed
when the sea ice probability crosses a certain threshold, and the proxy age of
sea ice is converted to (normalized VV C-band, or HH and VV Ku-band) sea ice
backscatter using the instructions detailed in the User Manual.
The EUMETSAT Ocean and Sea Ice Satellite Application Facility (OSI SAF) and KNMI
present a first version of a consistent long-term record of sea ice extent
and backscatter from satellite scatterometry (ERS, Quikscat and ASCAT) dating
back from 1992 to 2016. The sea ice extents from scatterometers show good
agreement with the global sea ice concentration climate data records from
passive microwave instruments during the winter months, but present notable
differences during the summer months, scatterometers being more inclusive
regarding the detection of lower concentration and melting ice. The
scatterometer record also monitors the evolution of sea ice backscatter,
which is typically used to separate multiyear from first year ice, and informs
about the physical characteristics of the most dominant sea ice types.
Note that these data records are not officially committed OSI SAF products. They
are a by-product of the scatterometer wind data record generation and are needed
to distinguish between open water (where winds can be retrieved) and ice-covered
All intellectual property rights of the OSI SAF products belong to EUMETSAT. The use of
these data sets is granted to every interested user, free of charge. If you wish to use
these data, EUMETSAT's copyright credit must be shown by displaying the words "copyright
(year) EUMETSAT" on each of the products used.
Access to products
The data in NetCDF format are available on request from KNMI.
Please contact the
KNMI OSI SAF team