Comparison of Sea Ice Products from MiRS ATMS and VIIRS

The Microwave Integrated Retrieval System (MiRS) is the official NOAA microwave-only retrieval system which currently processes data from ten different low earth orbit satellites, including the recently-launched NOAA-20 satellite. MiRS is based on a one-dimensional variational approach. MiRS derived products include total sea ice concentration (SIC), first year sea ice concentration (SIFY), and multiyear sea ice concentration (SIMY). The SIC, SIFY, and SIMY products are generated based on the MIRS retrieved surface information such as surface emissivities, skin temperature, a lookup table of surface emissivities, ice fractions derived off-line from pure water emissivity spectra and ice surface types.

In this study, we focused on these MIRS derived products from the ATMS measurements on board both the SNPP and NOAA-20 satellites. The SNPP satellite was launched in 2011, and NOAA-20 was launched in November 2017. Both platforms contain several instruments in addition to ATMS, including the Visible/Infrared Imaging Radiometer Suite (VIIRS). The VIIRS measurements are also used to operationally retrieve sea ice information regarding the ice concentration, first year ice, and multiyear ice. Since the sea ice information from the VIIRS measurements depends on the visible and infrared bands having a higher spatial resolution and a completely different retrieval algorithm from MiRS, the study will assess both qualitatively and quantitatively the differences between MiRS and VIIRS ice concentration and ice age estimates, and whether these differences depend on time of the year (e.g. fall and winter freeze vs. spring melt), location (e.g. ice edge vs. thicker ice pack), or the availability of VIIRS visible channel data. This will be the first time that a systematic comparison is made between the VIIRS and MiRS sea ice products.