The diagram below illustrates the frequency channels of the candidate Copernicus Imaging Microwave Radiometer (CIMR) mission, and their targeted spatial resolutions. CIMR is also compared to two other similar Passive Microwave Radiometers (PMR): the Japanese AMSR2 in orbit since 2012, and the MWI to fly on-board the European EPS-SG satellites from ~2023 (MWI-SG).
On the left hand side, the ellipses illustrate the Instantaneous Field-Of-Views (iFOVs) at the different frequencies. Each ellipse corresponds to the footprint of a specific frequency channels, for a given instrument, and is an indication of the spatial resolution achieved.
It appears clearly that CIMR aims at a much improved spatial resolution than the AMSR series, in a largely overlapping range of frequencies (C-band to Ka-band). The W-band (near 90GHz) is not selected for CIMR. L-band (~1.4GHz) on board CIMR will continue the heritage of ESA SMOS and NASA SMAP. MWI-SG is similar to SSMIS, and lacks the lower frequency channels (L-, C- and X-band). It generally has too coarse resolution for ocean and sea-ice operational applications at the horizon 2025.
On the right hand side, the discs illustrate the size of the antenna reflectors of each instrument. The bigger the antenna, the better the spatial resolution at a given frequency. Small antennas (MWI-SG, AMSR2) are solid dishes, while larger ones are meshes. The observation zenith angles (oza) theta are also reported. The larger oza of CIMR yields wider swaths, and enables coverage of the whole polar region every day (noticeably: no polar observation hole).
It is underlined that the CIMR concept is under development for EU, under the lead of ESA. The values used here are realistic, but not final.
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The diagram above is shared on figshare, feel free to re-use and cite it as: Lavergne, T.: CIMR compared to other PMRs: Channels and Spatial resolution, , doi:10.6084/m9.figshare.7177730.v1, 2018.