Sea Ice and Atmospheric Parameter Retrieval From Satellite Microwave Radiometers: Synergy of AMSR2 and SMOS Compared With the CIMR Candidate Mission

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Scarlat, Raul Cristian, Spreen, Gunnar, Heygster, Georg, Huntemann, Marcus, Paţilea, Cătălin, Pedersen, Leif Toudal, Saldo, Roberto
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/climate_action; name=SDG 13 - Climate Action; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; name=SDG 14 - Life Below Water; Arctic; Sea ice
• Online Access: https://orbit.dtu.dk/en/publications/54044458-605e-42cd-8bd2-44be7abea1cf; https://doi.org/10.1029/2019jc015749; https://backend.orbit.dtu.dk/ws/files/210404749/2019JC015749.pdf

Research on improving the prediction skill of climate models requires refining the quality of observational data used for initializing and tuning the models. This is especially true in the Polar Regions where uncertainties about the interactions between sea ice, ocean and atmosphere are driving ongoing monitoring efforts. The Copernicus Imaging Microwave Radiometer (CIMR) is an European Space Agency (ESA) candidate mission which promises to offer high resolution, low uncertainty observation capabilities at the 1.4, 6.9,10.65,18.7 and 36.5 GHz frequencies. To assess the potential impact of CIMR for sea ice parameter retrieval, a comparison is made between retrievals based on present AMSR2 observations and a retrieval using future CIMR equivalent observations over a data set of validated sea ice concentration (SIC) values. An optimal estimation retrieval method (OEM) is used which can use input from different channel combinations to retrieve seven geophysical parameters (sea ice concentration, multi year ice fraction, ice surface temperature, columnar water vapor, liquid water path, over ocean wind speed and sea surface temperature). An advantage of CIMR over existing radiometers is that it would provide higher spatial resolution observations at the lower frequency channels (6.9, 10.65, 18.7 GHz) which are less sensitive to atmospheric influence. This enables the passive microwave based retrieval of SIC and other surface parameters with higher resolution and lower uncertainty than is currently possible. An information content analysis expands the comparison between AMSR2 and CIMR to all retrievable surface and atmospheric parameters. This analysis quantifies the contributions to the observed signal and highlights the differences between different input channel combinations. The higher resolution of the low frequency CIMR channels allow for unprecedented detail to be achieved in Arctic passive microwave sea ice retrievals. The presence of 1.4 GHz channels on board CIMR opens up the possibility for thin sea ice ...