Total Cloud Liquid Water Content Retrieval over the Arctic Sea Ice from the AMSR2 Data

An algorithm for total cloud liquid water content (CLW) retrieval from the data of the Advanced Scanning Microwave Radiometer 2 (AMSR2) over the Arctic sea ice is suggested. The algorithm is based on the joint possibility to retrieve both total atmospheric water vapor content (WVC) and optical thickness (τ) at 89 GHz over the Arctic sea ice from the AMSR2 data without any additional measurements. Numerical modelling of the brightness temperature (Tb) of the sea ice — atmosphere system microwave radiation at 89 GHz under non-scattering conditions is used to relate τ at 89 GHz to WVC and CLW and inversely express CLW through WVC and τ with a Neural Networks (NNs) approach. Characteristics of the algorithm performance are estimated using a testing data set not used for NNs training. The algorithm is also applied to the AMSR2 data over the Arctic sea ice for the January–April and November and December months of 2020. Sea ice areas are identified with a satellite product on sea ice concentration. It is shown that the CLW retrieval algorithm application leads to realistic CLW fields. The monthly mean CLW values are significantly higher than those from the ERA5 data.