Explicitly determined sea ice emissivity and emission temperature over the Arctic for surface‐sensitive microwave channels

• Published in: Quarterly Journal of the Royal Meteorological Society
• Main Authors: Kang, Eui‐Jong, Sohn, Byung‐Ju, Tonboe, Rasmus Tage, Noh, Young‐Chan, Kwon, In‐Hyuk, Kim, Sang‐Woo, Maturilli, Marion, Kim, Hyun‐Cheol, Liu, Chao
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Royal Meteorological Society 2023
• Subjects: Arctic; Sea ice
• Online Access: https://epic.awi.de/id/eprint/57848/; https://epic.awi.de/id/eprint/57848/1/Quart%20J%20Royal%20Meteoro%20Soc%20-%202023%20-%20Kang%20-%20Explicitly%20determined%20sea%20ice%20emissivity%20and%20emission%20temperature%20over%20the%20Arctic.pdf; https://hdl.handle.net/10013/epic.aa851a03-fcfe-49d6-88d8-cc387bb37704

Data assimilation of satellite microwave measurements is one of the importantkeys to improving weather forecasting over the Arctic region. However, the useofsurface-sensitivemicrowave-soundingchannelmeasurementsfordataassim-ilation or retrieval has been limited, especially during winter, due to the poorlyconstrained sea ice emissivity. In this study, aiming at more use of those channelmeasurements in the data assimilation, we propose an explicit method for speci-fying the surface radiative boundary conditions (namely emissivity and emittinglayer temperature of snow and ice). These were explicitly determined with aradiativetransfermodelforsnowandiceandwithsnow/icephysicalparameters(i.e. snow/ice depths and vertical distributions of temperature, density, salinity,and grain size) simulated from the thermodynamically driven snow/ice growthmodel. We conducted 1D-Var experiments in order to examine whether thisapproach can help to use the surface-sensitive microwave temperature channelmeasurements over the Arctic sea ice region for data assimilation. Results showthat (1) the surface-sensitive microwave channels can be used in the 1D-Varretrieval, and (2) the specification of the radiative boundary condition at thesurface using the snow/sea ice emission model can significantly improve theatmospheric temperature retrieval, especially in the lower troposphere (500hPato surface). The successful retrieval suggests that useful information can beextracted from surface-sensitive microwave-sounding channel radiances oversea ice surfaces through the explicit determination of snow/ice emissivity andemitting layer temperature.