Cloud Influence on ERA5 and AMPS Surface Downwelling Longwave Radiation Biases in West Antarctica
- Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, Pennsylvania
- Polar Meteorology Group, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, Ohio
- Polar Meteorology Group, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, Ohio, Atmospheric Sciences Program, Department of Geography, The Ohio State University, Columbus, Ohio
- NASA Goddard Institute for Space Studies, New York, New York
- Argonne National Laboratory, Argonne, Illinois
- Space Science and Engineering Center, University of Wisconsin–Madison, Madison, Wisconsin
- Pacific Northwest National Laboratory, Richland, Washington
Abstract The surface downwelling longwave radiation component (LW↓) is crucial for the determination of the surface energy budget and has significant implications for the resilience of ice surfaces in the polar regions. Accurate model evaluation of this radiation component requires knowledge about the phase, vertical distribution, and associated temperature of water in the atmosphere, all of which control the LW↓ signal measured at the surface. In this study, we examine the LW↓ model errors found in the Antarctic Mesoscale Prediction System (AMPS) operational forecast model and the ERA5 model relative to observations from the ARM West Antarctic Radiation Experiment (AWARE) campaign at McMurdo Station and the West Antarctic Ice Sheet (WAIS) Divide. The errors are calculated separately for observed clear-sky conditions, ice-cloud occurrences, and liquid-bearing cloud-layer (LBCL) occurrences. The analysis results show a tendency in both models at each site to underestimate the LW↓ during clear-sky conditions, high error variability (standard deviations > 20 W m−2) during any type of cloud occurrence, and negative LW↓ biases when LBCLs are observed (bias magnitudes >15 W m−2 in tenuous LBCL cases and >43 W m−2 in optically thick/opaque LBCLs instances). We suggest that a generally dry and liquid-deficient atmosphere responsible for the identified LW↓ biases in both models is the result of excessive ice formation and growth, which could stem from the model initial and lateral boundary conditions, microphysics scheme, aerosol representation, and/or limited vertical resolution.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- SC0017981
- OSTI ID:
- 1572106
- Journal Information:
- Journal of Climate, Journal Name: Journal of Climate Journal Issue: 22 Vol. 32; ISSN 0894-8755
- Publisher:
- American Meteorological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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