Cloud influence on ERA5 and AMPS surface downwelling longwave radiation biases in West Antarctica

Israel Silber, Johannes Verlinde, Sheng Hung Wang, David H. Bromwich, Ann M. Fridlind, Maria Cadeddu, Edwin W. Eloranta, Connor J. Flynn

Research output: Contribution to journalArticle

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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.

Original languageEnglish (US)
Pages (from-to)7935-7949
Number of pages15
JournalJournal of Climate
Volume32
Issue number22
DOIs
StatePublished - Nov 1 2019

Fingerprint

longwave radiation
downwelling
prediction
clear sky
ice
liquid
atmosphere
surface energy
polar region
Antarctica
energy budget
ice sheet
vertical distribution
boundary condition
aerosol
experiment
temperature

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Silber, Israel ; Verlinde, Johannes ; Wang, Sheng Hung ; Bromwich, David H. ; Fridlind, Ann M. ; Cadeddu, Maria ; Eloranta, Edwin W. ; Flynn, Connor J. / Cloud influence on ERA5 and AMPS surface downwelling longwave radiation biases in West Antarctica. In: Journal of Climate. 2019 ; Vol. 32, No. 22. pp. 7935-7949.
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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.",
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Silber, I, Verlinde, J, Wang, SH, Bromwich, DH, Fridlind, AM, Cadeddu, M, Eloranta, EW & Flynn, CJ 2019, 'Cloud influence on ERA5 and AMPS surface downwelling longwave radiation biases in West Antarctica', Journal of Climate, vol. 32, no. 22, pp. 7935-7949. https://doi.org/10.1175/JCLI-D-19-0149.1

Cloud influence on ERA5 and AMPS surface downwelling longwave radiation biases in West Antarctica. / Silber, Israel; Verlinde, Johannes; Wang, Sheng Hung; Bromwich, David H.; Fridlind, Ann M.; Cadeddu, Maria; Eloranta, Edwin W.; Flynn, Connor J.

In: Journal of Climate, Vol. 32, No. 22, 01.11.2019, p. 7935-7949.

Research output: Contribution to journalArticle

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