The performance of a global and mesoscale model over the central Arctic Ocean during the summer melt season

• Measurements of turbulent fluxes, clouds, radiation, and profiles of meanmeteorological parameters, obtained over an ice floe in the central Arctic Ocean during theArctic Ocean Experiment 2001, are used to evaluate the performance of U.K. Met OfficeUnified Model (MetUM) and Coupled Ocean/Atmosphere Mesoscale Prediction System(COAMPS) in the lower atmosphere during late summer. Both the latest version of theMetUM and the version operational in 2001 are used in the comparison to gain aninsight as to whether updates to the model have improved its performance over the Arcticregion. As with previous model evaluations over the Arctic, the pressure, humidity,and wind fields are satisfactorily represented in all three models. The older version of theMetUM underpredicts the occurrence of low-level Arctic clouds, and the liquid and icecloud water partitioning is inaccurate compared to observations made during SHEBA.In the newer version, simulated ice and liquid water paths are improved, but theoccurrence of low-level clouds are overpredicted. Both versions overestimate the amountof radiative heat absorbed at the surface, leading to a significant feedback of errorsinvolving the surface albedo, which causes a large positive bias the surface temperature.Cloud forcing in COAMPS produces similar biases in the downwelling shortwave andlongwave radiation fluxes to those produced by UM(G25). The surface albedoparameterization is, however, more realistic, and thus, the total heat flux and surfacetemperature are more accurate for the majority of the observation period.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Nyckelord

Arctic Atmospheric modeling

Meteorology

Meteorologi

meteorologi

Meteorology

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