Open AccessAn assessment of ECMWF analyses and model forecasts over the North Slope of Alaska using observations from the ARM Mixed‐Phase Arctic Cloud Experiment
Author(s) -
Xie Shaocheng,
Klein Stephen A.,
Yio John J.,
Beljaars Anton C. M.,
Long Charles N.,
Zhang Minghua
Publication year - 2006
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jd006509
Subject(s) - downwelling , environmental science , albedo (alchemy) , liquid water path , shortwave radiation , atmospheric sciences , shortwave , climatology , snow , longwave , arctic , atmosphere (unit) , meteorology , cloud albedo , boundary layer , cloud cover , radiation , radiative transfer , geology , precipitation , cloud computing , physics , upwelling , art , oceanography , quantum mechanics , performance art , computer science , thermodynamics , art history , operating system
European Centre for Medium‐Range Weather Forecasts (ECMWF) analysis and model forecast data are evaluated using observations collected during the Atmospheric Radiation Measurement (ARM) October 2004 Mixed‐Phase Arctic Cloud Experiment (M‐PACE) at its North Slope of Alaska (NSA) site. It is shown that the ECMWF analysis reasonably represents the dynamic and thermodynamic structures of the large‐scale systems that affected the NSA during M‐PACE. The model‐analyzed near‐surface horizontal winds, temperature, and relative humidity also agree well with the M‐PACE surface measurements. Given the well‐represented large‐scale fields, the model shows overall good skill in predicting various cloud types observed during M‐PACE; however, the physical properties of single‐layer boundary layer clouds are in substantial error. At these times, the model substantially underestimates the liquid water path in these clouds, with the concomitant result that the model largely underpredicts the downwelling longwave radiation at the surface and overpredicts the outgoing longwave radiation at the top of the atmosphere. The model also overestimates the net surface shortwave radiation, mainly because of the underestimation of the surface albedo. The problem in the surface albedo is primarily associated with errors in the surface snow prediction. Principally because of the underestimation of the surface downwelling longwave radiation at the times of single‐layer boundary layer clouds, the model shows a much larger energy loss (−20.9 W m −2 ) than the observation (−9.6 W m −2 ) at the surface during the M‐PACE period.