Cooperative Institute for Research in Environmental Sciences

Analysis of the Arctic heat budget in WRF: A comparison with reanalyses and satellite observations

Porter, D.F., J.J. Cassano, and M.C. Serreze

2011, Journal of Geophysical Research, 116, D22108, doi:10.1029/2011JD016622.

The Weather Research and Forecasting (WRF) model is used to dynamically downscale the regional climate of the Arctic, an area undergoing rapid climate changes. Because the WRF model is increasingly being run over larger spatial and temporal scales, an assessment of its ability to reconstruct basic properties of regional climates, such as terms in the energy budget, is crucial. Estimates of the Arctic energy budget from WRF are compared with estimates from reanalyses and satellite observations. The WRF model version 3.1.0 was run on a large pan-Arctic domain continuously from 2000-2008. Five-year monthly means of each of the energy budget terms and their components show that WRF sufficiently captures the Arctic energy budget apart from a few systematic shortcomings. The major deficiency, with biases as large as 60 W m-2 in the summer months, is in the shortwave radiative fluxes at the both the surface and the top of the atmosphere. WRF?s positive bias in upwelling shortwave radiation is generated at the surface due to a specified constant sea ice albedo of 0.8, which is often incorrect and too high. A second, similar WRF simulation was performed, but with gridded nudging enabled, to test how sensitive the energy budget estimates from WRF are to the specific patterns of atmospheric circulation. When the large-scale circulation is constrained to the reanalyses, the two energy budget terms that are most dependent on weather patterns, the convergence of atmospheric energy transport and the tendency of column-integrated energy, closely resemble their reanalysis counterparts.