89th American Meteorological Society Annual Meeting

Thursday, 15 January 2009: 11:30 AM
Investigations on simulating winter inversions causing poor air quality in Fairbanks, Alaska
Room 127A (Phoenix Convention Center)
Nicole Mölders, University of Alaska, Fairbanks, AK; and S. Chigullapalli and G. Kramm
In the extreme winters of Interior Alaska, air quality often violates the EPA regulations in Fairbanks. Simulations from cases studies with the Weather Research and Forecasting (WRF) model with chemistry will be presented. Focus will be on (1) how well WRF captures these synoptic situations and (2) the processes for the formation of poor air quality. Preliminary results with respect to (1) show that WRF well captures the temporal evolution of wind-speed, 2m-temperature and acceptably predicts dew point temperature and relative humidity in the Interior; WRF slightly overestimates wind-speed, while it underestimates temperature and relative humidity on average within the domain. Differences in performance can be detected for sites located above and below the inversions. Sensitivity studies using different parameterization schemes show differences in average RMSE of more than 2K; average RMSE of solar incoming radiation differ more than 30Wm-2. Given the low amount of daily incoming solar radiation in Interior Alaska in winter some combination of physical packages must be considered as less suitable for simulating these extreme conditions than other conditions. Sensitivity studies also show that assumptions on land-cover type strongly affect inversion strength.

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