Chukchi-Beaufort Seas High-Resolution Atmosphere Reanalysis (CBHAR): Data Verification and Climate Analysis

The Chukchi-Beaufort Seas and the North Slope region has experienced drastic changes over recent decades, as evidenced by a rapid sea ice reduction, pronounced surface air temperature increase, noticeable permafrost thawing, and more frequent extreme weather events. These changes may increase threats to the environment and the economic activities. To better understand these regional climate changes and their broader impacts, there is an impressive need to obtain the best estimate of high-resolution atmospheric state in this data-sparse region. We therefore conducted a regional reanalysis project. Under this project, a physically-optimized, Arctic-processes-enhanced Weather Forecasting and Research (WRF) model and WRF-based data assimilation system have been established; a meteorological buoy was successfully deployed over the highly sea-ice-dynamic Beaufort Sea; a quality-controlled observational database was developed from available sources; and, finally, the high-resolution Chukchi-Beaufort Seas High-Resolution Atmospheric Reanalysis (CBHAR) was constructed for the period 1979-2009 with the optimized model and quality-controlled observations. We also verified the CBHAR data against various observations. The results indicate that the CBHAR represents an improved estimate of the regional atmospheric state throughout the study area. Climate analysis using CBHAR reveals that winds, particularly extreme winds, have enhanced over the Chukchi-Beaufort Seas, especially during autumn. CBHAR also provides a unique opportunity to analyze mesoscale processes. We found that intensified onshore winds have occurred during summer due to combined sea and mountain breezes along the eastern Brooks Range and Chukotka Mountains. During winter, the mesoscale cold-air damming effect diverts the synoptic northeasterly winds to the southeast along the northern slope of the Chukotka Mountains. In the Brooks Range, downslope winds are the predominant driver of the surface wind field.