Boundary Layer Winds during Winters in the Interior of Alaska

Low level winds in high latitudes winters play an important role in weather forecast. For example, the forecast of surface temperatures becomes highly affected by wind chill factor. Similarly, low level winds also affect the prediction of meteorological hazards such as blizzards, air quality and extreme fog events disconnecting isolated communities by interrupting transportation systems. Depending upon the synoptic meteorological conditions winds in the planetary boundary layer (PBL) can be represented to a certain extend. However, during the Alaskan winter local topographies, surface thermal gradients and mountain shadows becomes prominent in defining the presence and intensity of low level winds specially when the polar front migrates southward.

To investigate this problem, we conducted the Winter Boundary Layer Experiment (Wi-BLEx) in two phases. During the winter of 2009-10 a Doppler sodar was collocated at the Fairbanks International Airport to regular radiosonde launches at 00-12Z to bring confidence to the acoustic sounder to be deployed elsewhere in Alaska. During the winter of 2010-11 the sounder was moved to the northern foothills of the Tanana Valley to record wind features closer to the foothills and compare to the long term meteorological sounding.

In this work a side-by-side comparison between the Doppler sodar and radio sounding systems is develop as well as a winter-long monitoring and assessment of PBL-winds in the central Tanana Valley and the nearby the foothills area is presented. Similarly, PBL-wind statistics is compared to recent retrievals of the Global Winds Aeolus platform.