An analysis of wintertime cold-air pool in Armenia using climatological observations and WRF model data

摘要

The number of extreme weather events including strong frosts, cold waves, heat waves, droughts, hails, strong winds has increased in Armenia by 20% during the last 20 years. The paper studies the formation of cold-air pools in Ararat Valley, Armenia during the winter season. Observational data from 47 meteorological stations of Armenia were used, and daily minimum temperatures lower than -10 °C were assessed over the period 1966-2017. December, 2016 was considered as the 4-th coldest month, after the years 2013, 2002 and 1973. The focus area of this study is the low-elevated basin of Ararat Valley for which climatological analysis of winter temperature regime has been performed. Monthly average temperatures for December were significantly below normal values, particularly, for low-elevated part of Ararat Valley. 24-hour simulations derived from Weather Research and Forecasting model (WRF) were used to assess the WRF model's capabilities to reproduce strong cold-air pool (CAP) over the Ararat Valley observed on 20 December 2016 when minimum temperatures decreased up to -20 °C and lower. The WRF model was applied with spatial resolutions of 9 and 3 km and 65 vertical levels based on Global Forecast System model's (GFS) initial and boundary conditions at 0.25×0.25 deg. resolution.