Formation of the Novaya Zemlya Bora

Abstract

Structure of the atmospheric fields for a few cases of strong southeast and west winds is reproduced and considered based on the WRF-ARW high-resolution numerical model of atmospheric circulation. Typical distribution of the wind speed and temperature fields for these cases is presented. It is shown that the main condition of bora occurring consists in stable stratification in the atmosphere low layer above the Kara Sea under the east and southeast winds. Blocking of an air flow on the windward eastern slope of the mountains is followed by arising of a strong near-surface wind – the bora – on the western slope and in the nearshore area of the Barents Sea. As a result, in case of a bora the air temperature above the Barents Sea significantly exceeds that above the Kara Sea on the same heights. Under the west winds, a weakly stable atmospheric boundary layer above the Barents Sea does not constitute a considerable block (by mountains) for a running flow which is one of the basic conditions of the bora development. Thus, as for the west wind, Novaya Zemlya is not a barrier separating the atmosphere lower layers between the Kara and Barents seas in winter.

Keywords

• Novaya Zemlya
• bora
• WRF-ARW atmospheric circulation model
• baroclinic stream
• stability frequency