Spatial-temporal structure of bora in Yalta

Abstract

Using a numerical model of the regional atmospheric circulation WRF-ARW, evolution of a strong bora in winter, 2013 (December, 2–3) near the Southern coast of the Crimea was reproduced. The features of the wind speed and temperature fields that describe formation of intensive atmospheric near-surface airflow over the leeward slope of the mountain ridge are considered. According to the results of numerical simulations carried out at high temporal resolution, strong temporal variability of the wind speed and temperature fields is observed, especially at the foot of the mountains near the coast. Vertical structure of the wind speed and temperature fields for bora is calculated. Quantitative estimates of the temperature, wind speed, stability frequency and the Froude number vertical profiles conditioning the mode of the airflow around the Crimea Mountains ridge are obtained. Fluctuations of the wind speed which are of the character of stationary internal gravity waves induced in the atmosphere behind a leeward slope of the mountains, are shown in a form of wave disturbances of the near-surface wind speed field over the sea. It is shown that the wind speed and temperature fields are conditioned by the post-critical wave mode of the airflow in the Crimea Mountains ridge. Spatial-temporal variability of these fields is a characteristic feature of the Black Sea bora.

Keywords

bora, Southern сoast of the Crimea, numerical model of regional atmospheric circulation WRF-ARW.

DOI: 10.22449/1573-160X-2015-3-3-13

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