Методические подходы к исследованию циклонических систем, соответствующих разным типам интенсивных штормов в северочерноморском регионе

Abstract

The aim of the paper is to study the surface and mid – tropospheric synoptic fields, the location of trajectories and of the deep cyclones centers for different selected types of storm for the cases if the wave heights are of at least 5 m. The sets of cyclone parameters in the Black Sea region were analysef within the 37°-50° N, 27°-45° E. Cyclones and their main parameters were determined using 4-term NCEP / NCAR reanalysis data sets on the 1000 and 500 hPa geopotential height (GPH) in 1951-2017. Bardin’s methodology was used for calculation. Deep cyclones were identified by the criterion of exceeding the upper 75% quartile threshold of the depth (≥40 gpm) and intensity (≥16.8 gpm) of cyclones. It was done by analogy with the method used earlier by the authors to calculate extreme precipitation and statistical characteristics of storms. In addition, we used the author’s method of objective tracking using spline interpolation on the bases of sea surface pressure from the same NCEP / NCAR reanalysis. The reason to apply an additional method was the result obtained during the work realisation: about 30% of extreme storms in the region are caused by small local cyclones that occur over the Black sea. however, some of them cannot be determined using method 1 due to the coarser step of isogyps. As a result, the distribution of deep cyclone centers and their trajectories of different storm types at the Northern Black Sea coast for the cases if the wave height of at least 5 m is shown. It is found that storm types depend of synoptic field features. The centers of deep cyclones are concentrated to the North from the Black Sea coast (for Western type 1B), to the Northwest (for mixed type 2A), to the North-East (for mixed type 2B), and to the South-Eeast (for Central type 3).