On integral characteristics of Polar Lows

Abstract

Abstract Polar mesocyclones, also known as polar lows (PLs), are important maritime mesoscale (horizontal diameter up to 1000 km) weather systems at high latitudes, forming to the pole from the polar front. We consider the possible prognostic criteria of the PLs, in particular, the kinematic helicity as a squared characteristic related to the integral vortex formations and kinematic vorticity number. To calculate such characteristics we use reanalysis data and the results of numerical modeling with the WRF-ARW model for the PLs over the Nordic (Norwegian and Barents)seas. For comparison, experimental data are used. Our estimation of the helicity is based on its remarkable property – the connection of integral helicity content in the Ekman layer with the geostrophic wind velocity. Criteria associated with vorticity and helicity manifested through the PL genesis and development quite clearly. This criteria can be used to increase the efficiency and accuracy of complex forecasting techniques.