Моделирование экстремальных осадков зимнего периода для южного побережья Каспийского моря

Extreme precipitation on the Iranian coast of the Caspian Sea is most often observed during the cold season and results from the combination of synoptic processes and mesoscale effects arising under the influence of a large body of water and topography factors. Numerical simulation of the most intense precipitation events in the densely populated area is important for improving the methods of precipitation forecast. On the other hand, a number of questions arise about the physical mechanisms of extreme precipitation, i.e. the role of the planetary boundary layer, the lake effect, the topography. We carried out numerical modeling of eight episodes of extreme precipitation for the period of 2005–2016 using the WRF-ARW numerical mesoscale model; a detailed verification of the model by observational data was performed. It is shown that the model successfully reproduces maximum precipitation in the coastal areas. However, the precipitation modeling errors could be very high when comparing with the station data. Experiments with various parametrization of physical processes have shown the greatest sensitivity of the simulated precipitation to the parametrization of the atmospheric planetary boundary layer. The relationship between the intensity of precipitation on the Iranian coast of the Caspian Sea and the integral moisture content of the atmospheric column and the sea surface temperature in the southern part of the lake was also revealed.