Experimental technology for very-short-range numerical weather prediction based on a nonhydrostatic mesoscale meteorological model with assimilation of radar and ground-based observational data

A brief description of the very-short-range numerical weather prediction technology based on the WRF-ARW nonhydrostatic model is presented. Skill scores are provided for the short- and very-short-range forecasts of temperature, precipitation and wind of various intensity, which were calculated with this model as a result of its integration on the nested grid with a spacing of 3 km, with the direct simulation of deep convection and the assimilation of radar and ground-based weather station data. The forecasts for a location were verified for the central part of European Russia using radar and weather station data for the summer of 2020. It is demonstrated that the model adequately simulates mesoscale convective systems and the related zones of heavy precipitation, strong winds, and thunderstorms. Possible reasons for forecast biases and the ways to reduce the value of spatial and temporal errors are discussed. Keywords: numerical very-short-range forecasting, mesoscale meteorological model, radar data assimilation, precipitation, severe weather events, active convection

MESOSCALE METEOROLOGICAL MODEL TSUNM3 FOR THE STUDY AND FORECAST OF METEOROLOGICAL PARAMETERS OF THE ATMOSPHERIC SURFACE LAYER OVER A MAJOR POPULATION CENTER

The paper describes the mathematical formulation and numerical method of the TSUNM3 high-resolution mesoscale meteorological model being developed at Tomsk State University. The model is nonhydrostatic and includes three-dimensional nonstationary equations of hydrothermodynamics of the atmospheric boundary layer with parameterization of turbulence, moisture microphysics, long-wave and short-wave (solar) radiation, and advective and latent heat flows in the atmosphere and at the boundary of its interaction with the underlying surface. The numerical algorithm is constructed using structured grids with uniform spacing in horizontal directions and condensing to the Earth surface in the vertical direction. When approximating the differential formulation of the problem, the finite volume method with the second order approximation in the spatial variables is used. Explicit-implicit approximations in time (Adams–Bashforth and Crank–Nicolson) are used to achieve second-order accuracy in time. The paper presents results of numerical forecasting of the main meteorological parameters of the atmosphere (temperature, humidity, wind speed and direction) and precipitation in different seasons in the Siberian region. The models were tested with the help of observations obtained using the Volna-4M sodar, MTR-5 temperature profile meter, and Meteo-2 ultrasonic weather stations of the Atmosfera Collective Use Center. The improved TSUNM3 model is shown to adequately reflect the precipitation time and intensity. However, in some cases, the times of its beginning and end do not always coincide, the difference can reach several hours. The precipitation phase state is reflected reliably. Over 70% of precipitation cases are confirmed by numerical calculations. The model satisfactorily predicts temperature and humidity characteristics. The quality of the precipitation forecast model is comparable to the modern mesoscale models, such as the Weather Research and Forecasting (WRF) model.