PRACTICAL PREDICTABILITY OF METEOROLOGICAL VARIABLES WITH THE GLOBAL SPECTRAL MODEL AT THE HYDROMETEOROLOGICAL CENTER OF RUSSIA

A. V. Frolov, E. D. Astakhova, I. A. Rozinkina, V. I. Tsvetkov, T. Ya. Ponomareva, and I. V. Ruzanova

Accuracy is estimated of the meteorological variable forecasts produced within the framework of the forecasting system of the Hydrometeorological Center of Russia, as based on the T85L31 global spectral model of the atmosphere. On a large statistical data set, it is shown that in the Northern Hemisphere the predictability limit of geopotential height in the free atmosphere reaches 6—7 and 5—6 days in the cold and the warm period of the year. Improvement of horizontal and vertical resolution up to 85 harmonics (about 100 km) and to 31 levels, respectively, introduction of the diurnal radiation cycle, and fine adjustment of the subgrid process parametrization blocks allowed obtaining practically useful forecasts of midlatitude precipitation at the projection range from 24 to 84 h, of surface temperature, from 6 to 120 h, of surface pressure, from 6 to 120 h, and of cloudiness, from 18 to 84 h. Fairly high accuracy of surface weather forecasts implies that many adverse weather phenomena caused by mesoscale atmospheric processes are to a large extent determined by synoptic and other large-scale objects. That is why these phenomena can be successfully predicted by high-resolution numerical models with projections significantly exceeding the lifecycles of the phenomena.