Climate Forecasts. Part II: Probabilistic Approaches.

The main advantages of ensemble prediction systems and probabilistic climate forecasts as compared to deterministic ones are considered. Quality assessment has been performed for retrospective probabilistic forecasts of air temperature and precipitation on subseasonal timescales (the forecasts that were obtained with a new version of the SLAV072L96 global semi-Lagrangian atmospheric model developed in the Hydrometcenter of Russia and the Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences). Skill scores of probabilistic forecasts indicate the presence of a useful signal in the context of the forecasts of two extreme gradations of air temperature and precipitation at weekly and monthly integration intervals. It is concluded that the use of probabilistic approaches makes it possible to expand the time interval of the "usefulness" of forecasts from a week to a month, as well as to obtain estimates of uncertainty of a forecast and its potential economic value. The results of the study are expected to be used in the operational practice of the Hydrometcenter of Russia/North Eurasia Climate Centre, as well as in the preparation of consensus forecasts during sessions of regional climate forums. [ABSTRACT FROM AUTHOR]