Rubinstein, K. (Head of laboratory, Hydrometcentre of Russia)
Bardin, M. (Senior Researcher, Institute for Global Climate and Ecology)
Among the main problems of the modern climatology reliable assessment of climate changes and consequent changes both in the natural ecosystems and agriculture on regional scales, are of the first-rate importance, due to the fact that magnitude of changes and vulnerability are greatly varying in space, thus making certain regions "critical" with respect to changes considered. Undoubtedly, the Mediterranean region is among the most vulnerable ones, due to specific climatological and hydrological conditions, being of greatest importance for the mankind. It is well-known that existing numerical model estimates of changes in principal climatic parameters are characterised by the high degree of uncertainty on the regional scale, and, hence, could not be immediately applied to obtaining reliable conclusions concerning regional climatic and environmental changes.
That is why intense studies of methods for the translation of large scale modelling results on regional scales (statistical downscaling) are in progress in numerous research centers. This job is aimed at the study the possibility of low resolution numerical atmospheric GCM of Hydrometcentre of Russia to describe the characterristics of Mediterranean Cyclones. To fulfill this task, we employed empirical statistical data on Mediterranean Cyclones (H500 and PS) and the same obtained from numerical experiments. Consistency between the two ensembles is analyzed.
Within the framework of the downscaling method two approaches to the statistical analysis of relationships between the cyclonicity and large-scale circulation were utilised: (1) the method based on the (multiple) regression by predictors, representing the large-scale circulation (e.g., regional EOFs of the H500 field) in the "responsible" region, and (2) "synoptic climatology" of large-scale atmospheric regimes, applied to the statistics of Mediterranean region cyclones.
The hydrodynamic atmospheric model based on integrating set of primitive equations. A spectral-grid approach is used when solving equations of the model. The resolution in the horizontal is harmonics; the triangular truncation is used with T21 resolution and 45 min time step. The vertical resolution is 15 sigma-levels most frequently arranged in the lower troposphere. Sophisticated parameterisations of the sub-grid physical processes are included in the model. These are cloud-radiation interaction, convective processes, turbulent heat and moisture exchange, large-scale condensation, land surface processes. The scheme of land hydrology considers the orography at the scales of elementary valleys (runoff formation description) and of large river basins (horizontal runoff redistribution and soil moisture). During the experiments fixed ocean surface temperature was adopted. Experiments for periods of a decade to several decades are assumed to be accomplished for the study of the monthly and seasonal variability of model results.