POTENTIAL OF CONTINENTAL-SCALE CIRCULATION FOR THE DETERMINATION OF LOCAL DAILY SURFACE VARIABLES

This study deals with one aspect of statistical downscaling, viz. link s between the continental-scale upper-air circulation and surface weat her variables on a daily scale. The circulation-to-weather links are e xpressed in terms of multiple regression between either grid point val ues or intensities of circulation variability modes and weather elemen ts, including temperature variables, relative humidity, cloudiness, su nshine duration, zonal and meridional wind components, precipitation, and atmospheric pressure. The upper-air circulation influences the sur face pressure, temperature and zonal wind most strongly. The relative humidity, cloudiness and sunshine duration appear not to be connected with circulation in winter at all. The low-frequency part of circulati on (i.e. processes with periods longer than 10 days) is most efficient in specifying surface weather variables. The circulation-to-weather l inks manifest considerable intra- and interdecadal variations, posing doubts on the applicability of the 'downscaling-from-circulation' meth od of constructing climate change scenarios.