Shifts in meteorological regime of the late winter and early spring in Estonia during recent decades

Abstract

Wind, temperature and precipitation measurements at Vilsandi (the westernmost island of Estonia) and Tiirikoja (on the western coast of Lake Peipsi) collected during 1966–2005 were used to detect trends and regime shifts in monthly mean averages. A similar analysis was carried out for wind components in the free atmosphere calculated from aerological soundings. An abrupt increase in the upper-air zonal wind component around 1987 was detected in January and February over North-East Europe that may form a significant part of the intensification of the western flow. This increase is accompanied by a shift in the meteorological regime near the surface over a wider area. In March, the regime shift in the upper air flow that has taken place in the middle of the 1990s is not reflected in the meteorological parameters at the surface. Besides the regime shift at the end of the 1980s, also shifts in the middle of the 1970s and at the beginning of the 2000s are suggested.