Changes in spring weather conditions and atmospheric circulation in Estonia (1955–95)

• Published in: International Journal of Climatology
• Main Author: Keevallik, Sirje
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2003
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: http://dx.doi.org/10.1002/joc.875; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjoc.875; https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.875

Abstract An analysis has been undertaken at Tiirikoja Meteorological Station to investigate changes in the main weather elements in late winter and spring during the period 1955–95. The relationship between these changes and the trends in the atmospheric circulation above Estonia have also been analysed. The latter was estimated from wind speed and direction data recorded at Tallinn Aerological Station at two isobaric levels (500 and 850 hPa). These data permitted the analysts to calculate zonal and meridional components of wind velocity at both levels. Linear trends were fitted to time series of monthly averages of all parameters under consideration. The results indicate that significant changes in meteorological parameters took place in March. These changes are statistically related to the changes in the average airflow in the free atmosphere above Estonia. In March the wind speed at the 500 and 850 hPa isobaric levels increased and the average airflow turned from WNW or NW to SW or WSW. Such changes in the atmospheric circulation can only partly be attributed to the intensification of the North Atlantic oscillation. Copyright © 2003 Royal Meteorological Society