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The river ice regime is considered a sensitive indicator of climate change and within this study long term changes (in case of River Daugava starting from 1530, but for other studied rivers starting from first half of twentieth century) river ice regimes in the Baltic region have been studied. The ice cover duration on the rivers (17 rivers) in the Baltic countries and Belarus has decreased during the recent decades. In addition to this, long term observational records of ice break on the rivers of the studied region exhibit a pattern of periodic changes in the intensity of ice regime. Both the ice regime and the seasonal river discharge are shown to be strongly influenced by large-scale atmospheric circulation processes over North Atlantic that manifests through close correlation with North Atlantic Oscillation index. 相似文献
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Jaak Jaagus Agrita Briede Egidijus Rimkus Kalle Remm 《Theoretical and Applied Climatology》2014,118(1-2):57-68
Spatial distribution and trends in mean and absolute maximum and minimum temperatures and in the diurnal temperature range were analysed at 47 stations in the eastern Baltic region (Lithuania, Latvia and Estonia) during 1951–2010. Dependence of the studied variables on geographical factors (latitude, the Baltic Sea, land elevation) is discussed. Statistically significant increasing trends in maximum and minimum temperatures were detected for March, April, July, August and annual values. At the majority of stations, the increase was detected also in February and May in case of maximum temperature and in January and May in case of minimum temperature. Warming was slightly higher in the northern part of the study area, i.e. in Estonia. Trends in the diurnal temperature range differ seasonally. The highest increasing trend revealed in April and, at some stations, also in May, July and August. Negative and mostly insignificant changes have occurred in January, February, March and June. The annual temperature range has not changed. 相似文献
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This paper provides an overview of the thunderstorm climate of the Baltic countries during the period of 1951–2000. Our study area is in northeastern Europe and encompasses Estonia, Latvia, and Lithuania. Visual thunderstorm observations at 59 weather stations were used as a data source. The mean annual number of thunderstorm days was 12–29.5. The seasonal cycle of thunderstorm hours with a daily step unexpectedly showed two maxima, whereas the monthly numbers of thunderstorm days had one clear mid-latitude specific peak between June and August. The diurnal cycle of thunderstorm hours showed a peak between 1400 and 1800 local time and a minimum between 0400 and 1000 hours local time. The average annual duration of thunderstorm events was 112 min. The average number of thunderstorm events per thunderstorm day was around 1.1–1.2. Our results showed that the thunderstorm climate of the Baltic countries generally resembles that of other mid-latitude study sites. 相似文献
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