Shifts in early spring wind regime in North-East Europe (1955–2007)

Keevallik, Sirje; Soomere, Tarmo

doi:10.5194/cp-4-147-2008

Cited by 18 publications

(13 citation statements)

References 20 publications

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“…The shift year 1989 was found for the majority of time series analysed in this study. This result is in good concordance with the previous investigations in the same region (Keevallik and Soomere, 2008;Elken et al, 2014;Soomere et al, 2015).…”

Section: Discussionsupporting

confidence: 83%

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Trends and regime shifts in climatic conditions and river runoff in Estonia during 1951–2015

et al. 2017

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Abstract. Time series of monthly, seasonal and annual mean air temperature, precipitation, snow cover duration and specific runoff of rivers in Estonia are analysed for detecting of trends and regime shifts during 1951-2015. Trend analysis is realised using the Mann-Kendall test and regime shifts are detected with the Rodionov test (sequential t-test analysis of regime shifts). The results from Estonia are related to trends and regime shifts in time series of indices of large-scale atmospheric circulation. Annual mean air temperature has significantly increased at all 12 stations by 0.3-0.4 K decade −1 . The warming trend was detected in all seasons but with the higher magnitude in spring and winter. Snow cover duration has decreased in Estonia by 3-4 days decade −1 . Changes in precipitation are not clear and uniform due to their very high spatial and temporal variability. The most significant increase in precipitation was observed during the cold half-year, from November to March and also in June. A time series of specific runoff measured at 21 stations had significant seasonal changes during the study period. Winter values have increased by 0.4-0.9 L s −1 km −2 decade −1 , while stronger changes are typical for western Estonia and weaker changes for eastern Estonia. At the same time, specific runoff in April and May have notably decreased indicating the shift of the runoff maximum to the earlier time, i.e. from April to March. Air temperature, precipitation, snow cover duration and specific runoff of rivers are highly correlated in winter determined by the large-scale atmospheric circulation. Correlation coefficients between the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) indices reflecting the intensity of westerlies, and the studied variables were 0.5-0.8. The main result of the analysis of regime shifts was the detection of coherent shifts for air temperature, snow cover duration and specific runoff in the late 1980s, mostly since the winter of 1988/1989, which are, in turn, synchronous with the shifts in winter circulation. For example, runoff abruptly increased in January, February and March but decreased in April. Regime shifts in annual specific runoff correspond to the alternation of wet and dry periods. A dry period started in 1964 or 1963, a wet period in 1978 and the next dry period at the beginning of the 21st century.

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Section: Discussionsupporting

confidence: 83%

“…An increase in zonal circulation starting in 1987 was detected in February (Keevallik and Soomere, 2008). A similar shift at the end of the 1980s was found in the time series of cumulative wind stress calculated for December-January using data from Utö (Elken et al, 2014).…”

Section: Introductionmentioning

confidence: 52%

Trends and regime shifts in climatic conditions and river runoff in Estonia during 1951–2015

et al. 2017

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“…8b). Keevallik & Soomere (2008) observed a shift in the early-spring wind regime over the northeastern Baltic area. They concluded that multiple regime shifts in the wind components happened between different periods (PKS1: 1955-1966, PKS2: 1967-1995, PKS3: 1996, especially pronounced in March.…”

Section: Regional Atmospheric Variabilitymentioning

confidence: 92%

Detailed assessment of climate variability in the Baltic Sea area for the period 1958 to 2009

Lehmann¹,

Getzlaff²,

Harlaß³

2011

Clim. Res.

184

118

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. A specific warming period started around 1980 and continues until the present. This warming also occurred in the Baltic Sea catchment, which lies between maritime temperate and continental subarctic climate zones. A detailed study of climate variability and the associated impact on the Baltic Sea area for the period 1958 to 2009 revealed that the recent changes in the warming trend are associated with changes in large-scale atmospheric circulation over the North Atlantic. The number and pathways of deep cyclones changed considerably in line with an eastward shift of the North Atlantic Oscillation centers of action. There is a seasonal shift of strong wind events from autumn to winter and early spring. Since the late 1980s, the winter season (DJFM, i.e. December to March) of the Baltic Sea area has tended to be warmer, with less ice coverage and warmer sea surface temperatures, especially pronounced in the northern parts of the Baltic Sea. There is a tendency for increased cloud cover and precipitation in regions that are exposed to westerlies and less cloud coverage at the leeward side of the Scandinavian Mountains and over the Baltic Sea Basin. KEY WORDS: Baltic Sea · NAO · Climate variabilityResale or republication not permitted without written consent of the publisher OPEN PEN

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“…Comparable shifts for early spring were also reported for Finland by Keevallik and Soomere (2008) and Keevallik (2011) from the 1960s to 1990s with changes to more westerly than north-westerly winds. For the period 1966-2011, Jaagus and Kull (2011) also found a clear change in the main wind direction over Estonia in winter changing from south-east in the 1970s to south-west in the last decade.…”

Section: Wind Climate In Recent Decadesmentioning

confidence: 61%

Recent Change—Atmosphere

Rutgersson

Jaagus

Schenk

et al. 2015

Regional Climate Studies

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This chapter describes observed changes in atmospheric conditions in the Baltic Sea drainage basin over the past 200-300 years. The Baltic Sea area is relatively unique with a dense observational network covering an extended time period. Data analysis covers an early period with sparse and relatively uncertain measurements, a period with well-developed synoptic stations, and a final period with 30+ years of satellite data and sounding systems. The atmospheric circulation in the European/Atlantic sector has an important role in the regional climate of the Baltic Sea basin, especially the North Atlantic Oscillation. Warming has been observed, particularly in spring, and has been stronger in the northern regions. There has been a northward shift in storm tracks, as well as increased cyclonic activity in recent decades and an increased persistence of weather types. There are no long-term trends in annual wind statistics since the nineteenth century, but much variation at the (multi-)decadal timescale. There are also no long-term trends in precipitation, but an indication of longer precipitation periods and possibly an increased risk of extreme precipitation events.

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Shifts in early spring wind regime in North-East Europe (1955–2007)

Cited by 18 publications

References 20 publications

Trends and regime shifts in climatic conditions and river runoff in Estonia during 1951–2015

Trends and regime shifts in climatic conditions and river runoff in Estonia during 1951–2015

Detailed assessment of climate variability in the Baltic Sea area for the period 1958 to 2009

Recent Change—Atmosphere

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