Extreme values of air temperature in Poland according to different atmospheric circulation classifications

2010 ◽  
Vol 35 (9-12) ◽  
pp. 429-436 ◽  
Author(s):  
Zbigniew Ustrnul ◽  
Danuta Czekierda ◽  
Agnieszka Wypych
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Extreme Values

scholarly journals Regionalization of Ukraine based on the influence of extreme values of maximum air temperature during warm and cold periods of the year

2018 ◽  
pp. 46-56
Author(s):  
S. V. Savchuk ◽  
N. N. Yuvchenko ◽  
V. E. Timofeev
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Extreme Values ◽  
Warm Period ◽  
Synoptic Situation ◽  
The South ◽  
Cool Period ◽  
Near Surface ◽  
Average Maximum ◽  
Maximum Air Temperature

Based on the data of maximum daily near-surface air temperature (MSAT) taken from 186 meteorological stations of Ukraine the parameters of extremality with relation to maximum air temperature for different time periods as well as deviations between them during cold and warm periods of the year were calculated. Regionalization of Ukraine was carried out in order to identify climate-vulnerable regions by means of comparison, overlapping and match of the areas with the highest values towards selected extremality thresholds. The conclusion about general increase in extremality over the last decade with relation to a climatic standard is made, the areas with the greatest vulnerability are outlined, and the areas with increase in extremality degree are identified. During both periods of the year certain areas in the southern, central and eastern parts of Ukraine are considered, based on maximum air temperature data, as the most vulnerable ones. During both periods of the year over 2001-2010, as compared to 1991-2000, increase of recurrence of extreme values of average maximum of air temperature was observed: in March and December during the cold period and also from May to July, and in case of EHMP event – in August. Distribution of maximum air temperature of the EHMP category, in comparison to the category of extreme values, specifies and localizes the regions with the greatest vulnerability. The areas of the highest vulnerability during the cool period comprise the extreme west, south-western and southern regions and during the warm period – southern, south-eastern regions and the extreme east of Ukraine. The spatial distribution of the extreme values of the MSAT for the warm period has a predominantly meridional orientation. During both periods of the year regions in the south (areas of Black Sea region, Crimea, boundary subregions in the south) areas in the east and center of Ukraine affected by extreme MSAT values are the most vulnerable; in 2010-2014 this influence intensified. Increase in the vulnerability based on the maximum air temperature occurs on the background of certain changes in the atmospheric circulation, under conditions of anticyclonic fields prevalence throughout the year along with increase of the temporal exposure to the elementary synoptic process. On the other hand, the aforementioned increase of recurrence of extreme hydrometeorological phenomena is a consequence of sharp changes of synoptic situation, which is especially the case after a period of settled weather. The conclusion that atmospheric circulation is a main agent responsible for extreme weather and that it is not studied completely so far was made.

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

2017 ◽  
Vol 8 (4) ◽  
pp. 963-976 ◽  
Author(s):  
Jaak Jaagus ◽  
Mait Sepp ◽  
Toomas Tamm ◽  
Arvo Järvet ◽  
Kiira Mõisja
Keyword(s):  
Time Series ◽  
Snow Cover ◽  
Atmospheric Circulation ◽  
Air Temperature ◽  
Large Scale ◽  
Regime Shifts ◽  
The Arctic ◽  
Dry Period ◽  
Snow Cover Duration ◽  
Large Scale Atmospheric Circulation

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.

scholarly journals Relationships of surface air temperature anomalies over Europe to persistence of atmospheric circulation patterns conducive to heat waves

2008 ◽  
Vol 14 ◽  
pp. 243-249 ◽  
Author(s):  
J. Kyselý ◽  
R. Huth
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Heat Waves ◽  
Temperature Extremes ◽  
Human Society ◽  
Positive Temperature ◽  
Temperature Anomalies ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Air Temperature Anomalies

Abstract. Heat waves are among natural hazards with the most severe consequences for human society, including pronounced mortality impacts in mid-latitudes. Recent studies have hypothesized that the enhanced persistence of atmospheric circulation may affect surface climatic extremes, mainly the frequency and severity of heat waves. In this paper we examine relationships between the persistence of the Hess-Brezowsky circulation types conducive to summer heat waves and air temperature anomalies at stations over most of the European continent. We also evaluate differences between temperature anomalies during late and early stages of warm circulation types in all seasons. Results show that more persistent circulation patterns tend to enhance the severity of heat waves and support more pronounced temperature anomalies. Recent sharply rising trends in positive temperature extremes over Europe may be related to the greater persistence of the circulation types, and if similar changes towards enhanced persistence affect other mid-latitudinal regions, analogous consequences and implications for temperature extremes may be expected.

Air temperature trends related to changes in atmospheric circulation in the wider area of Greece

2011 ◽  
Vol 32 (3) ◽  
pp. 737-750 ◽  
Author(s):  
P. T. Nastos ◽  
C. M. Philandras ◽  
D. Founda ◽  
C. S. Zerefos
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Temperature Trends ◽  
Of Greece

scholarly journals Interdecadal Variations in the Walker Circulation and Its Connection to Inhomogeneous Air Temperature Changes from 1961–2012

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 469 ◽  
Author(s):  
Xiaoya Hou ◽  
Jianbo Cheng ◽  
Shujuan Hu ◽  
Guolin Feng
Keyword(s):  
Pacific Ocean ◽  
Atmospheric Circulation ◽  
Air Temperature ◽  
Walker Circulation ◽  
Tropical Indian Ocean ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
Temperature Changes ◽  
Pattern Decomposition ◽  
Global Atmospheric Circulation

The tropical Pacific Walker circulation (PWC) is fundamentally important to global atmospheric circulation, and changes in it have a vital influence on the weather and climate systems. A novel three-pattern decomposition of a global atmospheric circulation (3P-DGAC) method, which can be used to investigate atmospheric circulations including the PWC, was proposed in our previous study. Therefore, the present study aims to examine the capability of this 3P-DGAC method to acquire interdecadal variations in the PWC and its connection to inhomogeneous air temperature changes in the period from 1961–2012. Our findings reveal that interdecadal variations in the PWC, i.e., weakening (strengthening) between the periods 1961–1974 and 1979–1997 (1979–1997 and 1999–2012), can be observed using the zonal stream function (ZSF) derived from the 3P-DGAC method. Enhancement of the PWC is also associated with the strengthening and weakening of zonal circulations in the tropical Indian Ocean (IOC) and Atlantic (AOC), respectively, and vice versa, implying a connection between these zonal overturning circulations in the tropics. The interdecadal variations in the zonal circulations correspond well to inhomogeneous air temperature changes, i.e., an enhancement of the PWC is associated with a warming (cooling) of the air temperature from 1000 to 300 hPa in the western (mid–eastern) Pacific Ocean and a cooling (warming) of the air temperature in the tropopause in the western (mid–eastern) Pacific Ocean. Furthermore, a novel index for the PWC intensity based on air temperature is defined, and the capability of the novel index in representing the PWC intensity is evaluated. This novel index is potentially important for the prediction of the PWC by using dynamic equations derived from the 3P-DGAC method.

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