Long-term relationships between air flow indices and air temperature over Southeast Poland (original) (raw)
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If not NAO then what?—regional circulation patterns governing summer air temperatures in Poland
Theoretical and Applied Climatology
The correlation between the daily/monthly North Atlantic Oscillation (NAO) index and the daily/monthly anomalies of the summer (JJA) surface air temperatures in Poland is close to 0.00, being positive in most of the country (but hardly exceeding 0.15) and negative in the southeast. Therefore, the regional scale circulation patterns other than NAO were determined using principal component analysis (PCA) to establish the relationship between the air circulation and the daily anomalies of the mean, maximum and minimum air temperatures in Poland. Regression and correlation analysis were applied to define the strengths and spatial distributions of these relationships. The best results were obtained for the mean and maximum daily temperature anomalies, for which the Pearson correlation coefficient (r) between the modelled and observed values exceeded 0.75 in the vast areas of central and southeastern Poland, while, over the rest of the country, it amounted to 0.7. The weaker influence of the circulation on air temperatures is observed in the northwestern part of the country, along the Baltic Sea shore (r < 0.65). The weakest results were obtained for the anomalies of the daily minimum temperatures (r equals 0.5-0.6 over most of the country and drops below 0.4 in the northwest). Furthermore, the influences of each PCA-based regional circulation pattern on the variabilities of the surface temperatures were analysed. The circulation pattern recognized as the second principal component, distinguished in the positive phase by the high-pressure conditions with the anticyclonic centre located right over central and southeastern Poland, revealed the strongest positive relationship with the air temperature.
Strong heat and cold waves in Poland in relation with the large-scale atmospheric circulation
Theoretical and Applied Climatology
Occurrence of heat and cold waves in Poland in the years 1966-2015 (1966/1967-2015/2016) was described, and their circulation conditions were determined in this study. A heat wave is defined as a period of at least 3 days with Tmax > 30.0°C and a cold wave as a period of at least 3 days with Tmax <− 10.0°C. Heat waves occurred most often in central and southern Poland and cold waves in northeastern Poland. The occurrence of both heat and cold waves is related to high pressure systems. Anticyclonic blocking patterns both in winter and summer inhibit the zonal flow of air masses and intensify the meridional flow. Positive sea level pressure anomalies occurred over the study area, in the case of heat waves up to 3 hPa and in the case of cold waves up to 11 hPa. Perpendicular profiles showing geopotential height and air temperature anomalies in the troposphere were identified for the selected cases of extreme temperature episodes. Centres of geopotential height positive/negative anomalies were detected at the level of 300-250 hPa geopotential height, right over the area of the positive/negative surface temperature extremes.
The main characteristics of atmospheric circulation over East-Central Europe from 1871 to 2010
The main characteristics of atmospheric circulation over East-Central Europe from 1871 to 2010, 2017
The main objective of the paper concerns the determination of the annual and multi-annual variability of air flow over East-Central Europe in the period 1871–2010. Daily mean sea-level pressure and values of physical quantities provided the basis for distinguishing 27 circulation types, i.e., eight directional cyclonic, transitional, and anticyclonic types, and one non-directional cyclonic, anticyclonic, and an undefined type. Over the area of East-Central Europe, the highest frequency is recorded for air flow from the western sector, with a maximum in the period from December to January. In spring, a higher than average frequency of cyclonic and easterly circulation is observed, and in summer—anticyclonic and northerly. Increased zonal circulation was recorded in the years 1910–1930, and particularly after 1970, and eastern at the end of the nineteenth century and in the 1930s and 1940s. An increase in the frequency of days with non-directional anticyclonic type and westerly air flow, and a simultaneous decrease in frequency of days with south-easterly and easterly circulation were observed throughout the study period. Among the three classes of circulation types, the highest persistence (particularly in winter) was recorded for anticyclonic types, i.e., when the high pressure system occurred over the Scandinavian Peninsula or East Europe.
Atmospheric circulation conditions during winter warm spells in Central Europe
Natural Hazards
The objective of the paper was to characterise the temporal and spatial variability of winter warm spells in Central Europe in the years 1966/1967-2015/2016 and to determine the circulation conditions of their occurrence. The applied data were obtained from the Polish Institute of Meteorology and Water Management, Deutscher Wetterdienst and the National Centre for Environmental Prediction/National Centre for Atmospheric Research. A warm spell was defined as a sequence of at least three warm days, i.e. when the maximum air temperature is higher than the 95th percentile of the probability density function designated from observation. The research has proven that over the study period the air temperature increased in the winter season in Central Europe and this translated into an increase in the number of warm days. An average of 3-5 warm spells was recorded per 10 years. The most numerous warm spells occurred during three winter seasons, i.e. 1989/1990, 2006/2007 and 2015/2016. The occurrence of warm spells was related to positive anomalies of geopotential heights over the study area in the cross section of the entire troposphere. Maximum anomalies appeared at 250 hPa geopotential height, and they developed on average 9 days before the commencement of warm spells over the study area.
Snow cover in western Poland and macro-scale circulation conditions
International Journal of Climatology, 2002
The aim of the study was to find out the connection between the nature of winters in the western part of Poland (excluding the Sudety mountains) and the fluctuation in the atmospheric circulation in the North Atlantic region determined by the North Atlantic Oscillation (NAO) index. An attempt was made to establish the correlation between the NAO index and specific meteorological parameters in Poznań. The strongest positive correlation was obtained for the mean winter temperature (December-March) and strong negative correlation was found for the number of days with snow cover. Winter precipitation in Poznań was least associated with the NAO. The correlation coefficient was small and not significant. In the next stage of the study, the area of western Poland was examined; however, only one parameter, i.e. the number of days with snow cover, was taken into consideration. At each of 29 stations distributed in the study area the number of days with snow cover was proved to be strongly negatively correlated with the NAO index. Finally, the frequency of air flow directions was taken into consideration and their association with the NAO was examined. A strong negative correlation was obtained for the frequency of northeasterly and easterly air flow directions and a strong positive correlation was calculated for the frequency of westerly and northwesterly airflow directions. Such findings are consistent with the westerly flow of air masses during the positive phase and with the northerly and easterly flows during the negative phase. The results lead to the conclusion that the positive phase of the NAO causes mild and less snowy winters, whereas the negative phase increases the probability of severe and snowy winters in western Poland.
Variability of air mass occurrence in southern Poland (1951–2010)
Theoretical and Applied Climatology, 2013
The paper discusses the frequency, persistence and succession sequence of six types of air mass during the period 1951-2010. The study, which relied on a calendar of air masses in southern Poland published by T. Niedźwiedź, concludes that there is no simple relationship between the persistence and the frequency of specific air masses in the region. The study found that there was a great variety in the persistence of specific types of air mass and that persistence depended more on the direction of air mass advection than on their frequency of occurrence. The study also failed to identify any strict overall rule of succession, as any air mass could follow after any other, but certain finergrained patterns emerged. In winter and summer, arctic air (A) never followed directly after tropical air (T) or vice versa. Also, the most frequent succession sequence identified was from Polar maritime fresh air (mPf) to Polar maritime old and it accounted for the vast majority of successions from mPf into any other air mass (63 % annually and 76 % in summer).
Water, 2019
The purpose of this study is to find connections between the North Atlantic Thermohaline Circulation (NA THC), climate elements, such as cloud cover, precipitation, air temperature, sunshine duration, and relative humidity, and flow of rivers in Poland. The intensity of NA THC was characterized by the DG 3L index, which was established to assess changes in the amount of heat transported by NA THC along with the transport of water to the Arctic. The paper explains and discusses the mechanism of impact of the NA THC changeability on the elements of the catchment water balance variability. The positive and negative phases of the DG 3L index are strongly correlated with the heat anomalies in the upper layer of the North Atlantic waters. The obtained results show that changes of NA THC have significant impact on weather conditions and selected climate elements in Poland. Statistically significant positive correlations were found between the DG 3L index and average annual air temperatures, particularly in April, July, and August, while negative between the DG 3L index and the total cloud cover. Consequently, in the years with the positive values of the DG 3L index, there are favorable conditions for the strong increase in evaporation and evapotranspiration from the ground surface. This has impact on flow of rivers in Poland, which shows considerable regional differences.
Daily Minimum and Maximum Air Temperature in Poland in the Years 1951–2005
Bulletin of Geography. Physical Geography Series
In this study grid data of daily maximum and minimum air temperatures taken from the NCEP/NCAR reanalysis for the territory of Poland for the years 1951-2005 have been used as a basis for an analysis of the spatial distribution of daily maximum and minimum air temperature, the frequency of characteristic days and the variability of these parameters in the period analysed. The results obtained were then compared to the variability in atmospheric circulation in Europe, described by the North Atlantic Oscillation (NAO) index.
Theoretical and Applied Climatology
This work presents the influence of atmospheric circulation on the occurrence of dry and wet periods in the central Polish region of Kujawy. The material on which the authors relied encompassed monthly totals of precipitation obtained from 10 weather stations in the period 1954–2018. Both dry and wet periods have been identified on the basis of monthly values of the Standardised Precipitation Index (SPI). Additionally, the calendar of circulation types over Central Poland was used to determine the atmospheric circulation indices: western (W), southern (S) and cyclonicity (C). The analyses have indicated that the region concerned experiences low precipitation totals in comparison with the rest of Poland. According to the circulation indices W, S and C, for Central Poland, the air mass advection from the West prevails over that from the East. Moreover, a slightly more frequent inflow of air from the South than from the North has been observed. The frequency of anticyclonic situations ...