Air Temperature In Poland Research Articles

Variability in the occurrence of thermal seasons in Poland in 1961–2020

AbstractThe article analyses the variability of thermal seasons in Poland in 1961–2020. Based on the average monthly air temperature values from 55 stations, the onset and end dates as well as the duration of the six thermal seasons were calculated. Taking into account the thermal thresholds of 0°C, 5°C and 15°C for each year, early spring, spring, summer, autumn, early winter and winter can be distinguished. A significant spatial differentiation of the dates of the beginning and duration of the thermal seasons in Poland was observed. The influence of continentalism (in the east) and oceanic climate (in the west) and the influence of the Baltic Sea are noticeable, and in mountainous regions, altitude above sea level is the main factor. The air temperature in Poland increases at the rate of 0.3°C–0.4°C/10 years. This causes significant changes in the occurrence and duration of the thermal seasons. An early beginning of early spring and spring was observed. Summer arrives earlier and is significantly longer, becoming the longest season of the year (above 110 days in the south of Poland). Autumn and early winter are delayed and get shorter, whereas winter comes much later. Throughout the country, winter is 44 days shorter, and in the north‐west it does not occur at all. Changes in the onset of thermal seasons are a clear indicator of progressing global warming. They have also a decisive impact on the environment and human activity.

Thermal comfort assessment in the modern passenger car under actual operational conditions

Abstract People’s ever-increasing needs encourage designers of various vehicles to search for solutions that will provide the most comfortable internal environment conditions. Currently, partly due to the COVID-19 threat, many people use their individual cars to travel to work, college, shops, trips, and holidays. Proper internal air parameters that need to be maintained in vehicles are critical in the summer. The article discusses the thermal comfort of four passengers of a modern car produced in 2017 to verify if contemporary production technology can successfully meet the thermal needs of people under actual conditions in the Polish climate. For this purpose, five temperature values were tested: 20°C, 22°C, 24°C, 26°C, and 28°C for the car located in the shade and sun. In addition, the Testo 400 meter was used to control and measure the internal parameters, and questionnaires were used to find out about the thermal impressions of the respondents. The research was carried out in July when the air temperature in Poland was high.

Features of Multiannual Air Temperature Variability in Poland (1951–2021)

Over the last 71 years, the air temperature in Poland has increased on average by 0.28 °C per decade—which gives a total change in this period exceeding 2 °C. The subject of this study was an analysis of the long-term variability of the Polish climate in terms of thermal characteristics. The aim of the research was to verify the hypothesis on the lack of homogeneity of this change and to identify points of significant acceleration of the observed tendencies. The analysis utilized the average monthly air temperature at selected synoptic stations in Poland over the period 1951–2021. The values were then processed into a reference series using Alexandersson’s method, which provided synthetic information on the variability in thermal conditions in the country. The analyses were carried out on an annual and seasonal basis. The values of the trend coefficients (and their statistical significance) were also calculated in shorter periods (minimum 30 years), which enabled determination of the stability of the observed changes’ tendencies. In addition to the analysis of the basic characteristics, non-parametric tests (Wilcoxon, Kruskal–Wallis) were used to verify shifts between decades. The annual and seasonal analyses showed the existence of sub-periods with different directions and scales of the observed tendencies. Additionally, statistically significant changes in decadal characteristics were noted, e.g., in the decades 2001–2010 and 2011–2020 in the case of annual temperature, and 1961–1970 and 1971–1980 in the case of the winter season.

Relationships between sunshine duration and air temperature in Poland

The aim of the paper is to characterize the trends of sunshine duration (SDU) and air temperature in Poland, which may help understand the mechanism of contemporary climate change. The daily totals of SDU and daily data on air temperature from the years 1971-2020, from 25 synoptic stations in Poland are the basic source data. The series of records of the two variables showed that the points of change in the level of stabilization of the value of SDU and air temperature are close to each other, and confirm known in the literature “global dimming” and “global brightening” periods. The linear regression model confirmed that sunshine duration explains well the variability of, and increase in day-time air temperature in Poland in the warm part of the year.

Characteristics of air temperature in Poland from 1994 to 2019 based on hourly data

AbstractThis study was conducted to understand the characteristics of hourly air temperature across Poland over the period 1994–2019. For this purpose, hourly temperature observations from 38 stations were used. It was found that the average temperature at all stations in the period 2007–2019 (second half of data) is higher than that in the period 1994–2006 (first half of data). The increase in the average temperature in autumn was smaller than that in the other seasons. In the northern part of Poland, the increase in the average temperature in spring was more notable compared with that in the other seasons. In the southern part of Poland, the increase in the average temperature in winter and summer was more notable compared with that in the other seasons. At all stations, a statistically significant increasing trend in the average temperature was seen in the period 1994–2019. This trend was highest at Warszawa (0.067°C/year) and lowest at Kraków Balice (0.029°C/year). At all stations, the frequency of relatively low/high temperatures was lesser/higher in the period 2007–2019 compared with that in the period 1994–2006 indicating that temperature distribution has shifted toward a warmer climate. In comparison to the period 1994–2006, in the period 2007–2019, in the southern region of Poland, a large increase in the average number of hours per year above high percentiles and a large decrease in the average number of hours per year below low percentiles was observed. Also, it was found that warm/cold spells are becoming more/less frequent in Poland. In many stations, compared with the period 1994–2006, in the period 2007–2019, an increase in the length of the longest spell of hours above the 99th percentile and below the first percentile was observed.

Spatial diversity of air temperature changes in Poland in 1961–2018

The article comprises an analysis of the spatial distribution, and variability of air temperature in Poland in the years 1961–2018. It was found that the mean increase in air temperature was 0.33 °C/10 years. The most evident warming occurred in the west of the country and at the Baltic Sea (> 0.4 °C/10 years). The greatest increase in the temperature was observed in summer (July 0.48 °C/10 years), winter (January 0.46 °C/10 years) and spring (April 0.41 °C/10 years), whereas in autumn the warming was not statistically significant. The major role of atmospheric circulation in shaping air temperature in Poland was corroborated. The positive correlation with the NAO was confirmed, and Pearson’s linear correlation coefficient (r) reached 0.81 in the north of Poland in January. An analysis of the variability of air temperature in Torun (Central Poland) in 1991–2018 demonstrated that the increase in temperature was correlated with a solar irradiance (r = 0.69 in July). Moreover, the types of atmospheric circulation and incoming air masses are also significant. The type of baric centre was found to play a very important role that is opposite in winter to what it is in summer. In cyclonic situations, air temperature increased in winter (r = 0.65 in January) and decreased in the warm half of the year (r = − 0.47 in September). An intensified flow of incoming air masses from the west caused air temperature to increase in winter (r = 0.72 in January) and to cool in summer (r = − 0.69 in August). The role of meridional flow becomes particularly evident in autumn (r = 0.49 in October).

The influence of atmospheric circulation over Central Europe on the long-term variability of sunshine duration and air temperature in Poland

The aim of this study is to analyse the influence of atmospheric circulation over Central Europe on the long-term variability of relative sunshine duration (RSD) and air temperature in Poland. The analysis of data from 23 stations located in different parts of the country has made it possible to indicate to what extent the trends of these two climate elements are related to atmospheric circulation and whether they occur throughout the year or only in certain months. To this end, the author's own classification of circulation types was used, which relies on a set of indices related to the velocity and direction of geostrophic flow, as well as total shear vorticity, calculated using a gridded data set of sea-level pressures. The results of the research showed that atmospheric circulation over Central Europe has a significant impact on RSD and air temperature in Poland, but not on their upward trends in recent decades. The increase in the average annual values of both these climate elements was marked in almost every circulation type. This contradicts the assumption of classical synoptic climatology, which assumes that circulation types themselves are usually considered to be constant, i.e. that changes in air temperature can be related only to an increase or decrease in the incidence of the circulation types.

Temporal Changes of Near‐Surface Air Temperature in Poland for 1781–2016 and in Tbilisi (Georgia) for 1881–2016

AbstractAnalyses of near‐surface air temperature T in Poland for 1781–2016 and in Tbilisi (Georgia) for 1881–2016 have been carried out. We show that the centenary warming effect in Poland and in Tbilisi has almost the same peculiarities. An average centenary warming effect ΔT = (1.08 ± 0.29)°C is observed in Poland and in Tbilisi for 1881–2016. A warming effect is larger in winter season (ΔT = ~1.15°C) than in other seasons (average warming effect for these seasons ΔT = ~0.95°C). We show that a centenary warming is mainly related to the change of solar activity (estimated by sunspot number [SSN] and total solar irradiance [TSI]), particularly, a time interval about ~70 years (1890–1960), when correlation coefficients between 11‐year smoothed SSN and T, and TSI and T are high, r = 0.66 ± 0.07 and r = 0.73 ± 0.07 for Poland and r = 0.82 ± 0.05 and r = 0.90 ± 0.05 for Tbilisi, respectively; in this period solar activity contributes decisively in the global warming. We show that a global warming effect equals zero based on the temperature T data in Poland for period 1781–1880, when human activities were relatively less than in 1881–2016. We recognize a few feeble ~20 ± 3 years of disturbances in the temperature changes for period 1885–1980, most likely related with the fluctuations of solar magnetic cycles. We distinguish the fluctuations of ~7–8 years in Poland's T data, possibly connected with local effects of the North Atlantic Oscillation.

Thermal Conditions for Viticulture in Poland

The ongoing global warming promotes an expansion of the areas of land already used for viticulture, as well as the establishment of new vineyards in areas that were previously considered unsuitable. In this study, a temporal and spatial assessment of the thermal conditions for viticulture in Poland was conducted using a series (1971–2019) of daily data on air temperature (mean, maximum and minimum) obtained from 52 stations of the Polish Institute of Meteorology and Water Management—National Research Institute. On the basis of the values of air temperature for the year (January–December), the vegetative period (April–September), and July, as well as the duration of the period of active growth of the plant (air temperature >10 °C) and the sum of active temperatures (SAT) in this period, five potential areas for viticulture in Poland were identified with respect to thermal conditions. It was found that approx. 60% of the country’s area shows conducive and moderately conducive conditions for intense viticulture. In the analysed multiannual period, there is a dynamic increase in air temperature in Poland, an increase in the sums of active temperatures (SAT) as well as an increase in the duration of the period of active growth of the plant. The ongoing global warming causes a shift of the current boundary of intense viticulture to the north of Poland (from 100 to 150 km). The greatest increases in air temperature and SAT values were found in the south-west and west of Poland, with a marked decrease shown towards the north-east and east.

Długookresowe wahania przepływów rocznych głównych rzek w Polsce ich związek z cyrkulacją termohalinową Atlantyku Północnego

In this paper it is the associations between mean annual discharges of the main rivers in Poland and the surface component of the Northern Atlantic Thermohaline Circulation (NA THC) that are analysed. Relevant data derived from hydrometric profiles on the country’s main rivers, i.e. the Vistula at Tczew (years 1901-2015), the River Bug at Wyszkow (1921-2015), the Oder at Gozdowice (1901-2015) and the Warta in Poznan (1822-2015). Use was also made of the time series for annual discharges of the Vistula at Torun (1822-2000). Results show that, despite marked inter-annual variability to discharges in two periods (1921-2015 and 1822-2000), there is a common rhythm to long-term discharge fluctuations (Table 1, Figure 1), with consecutive increases and decreases in annual discharges. The analysis shows that the changeability of annual discharges and variability in the NA THC are characterised by weak, but highly statistically signifi cant associations (Table 2). In periods in which the NA THC intensifies (as indicated by the DG3L index), river discharges are found to decrease; whereas a fall in the intensity of NA THC is associated with an increase in the intensity of river discharges (Figs. 2, 3 and 4). While small, these differences do assume a high level of statistical significance (Fig. 4). Figs. 2, 3 and 4 also show how the occurrence of positive values for the NA THC (+DG3L) sees the degree of variability of annual discharges reduced in relation to that present when values for the NA THC are negative (–DG3L). Given that the variability characterising the DG3Lindex (NA THC) displays multi-decadal oscillations (Fig. 6), it is not surprising that such oscillations also occur where discharges from Poland’s main rivers are concerned. The differences between discharges occurring in the positive and negative phases of the NA THC (+DG3L and –DG3L amount to around 10%. The main reason for such an association is that variability in the NA THC (with which changes in the thermal state of the Northern Atlantic are connected) is what is known to regulate some aspects of atmospheric circulation. As a result, in the circumstances of positive values for the DG3L index, mean annual air temperature in Poland is higher (and in April, July and August significantly higher) than at times when a negative DG3L index is present. When positive values for the DG3L index arise, there are greater losses due to evaporation (or evapotranspiration) in the river catchments in Poland, with the result that discharges are reduced. No statistically significant relationships were found between the NA THC and precipitation in Poland. However, while there are no statistically significant relationships between mean annual discharges from the rivers in Poland and the AMO index, associations between discharges and the DG3L index – characterising the intensity of the thermohaline circulation in the Northern Atlantic – do achieve statistical significance. The results obtained suggest that the relationship between the intensity of the NA THC and the occurrence of droughts in Poland should be investigated.

The Role of Auxiliary Variables in Deterministic and Deterministic-Stochastic Spatial Models of Air Temperature in Poland

Our study examines the role of auxiliary variables in the process of spatial modelling and mapping of climatological elements, with air temperature in Poland used as an example. The multivariable algorithms are the most frequently applied for spatialization of air temperature, and their results in many studies are proved to be better in comparison to those obtained by various one-dimensional techniques. In most of the previous studies, two main strategies were used to perform multidimensional spatial interpolation of air temperature. First, it was accepted that all variables significantly correlated with air temperature should be incorporated into the model. Second, it was assumed that the more spatial variation of air temperature was deterministically explained, the better was the quality of spatial interpolation. The main goal of the paper was to examine both above-mentioned assumptions. The analysis was performed using data from 250 meteorological stations and for 69 air temperature cases aggregated on different levels: from daily means to 10-year annual mean. Two cases were considered for detailed analysis. The set of potential auxiliary variables covered 11 environmental predictors of air temperature. Another purpose of the study was to compare the results of interpolation given by various multivariable methods using the same set of explanatory variables. Two regression models: multiple linear (MLR) and geographically weighted (GWR) method, as well as their extensions to the regression-kriging form, MLRK and GWRK, respectively, were examined. Stepwise regression was used to select variables for the individual models and the cross-validation method was used to validate the results with a special attention paid to statistically significant improvement of the model using the mean absolute error (MAE) criterion. The main results of this study led to rejection of both assumptions considered. Usually, including more than two or three of the most significantly correlated auxiliary variables does not improve the quality of the spatial model. The effects of introduction of certain variables into the model were not climatologically justified and were seen on maps as unexpected and undesired artefacts. The results confirm, in accordance with previous studies, that in the case of air temperature distribution, the spatial process is non-stationary; thus, the local GWR model performs better than the global MLR if they are specified using the same set of auxiliary variables. If only GWR residuals are autocorrelated, the geographically weighted regression-kriging (GWRK) model seems to be optimal for air temperature spatial interpolation.

Daily amplitude of air temperature in Poland and Bulgaria - a comparative study

The work presented here aimed to compare daily amplitudes of air temperature in Poland and Bulgaria, by reference to data from 36 meteorological stations (i.e. 18 from each country) over the period 2000-2012. It proved possible to demonstrate that the average temperature amplitude at the stations in Poland is 2-3°C smaller than that noted for Bulgaria, with the spatial differentiation characterising such averages also being significantly more limited in Poland. Where the annual course for average amplitudes in air temperature in Poland are concerned, there are two maxima and two minima to be noted, as compared with one maximum and one minimum in Bulgaria. The highest values for average daily amplitude in air temperature to be noted in Poland are those typical for May, while highest values in Bulgaria fall in August. The differences between Poland and Bulgaria also manifest themselves in the markedly greater frequency of occurrence of large (>20°C) values for temperature amplitudes to be noted in Bulgaria.

Reliability of CMIP5 GCM simulations in reproducing atmospheric circulation over Europe and the North Atlantic: a statistical downscaling perspective

ABSTRACTReliability of GCM (general circulation model) simulations is a significant predictor selection criteria and seems to be essential for outcomes of the statistical downscaling. This article investigates the reliability of a wide ensemble of CMIP5 climate models in reproducing seasonal atmospheric circulation patterns over Europe and the North Atlantic, namely sea level pressure (SLP) and 500 hPa geopotential height (G500). GCMs were evaluated with respect to 1971–2000 NCEP/NCAR reanalysis data by means of MAE, correlation coefficient and standard deviation. An attempt was made to determine the range of biases introduced into the statistical models by biases in the GCM simulations. For this purpose, canonical correlation analysis (CCA) models linking large‐scale atmospheric circulation and air temperature in Poland were driven by historical GCM simulations expressed as anomalies with reference to the reanalysis data.It was shown that reliability of GCMs varies considerably, both seasonally and on an inter‐model basis, thus becoming unfavourable in the context of statistical downscaling application. Overall, GCM ability to reproduce G500 values is better than for SLP. The most important finding from the statistical downscaling perspective is that SLP and G500 biases may introduce considerable air temperature biases (T‐GCMbiases) into the downscaled reconstructions or projections of climate change. Seasonally, the highest T‐GCMbiases were found in DJF, when a significant overestimation of air temperature results from a GCM tendency to overestimate the meridional pressure gradient. A similar situation appears to be a significant factor in MAM and SON. Multiyear average GCM biases do not, however, explain a significant part of the inter‐model variability of T‐GCMbias, thus highlighting the need for a more in‐depth evaluation. Nevertheless, good GCM performance seems to ensure that T‐GCMbias is not of a considerable value. Overall, the results of the article emphasise the necessity for undertaking an application‐oriented assessment of GCM reliability prior to any statistical downscaling approach.

Niektóre cechy wieloletniej zmienności temperatury powietrza w Polsce (1951-2010)

The aim of the analysis presented here has been to describe long-term variability in air temperature in Poland over the 1951-2010 period. Certain spatial aspects have also been discussed. In order to provide a representative and homogeneous temperature series, station data were averaged for 7 geographical regions of Poland, and for the country as a whole. The distinction drawn between shoreland, lakelands, lowlands, highlands, Subcarpathia, the Sudetes and the Carpathians is as adopted after Kondracki (2002). It takes account of such important factors underpinning spatial variability in temperature as altitude, relief, land use, and, indirectly (as a result of latitudinal distribution) also distance from the Baltic Sea and the amount of received solar radiation. In total, monthly average temperature values from 45 synoptic stations were used to calculate an area-averaged temperature for Poland (Table 1). Further study then entailed analysis of annual, seasonal and monthly series with a view to determining trends (at an adopted statistical signifi cance of =0.05), decadal average temperature variability, the longterm course to be noted for air temperature anomalies and the range of variability. The most signifi cant feature of the long-term (1951-2010) variability in annual air temperature in Poland is the statistically signifi cant increase that displays in every analysed region, with an average rate of change exceeding 0.2°C per decade (Table 2). At the seasonal level, an upward trend is to be noted for spring (+0.36°C/10 years) and summer (almost 0.2°C/10 years). In line with this, the decade 2001-2010 was the hottest in the analyzed period (Table 3, 8-10), with the exception of winter (Table 7), for which a slight decrease in average air temperature relative to the 1991-2000 period could be observed. When set against the whole 1951-2000 period, the rate of annual warming remains approximately constant though the summer-season contribution to the warming trendis clearly increasing, while the winter contribution is reduced. On a monthly basis, statistically signifi cant warming over the period is to be observed for February (by over 0.5°C/10 years – the highest rate for any month), during spring (i.e. in March, April and May), and in July and August. Analysis addressing the spatial distribution to the trend revealed that the highest rate of temperature increase is affecting northern Poland (the shoreland and lakeland belts) and the Carpathians, while the lowest rate of increases is to be observed for the highlands and the Sudetes. The long-term course of air temperature anomalies is dominated by short-term variability, which manifests itself in relatively large changes from year to year and with the occurrence of short warm and cold periods. However, where annual series are concerned there has been a noticeable run of warmer years since 1988 (Fig. 1), with only a few exceptions (e.g. 1996 and 2010). A similar situation applies to spring (Fig. 3) and summer (Fig. 4). Furthermore, the spatial cohesion displayed by air-temperature variability indicates that observed changes in thermal conditions in Poland are mainly driven by large-scale factor(s). Fluctuations in annual air temperature averaged for Poland do not exceed ±2°C. On the seasonal scale, variability range varies from 3.9°C in summer to 10.2°C in winter, while at the level of individual months the range is between 4.7°C in June and 16.3°C in February. Relatively small variations in air temperature characterisethe Baltic coast (the shoreland belt). Another feature of long-term air temperature change in Poland is that the values for extreme negative anomalies in winter are clearly larger than the positive ones. In the annual cycle, July is most often the warmest month (in 60% of the years during the 1951-2010 period), while the minimal average air temperature has most often been recorded in January (in 45% of years).

Regression-based air temperature spatial prediction models: an example from Poland

A Geographically Weighted Regression – Kriging (GWRK) algorithm, based on the local Geographically Weighted Regression (GWR), is applied for spatial prediction of air temperature in Poland. Hengl’s decision tree for selecting a suitable prediction model is extended for varying spatial relationships between the air temperature and environmental predictors with an assumption of existing environmental dependence of analyzed temperature variables. The procedure includes the potential choice of a local GWR instead of the global Multiple Linear Regression (MLR) method for modeling the deterministic part of spatial variation, which is usual in the standard regression (residual) kriging model (MLRK). The analysis encompassed: testing for environmental correlation, selecting an appropriate regression model, testing for spatial autocorrelation of the residual component, and validating the prediction accuracy. The proposed approach was performed for 69 air temperature cases, with time aggregation ranging from daily to annual average air temperatures. The results show that, irrespective of the level of data aggregation, the spatial distribution of temperature is better fitted by local models, and hence is the reason for choosing a GWR instead of the MLR for all variables analyzed. Additionally, in most cases (78%) there is spatial autocorrelation in the residuals of the deterministic part, which suggests that the GWR model should be extended by ordinary kriging of residuals to the GWRK form. The decision tree used in this paper can be considered as universal as it encompasses either spatially varying relationships of modeled and explanatory variables or random process that can be modeled by a stochastic extension of the regression model (residual kriging). Moreover, for all cases analyzed, the selection of a method based on the local regression model (GWRK or GWR) does not depend on the data aggregation level, showing the potential versatility of the technique.

The course of phenological phases of potato and its determination by multi-annual variability of air temperature in Poland

The course of phenological phases of potato and its determination by multi-annual variability of air temperature in Poland

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

The paper focuses on synoptic and climate analysis with the application of circulation types based on six classification schemes, both subjective and objective. The principal goal of the study was to determine circulation types with respect to the occurrence of extreme values of air temperature. A comparison between different available classifications was also performed. Maximum and minimum daily temperatures for the 56-year study period (1951–2006) were used in the analysis. The necessary data series were obtained from 61 weather stations, relatively well spaced across Poland. Each series was checked for homogeneity and evaluated. Detailed calculations were performed for the summer (June–August) and winter (December–February) seasons. Extreme values were selected with respect to probability distribution bases. The top and bottom 5% were used for further analysis. Calculations of extreme values for particular types and classifications were the main phase of analysis. All extreme temperature values were analyzed for each type. This enabled the creation of histograms presenting types producing the highest number of particular extremes. The study showed that circulation types with an anticyclonic ridge were the most important for extremely hot days in the summer, while extremely low temperatures in the winter were usually associated with anticyclonic types with an easterly airflow. A special effort was made to identify the classification scheme yielding the best accuracy in evaluating extremes.

Daily Minimum and Maximum Air Temperature in Poland in the Years 1951–2005

Abstract 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.

Tendencies in Climate Changes in Poland and Ukraine During the Last Centuries and Their Causes

Abstract The paper describes tendencies in changes of air temperature in Poland and Ukraine on the basis of a long series of measurements made in Warsaw (1779–2000), Cracow (1826–2000), Lviv (1824–2002) and Kiev (1812–2002). Air temperature in these cities in the years 1825–2002 is positively correlated with the North Atlantic Oscillation (NAO) Index. Values of the r correlation coefficient are much higher in winter months than during the summer and they decrease with distance from the Atlantic Ocean. Of interest are air temperature changes in Warsaw, Cracow, Lviv and Kiev in the XIXth –XXth centuries together with forecasts until the year 2100. Significant dependence of the climate of Poland and Ukraine on the NAO index stems from similar temperature cycles and the eight-year, eleven-year and one-hundred-year NAO index. Forecast credibility results from the similar periodicity of air temperature, the NAO index and solar activity. The forecast mean annual temperature values for 2001–2100 were obtained from the interference of statistically important temperature cycles, determined by the sinusoidal regression method.

Spatial differentiation of air temperature in Poland using circulation types and GIS

AbstractThis paper is devoted to the synoptic–climatic analysis with the application of circulation types and Geographic Information Systems (GIS). Construction of daily climatic air temperature maps for the Polish territory was the main aim of the work. Analysis was based on the mean daily temperature data from all synoptic and some climatological stations (73 stations totally) for the 50‐year period of 1951–2000. The synoptic–climatic analysis was done using a well known circulation calendar developed by the German Meteorological Service ‘Grosswetterlagen’. Residual kriging was chosen for the map constructions. Several geographic parameters, including elevation, latitude, longitude, and distance to the Baltic coast, were used as predictor variables for air temperature. However, the particular circulation type was the crucial predictor. Maps were created for all months for the Grosswetterlagen circulation types, which occurred more than 30 times during 1951–2000. Special attention was paid to the extreme thermal months of January and July. Maps constructed in the way described confirmed that application of circulation types was quite a good tool for improving accuracy of thermal daily maps. Accuracy was much higher for most of the maps constructed for particular circulation types than for the maps created without application of circulation types. There was only one exception: non‐advective anticyclonic types during winter time. Then, relatively large variability of the temperature can be observed in the concave landforms and the constructed maps have only approximate meaning. Copyright © 2006 Royal Meteorological Society.