Multiannual variation of thermal specific days in Warsaw (1951 – 2010)

The paper focuses on the frequency, annual pattern and long-term variability of thermal specific days in Warsaw during the period 1951 – 2010. The following were distinguished: days with frost ( tmax ≥ 0.0 °C, tmin < 0.0 °C ), cold days ( t_max –0.1 – –10.0°C ), very cold days ( t_max – 10.1– – 20.0 °C ), extremely cold days ( t_max < –20.0°C ), hot days ( t_max 25.1–30.0 °C ), very hot days ( t_max 30.1–35.0 °C ) and extremely hot days ( t _max > 35.0 °C ) as well as warm nights ( t _min 15.1 – 18.0 °C ), very warm nights ( t _min 18.1 – 20.0 °C ) and tropical nights ( t _min > 20.0 °C ). The following average numbers of days/nights per year were found during the period 1951 – 2010: 109 days with t _min < 0.0°C, including 37 days with t _max < 0.0°C, 38 days with t_max > 25°C, and 21 nights with t _min > 15.0 °C. The minimum temperature ranged from –30.7 °C to 21.8 °C and the maximum temperature from –20.4 °C to 36.4 °C. The number of days with t_max ≥ 0.0 °C and t_min < 0.0 °C dropped by 1.8 day/10 years, days with t _max < 0.0 °C also by 1.8 day / 10 years; the number of days with t _max > 25.0 °C rose by 2.2 day / 10 years, while the number of days with t _min > 15.0 °C rose by 2.4 day / 10 years. The results are based the on data collected at the Okęcie airport station, which is located outside the town and therefore they are not representative of the Warsaw urban area, but rather of the eastern part of the Warsaw basin.

A comparison of the radiosonde data and the data set basing on the NCEP-NCAR reanalysis

The purpose of this study is to determine the usefulness of the NCEP-NCAR reanalysis for studying the geopotential height of isobaric levels, air temperature, wind speed and wind direction in the troposphere over the Central Europe. The study compares the values of selected meteorological elements obtained from the NCEP-NCAR data with the values measured at the aerological stations in Łeba, Legionowo, Lindenberg and Poprad. The results regarding geopotential height of isobaric levels reveal a very strong correlation between the NCEP-NCAR and radiosonde data at all the pressure levels studied. However, the analysis of the mean error and R M S E indicates less concordance, especially in the U T L S. The seasonal variability is very small and is noticeable only in Łeba, where the mean error and R M S E both increase in winter. The analysis carried out for the air temperature indicates a high concordance, especially up to 300 hPa. Above, a decrease in correlation is observed, as well as an increase in the values of both errors. It is most evident in summer and autumn. The comparison carried out for the wind speed shows that the correlation coefficients reach the highest values in the U T L S and decrease with decreasing altitude. High values of R M S E are noted at the level of 300 hPa. The values of the mean error and R M S E accompanying wind direction are the lowest in the U T L S and middle troposphere and increase at the 850 hPa pressure level. The differences between the frequencies of wind directions, calculated on the basis of the two datasets are very small ( 0–4 % ). It does not apply to the level of 850 hPa in Poprad, where substantial discrepancies are found. The results regarding wind parameters show very little seasonal variability. It is concluded that the NCEP-NCAR reanalysis is a valuable source that can be used to supplement or even replace radiosonde data. This applies to the entire troposphere, except for its lower layers over mountain areas, where reanalysis data should be verified every single time.

Methods of estimating stream water temperature and air temperature relationships – the Świder River case study

Due to the high significance of water temperature to lotic ecosystems, this paper presents the methods of estimating relationships between water temperature and air temperature on the example of the Świder River. Statistical relationships were determined using logistic and linear regression models for daily, weekly and monthly average temperatures, as well as for daily maximum and average weekly maximum temperatures. The data were obtained as a result of field measurements, conducted in the hydrological years 2012 and 2013. A strong non-linear relationship was found between water and air temperature, as indicated by the obtained coefficients of determination and the R M S E of logistic models. Despite the non- -linear nature of this relationship, the appropriate selection of measurement data allows the efficient use of linear models. A comparison of fit measures of the models based on microclimatic data (Wólka Mlądzka) and meteorological station data (Warszawa-Okęcie) revealed no significant differences in their quality. The results may have practical application for the fisheries management and the protection of the ecosystem of the Świder River.

The development of tourist trails network along the Polish-Czech state border in the Sudetes in the years 1945 – 2013

The paper presents the development of hiking tourist trails network in the vicinity of the Polish-Czechoslovakia border (from the beginning of 1993 the Polish-Czech border) in the Sudetes in the period from 1945 till 2013. A comparison of Polish and Czechoslovak (Czech) trails offer was presented, as well as the route of some trails was criticised. In order to attain this a comparative analysis of historical and present-day tourist maps was conducted, however also hitherto existing literature concerning the history of tourism in the Sudetes was used. The analysis of recent changes in the network was possible thanks to field studies. The development of tourist trails networks on both sides of the state border in the Sudetes was highly dependent on the political situation and restrictions concerning people’s stay within the border zone. Therefore three main periods of the development of trails networks can be distinguished: (a) period before 1989, when the restrictions were most rigorous (especially from the end of 1946 till 1956), (b) period after 1989, when the rules were significantly softened, however free wandering in the border zone and crossing the border was still impossible, and finally (c) the present period after the end of 2007, when Poland and the Czech Republic became a part of the Schengen area and all formal barriers were abolished. The present legal conditions enable a reorganisation and integration of tourist trails networks, up till now developing separately in both countries. Because of that the present-day lay-out of tourist trails along the Polish-Czech border cannot be considered as final.