Temperature Characteristics and Spring Frost Risk in the Sour Cherry (Prunus Cerasus L.) Blooming Period in 1985–2010

The aim of the paper is an attempt to present the relationships between sour cherry (Prunus cerasus L.) blooming time, climatic conditions and spring frost risk in western Poland (Great Poland Lowland). Air temperature indices from meteorological stations in Przybroda and Poznań for the period 1985-2010 representing contemporary climate warming were used. ‘English Morello’ sour cherry phenological records for the period 1985–2010 were collected at the Research Station of Poznań University of Life Sciences located in Przybroda. The earliest end of blooming was observed on 2nd of May 1999, and the latest one on 26th of May 1987. The average period of sour cherry blooming was between 30th April and 12th May. During 50% of the years the blooming period lasted from 11 to 15 days. Mean monthly temperature in Przybroda varied from -1.1ºC in January to 19.6ºC in July. A significant relationship between the beginning date of cherry blooming and the beginning of the thermal vegetation period was found. Variability of the index explained more than 50% of variability in the first dates of cherries blooming (coefficient of determination R2 = 0.505 is significant on the level p < 0.05). The beginning of blooming was also significantly (p < 0.05) correlated with mean April temperature, which could explain about 43% of variability in the dates of the first bloom. An increase in April temperature by 1.0ºC caused earlier blooming by about 2.8 days. During the period of 1985–2010 a significant increase in April temperature was observed (in Poznań 0.79ºC per decade). It had an effect on advanced dates of the beginning of sour cherry blooming of about 3 days per decade. In 26 of the years the last frost occurred 4 times (15% of seasons) during the blooming phenological phase or later in Przybroda. Frost occurred 10 days before blooming started and during blooming in 54% of the years

Regional differentation in probability of ice dayes occurrence in Poland

This paper aims at recognizing spatial differentiation in probability of ice days occurrence with reference to atmospheric circulation, using regional classification of circulation types for Poland. Daily maximum air temperatures measured at nine meteorological stations were used to recognize the ice days occurrence in the period from January 1951 to March 2014. The relations between the ice days occurrence and atmospheric circulation were analysed using catalogues of circulation types compiled for nine grid boxes within Poland. Linkage between the frequency of ice days and atmospheric circulation was recognized in the period of January 2001 - March 2014. A decreasing tendency in the frequency of the occurrence of winter ice days was found. The occurrence of ice days in Poland is clearly related to atmospheric circulation. In the entire area of Poland their occurrence is favoured by eastern and south-eastern advection of air during anticyclonic conditions (types Ea nad SEa). Regional variability is also noticeable

Surface-based nocturnal air temperature inversions in southern Poland and their influence on PM10 and PM2.5 concentrations in Upper Silesia

The frequency, strength and seasonal variations of surface-based temperature inversions (SBTIs) in Upper Silesia (Southern Poland) were examined using data from January 2001 to September 2020. Based on the air temperatures recorded at the meteorological station of the Institute of Earth Sciences in Sosnowiec (263 m a.s.l.) at heights of 2 m and 88 m above the ground, the vertical temperature gradient of the 100-m layer (γSos100 m) was determined. A lapse rate of γSos100 m > 0.5 K was defined as a temperature inversion. The measurements for 00 UTC (midnight) and 12 UTC (midday) were compared with data from the upper air station in Wrocław (116 m a.s.l.) located in the Lower Silesia Lowland, approximately 170 km NW of Sosnowiec. Based on soundings from Wrocław, in addition to the temperature gradient in the lower 100-m layer of air (γWrc100), three other characteristics of SBTIs were calculated: inversion depth (ID) or thickness in metres, inversion strength (ΔTi) in K and vertical temperature gradients across the whole SBTI layer γi in K 100 m−1. On an annual basis, the frequency of nighttime SBTIs (γ > 0.5 K 100 m−1) ranged from 47% in Sosnowiec to almost 59% in Wrocław. At both stations, the fewest SBTIs occurred in winter (23–38%) and the most in summer (64–75%). Moreover, they were more frequent in spring (52–61%) than in autumn (49–59%). The SBTI frequency was very low during the midday hours, amounting to 0.6–0.7% days a year, and it increased to 1–2% only in winter. Annually, the depth of 81% of inversions ranged between 50 and 300 m, varying seasonally from almost 67% in winter to 87% in summer. The presented research shows that SBTIs in winter were among the main factors contributing to a high concentration of particulate matter pollutants in the ground-level atmosphere. During nights with temperature inversions, the annual mean PM10 concentration reached 125% of the mean value, ranging from 114% in summer to 189% in winter

Regional differentiation in probability of ice days occurrence in Poland

This paper aims at recognizing spatial differentiation in probability of ice days occurrence with reference to atmospheric circulation, using regional classification of circulation types for Poland. Daily maximum air temperatures measured at nine meteorological stations were used to recognize the ice days occurrence in the period from January 1951 to March 2014. The relations between the ice days occurrence and atmospheric circulation were analysed using catalogues of circulation types compiled for nine grid boxes within Poland. Linkage between the frequency of ice days and atmospheric circulation was recognized in the period of January 2001 – March 2014. A decreasing tendency in the frequency of the occurrence of winter ice days was found. The occurrence of ice days in Poland is clearly related to atmospheric circulation. In the entire area of Poland their occurrence is favoured by eastern and south-eastern advection of air during anticyclonic conditions (types Ea nad SEa). Regional variability is also noticeable

Classification of precipitation types in Poland using machine learning and threshold temperature methods

Abstract The phase in which precipitation falls—rainfall, snowfall, or sleet—has a considerable impact on hydrology and surface runoff. However, many weather stations only provide information on the total amount of precipitation, at other stations series are short or incomplete. To address this issue, data from 40 meteorological stations in Poland spanning the years 1966–2020 were utilized in this study to classify precipitation. Three methods were used to differentiate between rainfall and snowfall: machine learning (i.e., Random Forest), daily mean threshold air temperature, and daily wet bulb threshold temperature. The key findings of this study are: (i) the Random Forest (RF) method demonstrated the highest accuracy in rainfall/snowfall classification among the used approaches, which spanned from 0.90 to 1.00 across all stations and months; (ii) the classification accuracy provided by the mean wet bulb temperature and daily mean threshold air temperature approaches were quite similar, which spanned from 0.86 to 1.00 across all stations and months; (iii) Values of optimized mean threshold temperature and optimized wet bulb threshold temperature were determined for each of the 40 meteorological stations; (iv) the inclusion of water vapor pressure has a noteworthy impact on the RF classification model, and the removal of mean wet bulb temperature from the input data set leads to an improvement in the classification accuracy of the RF model. Future research should be conducted to explore the variations in the effectiveness of precipitation classification for each station

A decade of glaciological and meteorological observations in the Arcti (Werenskioldbreen, Svalbard)

The warming of the Arctic climate is well documented, but the mechanisms of Arctic amplification are still not fully understood. Thus, monitoring of glaciological and meteorological variables and the environmental response to accelerated climate warming must be continued and developed in Svalbard. Long-term meteorological observations carried out in situ on glaciers in conjunction with glaciological monitoring are rare in the Arctic and significantly expand our knowledge about processes in the polar environment. This study presents glaciological and meteorological data collected for 2009–2020 in southern Spitsbergen (Werenskioldbreen). The meteorological data are composed of air temperature, relative humidity, wind speed, short-wave and long-wave upwelling and downwelling radiation on 10 min, hourly and daily resolution (2009–2020). The snow dataset includes 49 data records from 2009 to 2019 with the snow depth, snow bulk density and snow water equivalent data. The glaciological data consist of seasonal and annual surface mass balance measurements (point and glacier-wide) for 2009–2020. The paper also includes modelling of the daily glacier surface ablation (2009–2020) based on the presented data. The datasets are expected to serve as local forcing data in hydrological and glaciological models as well as validation of calibration of remote sensing products

Divergence in responses of juniper tree rings to climate conditions along a high-mountain transect in the semi-arid Fann Mountains, Pamir-Alay, western Tajikistan

This paper reports on a detailed dendrochronological and dendroclimatological study of juniper trees (Juniperus seravschanica Kom. and J. semiglobosa Regel), sampled at seven sites having different elevations (2200 – 3100 m) and exposures (south-north) in the Pamir-Alay mountains, north-western Tajikistan. We developed seven new, well-replicated ring-width chronologies extending back over the last 219–1320 years. Our results confirm that the main climate factor influencing radial growth in this semi-arid region is variability in precipitation. However, they also indicate that there is a divergence in dendroclimatic responses between low- and high-elevation sites, where different limiting factors play a dominant role. The radial growth of J. semiglobosa at the uppermost treeline locations is the most sensitive to winter precipitation. Tree-ring formation in J. seravschanica at low-elevation sites is strongly limited by spring-summer drought conditions and by winter temperatures. The results of PCA analysis indicate that the relationships between growth and climate are linked more to elevation than to exposure. It was also found that negative growth extremes at low elevation sites may be triggered by strong dust storm events. Our findings clearly show that precisely planned selections of topographically differentiated sites, including elevation and exposure, are crucial for the possible reconstruction of different climatic elements in the high mountains of Central Asia for the last hundreds to thousands of years

Variability of high rainfalls and related synoptic situations causing heavy floods at the northern foothills of the Tatra Mountains

This contribution provides the basics of the climatology of the Polish Tatra Mountains in a nutshell, with particular reference to intense precipitation and its relation to atmospheric circulation. Variability of various precipitation characteristics, including selected indices of intense precipitation in Zakopane and at Kasprowy Wierch, is illustrated in this paper. None of the trends in these characteristics and indices calculated for the entire time interval exhibit a statistical significance, but short-time fluctuations are evident. The occurrence of intense precipitation in the Tatra Mountains is strongly related to three circulation types. These situations (Nc, NEc, Bc) are associated with cyclones following track Vb after van Bebber. In addition to changing frequencies of circulation, this study also reveals an increase in the frequency of the circulation types associated with extreme precipitation