Extreme values of atmospheric instability indices in Poland and their relationship with factors inhibiting the development of convection

The primary goal of the study was to examine the temporal and spatial variability of values of selected atmospheric instability indices over Poland for the period 2005–2014. The research involved six indices most frequently applied in convection forecasting – Convective Available Potential Energy, K-Index, Lifted Index, Severe Weather Threat Index, Showalter Index and Total Totals Index. The data from three Polish upper air sounding stations ( Łeba, Legionowo, Wrocław ), as well as SYNOP codes on present and past weather and reports on severe meteorological phenomena from the European Severe Weather Database were used in this study. It was found that extremely high values of the selected indices were characterised by strong temporal and spatial variability. Moreover, a detailed analysis of the days when no convective events were observed, despite extreme values of instability indices, demonstrated that the occurrence of isothermal or inversion layers were the most common mechanisms inhibiting the development of severe convective phenomena. Convection was also inhibited when the area was free from an influence of atmospheric fronts, convergence zones or low-pressure troughs.

Monthly air temperature anomalies in Alaska (1951–2015)

The aim of this paper is to present both anomalously warm months ( AWM ) and anomalously cold months ( ACM ) in Alaska and to refine the linkage of Pacific Decadal Oscillation ( PDO ) with their occurrence. The study is based on mean monthly temperature data from 15 weather stations located in Alaska recorded during the period of 1951–2015. The anomalous months were defined as having an average temperature different from the long-term mean by at least 2 standard deviations. Temporal variability, spatial extent and temperature magnitude of AWM and ACM were characterized.
In total ( considering all 15 stations ), there were 243 cases of AWM and 298 cases of ACM, which occurred during 100 and 123 months of the 65-year period respectively. AWM occurred most frequently in January and from June to August while ACM from February to April and in November and December. To some degree months with the biggest number of AWM were the same as months with the smallest number of ACM and vice versa. This indicates that during particular months synoptic and/or local conditions may be more favourable for the occurrence of positive or negative anomalies. Both AWM and ACM covered from 1 to 11 weather stations simultaneously, though the majority of the anomalous months of each type were observed at single stations or at two neighboring stations. Generally, the scale of the anomaly tended to be larger during ACM than AWM ( i.e. down to –17,0°C compared to maximum 15,6°C for AWM ), during winter than summer, and in the central part of Alaska than at the seaside. There is a clearly visible increase in the frequency of AWM and a decrease in the frequency of ACM after 1976 when PDO shifted from dominantly negative to positive values. Comparing two periods, 1951–1976 and 1977–2015, one can notice that in the latter the mean annual number of ACM in Alaska decreased by one-third and the mean annual number of AWM doubled. The spatial extent of ACM was also considerably smaller ( on average ) and of AWM – larger. In total about 80% of AWM ( ACM ) occurred during the positive ( negative ) values of PDO index.
Monthly temperature anomalies in Alaska are mainly driven by atmospheric circulation patterns. AWM coincide with advection of warm air masses from the south while ACM tend to occur in association with northern cold advections. Local effects, which include radiative cooling, temperature inversions and local winds ( i.e. chinook ), also have a great contribution to the occurrence of anomalous months in Alaska.

Outflows of groundwater at the bottoms of lake basins on the example of Lake Raduńskie Górne (Kashubian Lake District)

The aim of the study was to locate and describe groundwater outflows in a selected lake basin. The second aim was to measure spring discharge and measure physical characteristics of the studied waters ( temperature, conductivity ). The time scope of the work comprised the period from January 2011 to September 2012. The spatial scope of the work included the area of Lake Raduńskie Górne located in the Kashubian Lake District in northern Poland. The study consisted mostly of fieldwork and reviewing archived materials. Four groundwater outflows were located in the course of the study. Their total discharge was 4.6 l·s-1 and ranged between 0.5 and 2.5 l·s-1. This produces an annual yield of about 145,000 m3·yr-1. This value is comparable to that for other lakes in the world. In effect, Lake Raduńskie Górne receives about 0.15% of its water from under-lake springs. This is a minute value in comparison with the lake’s total groundwater recharge ( 97 mln m3 per year ). However, it must be assumed that the actual number of under-lake springs is many times greater than that identified in the course of this study, which means that the share of water supplied in this manner is likely much higher and its effect on water chemistry and water levels in the lake is also likely much more pronounced.

Water chemistry of streams on the south slope Babia Góra Mt

The chemical composition of the waters of mountain streams depends on natural and anthropogenic conditions. The aim of the study was to determine the variability of physico-chemical properties of water in the streams in the massif of Babia Góra. The study selected fourteen streams located in the Babia Góra National Park and its buffer zone. Based on the results of analyses of macronutrients and micronutrients of ions, conditions determining the physico-chemical parameters of water were determined. The physical and chemical composition of stream waters proved to be conditioned by the geology of catchments, the process of dilution, water temperature and the type of plant communities as well as and the seasonality of vegetation.

Integration of a flood risk management and waters protection system on the example of the Warta Valley between Konin and Oborniki

The aim of the study was the analysis of the integration of a flood risk management and water protection system in a selected section of the Warta Valley with taking into consideration the guidelines of the Water Framework Directive and the Floods Directive. The structure of the valley is comprised within a distance of 201.1 km by stretches of: an urstromtal, between the towns of Konin and Śrem, and the Warta gorge stretch between Śrem and Oborniki. High environmental values of the valley are shown, related to the presence of conservation areas and, on the other hand, a high flood hazard risk, resulting e.g. from advancing land development in the valley and its low retention capacity. The Integrated Water Resources Management guidelines conception was used in the analysis, inlcuding pointing out the directions of relations between minimizing flood risk and protection of natural values of the Warta River and its valley. Spatial distribution of the flood hazard and risk in the Warta Valley was also analyzed. A detailed analysis covered activities of a technical and non-technical character intended to stop the growth of flood risk. In the field of water conservation, the considered objectives included: achieving and maintaining a good ecological potential of waters or the risk of failing to achieve it, which is determined by a high urbanisation ratio, draining of an open-pit lignite mine, extensive morphological change in the river bed and pollution discharged into the waters from land used for agriculture. The results proved that one of the most significant factors directly impacting the environmental condition and ecological potential of the waters is the activity related to flood risk reduction. Potential threats to the functioning of NATURA 2000 areas characterized by high natural values were also indicated.

Assessment of a potential use of satellite optical and radar data for the identification of agriculture land types

Fusion of satellite data from different sources is a technique commonly used in studies focused on land cover and land use. Combining images of various spectral bands allows to increase objects differentiation and thereby improve overall classification accuracy. In this study, I focused on crops maps creation using integrated optical and radar data. Landsat 8 multispectral data from OLI sensor and Sentinel-1A SAR ( Synthetic Aperture Radar ) data were applied here. The study was performed for a test area of the Żywiec Basin, which is a part of the Polish Carpathians. The advantage of this small, agricultural region was that it is covered by a mosaic of different-size cultivated fields. I tested six methods of satellite data integration ( IHS, HPF, PCA, Brovey, Ehlers and wavelet transforms ) and two classification algorithms ( Support Vector Machines and Random Forest ). The results demonstrated that the use of integrated optical and radar data is effective for crops classification – the highest overall accuracy achieved in this study was equal to 87.9% and was obtained for Random Forest classification and Ehlers fusion.