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Seawater temperature changes in the southern Baltic Sea (1959–2019) forced by climate change

Zalewska Tamara, Wilman Bartłomiej, Łapeta Bożena, Marosz Michał, Biernacik Dawid, Wochna Agnieszka, Saniewski Michał, Grajewska Agnieszka, Iwaniak Michał

Oceanologia

2024

Vol. 66 (1)

37--55

The study included the analysis of changes in sea surface and water column temperature and air temperature in the years 1959–2019 in the southern Baltic Sea based on in situ measurement (CTD probe), satellite data, and model data (ERA5). SST increased on average by 0.6°C per decade. Analyses at different depths showed that the highest temperature increase per decade at 0.60–0.65°C characterised the layers from 0 to 20 m. The smallest increase (0.11°C) was recorded at a depth of 70 m, below which the temperature change per decade increases again to 0.24°C. The results from satellite observations covering 1982–2019 were consistent with measurement data. The most intense water warming occured in the spring – summer (0.8–1°C per decade); in the winter, the change did not exceed 0.2°C. In the offshore area, in 1951–2020, air temperature increased by approx. 2°C, with an average increase of 0.37°C per decade. The average increase in seawater temperature in the coastal zone was 0.2°C per decade. The most intense warming characterised March to May (0.25–0.27°C). The average annual air temperature increase on the coast from 1951 to 2020 was 0.34°C per decade. The results represent an important contribution to research and prediction of changes in the marine environment caused by global climate change.

The kinematic and thermodynamic environment during cloud-to-ground lightning occurrence in Poland

Sulik Sławomir, Taszarek Mateusz

Meteorology Hydrology and Water Management. Research and Operational Applications

2024

Vol. 12, Iss. 1

83--103

This study identifies convective and kinematic parameters that positively influence elevated values of cloud-to-ground lightning flashes (CGs) in Poland. The analysis used data from the PERUN lightning detection and location system from IMGW-PIB and reanalyses of the ERA5 model from ECMWF for the period 2002-2020. In addition, a spatial-temporal distribution analysis was carried out for the period 1940-2022, covering the key parameters necessary for the appearance of convection. Results showed that thunderstorms most often occur in the summer, but also that there are increasingly favorable conditions for the appearance of organized multicellular systems in the spring. CG flashes most often form in a most-unstable convective available potential energy (MU CAPE) environment of about 1300 J/kg along with vertical wind shear (0-6 km AGL bulk wind shear) of 13-14 m/s. Using the WMAXSHEAR parameter, it was possible to conclude that overlapping CAPE and DLS values of about 500 m2/s2 imply increased electrical activity. At the same time, a high correlation with the Hail Size Index (HSI) parameter implies a positive relationship between the occurrence of hailstorms and an increased number of CGs generated in the case of supercells. The research also found a gradual increase in air temperature, MU CAPE, MU Mixing Ratio and the MU WMAXSHEAR parameter for the area under study.

Spatial and temporal evaluation of global rainfall products in a data-scarce region: The Dez Basin, Iran

Khoshchehreh Mostafa, Ghomeshi Mehdi, Shahbazi Ali, Bolboli Hossein, Saberi Hamed, Gorjizade Ali

Journal of Water and Land Development

2021

no. 48

148--161

The limitation in approachability to rainfall data sources with an appropriate spatial-temporal distribution is a significant challenge in different parts of the world. The development of general circulation models and mathematical algorithms has led to the generation of various rainfall products as new sources with the potential to overcome the shortage in datascarce basins. In this study, the performance of the PERSIANN-CCS and CMORPH satellite-based rainfall product, as well as the ERA5 and ERA-Interim reanalysis, was evaluated based on detection skill and quantitative metrics in a daily, monthly and seasonal time scales in the Dez basin located in the southwest of Iran. The basin has a wide topographic variation and scattered rain gauge stations. Overall results denote that the ERA5 dataset has the best performance in all statistic verification than other rainfall products. Based on the daily evaluation of all rainfall products, the false alarm rate (FAR) is higher than 0.5, so none of the datasets could capture the temporal variability of rainfall occurrence. This study has covered the western parts of the Zagros steep slopes in which the topographic conditions have a significant effect on the activity of rainfall systems. On a monthly scale, the mean value of the correlation coefficient (CC) for ERA5, ERA-Interim, PER-SIANN-CCS, and CMORPH was equal to 0.86, 0.85, 0.51, 0.39, respectively. The results of seasonal evaluation suggested that all datasets have better rainfall estimation in autumn and winter, and the capability of all datasets dramatically decreased in the spring. The current paper argues that the ERA5 reanalysis typically outperforms ERA-Interim and can be considered as a reliable rainfall source in the future hydrological investigation in the southwest of Iran.