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Ocena suszy hydrologicznej lat 2015-2020 w Polsce na tle wielolecia

Baran-Gurgul Katarzyna

Gospodarka Wodna

2022

Nr 2

5--11

Susza hydrologiczna jest często utożsamiana z niżówką rzeczną, którą określa się zazwyczaj jako nieprzerwany okres czasu, w którym przepływ w danym przekroju rzeki jest niższy niż poziom graniczny, który w artykule przyjęty został jako percentyl Q90%, odczytany z krzywej czasu przewyższenia przepływu. Celem artykułu jest ocena suszy hydrologicznej w latach 2015-2020 na tle ostatnich 50 lat w Polsce. Ostatnie 10 lat w Polsce było wyjątkowo suche. W około połowie rozpatrywanych przekrojów (66 ze 130) lata od 2015 r. do 2020 r. okazały się latami o największej liczbie dni niżówkowych w badanym wieloleciu.

Hydrological drought is often equated with a river low flow, which is most often defined as an uninterrupted time period in which the flow in a given river cross-section is lower than threshold level. The threshold level for this study is adopted as percentile Q90% read from the flow duration curve. The aim of the article is to assess the hydrological drought in 2015-2020 against the background of the last 50 years in Poland. The last 10 years in Poland have been exceptionally dry. In about half of the considered cross-sections (66 out of 130), the years 2015-2020 turned out to be the years with the highest number of low-flow days.

Multi-annual variability of global solar radiation in the agricultural area of Lower Silesia (SW Poland) and its relationship with the North Atlantic Oscillation

Bryś Krystyna, Bryś Tadeusz

Meteorology Hydrology and Water Management. Research and Operational Applications

2019

Vol. 7, Iss. 2

13--25

In this paper, the long-term variability of global solar radiation in the agricultural area of Lower Silesia is analyzed based on a 56-year long (1961-2016) measurement series recorded at the Agro- and Hydro-meteorological Wrocław-Swojec Observatory (SW Poland). Yearly and monthly global radiation sums with their extreme and mean values were compared with radiation data from Warsaw (Central Poland) and Potsdam (East Germany). The dynamics of variability between consecutive months, seasons and years was also taken into account. The conducted positive trends show a significant increase in the investigated global radiation sums for Lower Silesia and also for Central Poland and the eastern part of Germany. The trends are strongly related to long-term macro-circulation changes in the North Hemisphere, particularly with the phases and sub-phases of the North Atlantic Oscillation (NAO). The relations between the investigated values of global solar radiation and these macro-circulation patterns are very complicated and they very often have an asynchronous character. The first, juvenile stage of the NAO positive phase (the 1970s and 1980s), when annual sums of global solar radiation in Wrocław-Swojec reached only the average level of about 3700 MJ·m-2 and warm half-year about 2800 MJ·m-2 respectively, was cloudy and rainy. This period was distinctly different than the advanced stage of one (the 1990’s and later years) with bigger sunshine duration and smaller annual precipitation, when the adequate radiation sums amount to 3 900-4000 MJ·m-2 and 3 000-3 100 MJ·m-2 respectively.