Extreme rainless periods in Pannonian Basin

Abstract

This paper analyses extreme meteorological droughts in the territory of the Pannonian Basin in central and southeastern Europe. Droughts are treated from an agricultural perspective as periods of consecutive days with very little or no rainfall at all. By using data from the historical period 1981-2010, time intervals longer than 20 days with less than 3 mm per day during the growing season April-September are examined to determine theoretical and empirical distributions of their number and durations. Related discrete stochastic process of extremes is analysed by the Zelenhasic-Todorovic (ZT) method, successfully applied in hydrology and meteorology (e.g., peak flows, low flows, meteorological droughts, etc.). The method is applied to 52 locations across Pannonia Basin. At each location, the Poisson distribution is determined for the number of droughts, exponential distribution for the duration of droughts, and double exponential distribution for the duration of the (annually) longest droughts. To validate the quality of modelling and the results obtained, standard statistical goodness of fit tests are used. Historical data from the period 1981-2010 indicate that the central and northern part of Hungary and the entire territory of Vojvodina Province in the north of Serbia experienced the longest droughts, on average 55-60 days. In statistical terms, across Pannonia Basin once in 100 years drought may occur with an average duration of 56 days. Theoretically longest 100-year droughts could be expected in the northern part of Hungary (up to 70 days), the eastern part of Romania (up to 68 days), and Serbia (up to 69 days). The 2-year droughts are on the average duration of 3 weeks. Generated maps of the longest droughts in the basin may help to reduce agricultural risks due to global warming and other negative impacts of climate change.

Mesoclimatic Analysis of Non-Precipitation Periods in Lithuania

“…Therefore, it is important to consider not only macrosynoptic factors but also local geographic conditions in these studies. Some scientists believe that a day without precipitation can also be considered if more than 2 mm of precipitation does not fall per day (Byun & Wilhite, 1999;Gomboš et al, 2019), or more than 3 mm of precipitation during the vegetation period (Srdjevic et al, 2022), because this amount of precipitation has almost no effect on ecosystems. When defining the number of days without precipitation necessary for the onset of drought in our latitudes, some authors believe that there should be a period of at least 15 consecutive days (Huschke, 1970), others say that such a period should be longer than 20 days (Hlásny et al, 2015;Srdjevic et al, 2021).…”