Links between increasing drought severity and atmospheric circulation over Central Europe

0508555 - ÚFA 2020 DE eng A - Abstrakt
Lhotka, Ondřej - Dubrovský, Martin - Trnka, M. - Balek, J. - Kyselý, Jan - Možný, M.
Links between increasing drought severity and atmospheric circulation over Central Europe.
EMS Annual Meeting Abstracts, Vol. 16. Berlin: European Meteorological Society, 2019.
[EMS Annual Meeting 2019. 09.09.2019-13.09.2019, Copenhagen]
Institucionální podpora: RVO:68378289
Klíčová slova: atmospheric circulation * meteorological drought events * reanalysis * Central Europe
Obor OECD: Climatic research
https://meetingorganizer.copernicus.org/EMS2019/EMS2019-83-1.pdf

Long-lasting and severe droughts are one of the main threats to agriculture, ecosystems and society. The recent
2018 summer in Central Europe was characterised by unusually persistent heat and extraordinary drought, causing
substantial economic losses especially in agriculture and forestry, and became a part of a several years long dry
period observed across this region. The aim of the study is to assess a long-term variability of drought over Central
Europe, with respect to changes in atmospheric circulation. Drought conditions were analysed using Palmer
Drought Severity Index (PDSI) and Palmer Z-Index (PZI). PDSI was used to assess long-term drought variability
since the end of the 19th century, using data from 8 stations distributed across the Czech Republic. Shorter-term
droughts and their links to atmospheric circulation were evaluated using PZI. Changes in atmospheric circulation
were analysed through circulation indices (flow strength, direction and vorticity) and respective circulation types,
using mean sea level pressure data from the NCEP/NCAR reanalysis that is available since 1948 to present.
Preliminary results show an increasing drought tendency across Central Europe with record-low PDSI values
in the 2013–2018 period at the majority of stations. Changes in PZI are rather associated with flow vorticity
(indicating cyclonic or anticyclonic conditions) than flow direction. An increased frequency of anticyclonic
circulation types in the recent decades was found and this is associated with more severe droughts in this period.
The outcomes of this study are useful also for conditioning an existing stochastic spatial weather generator on
atmospheric circulation, which may result in more realistic weather data produced by the generator.

Trvalý link: http://hdl.handle.net/11104/0299428