Volume 125, Issue 18 ee2019JD032269
Research Article

Atmospheric Circulation as a Factor Contributing to Increasing Drought Severity in Central Europe

Ondřej Lhotka

Corresponding Author

Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czech Republic

Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic

Correspondence to:

O. Lhotka,

ondrej.lhotka@ufa.cas.cz

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Mirek Trnka

Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic

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Jan Kyselý

Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Czech Republic

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Yannis Markonis

Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Czech Republic

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Jan Balek

Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic

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Martin Možný

Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic

Czech Hydrometeorological Institute, Prague, Czech Republic

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First published: 09 September 2020

Abstract

Long‐lasting and severe droughts seriously threaten agriculture, ecosystems, and society. Summer 2018 in central Europe was characterized by unusually persistent heat and drought, causing substantial economic losses, and became a part of a several years long dry period observed across this region. This study assesses the magnitude of the recent drought within a long‐term context and links the increased drought severity to changes in atmospheric circulation. Temporal variability of drought conditions since the late 19th century was analyzed at seven long‐term stations distributed across the Czech Republic using the Palmer Drought Severity Index and the Standardized Precipitation Evaporation Index. The Palmer Z Index and a variation of the Standardized Precipitation Evaporation Index were used to study rapidly emerging short‐term droughts and to link these episodes to atmospheric circulation. Changes in circulation were analyzed through circulation types calculated from flow strength, direction and vorticity in mean sea level pressure data from the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis for 1948–2018. Increasing drought severity across the Czech Republic with record‐low values of the drought indices during 2015–2018 was found. The trend was distinctive in both vegetation (April–September) and cold (October–March) periods. The tendency toward more severe droughts in recent decades was linked to changes in frequency of dry and wet circulation types, highlighting the important role of atmospheric circulation in regional climate. It remains an open question whether the significantly increasing frequency of dry circulation types in the vegetation period is related to climate change, or rather represents multidecadal climate variability.

Data Availability Statement

Drought indices calculated for this study are available on following data repository: https://data.mendeley.com/datasets/7rfdm4bg9g/1.