Project team:

• Vittal Hari, Jignesh Shah, Rohini Kumar, Stephan Thober, Luis Samaniego, and Oldrich Rakovec
  
• Yannis Markonis, Sadaf Rani, Jan Kysely, Petr Maca, Vojtech Moravec and Martin Hanel

About project:

This bilateral/joint German (DFG) - Czech (GACR) project XEROS (meaning 'dry' in Greek) represents a unique opportunity of bringing together two research groups of complementary scientific knowledge. The German-based team (CHS @UFZ) focus on understanding and modelling the complex interaction of land-surface hydrologic processes and their spatial and temporal variability at meso- to macro-scales. The Czech-based team (@ CULS) have strong scientific background in statistical analysis of hydrologic and climate variability.

Project news/outreach:

[November 2023] On the role of the Atlantic Meridional Mode in eastern European temperature variability Here we seek to further clarify the effect of Atlantic Meridional Mode (AMM) on the EE region temperature variability. Using observations and climate model experiments, we show a significant association between the AMM and temperature variability across the region. The positive phase of AMM leads to a significant increase in EE temperature of 0.9 °C, p-value 0.1, for a one standard deviation AMM anomaly, and vice-versa. The mechanism through which the AMM can modulate the EE temperature arises through a persistent planetary-scale Rossby wave which causes an anomalous anticyclone circulation leading to a positive temperature anomaly. This relationship, along with the mutually exclusive and independent large-scale climatic modes such as the El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), have important implications for improving the prediction of EE heatwaves.

[June 2023] On the role of antecedent meteorological conditions on flash drought initialization in Europe Here, we examine the role of antecedent meteorological conditions that lead to flash droughts across Europe over the last 70 years (1950–2019) using ERA5 dataset. We find two major flash-drought types based on a sequence of development of antecedent hydro-meteorological conditions. The first type is characterized by a joint occurrence of two mechanisms, a decline of precipitation in conjunction with an increase of the evaporative demand, both occurring before the onset of a flash drought event. The second type, on the contrary, is characterized by high precipitation preceding the event's start, followed by a sudden precipitation deficit combined with an increase in evaporative demand at the onset of the drought. Both drought types showed increased occurrence and higher spatial coverage over the last 70 years; the second drought type has increased at a much faster rate compared to the first one specifically, over Central Europe and the Mediterranean region. Overall our study highlights the differences between the two types of flash droughts, related to varying antecedent meteorological conditions, and their changes under recent climate warming.

[April 2022] Our new paper on "Increasing footprint of climate warming on flash droughts occurrence in Europe" was published in Environmental Research Letters. We focused on the rapid changes in the spatio-temporal anomalies of root zone soil moisture as it integrates the crucial components of the water and energy coupling. We used the recently released ERA5 reanalysis dataset, which took into account land-atmosphere feedback (https://cds.climate.copernicus.eu), to systematically investigate short-term (pentad) changes in soil moisture anomalies, characterising the flash drought events. We then examined the role of driving meteorological conditions (e.g. precipitation and temperature anomalies) promoting and sustaining the flash drought events, including the co-occurrence of 'warmer and drier' and 'colder and drier' conditions.

Altmetric summary:

[April 2022] Our new paper on "The 2018–2020 Multi-Year Drought Sets a New Benchmark in Europe" was published in Earth's Future. UFZ press-release

Altmetric summary:

Selected news articles: The Guardian, Deutschlandfunk, phys.org, MDR, EurekAlert, ZDF, Berliner Zeitung, SciencePost, Arte TV

[March 2021] Our new paper on "Europe under multi-year droughts: how severe was the 2014–2018 drought period?" was published in Environmental Research Letters. We demonstrate that when the multi-year 2014–2018 period is considered, its soil moisture drought severity is exceptional in a 253 year period, especially for Central Europe

Altmetric summary:

[February 2021] Our new paper on "The rise of compound warm-season droughts in Europe" was published in Science Advances. We analysed drought typology to assess the fluctuations of European drought seasonality and duration since 1900. UFZ press-release

Altmetric summary:

[December 2020] Our paper on "On the curious case of the recent decade, mid-spring precipitation deficit in central Europe" was published in npj Climate and Atmospheric Science. UFZ press-release AWI press-release

Altmetric summary:

[August 2020] Our paper on "Increased future occurrences of the exceptional 2018–2019 Central European drought under global warming" was published in Scientific reports. Nature Research highlights. UFZ press-release.

Altmetric summary:

Selected news articles: The Guardian, Deutsche Welle, The Daily Mail, FOCUS Online, MDR, ORF, France24, Die Zeit, Süddeutsche Zeitung, National Geographic

 Example of soil moisture deficit

Project objectives

The overarching goal of this project is to address the following research questions:

1. What is the extremity of the recent European drought events compared to the 500-year benchmark period?
2. How does the space-time variability of drought evolution change over time?
   
3. How do the large-scale atmospheric characteristics, responsible to generate land-surface droughts, co-evolve? How can we enhance the reliability of future hydro-climatic projections?

Work packages

• WP-1a: Historical reconstruction of climate forcing data to allow hydrologic simulations at finer spatial and temporal resolution. [led by the CULS team]
• WP-1b: Multi-model hydrologic simulations of key hydrologic variables [led by the UFZ team]
• WP-2a: Historical characterisation of large scale drought events [led jointly by the UFZ and CULS teams].
• WP-2b: Improved understanding on genesis of the large scale drought events [led by the CULS team]
• WP-3: Enhancing the reliability of future hydro-climatic projections [led by the UFZ team]