Weather Extremes (CWS)

Summary

The Climate, Water and Society (CWS) cluster investigates and teaches topics related to climate change and adaptation. The Extreme Weather case study involves multiple fields represented within CWS, from monodisciplinary studies to cross-disciplinary research. Our aim is to gain better understand fundamental coupled processes leading to extreme weather in climate change, by which we can improve representations of the hydrological cycle’s key processes (evaporation, clouds, precipitation) and subsequent reduction of uncertainties in the projections of weather extremes calculated by regional and global models. Potential impacts of extreme weather include fire, floods, air pollution and impacts on renewable energy. We present three examples of CWS studies to extreme weather acting at different time scales: days (clouds, precipitation, flooding), weeks (heatwaves) and months (droughts) (see infographics).

Case Description

 Background

Extreme weather poses major challenges for society, i.e. understanding and predicting weather’s severity, frequency and impacts. Within the CWS cluster, understanding climate change and extreme weather linkages is essential to research and education. The new Extreme Weather initiative stimulates multidisciplinary collaboration among CWS groups, setting up PhD projects involving multiple chair groups and joint MSc courses. The general approach starts with recognising the need to integrate natural science disciplines and to study various time scales to understand and model extreme weather. We present three examples carried out at CWS. Related to intense precipitation (occurring at time scales of hours and days), the research aims to identify cloud organisation changes possibly triggered by climate change. In researching heatwave extremes (timescales of days to weeks), we focus on analysing how heatwave enhancement is driven by abnormal atmospheric and land-based phenomena. This connects to droughts (typical time scales of weeks to months).

Concrete Collaborations and Joint Research Approach

Within the CWS cluster, there are active collaborations among groups on poorly understood processes in global and regional hydrological cycles. One collaboration is on the largest uncertainty in climate projections: clouds’ role in regulating climate. In a joint PhD project, the Aquatic Ecology and Water Quality Management (AEW) and Meteorology and Air Quality (MAQ) groups investigate how clouds organise in the trade wind (sub-tropics) region, which is highly sensitive to climate change. We combine AEW expertise in studying complex systems using a dynamic system approach, with MAQ expertise on physical processes associated with clouds. A second collaboration, between the Hydrology and Quantitative Water Management group (HWM) and MAQ, studies heatwave enhancements due to processes acting at a local scale and the role of large-scale atmospheric circulation in these enhancements. Joint publications by the HWM, MAQ and WSG groups in 2018 and 2020 show early spring mid-latitude heatwaves impact summer droughts, while tropical wet season droughts impact consecutive dry-season heat.  What links these studies is comprehensive observations collected at global and regional scales, combined with a weather and climate model hierarchy coupled to land surface, including hydrological and plant physiological processes.

Stakeholder involvement

  The improved representation of extreme weather in operational weather, climate and hydrological models is important for extreme weather short-term predictions (where is damage expected?) and long-term climate change predictions (e.g. relevant for insurance companies). Our research is at the forefront of representing important coupled processes. Our stakeholders are international research institutes developing and operationalising weather, hydrological and climate models. Active collaborations exist with the European Centre for Medium-Range Weather Forecast (ECMWF, https://www.ecmwf.int/), the Netherlands’ KNMI, commercial weather and sustainable energy companies (DTM and Whiffle) and applied research institutes working with water cycles and subsurface (DELTARES, https://www.deltares.nl/en/).

CWS emphasises transferring research methods to students. For example, Interdisciplinary Topics in Earth and Environment, a course taught in the first year of MSc programme Earth and Environment, devotes substantial time to why, when and how droughts are controlled by pedosphere, hydrosphere, biosphere and atmosphere processes. Through theoretical lectures, practical tutorials and discussion sessions, students learn about interactions between different spheres. Students compile information into a portfolio, including critiques of peer-published papers, and are ultimately required to draft a proposal emphasising multi-scale and multidisciplinary aspects of drought research.

Research Highlights

Our most representative research papers[1] show our approach’s relevance. We have selected papers in which three CWS groups are actively involved: Aquatic Ecology and Water Quality Management (AEW), HWM and MAQ.

Impact

  Extreme weather impacts society, with dramatic effects on natural and urban ecosystems. Among the most important, water scarcity and flooding, food chain disruptions, human stress through worsened air quality and fires all relate with current research and education activities carried out at the CWS cluster. By improving understanding of extreme weather, we improve extreme weather predictability in climate and weather models coupled to hydrological and land conditions, and decisions can be based on better data, subsequently improving planning and reducing economic costs associated with extreme weather.

Main extreme weather studies carried out within the CWS cluster (upper panel) and their characterization as function of time scales. Specific investigations focusing on attributions to extreme weather (cloud organization and land-atmosphere interactions, or the education link to the MSc course) are shown.
Main extreme weather studies carried out within the CWS cluster (upper panel) and their characterization as function of time scales. Specific investigations focusing on attributions to extreme weather (cloud organization and land-atmosphere interactions, or the education link to the MSc course) are shown.

References

[1]

Benedict I, van Heerwaarden C.C. van der Linden E., Weerts A. H. Hazeleger W. (2018) Anomalous moisture sources of the Rhine basin during the extremely dry summers of 2003 and 2018. Weather and Climate extremes

Janssens, M., Vilà-Guerau de Arellano J, Scheffer M., et al. (2020) Cloud patterns have four interpretable dimensions. Geophysical Research Letters (under revision)

Miralles, D., Teuling, A. J., van Heerwaarden, C. and Vilà-Guerau de Arellano J. (2014) Mega-heatwave temperatures due to combined soil desiccation and atmospheric heat accumulation. Nature Geoscience 7, 345–349. https://doi.org/10.1038/ngeo2141 (314 citations).

Schumacher D.L., Keune J. van Heerwaarden C. C., Vilà-Guerau de Arellano J, Teuling, A. J. and Miralles D. (2019) Amplification of mega-heatwaves through heat torrents fuelled by upwind drought. Nature Geoscience 12, 712-717. https://doi.org/10.1038/s41561-019-0431-6 (20 citations)

Smith, N., Kooijmans, L., Koren, G., van Schaik, E., van der Woude, A., Wanders, N., Ramonet, M., Xueref-Remy, I., Siebicke, L., Manca, G., Brümmer, C., Baker, I., Haynes, K., Luijkx, I., Peters, W. (2020). Spring enhancement and summer reduction in carbon uptake during the 2018 drought in northwestern Europe Philosophical Transactions of the Royal Society B 375(1810), 20190509. https://dx.doi.org/10.1098/rstb.2019.0509

Koren, G., van Schaik, E., Araújo, A., Boersma, K., Gärtner, A., Killaars, L., Kooreman, M., Kruijt, B., van der Laan-Luijkx, I., Randow, C., Smith, N., Peters, W. (2018). Widespread reduction in sun-induced fluorescence from the Amazon during the 2015/2016 El Niño Philosophical Transactions Of The Royal Society Of London Series B-Biological Sciences 373(1760), 20170408. https://dx.doi.org/10.1098/rstb.2017.0408

Buitink, J., Swank, A. M., van der Ploeg, M., Smith, N. E., Benninga, H.-J. F., van der Bolt, F., Carranza, C. D. U., Koren, G., van der Velde, R., and Teuling, A. J.: Anatomy of the 2018 agricultural drought in The Netherlands using in situ soil moisture and satellite vegetation indices, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2020-358, in review, 2020.