Wim Thiery

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Thiery

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Wim

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0000-0002-5183-6145

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Publications 1 - 10 of 65

COSMO-CLM regional climate simulations in the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework: A review
Sørland, Silje L.; Brogli, Roman Andrea; Pothapakula, Praveen K.; et al. (2021)
Geoscientific Model Development
In the last decade, the Climate Limited-area Modeling Community (CLM-Community) has contributed to the Coordinated Regional Climate Downscaling Experiment (CORDEX) with an extensive set of regional climate simulations. Using several versions of the COSMO-CLM-Community model, ERA-Interim reanalysis and eight global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were dynamically downscaled with horizontal grid spacings of 0.44g (g1/4g50gkm), 0.22g (g1/4g25gkm), and 0.11g (g1/4g12gkm) over the CORDEX domains Europe, South Asia, East Asia, Australasia, and Africa. This major effort resulted in 80 regional climate simulations publicly available through the Earth System Grid Federation (ESGF) web portals for use in impact studies and climate scenario assessments. Here we review the production of these simulations and assess their results in terms of mean near-surface temperature and precipitation to aid the future design of the COSMO-CLM model simulations. It is found that a domain-specific parameter tuning is beneficial, while increasing horizontal model resolution (from 50 to 25 or 12gkm grid spacing) alone does not always improve the performance of the simulation. Moreover, the COSMO-CLM performance depends on the driving data. This is generally more important than the dependence on horizontal resolution, model version, and configuration. Our results emphasize the importance of performing regional climate projections in a coordinated way, where guidance from both the global (GCM) and regional (RCM) climate modeling communities is needed to increase the reliability of the GCM-RCM modeling chain.
Changes in Land Cover and Management Affect Heat Stress and Labor Capacity
Orlov, Anton; De Hertog, Steven; Havermann, Felix; et al. (2023)
Earth's Future
Global warming is expected to exacerbate heat stress. Additionally, biogeophysical effects of land cover and land management changes (LCLMC) could substantially alter temperature and relative humidity locally and non-locally. Thereby, LCLMC could affect the occupational capacity to safely perform physical work under hot environments (labor capacity). However, these effects have never been quantified globally using a multi-model setup. Building on results from stylized sensitivity experiments of (a) cropland expansion, (b) irrigation expansion, and (c) afforestation conducted by three fully coupled Earth System Models (ESMs), we assess the local as well as non-local effects on heat stress and labor capacity. We found that LCLMC leads to substantial changes in temperature; however, the concomitant changes in humidity could largely diminish the combined impact on moist heat. Moreover, cropland expansion and afforestation cause inconsistent responses of day- and night-time temperature, which has strong implications for labor capacity. Across the ESMs, the results are mixed in terms of sign and magnitude. Overall, LCLMC result in non-negligible impacts on heat stress and labor capacity in low-latitude regions during the warmest seasons. In some locations, the changes of monthly average labor capacity, which are induced by the local effects of individual LCLMC options, could reach −14 and +15 percentage points. Thus, LCLMC-induced impacts on heat stress and their consequences for adaptation should be accounted for when designing LCLMC-related policies to ensure sustainable development.
Widespread deoxygenation of temperate lakes
Jane, Stephen F.; Hansen, Gretchen J. A .; Kraemer, Benjamin M.; et al. (2021)
Nature
The concentration of dissolved oxygen in aquatic systems helps to regulate biodiversity1,2, nutrient biogeochemistry3, greenhouse gas emissions4, and the quality of drinking water5. The long-term declines in dissolved oxygen concentrations in coastal and ocean waters have been linked to climate warming and human activity6,7, but little is known about the changes in dissolved oxygen concentrations in lakes. Although the solubility of dissolved oxygen decreases with increasing water temperatures, long-term lake trajectories are difficult to predict. Oxygen losses in warming lakes may be amplified by enhanced decomposition and stronger thermal stratification8,9 or oxygen may increase as a result of enhanced primary production10. Here we analyse a combined total of 45,148 dissolved oxygen and temperature profiles and calculate trends for 393 temperate lakes that span 1941 to 2017. We find that a decline in dissolved oxygen is widespread in surface and deep-water habitats. The decline in surface waters is primarily associated with reduced solubility under warmer water temperatures, although dissolved oxygen in surface waters increased in a subset of highly productive warming lakes, probably owing to increasing production of phytoplankton. By contrast, the decline in deep waters is associated with stronger thermal stratification and loss of water clarity, but not with changes in gas solubility. Our results suggest that climate change and declining water clarity have altered the physical and chemical environment of lakes. Declines in dissolved oxygen in freshwater are 2.75 to 9.3 times greater than observed in the world’s oceans6,7 and could threaten essential lake ecosystem services2,3,5,11.
The local climate impact of an African city during clear-sky conditions-Implications of the recent urbanization in Kampala (Uganda)
Brousse, Oscar; Wouters, Hendrik; Demuzere, Matthias; et al. (2020)
International Journal of Climatology
This study aims at assessing and understanding the impact of recent urbanization on the (surface) urban heat island ((S)UHI) under clear‐sky conditions in a tropical African city using different sources of remotely sensed data sets together with an urban climate model (UCM). The observed SUHI during clear sky conditions is found to be about 4°C on average over the capital city of Kampala, Uganda. The UCM, consisting of TERRA_URB embedded in COSMO‐CLM, represents the SUHI well during night but overestimates it by about 3°C in the mean during day. Moreover, a systematic warm land surface temperature bias of about 4°C is identified by night. Improved urban input parameters—derived from Local Climate Zones following the World Urban Database and Access Portal Tool (WUDAPT) framework—lead to a more realistic representation of spatial land surface temperatures patterns. In addition, this parameterization of the UCM can properly represent atmospheric variables such as air temperature, specific and relative humidity, as observed by the automated weather stations. A model sensitivity study furthermore demonstrates that the stronger urban heat island induced by the recent urbanization of Kampala over the past 15 years strongly interacts with the lake–land breeze circulation. Stronger daytime convection over the hotter city leads to areas of convergence that amplify the afternoon lake breeze in the Southern parts of the metropolis. Overall, this study demonstrates that the city of Kampala has a tangible effect on the regional climate that needs to be considered when studying present and future climate impacts.
Global Mapping of Concurrent Hazards and Impacts Associated With Climate Extremes Under Climate Change
Messori, Gabriele; Muheki, Derrick; Batibeniz, Fulden; et al. (2025)
Earth's Future
Climate-related extreme events impose a heavy toll on humankind, and many will likely become more frequent in the future. The compound (joint) occurrence of different climate-related hazards and impacts can further exacerbate the detrimental consequences for society. By analyzing postprocessed data from the Inter-Sectoral Impact Model Intercomparison Project, we provide a global mapping of future changes in the compound occurrence of six categories of hazards or impacts related to climate extremes. These are: river floods, droughts, heatwaves, wildfires, tropical cyclone-induced winds and crop failures. In line with the existing literature, we find sharp increases in the occurrence of many individual hazards and impacts, notably heatwaves and wildfires. Under a medium-high emission scenario, many regions worldwide transition from chiefly experiencing a given category of hazard or impact in isolation to routinely experiencing compound hazard or impact occurrences. A similarly striking change is projected for the future recurrence of compound hazards or impacts, with many locations experiencing specific compound occurrences at least once a year for several years, or even decades, in a row. In the absence of effective global climate mitigation actions, we may thus witness a qualitative regime shift from a world dominated by individual climate-related hazards and impacts to one where compound occurrences become the norm. Plain Language Summary Climate-related extreme events often result in large and negative societal impacts, and many such events are likely to become more frequent in the future. The joint occurrence of different climate-related extreme events can lead to even larger impacts than those of extremes occurring in isolation. In the absence of effective global climate mitigation to minimize the ongoing climatic change, we find that many regions worldwide transition from chiefly experiencing extreme events in isolation to routinely experiencing the joint occurrence of different climate-related extreme events. Such joint occurrences may repeatedly affect the same region for several years, or even decades, in a row.
Flash Floods in the Rwenzori Mountains-Focus on the May 2013 Multi-Hazard Kilembe Event
Jacobs, Liesbet; Maes, Jan; Mertens, Kewan; et al. (2017)
Advancing Culture of Living with Landslides
Modelling the water balance of Lake Victoria (East Africa) - Part 1: Observational analysis
Vanderkelen, Inne; van Lipzig, Nicole P.M.; Thiery, Wim (2018)
Hydrology and Earth System Sciences
Lake Victoria is the largest lake in Africa and one of the two major sources of the Nile river. The water level of Lake Victoria is determined by its water balance, consisting of precipitation on the lake, evaporation from the lake, inflow from tributary rivers and lake outflow, controlled by two hydropower dams. Due to a scarcity of in situ observations, previous estimates of individual water balance terms are characterized by substantial uncertainties, which means that the water balance is often not closed independently. In this first part of a two-paper series, we present a water balance model for Lake Victoria, using state-of-the-art remote sensing observations, high-resolution reanalysis downscaling and outflow values recorded at the dam. The uncalibrated computation of the individual water balance terms yields lake level fluctuations that closely match the levels retrieved from satellite altimetry. Precipitation is the main cause of seasonal and interannual lake level fluctuations, and on average causes the lake level to rise from May to July and to fall from August to December. Finally, our results indicate that the 2004–2005 drop in lake level can be about half attributed to a drought in the Lake Victoria Basin and about half to an enhanced outflow, highlighting the sensitivity of the lake level to human operations at the outflow dam.
User-friendly workflows for catchment modelling: Towards reproducible SWAT+ model studies
Chawanda, Celray James; George, Chris; Thiery, Wim; et al. (2020)
Environmental Modelling & Software
A Graphical User Interface (GUI) is regularly used to support model applications in catchment hydrological modelling software. A GUI is generally user-friendly for novice users but opens sources of irreproducible research. We illustrate that none of the 10 Soil and Water Assessment Tool (SWAT) models over the Upper Blue Nile can easily be reproduced. Scripted workflows provide the ability to reproduce model set-ups, but they may be less user-friendly especially to novice users. We present a software (SWAT + AW) that promotes reproducible SWAT + model studies while remaining user-friendly for both novice and expert users. SWAT + AW uses a configuration file to create models that are compatible with GUI. We applied the workflow to the Blue Nile catchment and show that it yields the same results the SWAT + GUI. We conclude that such user-friendly scripted workflows enhance reproducibility, transparency and reusability of hydrological models. The software is publicly available at https://github.com/VUB-HYDR/SWATPlus-AW.
Land Use, Land Cover and Land Management Change: Definitions, Scenarios, and Role in the Climate System
Thiery, Wim; Davin, Edouard Léopold; Seneviratne, Sonia I. (2018)
Oxford Bibliographies in Environmental Science
Present-day irrigation mitigates heat extremes
Thiery, Wim; Davin, Edouard Léopold; Lawrence, David M.; et al. (2017)
Journal of Geophysical Research: Atmospheres
Irrigation is an essential practice for sustaining global food production and many regional economies. Emerging scientific evidence indicates that irrigation substantially affects mean climate conditions in different regions of the world. Yet how this practice influences climate extremes is currently unknown. Here we use ensemble simulations with the Community Earth System Model to assess the impacts of irrigation on climate extremes. An evaluation of the model performance reveals that irrigation has a small yet overall beneficial effect on the representation of present-day near-surface climate. While the influence of irrigation on annual mean temperatures is limited, we find a large impact on temperature extremes, with a particularly strong cooling during the hottest day of the year (−0.78 K averaged over irrigated land). The strong influence on extremes stems from the timing of irrigation and its influence on land-atmosphere coupling strength. Together these effects result in asymmetric temperature responses, with a more pronounced cooling during hot and/or dry periods. The influence of irrigation is even more pronounced when considering subgrid-scale model output, suggesting that local effects of land management are far more important than previously thought. Our results underline that irrigation has substantially reduced our exposure to hot temperature extremes in the past and highlight the need to account for irrigation in future climate projections.

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