Articles | Volume 4, issue 3
https://doi.org/10.5194/wcd-4-701-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-4-701-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
14 Aug 2023
Research article |
| 14 Aug 2023
| 14 Aug 2023
Validation of boreal summer tropical–extratropical causal links in seasonal forecasts
Department of Water, Environment, Construction and Safety,
Magdeburg-Stendal University of Applied Sciences, 39114 Magdeburg, Germany
Earth System Analysis, Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 60 12 03, 14412 Potsdam, Germany
Dim Coumou
Earth System Analysis, Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 60 12 03, 14412 Potsdam, Germany
Institute for Environmental Studies (IVM), Department of Water and Climate
Risk, VU Amsterdam, Amsterdam, 1081 HV, the Netherlands
Royal Netherlands Meteorological Institute (KNMI), De Bilt, 3730 AE, the Netherlands
Bart van den Hurk
Institute for Environmental Studies (IVM), Department of Water and Climate
Risk, VU Amsterdam, Amsterdam, 1081 HV, the Netherlands
Department of Climate Adaptation, Deltares, Delft, 2629 HV,
the Netherlands
Antje Weisheimer
European Centre for Medium-Range Weather Forecasts, Reading, RG2 9AX, United Kingdom
Department of Physics (AOPP), National Centre for Atmospheric Science, University of Oxford, Oxford, OX1 4BH, United Kingdom
Andrew G. Turner
National Centre for Atmospheric Science, University of Reading,
Reading, RG6 6ES, United Kingdom
Department of Meteorology, University of Reading, Reading, RG6 6ES,
United Kingdom
Reik V. Donner
Department of Water, Environment, Construction and Safety,
Magdeburg-Stendal University of Applied Sciences, 39114 Magdeburg, Germany
Earth System Analysis, Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 60 12 03, 14412 Potsdam, Germany
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We present an application of multivariate statistical models to assess compound flooding events in a managed reservoir. Data (from a previous study) were obtained from a physical-based hydrological model driven by a regional climate model large ensemble, providing a time series expanding up to 800 years in length that ensures stable statistics. The length of the data set allows for a sensitivity assessment of the proposed statistical framework to natural climate variability.
Sarah Sparrow, Andrew Bowery, Glenn D. Carver, Marcus O. Köhler, Pirkka Ollinaho, Florian Pappenberger, David Wallom, and Antje Weisheimer
Geosci. Model Dev., 14, 3473–3486, https://doi.org/10.5194/gmd-14-3473-2021, https://doi.org/10.5194/gmd-14-3473-2021, 2021
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This paper describes how the research version of the European Centre for Medium-Range Weather Forecasts’ Integrated Forecast System is combined with climateprediction.net’s public volunteer computing resource to develop OpenIFS@home. Thousands of volunteer personal computers simulated slightly different realizations of Tropical Cyclone Karl to demonstrate the performance of the large-ensemble forecast. OpenIFS@Home offers researchers a new tool to study weather forecasts and related questions.
Sazzad Hossain, Hannah L. Cloke, Andrea Ficchì, Andrew G. Turner, and Elisabeth M. Stephens
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2021-97, https://doi.org/10.5194/hess-2021-97, 2021
Manuscript not accepted for further review
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Hydrometeorological drivers are investigated to study three different flood types: long duration, rapid rise and high water level of the Brahmaputra river basin in Bangladesh. Our results reveal that long duration floods have been driven by basin-wide rainfall whereas rapid rate of rise due to more localized rainfall. We find that recent record high water levels are not coincident with extreme river flows. Understanding these drivers is key for flood forecasting and early warning.
Frederik Wolf, Aiko Voigt, and Reik V. Donner
Earth Syst. Dynam., 12, 353–366, https://doi.org/10.5194/esd-12-353-2021, https://doi.org/10.5194/esd-12-353-2021, 2021
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In our work, we employ complex networks to study the relation between the time mean position of the intertropical convergence zone (ITCZ) and sea surface temperature (SST) variability. We show that the information hidden in different spatial SST correlation patterns, which we access utilizing complex networks, is strongly correlated with the time mean position of the ITCZ. This research contributes to the ongoing discussion on drivers of the annual migration of the ITCZ.
Frederik Wolf, Ugur Ozturk, Kevin Cheung, and Reik V. Donner
Earth Syst. Dynam., 12, 295–312, https://doi.org/10.5194/esd-12-295-2021, https://doi.org/10.5194/esd-12-295-2021, 2021
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Motivated by a lacking onset prediction scheme, we examine the temporal evolution of synchronous heavy rainfall associated with the East Asian Monsoon System employing a network approach. We find, that the evolution of the Baiu front is associated with the formation of a spatially separated double band of synchronous rainfall. Furthermore, we identify the South Asian Anticyclone and the North Pacific Subtropical High as the main drivers, which have been assumed to be independent previously.
Jonathan K. P. Shonk, Andrew G. Turner, Amulya Chevuturi, Laura J. Wilcox, Andrea J. Dittus, and Ed Hawkins
Atmos. Chem. Phys., 20, 14903–14915, https://doi.org/10.5194/acp-20-14903-2020, https://doi.org/10.5194/acp-20-14903-2020, 2020
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We use a set of model simulations of the 20th century to demonstrate that the uncertainty in the cooling effect of man-made aerosol emissions has a wide range of impacts on global monsoons. For the weakest cooling, the impact of aerosol is overpowered by greenhouse gas (GHG) warming and monsoon rainfall increases in the late 20th century. For the strongest cooling, aerosol impact dominates over GHG warming, leading to reduced monsoon rainfall, particularly from 1950 to 1980.
Liang Guo, Ruud J. van der Ent, Nicholas P. Klingaman, Marie-Estelle Demory, Pier Luigi Vidale, Andrew G. Turner, Claudia C. Stephan, and Amulya Chevuturi
Geosci. Model Dev., 13, 6011–6028, https://doi.org/10.5194/gmd-13-6011-2020, https://doi.org/10.5194/gmd-13-6011-2020, 2020
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Precipitation over East Asia simulated in the Met Office Unified Model is compared with observations. Moisture sources of EA precipitation are traced using a moisture tracking model. Biases in moisture sources are linked to biases in precipitation. Using the tracking model, changes in moisture sources can be attributed to changes in SST, circulation and associated evaporation. This proves that the method used in this study is useful to identify the causes of biases in regional precipitation.
Christopher H. O'Reilly, Daniel J. Befort, and Antje Weisheimer
Earth Syst. Dynam., 11, 1033–1049, https://doi.org/10.5194/esd-11-1033-2020, https://doi.org/10.5194/esd-11-1033-2020, 2020
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This study examines how the output of large single-model ensembles can be calibrated using observational data to provide improved future projections over Europe. Using an out-of-sample
imperfect modeltest, in which calibration techniques are applied to individual climate model realisations, these techniques are shown to generally improve the reliability of European climate projections for the next 40 years, particularly for regional surface temperature.
Maialen Iturbide, José M. Gutiérrez, Lincoln M. Alves, Joaquín Bedia, Ruth Cerezo-Mota, Ezequiel Cimadevilla, Antonio S. Cofiño, Alejandro Di Luca, Sergio Henrique Faria, Irina V. Gorodetskaya, Mathias Hauser, Sixto Herrera, Kevin Hennessy, Helene T. Hewitt, Richard G. Jones, Svitlana Krakovska, Rodrigo Manzanas, Daniel Martínez-Castro, Gemma T. Narisma, Intan S. Nurhati, Izidine Pinto, Sonia I. Seneviratne, Bart van den Hurk, and Carolina S. Vera
Earth Syst. Sci. Data, 12, 2959–2970, https://doi.org/10.5194/essd-12-2959-2020, https://doi.org/10.5194/essd-12-2959-2020, 2020
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We present an update of the IPCC WGI reference regions used in AR5 for the synthesis of climate change information. This revision was guided by the basic principles of climatic consistency and model representativeness (in particular for the new CMIP6 simulations). We also present a new dataset of monthly CMIP5 and CMIP6 spatially aggregated information using the new reference regions and describe a worked example of how to use this dataset to inform regional climate change studies.
Laura J. Wilcox, Zhen Liu, Bjørn H. Samset, Ed Hawkins, Marianne T. Lund, Kalle Nordling, Sabine Undorf, Massimo Bollasina, Annica M. L. Ekman, Srinath Krishnan, Joonas Merikanto, and Andrew G. Turner
Atmos. Chem. Phys., 20, 11955–11977, https://doi.org/10.5194/acp-20-11955-2020, https://doi.org/10.5194/acp-20-11955-2020, 2020
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Projected changes in man-made aerosol range from large reductions to moderate increases in emissions until 2050. Rapid reductions between the present and the 2050s lead to enhanced increases in global and Asian summer monsoon precipitation relative to scenarios with continued increases in aerosol. Relative magnitude and spatial distribution of aerosol changes are particularly important for South Asian summer monsoon precipitation changes, affecting the sign of the trend in the coming decades.
Giorgia Di Capua, Jakob Runge, Reik V. Donner, Bart van den Hurk, Andrew G. Turner, Ramesh Vellore, Raghavan Krishnan, and Dim Coumou
Weather Clim. Dynam., 1, 519–539, https://doi.org/10.5194/wcd-1-519-2020, https://doi.org/10.5194/wcd-1-519-2020, 2020
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We study the interactions between the tropical convective activity and the mid-latitude circulation in the Northern Hemisphere during boreal summer. We identify two circumglobal wave patterns with phase shifts corresponding to the South Asian and the western North Pacific monsoon systems at an intra-seasonal timescale. These patterns show two-way interactions in a causal framework at a weekly timescale and assess how El Niño affects these interactions.
Paolo De Luca, Gabriele Messori, Davide Faranda, Philip J. Ward, and Dim Coumou
Earth Syst. Dynam., 11, 793–805, https://doi.org/10.5194/esd-11-793-2020, https://doi.org/10.5194/esd-11-793-2020, 2020
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In this paper we quantify Mediterranean compound temperature and precipitation dynamical extremes (CDEs) over the 1979–2018 period. The strength of the temperature–precipitation coupling during summer increased and is driven by surface warming. We also link the CDEs to compound hot–dry and cold–wet events during summer and winter respectively.
Dim Coumou and Paolo De Luca
Weather Clim. Dynam. Discuss., https://doi.org/10.5194/wcd-2020-40, https://doi.org/10.5194/wcd-2020-40, 2020
Preprint withdrawn
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We show that the persistence of summer weather has increased throughout the mid-latitudes over the last 40 years, in both observations and CMIP6 models. Our results provide solid evidence that the weakening of the summer jet-stream has already made weather more persistent. We also show that future greenhouse-gases emissions will further increase weather persistence, creating risks from high-impact, stalling weather extremes like persistent heat waves and stalling cyclones.
Jaqueline Lekscha and Reik V. Donner
Nonlin. Processes Geophys., 27, 261–275, https://doi.org/10.5194/npg-27-261-2020, https://doi.org/10.5194/npg-27-261-2020, 2020
Giorgia Di Capua, Marlene Kretschmer, Reik V. Donner, Bart van den Hurk, Ramesh Vellore, Raghavan Krishnan, and Dim Coumou
Earth Syst. Dynam., 11, 17–34, https://doi.org/10.5194/esd-11-17-2020, https://doi.org/10.5194/esd-11-17-2020, 2020
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Drivers from both the mid-latitudes and the tropical regions have been proposed to influence the Indian summer monsoon (ISM) subseasonal variability. To understand the relative importance of tropical and mid-latitude drivers, we apply recently developed causal discovery techniques to disentangle the causal relationships among these processes. Our results show that there is indeed a two-way interaction between the mid-latitude circulation and ISM rainfall over central India.
James Brooks, Dantong Liu, James D. Allan, Paul I. Williams, Jim Haywood, Ellie J. Highwood, Sobhan K. Kompalli, S. Suresh Babu, Sreedharan K. Satheesh, Andrew G. Turner, and Hugh Coe
Atmos. Chem. Phys., 19, 13079–13096, https://doi.org/10.5194/acp-19-13079-2019, https://doi.org/10.5194/acp-19-13079-2019, 2019
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Our study presents an analysis of the vertical and horizontal black carbon properties across northern India using aircraft measurements. The Indo-Gangetic Plain saw the greatest black carbon mass concentrations during the pre-monsoon season. Two black carbon modes were recorded: a small black carbon mode (traffic emissions) in the north-west and a moderately coated mode (solid-fuel emissions) in the Indo-Gangetic Plain. In the vertical profile, absorption properties increase with height.
Sazzad Hossain, Hannah L. Cloke, Andrea Ficchì, Andrew G. Turner, and Elisabeth Stephens
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2019-286, https://doi.org/10.5194/hess-2019-286, 2019
Manuscript not accepted for further review
James Brooks, James D. Allan, Paul I. Williams, Dantong Liu, Cathryn Fox, Jim Haywood, Justin M. Langridge, Ellie J. Highwood, Sobhan K. Kompalli, Debbie O'Sullivan, Suresh S. Babu, Sreedharan K. Satheesh, Andrew G. Turner, and Hugh Coe
Atmos. Chem. Phys., 19, 5615–5634, https://doi.org/10.5194/acp-19-5615-2019, https://doi.org/10.5194/acp-19-5615-2019, 2019
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Our study, for the first time, presents measurements of aerosol chemical composition and physical characteristics across northern India in the pre-monsoon and monsoon seasons of 2016 using the FAAM BAe-146 UK research aircraft. Across northern India, an elevated aerosol layer dominated by sulfate aerosol exists that diminishes with monsoon arrival. The Indo-Gangetic Plain (IGP) boundary layer is dominated by organics, whereas outside the IGP sulfate dominates with increased scattering aerosol.
Giorgia Di Capua, Marlene Kretschmer, Reik V. Donner, Bart van den Hurk, Ramesh Vellore, Raghavan Krishnan, and Dim Coumou
Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2019-11, https://doi.org/10.5194/esd-2019-11, 2019
Manuscript not accepted for further review
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Both drivers from the mid-latitudes and from the tropical regions have been proposed to influence the Indian summer monsoon (ISM) subseasonal variability. To understand the relative importance of tropical and mid-latitude drivers, we apply recently developed causal discovery techniques to disentangle the causal relationships among these processes. Our results show that there is indeed a two-way interaction between the mid-latitude circulation and ISM rainfall over central India.
Claudia Christine Stephan, Nicholas P. Klingaman, Pier Luigi Vidale, Andrew G. Turner, Marie-Estelle Demory, and Liang Guo
Geosci. Model Dev., 11, 3215–3233, https://doi.org/10.5194/gmd-11-3215-2018, https://doi.org/10.5194/gmd-11-3215-2018, 2018
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Summer precipitation over China in the MetUM reaches twice its observed values. Increasing the horizontal resolution of the model and adding air–sea coupling have little effect on these biases. Nevertheless, MetUM correctly simulates spatial patterns of temporally coherent precipitation and the associated large-scale processes. This suggests that the model may provide useful predictions of summer intraseasonal variability despite the substantial biases in overall intraseasonal variance.
Iris Manola, Bart van den Hurk, Hans De Moel, and Jeroen C. J. H. Aerts
Hydrol. Earth Syst. Sci., 22, 3777–3788, https://doi.org/10.5194/hess-22-3777-2018, https://doi.org/10.5194/hess-22-3777-2018, 2018
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In a warmer climate, it is expected that precipitation intensities will increase and form a considerable risk of high-impact precipitation extremes. We investigate how observed extreme precipitation events would look like if they took place in a future warmer climate. This study applies three methods to transform a historic extreme precipitation event in the Netherlands to a similar event in a future warmer climate, thus compiling a
future weatherscenario.
Claudia Christine Stephan, Nicholas P. Klingaman, Pier Luigi Vidale, Andrew G. Turner, Marie-Estelle Demory, and Liang Guo
Geosci. Model Dev., 11, 1823–1847, https://doi.org/10.5194/gmd-11-1823-2018, https://doi.org/10.5194/gmd-11-1823-2018, 2018
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Climate simulations are evaluated for their ability to reproduce year-to-year variability of precipitation over China. Mean precipitation and variability are too high in all simulations but improve with finer resolution and coupling. Simulations reproduce the observed spatial patterns of rainfall variability. However, not all of these patterns are associated with observed mechanisms. For example, simulations do not reproduce summer rainfall along the Yangtze valley in response to El Niño.
Sonu Khanal, Nina Ridder, Hylke de Vries, Wilco Terink, and Bart van den Hurk
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-103, https://doi.org/10.5194/hess-2018-103, 2018
Revised manuscript not accepted
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This study assesses the possibility of finding near simultaneous storm surge and extreme river discharge using an extended data set derived from a storm surge model and two hydrological river-discharge models forced with conditions from a highresolution climate model in ensemble model. The study highlights that the hazard of a co-occurrence of high river discharge and coastal water levels cannot be neglected in a robust risk assessment.
Konstantinos Bischiniotis, Bart van den Hurk, Brenden Jongman, Erin Coughlan de Perez, Ted Veldkamp, Hans de Moel, and Jeroen Aerts
Nat. Hazards Earth Syst. Sci., 18, 271–285, https://doi.org/10.5194/nhess-18-271-2018, https://doi.org/10.5194/nhess-18-271-2018, 2018
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Preparedness activities and flood forecasting have received increasing attention and have led towards new science-based early warning systems. Understanding the flood triggering mechanisms will result in increasing warning lead times, providing sufficient time for early action. Findings of this study indicate that the consideration of short- and long-term antecedent conditions can be used by humanitarian organizations and decision makers for improved flood risk management.
Tim Kittel, Catrin Ciemer, Nastaran Lotfi, Thomas Peron, Francisco Rodrigues, Jürgen Kurths, and Reik V. Donner
Nonlin. Processes Geophys. Discuss., https://doi.org/10.5194/npg-2017-69, https://doi.org/10.5194/npg-2017-69, 2017
Revised manuscript not accepted
Jasper G. Franke, Johannes P. Werner, and Reik V. Donner
Clim. Past, 13, 1593–1608, https://doi.org/10.5194/cp-13-1593-2017, https://doi.org/10.5194/cp-13-1593-2017, 2017
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We apply evolving functional network analysis, a tool for studying temporal changes of the spatial co-variability structure, to a set of
Late Holocene paleoclimate proxy records covering the last two millennia. The emerging patterns obtained by our analysis are related to
long-term changes in the dominant mode of atmospheric circulation in the region, the North Atlantic Oscillation (NAO). We obtain a
qualitative reconstruction of the NAO long-term variability over the entire Common Era.
Lukas Baumbach, Jonatan F. Siegmund, Magdalena Mittermeier, and Reik V. Donner
Biogeosciences, 14, 4891–4903, https://doi.org/10.5194/bg-14-4891-2017, https://doi.org/10.5194/bg-14-4891-2017, 2017
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Temperature extremes play a crucial role for vegetation growth and vitality in vast parts of the European continent. Here, we study the likelihood of simultaneous occurrences of extremes in daytime land surface temperatures and the normalized difference vegetation index (NDVI) for three main periods during the growing season. Our results reveal a particularly high vulnerability of croplands to temperature extremes, while other vegetation types are considerably less affected.
Erin Coughlan de Perez, Elisabeth Stephens, Konstantinos Bischiniotis, Maarten van Aalst, Bart van den Hurk, Simon Mason, Hannah Nissan, and Florian Pappenberger
Hydrol. Earth Syst. Sci., 21, 4517–4524, https://doi.org/10.5194/hess-21-4517-2017, https://doi.org/10.5194/hess-21-4517-2017, 2017
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Disaster managers would like to use seasonal forecasts to anticipate flooding months in advance. However, current seasonal forecasts give information on rainfall instead of flooding. Here, we find that the number of extreme events, rather than total rainfall, is most related to flooding in different regions of Africa. We recommend several forecast adjustments and research opportunities that would improve flood information at the seasonal timescale in different regions.
Paolo Davini, Jost von Hardenberg, Susanna Corti, Hannah M. Christensen, Stephan Juricke, Aneesh Subramanian, Peter A. G. Watson, Antje Weisheimer, and Tim N. Palmer
Geosci. Model Dev., 10, 1383–1402, https://doi.org/10.5194/gmd-10-1383-2017, https://doi.org/10.5194/gmd-10-1383-2017, 2017
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The Climate SPHINX project is a large set of more than 120 climate simulations run with the EC-Earth global climate. It explores the sensitivity of present-day and future climate to the model horizontal resolution (from 150 km up to 16 km) and to the introduction of two stochastic physics parameterisations. Results shows that the the stochastic schemes can represent a cheaper alternative to a resolution increase, especially for the representation of the tropical climate variability.
Tianjun Zhou, Andrew G. Turner, James L. Kinter, Bin Wang, Yun Qian, Xiaolong Chen, Bo Wu, Bin Wang, Bo Liu, Liwei Zou, and Bian He
Geosci. Model Dev., 9, 3589–3604, https://doi.org/10.5194/gmd-9-3589-2016, https://doi.org/10.5194/gmd-9-3589-2016, 2016
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This paper tells why to launch the Global Monsoons Model Inter-comparison Project (GMMIP) and how to achieve its scientific goals on monsoon variability. It addresses the scientific questions to be answered, describes three tiered experiments comprehensively and proposes a basic analysis framework to guide future research. It will help the monsoon research communities to understand the objectives of the GMMIP and the modelling groups involved in the GMMIP conduct the experiments successfully.
Jonatan F. Siegmund, Marc Wiedermann, Jonathan F. Donges, and Reik V. Donner
Biogeosciences, 13, 5541–5555, https://doi.org/10.5194/bg-13-5541-2016, https://doi.org/10.5194/bg-13-5541-2016, 2016
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In this study we systematically quantify simultaneities between meteorological extremes and the timing of flowering of four shrub species across Germany by using event coincidence analysis. Our study confirms previous findings of experimental studies, highlighting the impact of early spring temperatures on the flowering of the investigated plants. Additionally, the analysis reveals statistically significant indications of an influence of temperature extremes in the fall preceding the flowering.
Erin Coughlan de Perez, Bart van den Hurk, Maarten K. van Aalst, Irene Amuron, Deus Bamanya, Tristan Hauser, Brenden Jongma, Ana Lopez, Simon Mason, Janot Mendler de Suarez, Florian Pappenberger, Alexandra Rueth, Elisabeth Stephens, Pablo Suarez, Jurjen Wagemaker, and Ervin Zsoter
Hydrol. Earth Syst. Sci., 20, 3549–3560, https://doi.org/10.5194/hess-20-3549-2016, https://doi.org/10.5194/hess-20-3549-2016, 2016
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Many flood disaster impacts could be avoided by preventative action; however, early action is not guaranteed. This article demonstrates the design of a new system of forecast-based financing, which automatically triggers action when a flood forecast arrives, before a potential disaster. We establish "action triggers" for northern Uganda based on a global flood forecasting system, verifying these forecasts and assessing the uncertainties inherent in setting a trigger in a data-scarce location.
Bart van den Hurk, Hyungjun Kim, Gerhard Krinner, Sonia I. Seneviratne, Chris Derksen, Taikan Oki, Hervé Douville, Jeanne Colin, Agnès Ducharne, Frederique Cheruy, Nicholas Viovy, Michael J. Puma, Yoshihide Wada, Weiping Li, Binghao Jia, Andrea Alessandri, Dave M. Lawrence, Graham P. Weedon, Richard Ellis, Stefan Hagemann, Jiafu Mao, Mark G. Flanner, Matteo Zampieri, Stefano Materia, Rachel M. Law, and Justin Sheffield
Geosci. Model Dev., 9, 2809–2832, https://doi.org/10.5194/gmd-9-2809-2016, https://doi.org/10.5194/gmd-9-2809-2016, 2016
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This manuscript describes the setup of the CMIP6 project Land Surface, Snow and Soil Moisture Model Intercomparison Project (LS3MIP).
Dave MacLeod, Hannah Cloke, Florian Pappenberger, and Antje Weisheimer
Hydrol. Earth Syst. Sci., 20, 2737–2743, https://doi.org/10.5194/hess-20-2737-2016, https://doi.org/10.5194/hess-20-2737-2016, 2016
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Soil moisture memory is a key aspect of seasonal climate predictions, through feedback between the land surface and the atmosphere. Estimates have been made of the length of soil moisture memory; however, we show here how estimates of memory show large variation with uncertain model parameters. Explicit representation of model uncertainty may then improve the realism of simulations and seasonal climate forecasts.
Zun Yin, Stefan C. Dekker, Bart J. J. M. van den Hurk, and Henk A. Dijkstra
Biogeosciences, 13, 3343–3357, https://doi.org/10.5194/bg-13-3343-2016, https://doi.org/10.5194/bg-13-3343-2016, 2016
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Bimodality is found in aboveground biomass and mean annual shortwave radiation in West Africa, which is a strong evidence of alternative stable states. The condition with low biomass and low radiation is demonstrated under which ecosystem state can shift between savanna and forest states. Moreover, climatic indicators have different prediction confidences to different land cover types. A new method is proposed to predict potential land cover change with a combination of climatic indicators.
L. Guo, A. G. Turner, and E. J. Highwood
Atmos. Chem. Phys., 15, 6367–6378, https://doi.org/10.5194/acp-15-6367-2015, https://doi.org/10.5194/acp-15-6367-2015, 2015
J. F. Donges, R. V. Donner, N. Marwan, S. F. M. Breitenbach, K. Rehfeld, and J. Kurths
Clim. Past, 11, 709–741, https://doi.org/10.5194/cp-11-709-2015, https://doi.org/10.5194/cp-11-709-2015, 2015
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Paleoclimate records from cave deposits allow the reconstruction of Holocene dynamics of the Asian monsoon system, an important tipping element in Earth's climate. Employing recently developed techniques of nonlinear time series analysis reveals several robust and continental-scale regime shifts in the complexity of monsoonal variability. These regime shifts might have played an important role as drivers of migration, cultural change, and societal collapse during the past 10,000 years.
E. Coughlan de Perez, B. van den Hurk, M. K. van Aalst, B. Jongman, T. Klose, and P. Suarez
Nat. Hazards Earth Syst. Sci., 15, 895–904, https://doi.org/10.5194/nhess-15-895-2015, https://doi.org/10.5194/nhess-15-895-2015, 2015
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How can we use weather or climate forecasts to avoid disasters? This article offers a framework for determining when it is "worth" taking action to try to avoid a potential disaster. Considering forecast probabilities, actions, and funding constraints, we propose a novel forecast-based financing system that would automatically trigger action based on forecasts of increased risks.
Y. Zou, R. V. Donner, N. Marwan, M. Small, and J. Kurths
Nonlin. Processes Geophys., 21, 1113–1126, https://doi.org/10.5194/npg-21-1113-2014, https://doi.org/10.5194/npg-21-1113-2014, 2014
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We use visibility graphs to characterize asymmetries in the dynamics of sunspot areas in both solar hemispheres. Our analysis provides deep insights into the potential and limitations of this method, revealing a complex interplay between effects due to statistical versus dynamical properties of the observed data. Temporal changes in the hemispheric predominance of the graph connectivity are found to lag those directly associated with the total hemispheric sunspot areas themselves.
B. P. Guillod, B. Orlowsky, D. Miralles, A. J. Teuling, P. D. Blanken, N. Buchmann, P. Ciais, M. Ek, K. L. Findell, P. Gentine, B. R. Lintner, R. L. Scott, B. Van den Hurk, and S. I. Seneviratne
Atmos. Chem. Phys., 14, 8343–8367, https://doi.org/10.5194/acp-14-8343-2014, https://doi.org/10.5194/acp-14-8343-2014, 2014
S. J. Sutanto, B. van den Hurk, P. A. Dirmeyer, S. I. Seneviratne, T. Röckmann, K. E. Trenberth, E. M. Blyth, J. Wenninger, and G. Hoffmann
Hydrol. Earth Syst. Sci., 18, 2815–2827, https://doi.org/10.5194/hess-18-2815-2014, https://doi.org/10.5194/hess-18-2815-2014, 2014
L. Batlle-Bayer, B. J. J. M. van den Hurk, C. Müller, and J. van Minnen
Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esdd-5-585-2014, https://doi.org/10.5194/esdd-5-585-2014, 2014
Revised manuscript has not been submitted
Z. Yin, S. C. Dekker, B. J. J. M. van den Hurk, and H. A. Dijkstra
Geosci. Model Dev., 7, 821–845, https://doi.org/10.5194/gmd-7-821-2014, https://doi.org/10.5194/gmd-7-821-2014, 2014
R. V. Donner and G. Balasis
Nonlin. Processes Geophys., 20, 965–975, https://doi.org/10.5194/npg-20-965-2013, https://doi.org/10.5194/npg-20-965-2013, 2013
L. Guo, E. J. Highwood, L. C. Shaffrey, and A. G. Turner
Atmos. Chem. Phys., 13, 1521–1534, https://doi.org/10.5194/acp-13-1521-2013, https://doi.org/10.5194/acp-13-1521-2013, 2013
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Quantifying uncertainty in simulations of the West African monsoon with the use of surrogate models
Western disturbances and climate variability: a review of recent developments
Increasing frequency and lengthening season of western disturbances are linked to increasing strength and delayed northward migration of the subtropical jet
Sustained intensification of the Aleutian Low induces weak tropical Pacific sea surface warming
Multi-decadal pacemaker simulations with an intermediate-complexity climate model
Replicating the Hadley cell edge and subtropical jet latitude disconnect in idealized atmospheric models
Warm conveyor belt activity over the Pacific: modulation by the Madden–Julian Oscillation and impact on tropical–extratropical teleconnections
Understanding the dependence of mean precipitation on convective treatment and horizontal resolution in tropical aquachannel experiments
Identifying quasi-periodic variability using multivariate empirical mode decomposition: a case of the tropical Pacific
Examining the dynamics of a Borneo vortex using a balance approximation tool
Strengthening gradients in the tropical west Pacific connect to European summer temperatures on sub-seasonal timescales
Classification of large-scale environments that drive the formation of mesoscale convective systems over southern West Africa
Large uncertainty in observed estimates of tropical width from the meridional stream function
The impact of the Agulhas Current system on precipitation in southern Africa in regional climate simulations covering the recent past and future
Intensity fluctuations in Hurricane Irma (2017) during a period of rapid intensification
Investigation of links between dynamical scenarios and particularly high impact of Aeolus on numerical weather prediction (NWP) forecasts
Can low-resolution CMIP6 ScenarioMIP models provide insight into future European post-tropical-cyclone risk?
Non-linear intensification of monsoon low-pressure systems by the BSISO
Dynamics of gap winds in the Great Rift Valley, Ethiopia: emphasis on strong winds at Lake Abaya
Metrics of the Hadley circulation strength and associated circulation trends
Characterising the interaction of tropical and extratropical air masses controlling East Asian summer monsoon progression using a novel frontal detection approach
Extreme Atlantic hurricane seasons made twice as likely by ocean warming
Synoptic processes of winter precipitation in the Upper Indus Basin
Acceleration of tropical cyclones as a proxy for extratropical interactions: synoptic-scale patterns and long-term trends
Subtle influence of the Atlantic Meridional Overturning Circulation (AMOC) on seasonal sea surface temperature (SST) hindcast skill in the North Atlantic
Drivers of uncertainty in future projections of Madden–Julian Oscillation teleconnections
Zonal scale and temporal variability of the Asian monsoon anticyclone in an idealised numerical model
African easterly waves in an idealized general circulation model: instability and wave packet diagnostics
How Rossby wave breaking modulates the water cycle in the North Atlantic trade wind region
The effect of seasonally and spatially varying chlorophyll on Bay of Bengal surface ocean properties and the South Asian monsoon
Dominant patterns of interaction between the tropics and mid-latitudes in boreal summer: causal relationships and the role of timescales
Abrupt transitions in an atmospheric single-column model with weak temperature gradient approximation
The American monsoon system in HadGEM3 and UKESM1
Aleena M. Jaison, Lesley J. Gray, Scott M. Osprey, Jeff R. Knight, and Martin B. Andrews
Weather Clim. Dynam., 5, 1489–1504, https://doi.org/10.5194/wcd-5-1489-2024, https://doi.org/10.5194/wcd-5-1489-2024, 2024
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Models have biases in semi-annual oscillation (SAO) representation, mainly due to insufficient eastward wave forcing. We examined if the bias is from increased wave absorption due to circulation biases in the low–middle stratosphere. Alleviating biases at lower altitudes improves the SAO, but substantial bias remains. Alternative methods like gravity wave parameterization changes should be explored to enhance the modelled SAO, potentially improving sudden stratospheric warming predictability.
Matthew Davison and Peter Haynes
Weather Clim. Dynam., 5, 1153–1185, https://doi.org/10.5194/wcd-5-1153-2024, https://doi.org/10.5194/wcd-5-1153-2024, 2024
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A simple model is used to study the relation between small-scale convection and large-scale variability in the tropics arising from the coupling between moisture and dynamics. In the model, moisture preferentially lies at either moist or dry states, which merge to form large-scale aggregated regions. On an equatorial β plane, these aggregated regions are localised at the Equator and propagate zonally. This forms an intermediate model between past simpler models and general circulation models.
Nicolás García-Lee, Claudio Bravo, Álvaro Gónzalez-Reyes, and Piero Mardones
Weather Clim. Dynam., 5, 1137–1151, https://doi.org/10.5194/wcd-5-1137-2024, https://doi.org/10.5194/wcd-5-1137-2024, 2024
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This study analyses the 0 °C isotherm in Patagonia from 1959 to 2021, using observational and fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis data. The model aligns well with observations, highlighting significant altitude variations between the western and eastern sides of the austral Andes, a correlation between isotherm fluctuations and the Southern Annular Mode index, and an upward trend in the study area (especially in northwestern Patagonia).
Priya Bharati, Pranab Deb, and Kieran M. R. Hunt
EGUsphere, https://doi.org/10.5194/egusphere-2024-2845, https://doi.org/10.5194/egusphere-2024-2845, 2024
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Snowfall in the Karakoram and Western Himalayas (KH) correlates negatively with the Pacific Decadal Oscillation (PDO) during the winter (DJF). A wave-like pattern in the upper atmosphere, accompanied with a northward moving subtropical jet over KH, is associated with warm SST in the northwest Pacific Ocean. More frequent western disturbances (WDs) migrated north of KH region during the negative phase of PDO, resulting in increased moisture transport to the KH.
Ting-Yu Cha and Michael M. Bell
Weather Clim. Dynam., 5, 1013–1029, https://doi.org/10.5194/wcd-5-1013-2024, https://doi.org/10.5194/wcd-5-1013-2024, 2024
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Our study investigates the dynamics of polygonal eyewall structures observed in intensifying hurricanes like Michael (2018) by using a simplified modeling approach. We develop a two-layer model to simulate the interactions between the free atmosphere and boundary layer to demonstrate the importance of different physical mechanisms in the intensification process. This simplified model offers insights into the interactions between dynamics and convection during hurricane intensification.
Quentin Nicolas and William R. Boos
EGUsphere, https://doi.org/10.5194/egusphere-2024-2180, https://doi.org/10.5194/egusphere-2024-2180, 2024
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Rainfall in mountainous regions constitutes an important source of freshwater in the tropics. Yet, how it will change with global warming remains an open question. Here, we reveal a strong sensitivity of this rainfall to the speed of prevailing winds. This relationship, validated by theory, simulations, and observational data, suggests that regional wind shifts will significantly influence future rainfall changes in the tropics.
Matthias Fischer, Peter Knippertz, and Carsten Proppe
EGUsphere, https://doi.org/10.5194/egusphere-2024-1984, https://doi.org/10.5194/egusphere-2024-1984, 2024
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The West African monsoon is vital for millions, but difficult to represent with numerical models. Our research aims at improving monsoon simulations by optimizing three model parameters—entrainment rate, ice fall speed, and soil moisture evaporation—using an advanced surrogate-based multi-objective optimization framework. Results show that tuning these parameters can improve certain monsoon characteristics, sometimes, however, at the expense of others, yet highlighting the power of our approach.
Abu Bakar Siddiqui Thakur and Jai Sukhatme
Weather Clim. Dynam., 5, 839–862, https://doi.org/10.5194/wcd-5-839-2024, https://doi.org/10.5194/wcd-5-839-2024, 2024
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We analyze the present and future states of the tropical upper troposphere. Observations and climate model simulations suggest that interactions between disparate families of waves and the mean flow maintain present-day upper-level winds, and each component undergoes complex changes due to global warming. While the net east–west flow of the atmosphere may remain unaltered, this study indicates robust changes to local circulations that may influence tropical precipitation and regional climate.
Gill M. Martin and José M. Rodríguez
Weather Clim. Dynam., 5, 711–731, https://doi.org/10.5194/wcd-5-711-2024, https://doi.org/10.5194/wcd-5-711-2024, 2024
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Using sensitivity experiments, we show that model errors developing in the Maritime Continent region contribute substantially to the Asian summer monsoon (ASM) circulation and rainfall errors through their effects on the western North Pacific subtropical high-pressure region and the winds and sea surface temperatures in the equatorial Indian Ocean, exacerbated by local coupled feedback. Such information will inform future model developments aimed at improving model predictions for the ASM.
Clemens Spensberger
Weather Clim. Dynam., 5, 659–669, https://doi.org/10.5194/wcd-5-659-2024, https://doi.org/10.5194/wcd-5-659-2024, 2024
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It is well-established that variations in convection in the tropical Indo-Pacific can influence weather in far-away regions. In this idea, I argue that the main theory used to explain this influence over large distances is incomplete. I propose hypotheses that could lead the way towards a more fundamental explanation and outline a novel approach that could be used to test the hypotheses I raise. The suggested approach might be useful to address also other long-standing questions.
Richard J. Keane, Ankur Srivastava, and Gill M. Martin
Weather Clim. Dynam., 5, 671–702, https://doi.org/10.5194/wcd-5-671-2024, https://doi.org/10.5194/wcd-5-671-2024, 2024
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We evaluate the performance of two widely used models in forecasting the Indian summer monsoon, which is one of the most challenging meteorological phenomena to simulate. The work links previous studies evaluating the use of the models in weather forecasting and climate simulation, as the focus here is on seasonal forecasting, which involves intermediate timescales. As well as being important in itself, this evaluation provides insights into how errors develop in the two modelling systems.
Matthias Fischer, Peter Knippertz, Roderick van der Linden, Alexander Lemburg, Gregor Pante, Carsten Proppe, and John H. Marsham
Weather Clim. Dynam., 5, 511–536, https://doi.org/10.5194/wcd-5-511-2024, https://doi.org/10.5194/wcd-5-511-2024, 2024
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Our research enhances the understanding of the complex dynamics within the West African monsoon system by analyzing the impact of specific model parameters on its characteristics. Employing surrogate models, we identified critical factors such as the entrainment rate and the fall velocity of ice. Precise definition of these parameters in weather models could improve forecast accuracy, thus enabling better strategies to manage and reduce the impact of weather events.
Kieran M. R. Hunt, Jean-Philippe Baudouin, Andrew G. Turner, A. P. Dimri, Ghulam Jeelani, Pooja, Rajib Chattopadhyay, Forest Cannon, T. Arulalan, M. S. Shekhar, T. P. Sabin, and Eliza Palazzi
EGUsphere, https://doi.org/10.5194/egusphere-2024-820, https://doi.org/10.5194/egusphere-2024-820, 2024
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Western disturbances (WDs) are storms that predominantly affect north India and Pakistan during the winter months, where they play an important role in regional water security, but can also bring a range of natural hazards. In this review, we summarise recent literature across a range of topics: their structure and lifecycle, precipitation and impacts, interactions with large-scale weather patterns, representation in models, how well they are forecast, and their response to changes in climate.
Kieran M. R. Hunt
Weather Clim. Dynam., 5, 345–356, https://doi.org/10.5194/wcd-5-345-2024, https://doi.org/10.5194/wcd-5-345-2024, 2024
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This study investigates changes in weather systems that bring winter precipitation to south Asia. We find that these systems, known as western disturbances, are occurring more frequently and lasting longer into the summer months. This shift is leading to devastating floods, as happened recently in north India. By analysing 70 years of weather data, we trace this change to shifts in major air currents known as the subtropical jet. Due to climate change, such events are becoming more frequent.
William J. Dow, Christine M. McKenna, Manoj M. Joshi, Adam T. Blaker, Richard Rigby, and Amanda C. Maycock
Weather Clim. Dynam., 5, 357–367, https://doi.org/10.5194/wcd-5-357-2024, https://doi.org/10.5194/wcd-5-357-2024, 2024
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Changes to sea surface temperatures in the extratropical North Pacific are driven partly by patterns of local atmospheric circulation, such as the Aleutian Low. We show that an intensification of the Aleutian Low could contribute to small changes in temperatures across the equatorial Pacific via the initiation of two mechanisms. The effect, although significant, is unlikely to explain fully the recently observed multi-year shift of a pattern of climate variability across the wider Pacific.
Franco Molteni, Fred Kucharski, and Riccardo Farneti
Weather Clim. Dynam., 5, 293–322, https://doi.org/10.5194/wcd-5-293-2024, https://doi.org/10.5194/wcd-5-293-2024, 2024
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We describe some new features of an intermediate-complexity coupled model, including a three-layer thermodynamic ocean model suitable to explore the extratropical response to tropical ocean variability. We present results on the model climatology and show that important features of interdecadal and interannual variability are realistically simulated in a
pacemakercoupled ensemble of 70-year runs, where portions of the tropical Indo-Pacific are constrained to follow the observed variability.
Molly E. Menzel, Darryn W. Waugh, Zheng Wu, and Thomas Reichler
Weather Clim. Dynam., 5, 251–261, https://doi.org/10.5194/wcd-5-251-2024, https://doi.org/10.5194/wcd-5-251-2024, 2024
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Recent work exploring the tropical atmospheric circulation response to climate change has revealed a disconnect in the latitudinal location of two features, the subtropical jet and the Hadley cell edge. Here, we investigate if the surprising result from coupled climate model and meteorological reanalysis output is consistent across model complexity.
Julian F. Quinting, Christian M. Grams, Edmund Kar-Man Chang, Stephan Pfahl, and Heini Wernli
Weather Clim. Dynam., 5, 65–85, https://doi.org/10.5194/wcd-5-65-2024, https://doi.org/10.5194/wcd-5-65-2024, 2024
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Research in the last few decades has revealed that rapidly ascending airstreams in extratropical cyclones have an important effect on the evolution of downstream weather and predictability. In this study, we show that the occurrence of these airstreams over the North Pacific is modulated by tropical convection. Depending on the modulation, known atmospheric circulation patterns evolve quite differently, which may affect extended-range predictions in the Atlantic–European region.
Hyunju Jung, Peter Knippertz, Yvonne Ruckstuhl, Robert Redl, Tijana Janjic, and Corinna Hoose
Weather Clim. Dynam., 4, 1111–1134, https://doi.org/10.5194/wcd-4-1111-2023, https://doi.org/10.5194/wcd-4-1111-2023, 2023
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A narrow rainfall belt in the tropics is an important feature for large-scale circulations and the global water cycle. The accurate simulation of this rainfall feature has been a long-standing problem, with the reasons behind that unclear. We present a novel diagnostic tool that allows us to disentangle processes important for rainfall, which changes due to modifications in model. Using our diagnostic tool, one can potentially identify sources of uncertainty in weather and climate models.
Lina Boljka, Nour-Eddine Omrani, and Noel S. Keenlyside
Weather Clim. Dynam., 4, 1087–1109, https://doi.org/10.5194/wcd-4-1087-2023, https://doi.org/10.5194/wcd-4-1087-2023, 2023
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This study examines quasi-periodic variability in the tropical Pacific on interannual timescales and related physics using a recently developed time series analysis tool. We find that wind stress in the west Pacific and recharge–discharge of ocean heat content are likely related to each other on ~1.5–4.5-year timescales (but not on others) and dominate variability in sea surface temperatures on those timescales. This may have further implications for climate models and long-term prediction.
Sam Hardy, John Methven, Juliane Schwendike, Ben Harvey, and Mike Cullen
Weather Clim. Dynam., 4, 1019–1043, https://doi.org/10.5194/wcd-4-1019-2023, https://doi.org/10.5194/wcd-4-1019-2023, 2023
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We examine a Borneo vortex case using computer simulations and satellite observations. The vortex is identified with high humidity through the atmosphere and has heaviest rainfall on its northern flank. Simulations represent circulation and rainfall accumulation well. The low-level Borneo vortex is coupled with a higher-level wave, which moves westwards along a layer with a sharp vertical gradient in moisture. Vortex growth occurs through mechanisms usually considered outside the tropics.
Chiem van Straaten, Dim Coumou, Kirien Whan, Bart van den Hurk, and Maurice Schmeits
Weather Clim. Dynam., 4, 887–903, https://doi.org/10.5194/wcd-4-887-2023, https://doi.org/10.5194/wcd-4-887-2023, 2023
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Variability in the tropics can influence weather over Europe. This study evaluates a summertime connection between the two. It shows that strongly opposing west Pacific sea surface temperature anomalies have occurred more frequently since 1980, likely due to a combination of long-term warming in the west Pacific and the El Niño Southern Oscillation. Three to six weeks later, the distribution of hot and cold airmasses over Europe is affected.
Francis Nkrumah, Cornelia Klein, Kwesi Akumenyi Quagraine, Rebecca Berkoh-Oforiwaa, Nana Ama Browne Klutse, Patrick Essien, Gandomè Mayeul Leger Davy Quenum, and Hubert Azoda Koffi
Weather Clim. Dynam., 4, 773–788, https://doi.org/10.5194/wcd-4-773-2023, https://doi.org/10.5194/wcd-4-773-2023, 2023
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It is not yet clear which variations in broader atmospheric conditions of the West African monsoon may lead to mesoscale convective system (MCS) occurrences in southern West Africa (SWA). In this study, we identified nine different weather patterns and categorized them as dry-, transition-, or monsoon-season types using a method called self-organizing maps (SOMs). It was revealed that a warmer Sahel region can create favourable conditions for MCS formation in SWA.
Daniel Baldassare, Thomas Reichler, Piret Plink-Björklund, and Jacob Slawson
Weather Clim. Dynam., 4, 531–541, https://doi.org/10.5194/wcd-4-531-2023, https://doi.org/10.5194/wcd-4-531-2023, 2023
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Using ensemble members from the ERA5 reanalysis, the most widely used method for estimating tropical-width trends, the meridional stream function, was found to have large error, particularly in the Northern Hemisphere and in the summer, because of weak gradients at the tropical edge and poor data quality. Another method, using the latitude where the surface wind switches from westerly to easterly, was found to have lower error due to better-observed data.
Nele Tim, Eduardo Zorita, Birgit Hünicke, and Ioana Ivanciu
Weather Clim. Dynam., 4, 381–397, https://doi.org/10.5194/wcd-4-381-2023, https://doi.org/10.5194/wcd-4-381-2023, 2023
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As stated by the IPCC, southern Africa is one of the two land regions that are projected to suffer from the strongest precipitation reductions in the future. Simulated drying in this region is linked to the adjacent oceans, and prevailing winds as warm and moist air masses are transported towards the continent. Precipitation trends in past and future climate can be partly attributed to the strength of the Agulhas Current system, the current along the east and south coasts of southern Africa.
William Torgerson, Juliane Schwendike, Andrew Ross, and Chris J. Short
Weather Clim. Dynam., 4, 331–359, https://doi.org/10.5194/wcd-4-331-2023, https://doi.org/10.5194/wcd-4-331-2023, 2023
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We investigated intensity fluctuations that occurred during the rapid intensification of Hurricane Irma (2017) to understand their effects on the storm structure. Using high-resolution model simulations, we found that the fluctuations were caused by local regions of strong ascent just outside the eyewall that disrupted the storm, leading to a larger and more symmetrical storm eye. This alters the location and intensity of the strongest winds in the storm and hence the storm's impact.
Anne Martin, Martin Weissmann, and Alexander Cress
Weather Clim. Dynam., 4, 249–264, https://doi.org/10.5194/wcd-4-249-2023, https://doi.org/10.5194/wcd-4-249-2023, 2023
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Global wind profiles from the Aeolus satellite mission are an important recent substitute for the Global Observing System, showing an overall positive impact on numerical weather prediction forecasts. This study highlights atmospheric dynamic phenomena constituting pathways for significant improvement of Aeolus for future studies, including large-scale tropical circulation systems and the interaction of tropical cyclones undergoing an extratropical transition with the midlatitude waveguide.
Elliott Michael Sainsbury, Reinhard K. H. Schiemann, Kevin I. Hodges, Alexander J. Baker, Len C. Shaffrey, Kieran T. Bhatia, and Stella Bourdin
Weather Clim. Dynam., 3, 1359–1379, https://doi.org/10.5194/wcd-3-1359-2022, https://doi.org/10.5194/wcd-3-1359-2022, 2022
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Post-tropical cyclones (PTCs) can bring severe weather to Europe. By tracking and identifying PTCs in five global climate models, we investigate how the frequency and intensity of PTCs may change across Europe by 2100. We find no robust change in the frequency or intensity of Europe-impacting PTCs in the future. This study indicates that large uncertainties surround future Europe-impacting PTCs and provides a framework for evaluating PTCs in future generations of climate models.
Kieran M. R. Hunt and Andrew G. Turner
Weather Clim. Dynam., 3, 1341–1358, https://doi.org/10.5194/wcd-3-1341-2022, https://doi.org/10.5194/wcd-3-1341-2022, 2022
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More than half of India's summer monsoon rainfall arises from low-pressure systems: storms originating over the Bay of Bengal. In observation-based data, we examine how the generation and pathway of these storms are changed by the
boreal summer intraseasonal oscillation– the chief means of large-scale control on the monsoon at timescales of a few weeks. Our study offers new insights for useful prediction of these storms, important for both water resources planning and disaster early warning.
Cornelius Immanuel Weiß, Alexander Gohm, Mathias Walter Rotach, and Thomas Torora Minda
Weather Clim. Dynam., 3, 1003–1019, https://doi.org/10.5194/wcd-3-1003-2022, https://doi.org/10.5194/wcd-3-1003-2022, 2022
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Two gap flow events in the Great Rift Valley in Ethiopia were investigated based on observations, ERA5 reanalysis data, and simulations with the numerical weather prediction model WRF. The main focus was on strong winds in the area around Lake Abaya since the winds may generate waves on the lake which help to sustain the lake's ecology. That is important in terms of food supply for the local population. The gap winds exhibit a diurnal cycle and a seasonal dependence.
Matic Pikovnik, Žiga Zaplotnik, Lina Boljka, and Nedjeljka Žagar
Weather Clim. Dynam., 3, 625–644, https://doi.org/10.5194/wcd-3-625-2022, https://doi.org/10.5194/wcd-3-625-2022, 2022
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Potential future changes in the Hadley cells (HCs), either to their strength or their meridional extent, will profoundly impact the global distribution of precipitation. Therefore, to objectively evaluate and inter-compare past and future changes in the overall HC strength between different studies, a unified metric is required. The study proposes two new metrics, which alleviate the spatial inhomogeneities of the HC strength trend.
Ambrogio Volonté, Andrew G. Turner, Reinhard Schiemann, Pier Luigi Vidale, and Nicholas P. Klingaman
Weather Clim. Dynam., 3, 575–599, https://doi.org/10.5194/wcd-3-575-2022, https://doi.org/10.5194/wcd-3-575-2022, 2022
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In this study we analyse the complex seasonal evolution of the East Asian summer monsoon. Using reanalysis data, we show the importance of the interaction between tropical and extratropical air masses converging at the monsoon front, particularly during its northward progression. The upper-level flow pattern (e.g. the westerly jet) controls the balance between the airstreams and thus the associated rainfall. This framework provides a basis for studies of extreme events and climate variability.
Peter Pfleiderer, Shruti Nath, and Carl-Friedrich Schleussner
Weather Clim. Dynam., 3, 471–482, https://doi.org/10.5194/wcd-3-471-2022, https://doi.org/10.5194/wcd-3-471-2022, 2022
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Tropical cyclones are amongst the most dangerous weather events. Here we develop an empirical model that allows us to estimate the number and strengths of tropical cyclones for given atmospheric conditions and sea surface temperatures. An application of the model shows that atmospheric circulation is the dominant factor for seasonal tropical cyclone activity. However, warming sea surface temperatures have doubled the likelihood of extremely active hurricane seasons in the past decades.
Jean-Philippe Baudouin, Michael Herzog, and Cameron A. Petrie
Weather Clim. Dynam., 2, 1187–1207, https://doi.org/10.5194/wcd-2-1187-2021, https://doi.org/10.5194/wcd-2-1187-2021, 2021
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Western disturbances are mid-latitude, high-altitude, low-pressure areas that bring orographic precipitation into the Upper Indus Basin. Using statistical tools, we show that the interaction between western disturbances and relief explains the near-surface, cross-barrier wind activity. We also reveal the existence of a moisture pathway from the nearby seas. Overall, we offer a conceptual framework for western-disturbance activity, particularly in terms of precipitation.
Anantha Aiyyer and Terrell Wade
Weather Clim. Dynam., 2, 1051–1072, https://doi.org/10.5194/wcd-2-1051-2021, https://doi.org/10.5194/wcd-2-1051-2021, 2021
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We diagnose the mean circulations in the extratropics that are associated with rapid changes in the tropical storm storm speeds in the Atlantic. We show that rapid acceleration and deceleration are associated with distinct phasing between the tropical cyclone and weather waves of the extratropics. Over the past 5 decades, rapid acceleration and deceleration of tropical cyclones have reduced in magnitude. This might be related to the poleward shift and weakening of these extratropical waves.
Julianna Carvalho-Oliveira, Leonard Friedrich Borchert, Aurélie Duchez, Mikhail Dobrynin, and Johanna Baehr
Weather Clim. Dynam., 2, 739–757, https://doi.org/10.5194/wcd-2-739-2021, https://doi.org/10.5194/wcd-2-739-2021, 2021
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This work questions the influence of the Atlantic Meridional Overturning Circulation, an important component of the climate system, on the variability in North Atlantic sea surface temperature (SST) a season ahead, particularly how this influence affects SST prediction credibility 2–4 months into the future. While we find this relationship is relevant for assessing SST predictions, it strongly depends on the time period and season we analyse and is more subtle than what is found in observations.
Andrea M. Jenney, David A. Randall, and Elizabeth A. Barnes
Weather Clim. Dynam., 2, 653–673, https://doi.org/10.5194/wcd-2-653-2021, https://doi.org/10.5194/wcd-2-653-2021, 2021
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Storm activity in the tropics is one of the key phenomena that provide weather predictability on an extended timescale of about 10–40 d. The influence of tropical storminess on places like North America is sensitive to the overall average state of the climate system. In this study, we try to unpack the reasons why climate models do not agree on how the influence of these storms on weather over the North Pacific and North America will change in the future.
Philip Rupp and Peter Haynes
Weather Clim. Dynam., 2, 413–431, https://doi.org/10.5194/wcd-2-413-2021, https://doi.org/10.5194/wcd-2-413-2021, 2021
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We study a range of dynamical aspects of the Asian monsoon anticyclone as the response of a simple numerical model to a steady imposed heating distribution with different background flow configurations. Particular focus is given on interactions between the monsoon anticyclone and active mid-latitude dynamics, which we find to have a zonally localising effect on the time-mean circulation and to be able to qualitatively alter the temporal variability of the bulk anticyclone.
Joshua White and Anantha Aiyyer
Weather Clim. Dynam., 2, 311–329, https://doi.org/10.5194/wcd-2-311-2021, https://doi.org/10.5194/wcd-2-311-2021, 2021
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Using a simple general circulation model, we examine the structure of waves in the mid-tropospheric jet over North Africa. We show that waves occur in near-stationary groups or wave packets. As they are not swept out of the jet, this may provide the opportunity for the packets to amplify via feedback from other energy sources like rain-producing cloud complexes and mineral dust that are known to operate here. Our results address the criticism that the easterly jet is too short to sustain waves.
Franziska Aemisegger, Raphaela Vogel, Pascal Graf, Fabienne Dahinden, Leonie Villiger, Friedhelm Jansen, Sandrine Bony, Bjorn Stevens, and Heini Wernli
Weather Clim. Dynam., 2, 281–309, https://doi.org/10.5194/wcd-2-281-2021, https://doi.org/10.5194/wcd-2-281-2021, 2021
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The interaction of clouds in the trade wind region with the atmospheric flow is complex and at the heart of uncertainties associated with climate projections. In this study, a natural tracer of atmospheric circulation is used to establish a link between air originating from dry regions of the midlatitudes and the occurrence of specific cloud patterns. Two pathways involving transport within midlatitude weather systems are identified, by which air is brought into the trades within 5–10 d.
Jack Giddings, Adrian J. Matthews, Nicholas P. Klingaman, Karen J. Heywood, Manoj Joshi, and Benjamin G. M. Webber
Weather Clim. Dynam., 1, 635–655, https://doi.org/10.5194/wcd-1-635-2020, https://doi.org/10.5194/wcd-1-635-2020, 2020
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The impact of chlorophyll on the southwest monsoon is unknown. Here, seasonally varying chlorophyll in the Bay of Bengal was imposed in a general circulation model coupled to an ocean mixed layer model. The SST increases by 0.5 °C in response to chlorophyll forcing and shallow mixed layer depths in coastal regions during the inter-monsoon. Precipitation increases significantly to 3 mm d-1 across Myanmar during June and over northeast India and Bangladesh during October, decreasing model bias.
Giorgia Di Capua, Jakob Runge, Reik V. Donner, Bart van den Hurk, Andrew G. Turner, Ramesh Vellore, Raghavan Krishnan, and Dim Coumou
Weather Clim. Dynam., 1, 519–539, https://doi.org/10.5194/wcd-1-519-2020, https://doi.org/10.5194/wcd-1-519-2020, 2020
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We study the interactions between the tropical convective activity and the mid-latitude circulation in the Northern Hemisphere during boreal summer. We identify two circumglobal wave patterns with phase shifts corresponding to the South Asian and the western North Pacific monsoon systems at an intra-seasonal timescale. These patterns show two-way interactions in a causal framework at a weekly timescale and assess how El Niño affects these interactions.
Benjamin A. Stephens and Charles S. Jackson
Weather Clim. Dynam., 1, 389–404, https://doi.org/10.5194/wcd-1-389-2020, https://doi.org/10.5194/wcd-1-389-2020, 2020
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We analyze abrupt transitions between tropical rainfall regimes in a single-column model (SCM) of the tropical atmosphere. Multiple equilibria have been observed before in SCMs, but here we analyze actual bifurcations. We attribute the transitions to a sudden loss of evaporative cooling in the lower column due to nonlinearities in microphysics. This study may have implications for atmospheric dynamics more broadly but also for understanding abrupt transitions in paleoclimate.
Jorge L. García-Franco, Lesley J. Gray, and Scott Osprey
Weather Clim. Dynam., 1, 349–371, https://doi.org/10.5194/wcd-1-349-2020, https://doi.org/10.5194/wcd-1-349-2020, 2020
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The American monsoon system is the main source of rainfall for the subtropical Americas and an important element of Latin American agriculture. Here we use state-of-the-art climate models from the UK Met Office in different configurations to analyse the performance of these models in the American monsoon. Resolution is found to be a key factor to improve monsoon representation, whereas integrated chemistry does not improve the simulated monsoon rainfall.
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Short summary
Heavy rainfall in tropical regions interacts with mid-latitude circulation patterns, and this interaction can explain weather patterns in the Northern Hemisphere during summer. In this analysis we detect these tropical–extratropical interaction pattern both in observational datasets and data obtained by atmospheric models and assess how well atmospheric models can reproduce the observed patterns. We find a good agreement although these relationships are weaker in model data.
Heavy rainfall in tropical regions interacts with mid-latitude circulation patterns, and this...
