Articles | Volume 4, issue 1
https://doi.org/10.5194/wcd-4-189-2023
© 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-4-189-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
02 Feb 2023
Research article |
| 02 Feb 2023
| 02 Feb 2023
Vortex streets to the lee of Madeira in a kilometre-resolution regional climate model
Qinggang Gao
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
now at: Ice Dynamics and Paleoclimate, British Antarctic Survey, Cambridge, United Kingdom
now at: Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom
Christian Zeman
CORRESPONDING AUTHOR
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
Jesus Vergara-Temprado
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
now at: UBS, Zurich, Switzerland
Daniela C. A. Lima
Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisbon, Portugal
Peter Molnar
Institute of Environmental Engineering, ETH Zurich, Zurich, Switzerland
Christoph Schär
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
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Daniel Regenass, Linda Schlemmer, Elena Jahr, and Christoph Schär
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Manuscript not accepted for further review
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Landslides are a natural hazard that affects alpine regions. Here we focus on rainfall-induced shallow landslides and one of the most widely used approaches for their predictions: rainfall thresholds. We design several comparisons utilizing a landslide database and rainfall records in Switzerland. We find that using daily rather than hourly rainfall might be a better option in some circumstances, and mean annual precipitation and antecedent wetness can improve predictions at the regional scale.
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Giulia Battista, Peter Molnar, and Paolo Burlando
Earth Surf. Dynam., 8, 619–635, https://doi.org/10.5194/esurf-8-619-2020, https://doi.org/10.5194/esurf-8-619-2020, 2020
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Suspended sediment load in rivers is highly uncertain because of spatial and temporal variability. By means of a hydrology and suspended sediment transport model, we investigated the effect of spatial variability in precipitation and surface erodibility on catchment sediment fluxes in a mesoscale river basin.
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Nadav Peleg, Chris Skinner, Simone Fatichi, and Peter Molnar
Earth Surf. Dynam., 8, 17–36, https://doi.org/10.5194/esurf-8-17-2020, https://doi.org/10.5194/esurf-8-17-2020, 2020
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Extreme rainfall is expected to intensify with increasing temperatures, which will likely affect rainfall spatial structure. The spatial variability of rainfall can affect streamflow and sediment transport volumes and peaks. The sensitivity of the hydro-morphological response to changes in the structure of heavy rainfall was investigated. It was found that the morphological components are more sensitive to changes in rainfall spatial structure in comparison to the hydrological components.
Samuel Monhart, Massimiliano Zappa, Christoph Spirig, Christoph Schär, and Konrad Bogner
Hydrol. Earth Syst. Sci., 23, 493–513, https://doi.org/10.5194/hess-23-493-2019, https://doi.org/10.5194/hess-23-493-2019, 2019
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Stefan Brönnimann, Jan Rajczak, Erich M. Fischer, Christoph C. Raible, Marco Rohrer, and Christoph Schär
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We analyse the control of hydroclimatic factors – erosive rainfall, ice melt, and snowmelt – on suspended sediment concentration (SSC) of Alpine catchments regulated by hydropower, and we develop a multivariate hydroclimatic–informed rating curve. We show that while erosive rainfall determines the variability of SSC, ice melt generates the highest contribution to SSC per unit of runoff. This approach allows the exploration of climate–driven changes in fine sediment dynamics in Alpine catchments.
Erik Kjellström, Grigory Nikulin, Gustav Strandberg, Ole Bøssing Christensen, Daniela Jacob, Klaus Keuler, Geert Lenderink, Erik van Meijgaard, Christoph Schär, Samuel Somot, Silje Lund Sørland, Claas Teichmann, and Robert Vautard
Earth Syst. Dynam., 9, 459–478, https://doi.org/10.5194/esd-9-459-2018, https://doi.org/10.5194/esd-9-459-2018, 2018
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Based on high-resolution regional climate models we investigate European climate change at 1.5 and 2 °C of global warming compared to pre-industrial levels. Considerable near-surface warming exceeding that of the global mean is found for most of Europe, already at the lower 1.5 °C of warming level. Changes in precipitation and near-surface wind speed are identified. The 1.5 °C of warming level shows significantly less change compared to the 2 °C level, indicating the importance of mitigation.
Anna Costa, Peter Molnar, Laura Stutenbecker, Maarten Bakker, Tiago A. Silva, Fritz Schlunegger, Stuart N. Lane, Jean-Luc Loizeau, and Stéphanie Girardclos
Hydrol. Earth Syst. Sci., 22, 509–528, https://doi.org/10.5194/hess-22-509-2018, https://doi.org/10.5194/hess-22-509-2018, 2018
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We explore the signal of a warmer climate in the suspended-sediment dynamics of a regulated and human-impacted Alpine catchment. We demonstrate that temperature-driven enhanced melting of glaciers, which occurred in the mid-1980s, played a dominant role in suspended sediment concentration rise, through increased runoff from sediment-rich proglacial areas, increased contribution of sediment-rich meltwater, and increased sediment supply in proglacial areas due to glacier recession.
Prisco Frei, Sven Kotlarski, Mark A. Liniger, and Christoph Schär
The Cryosphere, 12, 1–24, https://doi.org/10.5194/tc-12-1-2018, https://doi.org/10.5194/tc-12-1-2018, 2018
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Snowfall is central to Alpine environments, and its future changes will be associated with pronounced impacts. We here assess future snowfall changes in the European Alps based on an ensemble of state-of-the-art regional climate model experiments and on two different greenhouse gas emission scenarios. The results reveal pronounced changes in the Alpine snowfall climate with considerable snowfall reductions at low and mid-elevations but also snowfall increases at high elevations in midwinter.
Martin Wild, Atsumu Ohmura, Christoph Schär, Guido Müller, Doris Folini, Matthias Schwarz, Maria Zyta Hakuba, and Arturo Sanchez-Lorenzo
Earth Syst. Sci. Data, 9, 601–613, https://doi.org/10.5194/essd-9-601-2017, https://doi.org/10.5194/essd-9-601-2017, 2017
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The Global Energy Balance Archive (GEBA) is a database for the central storage of worldwide measured energy fluxes at the Earth's surface, maintained at ETH Zurich (Switzerland). This paper documents the status of the GEBA version 2017 database, presents the new web interface and user access, and reviews the scientific impact that GEBA data had in various applications. GEBA has continuously been expanded and updated and to date contains around 500 000 monthly mean entries from 2500 locations.
Anna Costa, Daniela Anghileri, and Peter Molnar
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-419, https://doi.org/10.5194/hess-2017-419, 2017
Manuscript not accepted for further review
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We develop a novel rating curve to simulate suspended sediment concentration (SSC) in Alpine catchments (Process-Based Rating Curve, PBRC). Instead of relating SSC to discharge, as in traditional approaches, we model SSC by differentiating the potential contributions of the main erosional and transport processes of Alpine environments: erosive rainfall, snowmelt, and icemelt. We show that PBRC significantly improves predictions of SSC, especially when analysing climate-induced changes.
Nadav Peleg, Frank Blumensaat, Peter Molnar, Simone Fatichi, and Paolo Burlando
Hydrol. Earth Syst. Sci., 21, 1559–1572, https://doi.org/10.5194/hess-21-1559-2017, https://doi.org/10.5194/hess-21-1559-2017, 2017
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We investigated the relative contribution of the spatial versus climatic rainfall variability for flow peaks by applying an advanced stochastic rainfall generator to simulate rainfall for a small urban catchment and simulate flow dynamics in the sewer system. We found that the main contribution to the total flow variability originates from the natural climate variability. The contribution of spatial rainfall variability to the total flow variability was found to increase with return periods.
Søren Thorndahl, Thomas Einfalt, Patrick Willems, Jesper Ellerbæk Nielsen, Marie-Claire ten Veldhuis, Karsten Arnbjerg-Nielsen, Michael R. Rasmussen, and Peter Molnar
Hydrol. Earth Syst. Sci., 21, 1359–1380, https://doi.org/10.5194/hess-21-1359-2017, https://doi.org/10.5194/hess-21-1359-2017, 2017
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This paper reviews how weather radar data can be used in urban hydrological applications. It focuses on three areas of research: (1) temporal and spatial resolution of rainfall data, (2) rainfall estimation, radar data adjustment and data quality, and (3) nowcasting of radar rainfall and real-time applications. Moreover, the paper provides examples of urban hydrological applications which can benefit from radar rainfall data in comparison to tradition rain gauge measurements of rainfall.
Claudio I. Meier, Jorge Sebastián Moraga, Geri Pranzini, and Peter Molnar
Hydrol. Earth Syst. Sci., 20, 4177–4190, https://doi.org/10.5194/hess-20-4177-2016, https://doi.org/10.5194/hess-20-4177-2016, 2016
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We show that the derived distribution approach is able to characterize the interannual variability of precipitation much better than fitting a probabilistic model to annual rainfall totals, as long as continuously gauged data are available. The method is a useful tool for describing temporal changes in the distribution of annual rainfall, as it works for records as short as 5 years, and therefore does not require any stationarity assumption over long periods.
Bahareh Kianfar, Simone Fatichi, Athansios Paschalis, Max Maurer, and Peter Molnar
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2016-536, https://doi.org/10.5194/hess-2016-536, 2016
Revised manuscript has not been submitted
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Raingauge observations show a large variability in extreme rainfall depths in the current climate. Climate model predictions of extreme rainfall in the future have to be compared with this natural variability. Our work shows that predictions of future extreme rainfall often lie within the range of natural variability of present-day climate, and therefore predictions of change are highly uncertain. We demonstrate this by using stochastic rainfall models and 10-min rainfall data in Switzerland.
David Leutwyler, Oliver Fuhrer, Xavier Lapillonne, Daniel Lüthi, and Christoph Schär
Geosci. Model Dev., 9, 3393–3412, https://doi.org/10.5194/gmd-9-3393-2016, https://doi.org/10.5194/gmd-9-3393-2016, 2016
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The representation of moist convection (thunderstorms and rain showers) in climate models represents a major challenge, as this process is usually approximated due to the lack of appropriate computational resolution. Climate simulations using horizontal resolution of O(1 km) allow one to explicitly resolve deep convection and thus allow for an improved representation of the water cycle. We present a set of such simulations covering the European scale using a climate model enabled for GPUs.
Matteo Saletti, Peter Molnar, Marwan A. Hassan, and Paolo Burlando
Earth Surf. Dynam., 4, 549–566, https://doi.org/10.5194/esurf-4-549-2016, https://doi.org/10.5194/esurf-4-549-2016, 2016
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This study presents a new reduced-complexity model with few parameters linked to basic physical processes, which aims to reproduce the transport of sediment as bed load and the formation and stability of channel morphology in steep mountain streams. The model is able to simulate the formation and stability of steps, bed structures commonly encountered in steep channels, by assuming that their formation is due to intense sediment transport during high flows causing jamming of particles.
J. Hall, B. Arheimer, G. T. Aronica, A. Bilibashi, M. Boháč, O. Bonacci, M. Borga, P. Burlando, A. Castellarin, G. B. Chirico, P. Claps, K. Fiala, L. Gaál, L. Gorbachova, A. Gül, J. Hannaford, A. Kiss, T. Kjeldsen, S. Kohnová, J. J. Koskela, N. Macdonald, M. Mavrova-Guirguinova, O. Ledvinka, L. Mediero, B. Merz, R. Merz, P. Molnar, A. Montanari, M. Osuch, J. Parajka, R. A. P. Perdigão, I. Radevski, B. Renard, M. Rogger, J. L. Salinas, E. Sauquet, M. Šraj, J. Szolgay, A. Viglione, E. Volpi, D. Wilson, K. Zaimi, and G. Blöschl
Proc. IAHS, 370, 89–95, https://doi.org/10.5194/piahs-370-89-2015, https://doi.org/10.5194/piahs-370-89-2015, 2015
P. Molnar, S. Fatichi, L. Gaál, J. Szolgay, and P. Burlando
Hydrol. Earth Syst. Sci., 19, 1753–1766, https://doi.org/10.5194/hess-19-1753-2015, https://doi.org/10.5194/hess-19-1753-2015, 2015
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We present an empirical study of the rates of increase in precipitation intensity with air temperature using high-resolution 10 min precipitation records in Switzerland. We estimated the scaling rates for lightning (convective) and non-lightning event subsets and show that scaling rates are between 7 and 14%/C for convective rain and that mixing of storm types exaggerates the relations to air temperature. Doubled CC rates reported by other studies are an exception in our data set.
K. Džubáková, P. Molnar, K. Schindler, and M. Trizna
Hydrol. Earth Syst. Sci., 19, 195–208, https://doi.org/10.5194/hess-19-195-2015, https://doi.org/10.5194/hess-19-195-2015, 2015
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We use a high-resolution ground-based camera system with near-infrared sensitivity to quantify the response of riparian vegetation in an Alpine river to floods with the use of vegetation indices. The vegetation showed both damage and enhancement within 1 week following floods, with a selective impact determined by pre-flood vegetation vigour, morphological setting and intensity of flood forcing. The tested vegetation indices differed in the direction of predicted change in the range 0.7-35.8%.
J. Hall, B. Arheimer, M. Borga, R. Brázdil, P. Claps, A. Kiss, T. R. Kjeldsen, J. Kriaučiūnienė, Z. W. Kundzewicz, M. Lang, M. C. Llasat, N. Macdonald, N. McIntyre, L. Mediero, B. Merz, R. Merz, P. Molnar, A. Montanari, C. Neuhold, J. Parajka, R. A. P. Perdigão, L. Plavcová, M. Rogger, J. L. Salinas, E. Sauquet, C. Schär, J. Szolgay, A. Viglione, and G. Blöschl
Hydrol. Earth Syst. Sci., 18, 2735–2772, https://doi.org/10.5194/hess-18-2735-2014, https://doi.org/10.5194/hess-18-2735-2014, 2014
S. Kotlarski, K. Keuler, O. B. Christensen, A. Colette, M. Déqué, A. Gobiet, K. Goergen, D. Jacob, D. Lüthi, E. van Meijgaard, G. Nikulin, C. Schär, C. Teichmann, R. Vautard, K. Warrach-Sagi, and V. Wulfmeyer
Geosci. Model Dev., 7, 1297–1333, https://doi.org/10.5194/gmd-7-1297-2014, https://doi.org/10.5194/gmd-7-1297-2014, 2014
L. Gaál, P. Molnar, and J. Szolgay
Hydrol. Earth Syst. Sci., 18, 1561–1573, https://doi.org/10.5194/hess-18-1561-2014, https://doi.org/10.5194/hess-18-1561-2014, 2014
Related subject area
Boundary-layer dynamics incl. coupling to land, ocean and ice
Revealing the dynamics of a local Alpine windstorm using large-eddy simulations
Investigating the influence of changing ice surfaces on gravity wave formation and glacier boundary-layer flow with large-eddy simulations
Exploring the daytime boundary layer evolution based on Doppler spectrum width from multiple coplanar wind lidars during CROSSINN
Forcing for varying boundary layer stability across Antarctica
Variations in boundary layer stability across Antarctica: a comparison between coastal and interior sites
Adverse impact of terrain steepness on thermally driven initiation of orographic convection
Effects on early monsoon rainfall in West Africa due to recent deforestation in a convection-permitting ensemble
Benefits and challenges of dynamic sea ice for weather forecasts
Extratropical-cyclone-induced sea surface temperature anomalies in the 2013–2014 winter
Nicolai Krieger, Heini Wernli, Michael Sprenger, and Christian Kühnlein
EGUsphere, https://doi.org/10.5194/egusphere-2024-3461, https://doi.org/10.5194/egusphere-2024-3461, 2024
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This study investigates the Laseyer, a local windstorm in a narrow Swiss valley, characterized by strong south-easterly winds during north-westerly ambient flow. Using large-eddy simulations (LES) with 30 m grid spacing, this is the first study to reveal that the extreme gusts in the valley are caused by an amplifying interplay of two recirculation regions. Modifying terrain and ambient wind conditions affects the windstorm's intensity and highlights the importance of topographic details in LES.
Brigitta Goger, Lindsey Nicholson, Matthis Ouy, and Ivana Stiperski
EGUsphere, https://doi.org/10.5194/egusphere-2024-2634, https://doi.org/10.5194/egusphere-2024-2634, 2024
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We study with simulations if changing glacier ice surfaces surrounding a glacier impacts the atmospheric structure. Under North-Westerly flow conditions, a gravity wave forms over the glacier. This gravity wave is, however, weakened and breaks faster, when the surrounding glaciers are removed. This leads to stronger turbulent mixing over the remaining glacier and higher temperatures. This affects glacier melting patterns, and glaciers should be studied as a system.
Nevio Babić, Bianca Adler, Alexander Gohm, Manuela Lehner, and Norbert Kalthoff
Weather Clim. Dynam., 5, 609–631, https://doi.org/10.5194/wcd-5-609-2024, https://doi.org/10.5194/wcd-5-609-2024, 2024
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Day-to-day weather over mountains remains a significant challenge in the domain of weather forecast. Using a combination of measurements from several instrument platforms, including Doppler lidars, aircraft, and radiosondes, we developed a method that relies primarily on turbulence characteristics of the lowest layers of the atmosphere. As a result, we identified new ways in which atmosphere behaves over mountains during daytime, which may serve to further improve forecasting capabilities.
Mckenzie J. Dice, John J. Cassano, and Gina C. Jozef
Weather Clim. Dynam., 5, 369–394, https://doi.org/10.5194/wcd-5-369-2024, https://doi.org/10.5194/wcd-5-369-2024, 2024
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This study aims to identify the main reasonings for changes in boundary layer stability, namely changes in radiative forcing or mechanical mixing (wind shear). Across the continent of Antarctica, varying stability in the boundary layer is affected by many different forces, and this study seeks to characterize the main forcing mechanisms for these variations in stability across Antarctica, annually and seasonally.
Mckenzie J. Dice, John J. Cassano, Gina C. Jozef, and Mark Seefeldt
Weather Clim. Dynam., 4, 1045–1069, https://doi.org/10.5194/wcd-4-1045-2023, https://doi.org/10.5194/wcd-4-1045-2023, 2023
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This study documents boundary layer stability profiles, from the surface to 500 m above ground level, present in radiosonde observations across the Antarctic continent. A boundary layer stability definition method is developed and applied to the radiosonde observations to determine the frequency and seasonality of stability regimes. It is found that, in the continental interior, strong stability is dominant throughout most of the year, while stability is more varied at coastal locations.
Matthias Göbel, Stefano Serafin, and Mathias W. Rotach
Weather Clim. Dynam., 4, 725–745, https://doi.org/10.5194/wcd-4-725-2023, https://doi.org/10.5194/wcd-4-725-2023, 2023
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On summer days over mountains, upslope winds transport moist air towards mountain tops and beyond, making local rain showers more likely. We use idealized simulations to investigate how mountain steepness affects this mechanism. We find that steeper mountains lead to a delayed onset and lower intensity of the storms, because less moisture accumulates over the ridges and the thermal updraft zone at the top is narrower and thus more prone to the intrusion of dry air from the environment.
Julia Crook, Cornelia Klein, Sonja Folwell, Christopher M. Taylor, Douglas J. Parker, Adama Bamba, and Kouakou Kouadio
Weather Clim. Dynam., 4, 229–248, https://doi.org/10.5194/wcd-4-229-2023, https://doi.org/10.5194/wcd-4-229-2023, 2023
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We estimate recent deforestation in West Africa and use a climate model allowing explicit convection to determine impacts on early season rainfall. We find enhanced rainfall over deforestation, in line with recent observational results, due to changes in circulation rather than humidity, showing potential for future studies. Local changes depend on initial soil moisture, deforestation extent, and ocean proximity, with sea breezes shifting inland where surface friction decreased.
Jonathan J. Day, Sarah Keeley, Gabriele Arduini, Linus Magnusson, Kristian Mogensen, Mark Rodwell, Irina Sandu, and Steffen Tietsche
Weather Clim. Dynam., 3, 713–731, https://doi.org/10.5194/wcd-3-713-2022, https://doi.org/10.5194/wcd-3-713-2022, 2022
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A recent drive to develop seamless forecasting systems has culminated in the development of weather forecasting systems that include a coupled representation of the atmosphere, ocean and sea ice. Before this, sea ice and sea surface temperature anomalies were typically fixed throughout a given forecast. We show that the dynamic coupling is most beneficial during periods of rapid ice advance, where persistence is a poor forecast of the sea ice and leads to large errors in the uncoupled system.
Helen F. Dacre, Simon A. Josey, and Alan L. M. Grant
Weather Clim. Dynam., 1, 27–44, https://doi.org/10.5194/wcd-1-27-2020, https://doi.org/10.5194/wcd-1-27-2020, 2020
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The 2013–2014 winter sea surface temperature (SST) was anomalously cool in the mid-North Atlantic region. We investigate the processes by which cyclones can lead to SST cooling and their contribution towards the 2013–2014 SST anomaly. We find that cyclones induce a cold wake, which extends along the cyclones' cold front. Cyclones account for over 40 % of the observed cooling in the mid-North Atlantic. Thus, cyclones play a major role in determining the extreme 2013–2014 winter SST cooling.
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Short summary
We developed a vortex identification algorithm for realistic atmospheric simulations. The algorithm enabled us to obtain a climatology of vortex shedding from Madeira Island for a 10-year simulation period. This first objective climatological analysis of vortex streets shows consistency with observed atmospheric conditions. The analysis shows a pronounced annual cycle with an increasing vortex shedding rate from April to August and a sudden decrease in September.
We developed a vortex identification algorithm for realistic atmospheric simulations. The...
