A5049525337- Climate variability and models
- Meteorological Phenomena and Simulations
- Tropical and Extratropical Cyclones Research
- Atmospheric and Environmental Gas Dynamics
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Oceanographic and Atmospheric Processes
- Cryospheric studies and observations
- Energy Load and Power Forecasting
- Atmospheric chemistry and aerosols
- Arctic and Antarctic ice dynamics
- Ocean Waves and Remote Sensing
- Integrated Energy Systems Optimization
- Geophysics and Gravity Measurements
- Hydrology and Drought Analysis
- Solar and Space Plasma Dynamics
- Aeolian processes and effects
- Wind and Air Flow Studies
- Wind Energy Research and Development
- Plant Water Relations and Carbon Dynamics
- Geology and Paleoclimatology Research
- Belt Conveyor Systems Engineering
- Geomagnetism and Paleomagnetism Studies
- Icing and De-icing Technologies
- Landslides and related hazards
Karlsruhe Institute of Technology
2015-2025
Federal Office of Meteorology and Climatology MeteoSwiss
2023-2025
Zürich Airport (Switzerland)
2024-2025
ETH Zurich
2013-2023
German Meteorological Service
2017-2023
National Institute of Meteorology
2013-2023
Oeschger Centre for Climate Change Research
2017-2019
University of Bern
2017-2019
Université Paris Sciences et Lettres
2019
Centre National de la Recherche Scientifique
2019
Abstract This study highlights the importance of diabatic processes for complex interaction weather systems in North Atlantic–European sector during week 7–14 September 2008. A chain events occurred including extratropical transition (ET) hurricane Hanna , a subsequently developing cyclone, formation an upper‐level potential vorticity (PV) streamer that protruded towards Europe and triggered intense rainfall, genesis Mediterranean cyclone. PV perspective is adopted along with trajectory...
Abstract This paper introduces a newly compiled set of feature-based climatologies identified from ERA-Interim (1979–2014). Two categories flow features are considered: (i) Eulerian jet streams, tropopause folds, surface fronts, cyclones and anticyclones, blocks, potential vorticity streamers cutoffs (ii) Lagrangian climatologies, based on large ensemble air parcel trajectories, stratosphere–troposphere exchange, warm conveyor belts, tropical moisture exports. Monthly means these feature...
Abstract The North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) explored the impact of diabatic processes on disturbances jet stream their influence downstream high-impact weather through deployment four research aircraft, each with a sophisticated set remote sensing in situ instruments, coordinated suite ground-based measurements. A total 49 flights were performed, including, for first time, aircraft: German High Altitude Long Range Research Aircraft (HALO), Deutsches...
Better preparedness for summer heatwaves could mitigate their adverse effects on society. This can potentially be attained through an increased understanding of the relationship between and one main dynamical drivers, atmospheric blocking. In 1979–2015 period, we find that there is a significant correlation heatwave magnitudes number days influenced by blocking in Northern Europe Western Russia. Using three large global climate model ensembles, similar correlations, indicating these models...
Abstract. In June 2013, central Europe was hit by a century flood affecting the Danube and Elbe catchments after 4 day period of heavy precipitation causing severe human economic loss. this study model analysis observational data are investigated to reveal key atmospheric processes that caused event. The preceding characterised weather regime associated with cool unusual wet conditions resulting from repeated Rossby wave breaking (RWB). During event single RWB established reversed...
Extratropical transition (ET) is the process by which a tropical cyclone, upon encountering baroclinic environment and reduced sea surface temperature at higher latitudes, transforms into an extratropical cyclone. This influenced by, influences, phenomena from tropics to midlatitudes meso- planetary scales extents that vary between individual events. Motivated in part recent high-impact and/or extensively observed events such as North Atlantic Hurricane Sandy 2012 western Pacific Typhoon...
In situ observations from a flight made during the Geostationary Earth Radiation Budget Intercomparison of Longwave and Shortwave (GERBILS) field campaign (June 2007) show significant dust uplift into monsoon flow immediately south intertropical discontinuity in western Sahara. Dust loadings were highest moist air are consistent with by nocturnal winds. There is some evidence that cold pools within contributed to uplift: regions elevated dust, water vapor, ozone precipitation cooling...
Abstract Recurving tropical cyclones (TCs) undergoing extratropical transition (ET) may substantially modify the large-scale midlatitude flow pattern. This study highlights role of diabatic outflow in amplification within context a review physical and dynamical processes involved ET. Composite fields 12 western North Pacific ET cases are used as initial boundary conditions for high-resolution numerical simulations Pacific–North American sector with without TC present. It is demonstrated that...
This study reconciles two perspectives on wintertime atmospheric variability in the North Atlantic–European sector: zonal‐mean framework comprising three preferred locations of eddy‐driven jet (southern, central, northern), and weather regime four classical Atlantic‐European regimes (Atlantic ridge AR , zonal ZO European/Scandinavian blocking BL Greenland anticyclone GA ). A k ‐means clustering algorithm is used to characterize two‐dimensional stream, defined by lower tropospheric wind ERA...
Abstract The subseasonal-to-seasonal (S2S) predictive time scale, encompassing lead times ranging from 2 weeks to a season, is at the frontier of forecasting science. Forecasts on this scale provide opportunities for enhanced application-focused capabilities complement existing weather and climate services products. There is, however, “knowledge–value” gap, where lack evidence awareness potential socioeconomic benefits S2S forecasts limits their wider uptake. To address here we present first...
The variability of large-scale moisture transport by atmospheric rivers (AR) and its linkage to precipitation extremes in the North Atlantic-European region is studied. A weather regime approach adopted describe circulation. Weather regimes modulate climatologically mean westerly flow into Europe, which ARs are commonly embedded. In cyclonic regimes, AR landfall enhanced wide parts Iberia, Western British Isles, southern Scandinavia. blocked deviated around blocking anticyclone enhancing at...
Abstract. Sudden stratospheric warming (SSW) events can significantly impact tropospheric weather for a period of several weeks, in particular the North Atlantic–European (NAE) region. While forcing often projects onto Atlantic Oscillation (NAO), response to SSW events, if any, is highly variable, and what determines existence, location, timing, strength downward remains an open question. We here explore how variable NAE region be characterized terms refined set seven regimes flow around...
Abstract The extratropical transition (ET) of tropical cyclones often has an important impact on the nature and predictability midlatitude flow. This review synthesizes current understanding dynamical physical processes that govern this highlights relationship downstream development during ET to high-impact weather, with a focus regions. It updates previous from 2003 identifies new emerging challenges future research needs. First, mechanisms through which transitioning cyclone impacts flow...
Despite huge progress made, state‐of‐the‐art numerical weather prediction systems occasionally experience severe forecast busts for the large‐scale extratropical circulation. This study investigates one of most Europe in European Centre Medium‐Range Weather Forecasts integrated forecasting system (IFS) recent years. The bust occurred March 2016 and was associated with a misforecast onset blocking regime. We investigate evolution error IFS ensemble by employing potential vorticity perspective...
Abstract In June 2021, Western North America experienced an intense heat wave with unprecedented temperatures and far‐reaching socio‐economic consequences. Anomalous rainfall in the West Pacific triggers a cascade of weather events across Pacific, which build up high‐amplitude ridge over Canada ultimately lead to wave. We show that response jet stream diabatically enhanced ascending motion extratropical cyclones represents predictability barrier regard magnitude. Therefore, probabilistic...
Abstract. Blocked weather regimes are an important phenomenon in the Euro-Atlantic region and frequently linked to extreme events. Despite their importance for surface weather, correct prediction of blocking events remains challenging. Previous studies indicated a link between misrepresentation numerical models sea temperature (SST) biases, particularly Gulf Stream region. However, pathway that links SST downstream upper-level flow is not yet fully understood. To deepen our physical...
Abstract In both 2003 and 2018 a heatwave in Scandinavia July was followed by Central Europe August. Whereas the transition occurred abruptly 2003, it gradual with 12‐day period of concurrent heatwaves regions. This study contrasts these two events context climatology to elucidate dynamics sequential heatwaves. European and, particular, are climatologically associated weak pressure gradient (WPG) over Europe, which indicate absence synoptic activity this region. One pattern such is...
Abstract The extratropical transition (ET) of tropical cyclones (TCs) can significantly influence the evolution midlatitude flow. However, interaction between recurving TCs and upstream upper-level troughs features a large partly unexplained case-to-case variability. In this study, synoptic, feature-based climatology TC–trough interactions is constructed to discriminate that interact with decelerating accelerating troughs. Upper-level reducing their eastward propagation speed during exhibit...
Abstract Extreme states of the stratospheric polar vortex can have long‐lasting impacts on extratropical circulation patterns, such as North Atlantic Oscillation (NAO). This provides windows subseasonal predictability beyond typical weather forecast horizon about 10 days. Subseasonal forecasts surface are significant interest in weather‐dependent socio‐economic sectors. For example, demand and supply for electricity gas dependent therefore accurate important energy industry trading. Here we...
Abstract Weather regime forecasts are a prominent use case of sub‐seasonal prediction in the midlatitudes. A systematic evaluation and understanding year‐round forecast performance is still missing, however. Here we evaluate representation skill for seven Atlantic–European weather regimes reforecasts from European Centre Medium‐Range Forecasts. Forecast calibration improves frequency biases most strongly summer, but scarcely winter, due to considerable large‐scale flow summer. The average...
Abstract The subseasonal variability of the extratropical large‐scale atmospheric flow is characterized by recurrent or quasi‐stationary circulation anomalies, termed weather regimes. Despite usefulness these regimes in numerous meteorological and socioeconomic applications, there an ongoing debate as to whether they represent physical modes atmosphere, are merely useful statistical categorizations. Here, we answer this question for wintertime Atlantic‐European We argue that dynamical...
<p>The subseasonal variability of the extratropical large-scale atmospheric flow is characterized by recurrent or quasi-stationary circulation anomalies, termed weather regimes. Despite usefulness these regimes in numerous meteorological and socioeconomic applications, there an ongoing debate as to whether they represent physical modes atmosphere, are merely useful statistical categorizations. Here, we answer this question for wintertime Atlantic-European We argue that...
Abstract Renewable power generation from wind and solar energy is strongly dependent on the weather. To plan future sustainable systems that are robust to weather variability, a better understanding of why when periods low output occur valuable. We call such speed insolation “Dunkelflauten”, German word for “dark lulls”. In this article, we analyse meteorological conditions during Dunkelflauten in Germany by applying concept regimes. Weather regimes quasi‐stationary, recurrent persistent...