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Dry Intrusions: Climatology, Dynamics and Link to extreme Weather

Applicant Raveh-Rubin Shira
Number 158347
Funding scheme Marie Heim-Voegtlin grants
Research institution Institut für Atmosphäre und Klima ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Meteorology
Start/End 01.02.2015 - 31.05.2017
Approved amount 257'466.00
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All Disciplines (2)

Discipline
Meteorology
Climatology. Atmospherical Chemistry, Aeronomy

Keywords (8)

meteorology; climatology; extratropical cyclones; trajectories; dry-intrusions; weather extreme; wind gusts; convection

Lay Summary (German)

Lead
Trockene Intrusionen: Klimatologie, Dynamik und Link zu extremen WetterereignissenDry intrusions: Climatology, Dynamics and Link to Extreme WeatherTrockene Intrusionen sind Luftströmungen, die rasch von der Tropopausenregion in die untere Troposphäre absinken. Sie können zu bodennahen Starkwinden beitragen, Gewitter auslösen und stratosphärisches Ozon zum Boden transportieren. In diesem Projekt werden wir mit Hilfe von Trajektorien eine erste globale Klimatologie trockener Intrusionen erstellen. Speziell untersuchen wir den Zusammenhang zwischen trockenen Intrusionen, Zyklonen und Extremereignissen (Wind, Niederschlag) am Boden.
Lay summary
Inhalt und Ziel des Forschungsprojekts

Unser übergeordnetes Ziel ist es, ein wichtiges Strömungsphänomen im Klimasystem, die sogenannten trockenen Intrusionen, und ihre Rolle für Extremwetter besser zu verstehen. Mit Hilfe von Trajektorien soll zunächst ein Algorithmus entwickelt werden, der es erlaubt, trockene Intrusionen in globalen Datensätzen objektiv zu identifizieren. Damit wird es möglich sein, eine globale Klimatologie trockener Intrusionen für mehr als 30 Jahre zu erstellen und ihre Verbindung zu anderen Strömungsphänomenen (Tiefdruckgebiete, brechende Rossby-Wellen) zu untersuchen. Mit hochauflösenden Modellsimulationen trockener Intrusionen, die mit Extremwetter (Gewitter, starke Winde) verbunden sind, können dann die wesentlichen involvierten physikalischen Prozesse im Detail analysiert werden.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Dieses Projekt wird neue und wichtige Resultate zu physikalischen Prozessen hervorbringen, die für die Entstehung von Extremwetterereignissen von Bedeutung sind. Die Ergebnisse werden für die Grundlagenwissenschaft relevant sein und können auch für die operationelle Wettervorhersage wichtige Hinweise liefern.

Direct link to Lay Summary Last update: 16.12.2014

Responsible applicant and co-applicants

Employees

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Bilateral meeting on Warm Conveyor Belts Talk given at a conference Dry intrusions and their role for intense ocean evaporation and for triggering severe surface weather 23.05.2017 ECMWF, Reading, Great Britain and Northern Ireland Raveh-Rubin Shira;
European Geosciences Union General Assembly Poster The dynamical link between deep Atlantic extratropical cyclones and intense Mediterranean cyclones 26.04.2017 Vienna, Austria Raveh-Rubin Shira;
European Geosciences Union General Assembly Talk given at a conference Dry intrusions: Lagrangian climatology and impact on the boundary layer 26.04.2017 Vienna, Austria Raveh-Rubin Shira;
HyMeX Mediterranean Cyclones science-team meeting Talk given at a conference Initiative: Frontal heavy precipitation events – dynamical mechanism and moisture pathways 10.03.2017 Paris, France Raveh-Rubin Shira;
Departmental seminar Individual talk Dry intrusions and warm conveyor belts: feature-based climatologies for understanding extratropical weather dynamics 04.01.2017 Department of Earth and Planetary Sciences, Weizmann Institute of Science, Israel Raveh-Rubin Shira;
Swiss Meteorological Society annual meeting Poster Large-scale surface wind extremes in the Mediterranean 25.11.2016 Zurich, Switzerland Raveh-Rubin Shira;
Departmental seminar Individual talk Dry air intrusions: climatology and their relevance for strong surface winds in the Euro-Mediterranean region 09.11.2016 Institute of Earth Sciences, Hebrew University of Jerusalem, Israel Raveh-Rubin Shira;
Departmental seminar Individual talk Dry air intrusions: climatology and their relevance for strong surface winds in the Euro-Mediterranean region 07.11.2016 Department of Geosciences, Tel Aviv University, Israel Raveh-Rubin Shira;
Departmental seminar Individual talk Dry air intrusions: climatology and their relevance for strong surface winds in the Euro-Mediterranean region 28.06.2016 Faculty of Civil and Environmental Engineering, Technion, Israel Raveh-Rubin Shira;
15th Plinius Conference on Mediterranean Risks Talk given at a conference Dry air intrusions: climatology and their relevance for strong surface winds 09.06.2016 Giardini Naxos, Italy Raveh-Rubin Shira;
Departmental seminar Individual talk Dry air intrusions: climatology and their relevance for strong surface winds in the Euro-Mediterranean region 27.12.2015 Department of Earth and Planetary Sciences, Weizmann Institute of Science, Israel Raveh-Rubin Shira;
17th Cyclone Workshop Talk given at a conference Climatology of Dry Air Intrusions and Their Relation to Strong Surface Winds in Extratropical Cyclones 25.10.2015 Pacific Grove, CA, United States of America Raveh-Rubin Shira;
4th Stormex Workshop Talk given at a conference Climatology of dry air intrusions and their relation to strong surface winds in extratropical cyclones 31.08.2015 Bern, Switzerland Raveh-Rubin Shira;


Abstract

Dry intrusions (DIs) are distinct air streams, which descend from the vicinity of the tropopause to middle and low tropospheric levels, while travelling equatorward. The DI origin and their interaction with the surrounding environment determine their dynamical and thermodynamical characteristics and impact. DIs are a fundamental component of the atmospheric circulation, and as such, their impact is revealed in a variety of aspects, over a range of scales. Considering atmospheric composition, ozone and other trace gases typical for stratospheric air are transported and mixed down to the atmospheric boundary layer (Danielsen 1968; Stohl 2001) and into tropical latitudes (Waugh and Funatsu 2003). In the context of climate variability, DIs affect the radiative response of the atmosphere to solar forcing, by creating areas with very low atmospheric albedo, and serve to distribute dry air to the subtropical and tropical regions, affecting, in turn, tropical convection (Waugh and Funatsu 2003). In the midlatitudes, DIs interact with low-level baroclinic zones, and serve as a central component of airflow around cyclones (Carlson 1980), directly contributing to severe weather (Browning and Reynolds 1994). It is therefore somewhat surprising, that although being recognized for more than six decades, quantitative understanding of the global occurrence and variability of DIs, as well as the dynamical and thermodynamical processes that determine their behavior and impact has not been systematically investigated. Also, it is not fully clear, what fraction of DIs has a stratospheric origin, compared to a descent from the upper troposphere.In this study, we aim to systematically analyse the dynamics of DIs and quantify their global occurrence and variability. To gain new insight on the dynamical evolution of the DI and their impact on the surrounding environment, we will employ a Lagrangian perspective and construct a novel criterion to identify dry descending trajectories objectively. We will apply the criterion for identifying DIs in the ERA Interim dataset for 1979-2014 and compile a global climatology of their occurrence and temporal evolution. The results of this study will provide a tool for DI identification that can be applied to different datasets, as well as an extensive and detailed present-day climatology. Such a climatology is highly valuable for further investigating DI interaction with other flow features such as, e.g., Rossby wave breaking, cyclones, fronts, warm conveyor belts, jet streams, and extreme weather phenomena. Here, we propose to examine the connection of DIs to Rossby wave breaking, DI interaction with cyclones, and their contribution to extreme precipitation and wind storms both statistically and with a mesoscale model analysis of a few selected case studies.
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