Description: Das Projekt "Diabatic processes in North Atlantic weather systems: dynamics and impact on forecast errors" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Atmosphäre und Klima durchgeführt. Extratropical cyclones and persistent anticyclones, also referred to as atmospheric blockings, are key synoptic-scale weather systems that strongly determine the evolution of daily weather in Europe. Recent research has quantified that also many extreme events are linked to the passage of these systems; e.g., extreme precipitation and wind co-occur frequently with cyclones. It is therefore of crucial importance to understand the dynamics of cyclones and blockings and the reasons why their prediction at times fails. A central aspect, which has been increasingly considered during the last years, is the interaction of dry dynamical and moist physical processes for the dynamics and forecasting of cyclones and blockings. In our current SNF project and in accompanying group activities, we have been mainly focusing on the role of moist ascending airstreams in extratropical cyclones, so-called warm conveyor belts (WCBs), and could clarify their role for the formation of low-level positive and upper-level negative potential vorticity (PV) anomalies, both in detailed case study simulations and from a climatological point of view. Due to their cross-isentropic transport of low-PV air into the upper-level ridges, WCBs tend to intensify these ridges and modify the downstream flow at the level of the jet stream. The cloud microphysical processes within the ascending WCB air have been investigated, leading to a refined picture of the various phase transitions and the related release of latent heat associated with the cloud and precipitation mechanisms in WCBs. The aircraft field experiment T-NAWDEX-Falcon, to which we will contribute in October 2012, will provide in-situ observations of these complex processes. In this continuation project, novel aspects of the role of diabatic processes for the evolution of cyclones and blockings will be addressed, which extend our current work on WCBs. To further advance the understanding of these fundamental and complex processes, the main objectives of this project are to (i) investigate the role of positive low-level PV anomalies in WCBs for the evolution of the associated cyclones, (ii) identify the impact of various cloud microphysical processes on the mesoscale PV structures within cyclones, (iii) quantify the evolution of cirrus cloud properties and associated radiative impact in the WCB outflow, (iv) utilize observational data from the aircraft field experiment T-NAWDEX-Falcon to better characterize these processes in nature and for assessing the accuracy of their implementation in numerical models, and (v) assess the role of microphysical PV modifications for the quality of weather system predictions. The project will also contribute to the aircraft experiment ML-CIRRUS in 2014 and to the planning of an international T-NAWDEX activity in 2015. usw.
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Wolke ? Zyklon ? Hurrikan ? Klimatologie ? Latentwärme ? Wasserdampf ? Wind ? Luftbewegung ? Monitoringdaten ? Flugzeug ? Wetterdaten ? Starkregen ? Eis ? Prognosemodell ? Evolution ? Kondensation ? Kristallisation ? Luftfahrzeug ? Luftverkehr ? Simulation ? Studie ? Wettervorhersage ? Daten ? Luftfeuchtigkeit ? Fallstudie ? Modellierung ? Europa ? Nordatlantik ? Kausalzusammenhang ? Niederschlag ? Wetter ? Fernerkundung ? Wettermanipulation ? Physikalischer Vorgang ? Atmosphärischer Prozess ? Freilandversuch ? Modellrechnung ? cloud microphysics ? diabatic processes ? Tiefdruckgebiet ? atmospheric dynamics ? extratropical cyclone ? numerical weather prediction ? potential vorticity ? warm conveyor belt ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2013-06-01 - 2016-05-31
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