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Observations and simulation of intense convection embedded in a warm conveyor belt – how ambient vertical wind shear determines the dynamical impact

Oertel, Annika; Sprenger, Michael; Joos, Hanna; Boettcher, Maxi; Konow, Heike; Hagen, Martin; Wernli, Heini

Abstract:
Warm conveyor belts (WCBs) are dynamically important, strongly ascending and mostly stratiform cloud-forming airstreams in extratropical cyclones. Despite the predominantly stratiform character of the WCB's large-scale cloud band, convective clouds can be embedded in it. This embedded convection leads to a heterogeneously structured cloud band with locally enhanced hydrometeor content, intense surface precipitation and substantial amounts of graupel in the middle troposhere. Recent studies showed that embedded convection forms dynamically relevant quasi-horizontal potential vorticity (PV) dipoles in the upper troposphere. Thereby one pole can reach strongly negative PV values associated with inertial or symmetric instability near the upper-level PV waveguide, where it can interact with and modify the upper-level jet. This study analyses the characteristics of embedded convection in the WCB of cyclone Sanchez based on WCB online trajectories from a convection-permitting simulation and airborne radar observations during the North Atlantic Waveguide and Downstream Impact EXperiment (NAWDEX) field campaign (IOPs 10 and 11). In the first part, we present the radar reflectivity structure of the WCB and corroborate its heterogeneous cloud structure and the occurrence of embedded convection. ... mehr

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Volltext §
DOI: 10.5445/IR/1000129005
Veröffentlicht am 26.01.2021
Originalveröffentlichung
DOI: 10.5194/wcd-2020-49
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Forschungsbereich Troposphäre (IMK-TRO)
Publikationstyp Forschungsbericht/Preprint
Publikationsjahr 2020
Sprache Englisch
Identifikator KITopen-ID: 1000129005
HGF-Programm 12.01.01 (POF III, LK 01) Clouds in a pertubed atmosphere
Verlag Copernicus Publications
Umfang 35 S.
Bemerkung zur Veröffentlichung Weather Clim. Dynam. Discuss. [preprint], in review, 2020.
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