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On the intermittency of orographic gravity wave hotspots and its importance for middle atmosphere dynamics

Kuchar, Ales and Sácha, Petr and Eichinger, Roland and Jacobi, Christoph and Pisoft, Petr and Rieder, Harald E. (2020) On the intermittency of orographic gravity wave hotspots and its importance for middle atmosphere dynamics. Climate Dynamics, 1, pp. 481-495. Springer. doi: 10.5194/wcd-1-481-2020. ISSN 0930-7575.

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Official URL: https://wcd.copernicus.org/articles/1/481/2020/

Abstract

When orographic gravity waves (OGWs) break, they dissipate their momentum and energy and thereby influence the thermal and dynamical structure of the atmosphere. This OGW forcing mainly takes place in the middle atmosphere. It is zonally asymmetric and strongly intermittent. So-called "OGW hotspot regions" have been shown to exert a large impact on the total wave forcing, in particular in the lower stratosphere (LS). Motivated by this we investigate the asymmetrical distribution of the three-dimensional OGW drag (OGWD) for selected hotspot regions in the specified dynamics simulation of the chemistry-climate model CMAM (Canadian Middle Atmosphere Model) for the period 1979-2010. As an evaluation, we first compare zonal mean OGW fluxes and GW drag (GWD) of the model simulation with observations and reanalyses in the Northern Hemisphere. We find an overestimation of GW momentum fluxes and GWD in the model's LS, presumably attributable to the GW parameterizations which are tuned to correctly represent the dynamics of the Southern Hemisphere. In the following, we define three hotspot regions which are of particular interest for OGW studies, namely the Himalayas, the Rocky Mountains and East Asia. The GW drags in these hotspot regions emerge as strongly intermittent, a result that can also quantitatively be corroborated with observational studies. Moreover, a peak-detection algorithm is applied to capture the intermittent and zonally asymmetric character of OGWs breaking in the LS and to assess composites for the three hotspot regions. This shows that LS peak OGW events can have opposing effects on the upper stratosphere and mesosphere depending on the hotspot region. Our analysis constitutes a new method for studying the intermittency of OGWs, thereby facilitating a new possibility to assess the effect of particular OGW hotspot regions on middle atmospheric dynamics.

Item URL in elib:https://elib.dlr.de/136465/
Document Type:Article
Title:On the intermittency of orographic gravity wave hotspots and its importance for middle atmosphere dynamics
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Kuchar, AlesInstitute for Meteorology, Universität Leipzighttps://orcid.org/0000-0002-3672-6626
Sácha, PetrUniv. Prag, Tschechische RepublikUNSPECIFIED
Eichinger, RolandDLR, IPA und MIM, Univ. Münchenhttps://orcid.org/0000-0001-6872-5700
Jacobi, ChristophInstitute for Meteorology,University Leipzig, Germanyhttps://orcid.org/0000-0002-7878-0110
Pisoft, PetrUniv. Prag, Tschechische Republikhttps://orcid.org/0000-0002-5034-9169
Rieder, Harald E.Institute of Meteorology and Climatology, University of Natural Resources and Life Sciences, Vienna (BOKU)UNSPECIFIED
Date:29 September 2020
Journal or Publication Title:Climate Dynamics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:1
DOI:10.5194/wcd-1-481-2020
Page Range:pp. 481-495
Editors:
EditorsEmailEditor's ORCID iD
Domeisen, DanielaUNSPECIFIEDUNSPECIFIED
Publisher:Springer
ISSN:0930-7575
Status:Published
Keywords:gravity wave hotspot dynamics stratosphere intermittency mesosphere climate modeling
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Middle Atmosphere, R - Atmospheric and climate research
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Eichinger, Roland
Deposited On:07 Oct 2020 09:41
Last Modified:07 Oct 2020 09:41

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