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Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models

Erbertseder, Thilo and Eyring, Veronika and Bittner, Michael and Dameris, Martin and Grewe, Volker (2006) Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models. Atmospheric Chemistry and Physics, 6, pp. 5105-5120.

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Official URL: http://www.atmos-chem-phys.net/6/5105/2006


Dynamics and chemistry of the lower and middle stratosphere are characterized by manifold processes on different scales in time and space. The total column density of ozone, measured by numerous instruments, can be used to trace the resulting variability. In particular, satellite-borne spectrometers allow global observation of the total ozone distribution with proven accuracy and high temporal and spatial resolution. In order to analyse the zonal and hemispherical ozone variability a spectral statistical Harmonic Analysis is applied to multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. In order to demonstrate the capability of the diagnostic for intercomparison studies we apply the hemispheric ozone variability indices to evaluate total ozone fields of the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. Results of a multi-year model simulation representing ''2000" climate conditions with an updated version of E39/C and corresponding total ozone data of TOMS from 1996 to 2004 (Version 8.0) are used. It is quantified to what extent E39/C is able to reproduce the zonal and hemispherical large scale total ozone variations. The different representations of the hemispheric ozone variability indices are discussed. Summarizing the main differences of model and reference observations, we show that both indices, one and two, in E39/C are preferably too high in the Northern Hemisphere and preferably too low in the Southern Hemisphere. In the Northern Hemisphere, where the coincidence is generally better, E39/C produces a too strong planetary wave one activity in winter and spring as well as a too high interannual variability. For the Southern Hemisphere we conclude that model and observations differ significantly during the ozone hole season. In October and November amplitudes of wave number one and two are underestimated. This explains that E39/C exhibits a too stable polar vortex and a too low interannual variability of the ozone hole. Further, a strong negative bias of wave number one amplitudes in the tropics and subtropics from October to December is identified, which may also contribute to the zonal-symmetric polar vortex. The lack of wave two variability in October and November leads to weak vortex elongation and eventually a too late final warming. Contrary, too high wave number two amplitudes in July and August indicate why the polar vortex is formed too late in season by E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust approach to quantify differences in total ozone variability on a monthly mean basis. Therefore, the diagnostic represents a core diagnostic for model intercomparisons within the CCM Validation Activity for WCRP's (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) regarding stratospheric dynamics.

Document Type:Article
Title:Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models
AuthorsInstitution or Email of Authors
Erbertseder, ThiloDFD, Wessling
Eyring, VeronikaUNSPECIFIED
Bittner, MichaelDFD, Wessling
Dameris, MartinUNSPECIFIED
Date:30 June 2006
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
In Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 5105-5120
Keywords:ozone, hemispheric ozone variability index, CCM, comparison
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Datenprodukte für Klima- und Atmosphärenanwendungen (old)
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Climate and Atmospheric Products
Institute of Atmospheric Physics > Atmospheric Dynamics
Deposited By: Thilo Erbertseder
Deposited On:23 Nov 2006
Last Modified:11 Nov 2014 21:56

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