388 research outputs found
Implications of constant CFC-11 concentrations for the future ozone layer
No full textThe presentation given at the symposium was based on the discussion version of the following article: Dameris, M., Jöckel, P., and Nützel, M.: Possible implications of enhanced chlorofluorocarbon-11 concentrations on ozone, Atmos. Chem. Phys., 19, 13759–13771, https://doi.org/10.5194/acp-19-13759-2019, 2019.
This article is listed in ELIB as https://elib.dlr.de/130746/
Numerical Modeling of Climate-Chemistry Connections: Recent Developments and Future Challenges
No full textThis paper reviews the current state and development of different numerical model classes that are used to simulate the global atmospheric system, particularly Earth’s climate and climate-chemistry connections. The focus is on Chemistry-Climate Models. In general, these serve to examine dynamical and chemical processes in the Earth atmosphere, their feedback, and interaction with climate. Such models have been established as helpful tools in addition to analyses of observational data. Definitions of the global model classes are given and their capabilities as well as weaknesses are discussed. Examples of scientific studies indicate how numerical exercises contribute to an improved understanding of atmospheric behavior. There, the focus is on synergistic investigations combining observations and model results. The possible future developments and challenges are presented, not only from the scientific point of view but also regarding the computer technology and respective consequences for numerical modeling of atmospheric processes. In the future, a stronger cross-linkage of subject-specific scientists is necessary, to tackle the looming challenges. It should link the specialist discipline and applied computer science
Update on Polar ozone: Past, present, and future
No full textDameris, M., and Sophie Godin-Beekmann(Lead Authors)International audienceAs stated in the previous Assessments, ozone-depleting substance (ODS) levels reached a maximum in the polar regions around the beginning of this century and have been slowly decreasing since then, consistent with the expectations based on compliance with the Montreal Protocol and its Amendments and adjustments. Considering the current elevated levels od ODSs, and their slow rate of decrease, changes in the size and depth of the Antarctic ozone hole and in the magnitude of the Arctic ozone depletion since 2000 have been mainly controlled by variatins in temperature and dynamical processe
Hemispheric differences in the return of midlatitude stratospheric ozone to historical levels
No full textChemistry-climate models (CCMs) project an earlier
return of northern mid-latitude total column ozone to
1980 values compared to the southern mid-latitudes. The
chemical and dynamical drivers of this hemispheric difference
are investigated in this study. The hemispheric asymmetry
in return dates is a robust result across different CCMs
and is qualitatively independent of the method used to estimate
return dates. However, the differences in dates of return
to 1980 levels between the southern and northern midlatitudes
can vary between 0 and 30 yr across the range of
CCM projections analyzed. Positive linear trends in ozone
lead to an earlier return of ozone than expected from the
return of Cly to 1980 levels
A model intercomparison analysing the link between column ozone and geopotential height anomalies in January
No full textA statistical framework to evaluate the performance of chemistry-climate models with respect to the interaction between meteorology and column ozone during northern hemisphere mid-winter, in particularly January, is used. Different statistical diagnostics from four chemistry-climate models (E39C, ME4C, UMUCAM, ULAQ) are compared with the ERA-40 re-analysis. First, we analyse vertical coherence in geopotential height anomalies as described by linear correlations between two different pressure levels (30 and 200 hPa) of the atmosphere. In addition, linear correlations between column ozone and geopotential height anomalies at 200 hPa are discussed to motivate a simple picture of the meteorological impacts on column ozone on interannual timescales. Secondly, we discuss characteristic spatial structures in geopotential height and column ozone anomalies as given by their first two empirical orthogonal functions. Finally, we describe the covariance patterns between reconstructed anomalies of geopotential height and column ozone. In general we find good agreement between the models with higher horizontal resolution (E39C, ME4C, UMUCAM) and ERA-40. The Pacific-North American (PNA) pattern emerges as a useful qualitative benchmark for the model performance. Models with higher horizontal resolution and high upper boundary (ME4C and UMUCAM) show good agreement with the PNA tripole derived from ERA-40 data, including the column ozone modulation over the Pacfic sector. The model with lowest horizontal resolution does not show a classic PNA pattern (ULAQ), and the model with the lowest upper boundary (E39C) does not capture the PNA related column ozone variations over the Pacific sector. Those discrepancies have to be taken into account when providing confidence intervals for climate change integrations
Einsatz und Weiterentwicklung eines Modells zur Prognose der zukuenftigen Entwicklung der stratosphaerischen Ozonschicht Abschlussbericht
No full textIn this project first assessments of the future development of the stratospheric ozone layer have been carried out (Dameris et al., 1998c). For that purpose the climate-chemistry model in version ECHAM3/CHEM has been used. During the project the model has been further developed to an interactively coupled system, based on very recent versions of ECHAM and CHEM (ECHAM4.L39) ((DLR)/CHEM). Results of model scenarios of the past and present time have been extensively evaluated against observations (Hein et al., 1999). It is obvious that the model system is able to reproduce well the mean conditions of the atmosphere in its current situation and also the observed changes (trends) during the last decade. Regional differences are found for the recovery of stratospheric ozone in the future scenarios. Particularly in polar latitudes the reformation of the ozone layer is delayed since the greenhouse effect yields a cooling of the lower stratosphere. According to an increased denitrification in the lower stratosphere a more effective chlorine activation is found. (orig.)Im Rahmen dieses Vorhabens wurden erste Abschaetzungen zur zukuenftigen Entwicklung der stratosphaerischen Ozonschicht durchgefuehrt (Dameris et al., 1998c). Dazu wurde das Klima-Chemie-Modell in der Version ECHAM3/CHEM verwendet. Im Verlauf des Projekts wurde das Modell zu einem interaktiv rueckkoppelnden System weiterentwickelt, auf der Grundlage neuester Versionen von ECHAM und CHEM (ECHAM4.L39 (DLR)/CHEM). Ergebnisse von Modellszenarien der Vergangenheit und Gegenwart wurden ausfuehrlich mit Beobachtungen verglichen (Hein et al., 1999). Es zeigt sich, dass das Modellsystem sowohl den gegenwaertigen mittleren Zustand der Atmosphaere gut beschreibt als auch die Veraenderungen waehrend der letzten Jahre (Trends) richtig wiedergibt. Die Ergebnisse der Zukunftsszenarien zeigen, dass es zu einer regional unterschiedlichen Rueckbildung der Ozonschicht kommt. Vor allem in den Polargebieten erholt sich das Ozon nur langsam, da es durch den Treibhauseffekt zu einer Abkuehlung der Stratosphaere kommt. Als Folge einer verstaerkten Denitrifizierung in der unteren Stratosphaere kommt es zu einer effektiveren Chloraktivierung. (orig.)SIGLEAvailable from TIB Hannover: DtF QN1(85,16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman
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