Validation and Further Development of an Interactively Coupled Climate-Chemistry Model for Detection, Attribution
and Prediction of Changes in the UTLS

A contribution to ACCENT-TROPOSAT-2, Task Group 2

Martin Dameris

Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)
Oberpfaffenhofen, D-82234 Wessling, Germany
Tel.:  +49-(0)8153-281558
Fax:  +49-(0)8153-281841

During recent years the development of interactively coupled chemistry-climate models (CCMs) has made significant progress. Inter-comparisons of first long-term model simulations with respective data derived from observations indicated that the CCMs can realistically reproduce most relevant processes and features (e.g. climatological mean state of dynamical parameters and chemical compounds in the UTLS and its seasonal and inter-annual variability), but on the other hand, the different model systems do contain obvious deficiencies, for example the well known “cold-bias” in the polar lowermost stratosphere (e.g. Schnadt et al., 2002; Austin et al., 2003). Therefore, further developments of models are strongly required before reliable predictions of possible future changes of atmospheric composition and climate can be made. Within the framework of AT2 a number of contributions are envisaged, which build up on experiences made during TROPOSAT (e.g. Lauer et al., 2002).

Within this project it is planned to employ two versions of the chemistry-climate model ECHAM5/MECCA. First, we will use ECHAM5.L41(DLR)/MECCA (E41/M) for long-term simulations (years to decades). E41/M is characterised by a high vertical resolution in the UTLS (i.e. 700 m near the tropopause instead of 2 km in the standard model version). This model version is mainly employed to investigate changes in climate and atmospheric composition. Second, the version E41/M(nudge) is available which uses meteorological analyses (e.g. ERA40); this model version can be used to investigate individual episodes (months), in particular to support the planning and analysis of measurement campaigns.

Key-questions to be answered are: (1) What are the past changes and variations in the UTLS? (2) How well can we explain past changes in terms of natural and anthropogenic effects? (3) How do changes in the UTLS composition affect climate, and vice versa? (4) Can E41/M(nudge) reproduce relevant processes and features which have been detected during measurement campaigns? (5) How do we expect the UTLS to evolve in the future, and what confidence do we have in those predictions?

Data products derived from satellite and non-satellite measurements (ground based, airborne) will be used to compare and evaluate the results of E41/M. Further development of E41/M will lead to an improved model system and a better understanding of tropospheric and stratospheric processes. The synergistic use of model data and observations is the basis for a better understanding of chemical, physical and dynamic processes and their interaction, and for reliable assessments of future atmospheric changes.

 

Time schedule

 

2004

2005

2006

2007

2008

2009

CCM validation development simulations

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Approximate manpower and cost

 

2004

2005

2006

2007

2008

2009

Personnel / man-months

1

2

2

2

2

1

Yearly cost (kEURO)

5

10

10

10

10

5

Consumables (kEURO)

1

2

2

2

2

1

Likely funding agencies

CEC

Co-workers

Rudolf Deckert and Christian Kurz

References

Austin, J., D. Shindell, S.R. Beagley, C. Brühl, M. Dameris, E. Manzini, T. Nagashima, P. Newman, S. Pawson, G. Pitari, E. Rozanov, C. Schnadt, and T.G. Shepherd, Uncertainties and assessments of chemistry-climate models of the stratosphere,  Atmos. Chem. Phys., 3, 1-27, 2003.

Lauer, A., M. Dameris, A. Richter, J.P. Burrows, Tropospheric NO2 columns: a comparison between model and retrived data from  GOME measurements, Atmos. Chem. Phys., 2, 67-78, 2002.

Schnadt, C., M. Dameris, M. Ponater, R. Hein, V. Grewe, and B. Steil, Interaction of atmospheric chemistry and climate and its impact on stratospheric ozone, Climate Dynamics, 18, 501-517, 2002.

 


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