Aerosol forces

Charlson, R. J., and J. Heintzenberg, Eds., Aerosol Forcing of Climate, Wiley, New York, 1995. 

Lacis, A. A., and M. I. Mishchenko, Climate Forcing, Climate Sensitivity, and Climate Response A Radiative Modeling Perspective on Atmospheric Aerosols, in Aerosol Forcing of Climate (R. J. Charlson and J. Heintzenberg, Eds.), Wiley, New York, 1995. 

G. J. Boer et at., A Transient Climate Change Simulation with Historical and Projected Greenhouse Gas and Aerosol Forcing Experimental Design and Comparison with the Instrumental Record for the 20th Century, ibid. 16 (2000) 405-25. 

Satheesh, S. K., and Ramanathan, V. (2000). Large differences in tropical aerosol forcing at the top of the atmosphere and earth s surface. Nature 405, 60-63. 

The most promising prospect for estimation and prediction of anthropogenic SAT changes has to do with an analysis of the spatiotemporal variability of SAT fields, which takes into account the impacts of the greenhouse effect and aerosols. Realization of this approach is seriously complicated, however, by the impossibility of reliably assigning the aerosol forcing on the SAT field. Another serious problem is the necessity to take into account the impact on climate of changes in the content of stratospheric and tropospheric ozone. 

In urban areas the pattern of distribution of aerosol forcing on climate changes drastically, and due to the high concentration of aerosol the process of cloud formation changes, which breaks natural levels in the atmosphere-surface system s albedo. 

Module of feedback mechamisms Direct gas aerosol forcing Cloud condensation nuclei model Other semidirect indirect effects... 

Possibility exists to consider feedback mechanisms, e.g. aerosol forcing... 

Feedback Mechanisms, Aerosol Forcing in Meso-meteorological Models... 

In this concern one of the important tasks is to develop a modelling instrument of coupled Atmospheric chemistry/Aerosol and Atmospheric Dynamics/Climate models for integrated studies, which is able to consider the feedback mechanisms, e.g. aerosol forcing (direct and indirect) on the meteorological processes and climate change (see Fig. 1.2). 

The chemical composition fields from ACTMs may be used as a driver for Regional/Global Climate Models, including aerosol forcing on meteorological processes. This strategy could also be reahzed for NWP or MetMs. 

For the realization of all aerosol forcing mechanisms in integrated systems it is necessary to improve not only ACTMs, but also NWP/MetMs. The boundary layer structure and processes, including radiation transfer, cloud development and precipitation must be improved. Convection and condensation schemes need to be adjusted to take the aerosol-cloud microphysical interactions into account, and the radiation scheme needs to be modified to include the aerosol effects. 

DMI is actively working with development of the fully on-line integrated system Enviro-HIRLAM, that considers chemistry, aerosol forcing mechanisms, etc. 

ACTM chemical composition fields as a driver for regional climate modelling (e.g. for aerosol forcing on meteo-processes, it could also be realized for NWP, e.g. for HIRLAM)... 

Feedback mechanisms are considered to be important for a coupling strategy. This is especially relevant for aerosols. Aerosol forcing mechanisms influence radiative and optical properties as well as cloud processes, leading for instance to changes of precipitation and circulation. 

Aerosol Forcing Relative to Other Forcings of Climate Change over the Industrial Period... 

For nonabsorbing tropospheric aerosols, forcing is almost entirely at surface for stratospheric aerosols, there is a small heating resulting in a transient warming of stratosphere... 

Early studies employed (24.22) to estimate direct aerosol forcing by sulfate aerosols in a column of air extending from the surface to the top of the atmosphere (Charlson et al. 1991, 1992 Pilinis et al. 1995 Nemesure et al. 1995 Penner et al. 1994). The mean optical depth is computed as the product of the aerosol mass scattering coefficient [m2(g SO2-)-1] and the column integrated mass of aerosol (gSO2- itT2) ... 

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