328
effect of sulfate aerosols has been investigated in recent studies by Taylor
and Penner (1994), Bengtsson et al. 1995, and Mitchell et al. 1995. In these
studies the direct effect of sulfate aerosols has been considered. The experiments have been done in two steps, first by calculating the atmospheric
load of sulfate from a stand-by chemical model using known sources of
sulfate dioxide emission. Secondly, a simple empirical relation between the
overall sulfate concentration and the clear air albedo have been employed,
implying higher albedo at high sulfate concentrations. The overall effect
on climate is a minor cooling. It has a strong regional variation due to the
short residence time of sulfate aerosols in the troposphere (5-7 days) and is
therefore mainly found near and downstream the areas of major emission
(mainly industrial and densely populated areas of Europe, United States,
China). Due to lack of accurate observational data these experiments are
less reliable than the greenhouse experiments. Furthermore, other aerosols
like soot, not yet considered in the experiments, may partly counteract the
effect of sulphate aerosols. For the time being we must consider the results
obtained so far in these experiments as indicative only.
Acknowledgement
The author acknowledges the assistance of staff at the Max Planck Institute for Meteorology and DKRZ, in particular Erich Roeckner and Josef
Oberhuber. Kornelia Muller and Norbert Noreiks are specially thanked for
their technical assistance.
References
ARRHENIUS, S., 1896: On the Influence of Carbonic Acid in the Air upon the Temperature of
the Ground. Philosophical Magazine and Journal of Science, 236-276.
BACHER, A. AND J. M. OBERHUBER, 1996: Global coupling in the ECHAM4/0PYC3
atmosphere-sea ise-ocean GCM with annual mean flux correction restricted to heat and
freshwater. In preparation.
BAUMGARTNER, A. AND E. REICHEL, 1975: The World Water Balance. Elsevier, New York.
BENGTSSON, L., P. CRUTZEN, M. KANAKIDOU, H. KELDER, J. LELIEVELD, F. RAES, H.
RODHE AND E. ROECKNER, 1995: Study of the indirect and direct climate influences of
anthropogenic trace gas emissions (SINDICATE). Final Report of a Project of the EO
Environmental Research Programme, Max-Planck-Institut ffir Meteorologie, Hamburg.
BENGTSSON, L., K. ARPE, E. ROECKNER AND U. SCHULZWEIDA, 1996: Climate predictability experiments with a general circulation model. Climate Dynamics. 12, 261-278.
effect of sulfate aerosols has been investigated in recent studies by Taylor
and Penner (1994), Bengtsson et al. 1995, and Mitchell et al. 1995. In these
studies the direct effect of sulfate aerosols has been considered. The experiments have been done in two steps, first by calculating the atmospheric
load of sulfate from a stand-by chemical model using known sources of
sulfate dioxide emission. Secondly, a simple empirical relation between the
overall sulfate concentration and the clear air albedo have been employed,
implying higher albedo at high sulfate concentrations. The overall effect
on climate is a minor cooling. It has a strong regional variation due to the
short residence time of sulfate aerosols in the troposphere (5-7 days) and is
therefore mainly found near and downstream the areas of major emission
(mainly industrial and densely populated areas of Europe, United States,
China). Due to lack of accurate observational data these experiments are
less reliable than the greenhouse experiments. Furthermore, other aerosols
like soot, not yet considered in the experiments, may partly counteract the
effect of sulphate aerosols. For the time being we must consider the results
obtained so far in these experiments as indicative only.
Acknowledgement
The author acknowledges the assistance of staff at the Max Planck Institute for Meteorology and DKRZ, in particular Erich Roeckner and Josef
Oberhuber. Kornelia Muller and Norbert Noreiks are specially thanked for
their technical assistance.
References
ARRHENIUS, S., 1896: On the Influence of Carbonic Acid in the Air upon the Temperature of
the Ground. Philosophical Magazine and Journal of Science, 236-276.
BACHER, A. AND J. M. OBERHUBER, 1996: Global coupling in the ECHAM4/0PYC3
atmosphere-sea ise-ocean GCM with annual mean flux correction restricted to heat and
freshwater. In preparation.
BAUMGARTNER, A. AND E. REICHEL, 1975: The World Water Balance. Elsevier, New York.
BENGTSSON, L., P. CRUTZEN, M. KANAKIDOU, H. KELDER, J. LELIEVELD, F. RAES, H.
RODHE AND E. ROECKNER, 1995: Study of the indirect and direct climate influences of
anthropogenic trace gas emissions (SINDICATE). Final Report of a Project of the EO
Environmental Research Programme, Max-Planck-Institut ffir Meteorologie, Hamburg.
BENGTSSON, L., K. ARPE, E. ROECKNER AND U. SCHULZWEIDA, 1996: Climate predictability experiments with a general circulation model. Climate Dynamics. 12, 261-278.