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Impact of atmospheric aerosol light scattering and absorption on terrestrial net primary productivity
Author(s) -
Cohan Daniel S.,
Xu Jin,
Greenwald Roby,
Bergin Michael H.,
Chameides William L.
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2001gb001441
Subject(s) - primary production , aerosol , environmental science , atmospheric sciences , photosynthetically active radiation , irradiance , sunlight , absorption (acoustics) , overcast , photosynthesis , cloud cover , meteorology , chemistry , ecosystem , physics , ecology , optics , sky , biology , cloud computing , biochemistry , computer science , operating system
Scattering and absorption of sunlight by anthropogenic aerosols reduce the photosynthetically active radiation (PAR) incident upon the Earth's surface, but increase the fraction of the PAR that is diffuse. These alterations to irradiance may elicit conflicting responses in terrestrial plants: photosynthesis and net primary productivity (NPP) are slowed by reductions in total PAR, but enhanced by increases in diffuse PAR. In this paper, we use two canopy photosynthesis models to estimate the net effect of aerosols on carbon assimilation by green plants during summertime at midlatitudes. The model calculations indicate that the net effect of PAR scattering and absorption by atmospheric aerosols on NPP can be positive, neutral, or negative. Two parameters that strongly influence the net effect are the aerosol optical depth (integral of light extinction with height) and the cloud cover. On cloudless days NPP peaks under moderately thick aerosol loadings. On overcast days, aerosols slow NPP. The implications of these results for various regions of the globe and possible directions for future studies on the effect of aerosols on plant growth are discussed.