The Impacts Of Radiative Effects Of Atmospheric Aerosol On Primary Crops' Growth In The Yangtze Delta Region

With the rapid development of industrialization and urbanization, the increase of the atmospheric aerosol concentration at striking rates caused effects on biosphere, especially on crops, which is gradually arousing scientists'attention. Without especial experimentation about the impacts of radiative effects of aerosol on crop's growth, so the impacts are to be assessed with the numerical simulation method in this paper. The research couples Carbon and Nitrogen Biogeochemistry in Agroecosystems Model (DNDC) with the impacting model of atmospheric aerosol concentration to photosynthetically active radiation. The paper's research objects are the Yangtze Delta region's primary crops as winter wheat and rice, so the paper analyses the impacts of changes of the atmospheric aerosol concentration on crop growth and yield with the coupled model in the Yangtze Delta region.Firstly, the paper improves photosynthesis subschema in the model DNDC; secondly, it couples DNDC with the impacting model of atmospheric aerosol concentration to photosynthetically active radiation; then, it analyses the impacts in the Yangtze Delta region with the coupled model.The elementary conclusions of the paper are listed below:1. The total solar irradiation is gradually reducing in the Yangtze Delta region in the years of 1961 to 2000. The scatter solar irradiation is reducing lightly, even increasing in individual region. As a whole, the clearness's frequency is lower.2. The improved model thinks about the direct impacts of radiative effects on crop photosynthesis and yield well and turely. The simulation closes to observation.3. The results indicate that the increase of radiation in Yangtze Delta region may restrain the growth of winter wheat and rice and reduce the yield. The photosynthetic yield and grain yield are sensitive to the radiation. And more radiation is not always better for the crop.4. The coupled model that roots in observation could reflect how the crop receives the photosynthetically active radiation exactly.5. With the coupled model, when the atmospheric aerosol optical depth is 0.311,0.482,0.692,0.878,1.09,1.33 and 1.93, the photosynthetically active radiation and grain yield of winter wheat and rice are reducing with the atmospheric aerosol optical depth's increase.6. When the atmospheric aerosol optical depth is 0.78 that is the current sky condition, the photosynthetically active radiation of winter wheat and rice may cut down 22% and 18% in contrast with the atmospheric aerosol optical depth is zero. Similarly the grain yield of winter wheat and rice may cut down 12% and 9%. The simulation showes that if the atmospheric aerosol optical depth is double, the photosynthetically active radiation of winter wheat and rice may reduce more 19% and more 16%. The grain yield of winter wheat and rice may reduce more 9% and more 8%.The innovations in this paper are: the coupling of DNDC and the impacting model of atmospheric aerosol concentration to photosynthetically active radiation. And the research before is only about the impact of the total solar radiation on crop, the research in this paper thinks about the positive affect of the scatter solar radiation on crop. So the simulations show that the influence range is smaller than 15% which is W. L. Chameides'[1]conclusion. The paper's analyses include six station's condition in 40 years, which are more general.