Atmospheric Aerosol Spatial-temporal Characteristics And Its Climatic Effect On Crop In North China

The North China Plain is major grain-producing region of China, which is also one of area with the highest concentration of aerosols. A lot of work has revealed that aerosols have an significant impacts on the meteorological, such as radiation, air temperature, precipitation, which are closely related to crop yield and growth stage.Because of this, quantitative research on climatic effect of aerosols and its possible impacts on corp growth have become a hot spot of research at home and abroad in recent years. In this study, the products of Terra and Aqua MODIS were collaboratively used to retrieve aerosol optical depth(AOD) over North China before the accuracy of this collaborative data verified by AERONET data. Then, spatial-temporal variation characteristics of AOD over North China from 2003 to 2014 was studied. And on this basis, taking winter wheat as an example, the change of crop yield and growth stage was affected synthetically by radiation and air temperature which caused by the climatic effect of aerosols was simulated with DNDC model. This study will provide basis data to evaluate fully the impacts of climatic effect of aerosols on crop in China.Main conclusions are listed as follows:(1) NASA MODIS Level2 Collection 051 data product(MOD04_L2_C051), based on a merged Deep Blue-Dark Target aerosol retrieval algorithm, was validated using the AERONET ground observation data, and as a result, it has a good accuracy(R=0.927,MRE =0.326) to meet the requirement of studying the regional spatial-temporal variation characteristics of aerosol optical depth(AOD) distribution over North China.(2) The spatial distributing changes of AOD in this region during the nearly 10 years were analyzed. The results showed that the high AOD were at the North China plain, while the low AOD were at mountains and hills. Temporal variation of AOD during the nearly 10 years were analyzed. There is a weak overall upward trend with an average increment of 0.004 over North China during this decade. The AOD values during the period of spring and summer were obviously higher than that of the period of autumn and winter. The regional temporal of AOD changes showed that the peak value(average AOD>0.7) was appeared in June or July each year, while the valley value(average AOD<0.2) was in January or December.(3) With the condition of value 0.55 of AOD, reduced-0.6℃ of air temperature and full irrigation, the yield would increase 1.5% in Quzhou station. The seeding stageand turning-green stage remained unchanged, while heading stage and maturation stage were postponed 4 d and 2 d, respectively. In Yucheng and Zhengzhou station, the yield would decease 12.2% and 18.3%, respectively. The seeding stage and tuning-green stage remained unchanged, while heading stage and maturation stage were postponed 4d and 4 d, respectively.(4) With the condition of value 1.1 of AOD, reduced-1.2℃ of air temperature and full irrigation, the yield would increase 2% in Quzhou station. The seeding stage and turning-green stage remained unchanged, while heading stage and maturation stage were postponed 8 d and 6 d, respectively. In Yucheng and Zhengzhou station, the yield would decease 12.2% and 18.3%, respectively. The seeding stage and tuning-green stage remained unchanged, while heading stage and maturation stage were postponed(4d, 4d) and(8d, 7d), respectively.(5) It is a diversity and complex mechanism that aerosols climatic effect on crop.But we believe that reduce of the solar radiation and aie temperature caused by aerosols was the main reason to yield reduced and the growth stage delayed. The result also has showed that the yield affected by lower temperature was stronger than the lower radiation in a certain range.(6) Because aerosols climatic effect on crop yield and growth stage was very complex, the result of this study still remains some uncertainties which need to be further researched.