Study On The Relationship Between Land Cover And Aerosol Optical Depth In South-central Plain Area Of Hebei

Atmospheric aerosol usually refers to the tiny particles suspended in the atmosphere, particle size can range from 0.001μm to dozens of micron, which is the important constituent of the earth, air and sea system. The shortwave radiation and longwave radiation transmission process and precipitation process of atmospheric aerosol make direct or indirect change in the earth-air system to influence the radiation balance of climate and environment. In recent years, climate change of resulting changes in atmospheric aerosol ,which is caused by human activities ,has become an important fields scientists concerned about. This paper does tentative research on whether there is a relationship between aerosol and different land cover under the influence of human activity.The studied area of this paper is for south-central plain of HeBei province in January 2009 to the December 2009. MODIS image is the main source. The ten-day NDVI is calculated through the pretreatment process of geometric correction, atmospheric correction. The calculation of ten-day data and month data on the vegetation coverage is based on the ten-day NDVI. Furthermore, we get the land cover data by using STACKING processing in ENVI4.6 and using the non-supervised classification with interstate variation curves on vegetation coverage; we also get the month data aerosol through the calculation and synthesis of aerosols optical depth after the process of pretreatment. First, this study does the time-space joint simulation to the vegetation coverage and aerosol by the analysis of time sequence changes'laws on the aerosols optical depth; And study the relationship through statistical analysis of aerosols optical depth corresponding the land cover. Secondly, the logistic regression is on the basis of county population density and annual aerosols optical depth, then, we get the divided area which is based on population density. Finally, we have the study on the relationship of the land cover and aerosols optical depth in different area.Research shows that the relations between land cover and aerosols optical depth are such below:Human activities of dense urban cover corresponding optical depth value is the highest. The second is nearly half a year time in bare state of cotton cover. AOD of rural residential areas, a year a ripe and year of two ripe land cover are similar . Because orchard cover is perennial tree, the cover status is stable and its AOD was level minimum.Each land cover corresponding optical depth on time sequence forms two obvious peaks, the first wave supreme appears in April, the second wave relatively low appears around in August. April corresponding to the spring, September corresponding to the summer. The AOD present the trend of turning decreasely on spring, summer, autumn, winter in the southern plain.The study area is mostly farmland. There are different crop sowing time and growing time , cause relatively complicate land cover, and result in large fluctuations of optical depth corresponding to crop at a specific time.It is concluded that the statistical comparison respectively the aerosols optical depth level 1 area in time and space distribution are higher than 2 area through correlation of the population density and the AOD, aerosols optical depth with 600 for standard of partition, statistical analysis of district 1 and 2 area. The study Shows that human activities factors on the optical depth have significant influence.There is consistency in the trend of time series on the changed intercept and aerosols optical depth corresponding to different land cover. The study show that climate factors have influence on the various aerosols optical depth corresponding to different land cover, also have characteristics of background.