Temporal And Spatial Distribution Of Aerosols And Their Influencing Factors In The Bohai Rim Region Based On MODIS Data

The article analysis the spatial and temporal variability of AOD and FMF in the circum-Bohai-Sea region utilizing the remote sensing MODIS data inversion of land surface aerosol optical depth and fine particle ratio data from 2000 to 2015 in the circum-Bohai-Sea region.We obtained the change rate chart after handling the space-time distribution map.Classifying the aerosol types in the circum-Bohai-Sea region based on the AOD-FMF numerical relationships and obtaining the typical cities AOD data.Finally,the data of population,GDP,DEM,meteorological factors and the air pollution index are the causes of aerosol distribution were obtained.The characteristics of the spatial and temporal distribution of aerosol optical depth and fine-particle ratio in the circum-Bohai-Sea region are as follows:(1)The high-level of AOD locates in Beijing,Tianjin,South-west of Shandong and South-east of Hebei which are densely populated and comparative developed area.The maximum can be above 1.2,however,the lowest level is below 0.2 which locates in north of Hebei.The overall of AOD disappears that the middle and southern areas are high and the north is low.According to the circum-Bohai-Sea region,the two maps show a significant negative correlation.(2)From the AOD map of each season,the whole area is characterized by high values in the central and southern parts of the circum-Bohai-Sea region and low values in the northeast and northwest of the circum-Bohai-Sea region.Some cities in the southwest of Shandong Province and the southern part of Hebei Province are in the high aerosol area during the whole year.Some cities in the northern part of Hebei Province are in the low aerosol area throughout the year.The AOD values in the Shandong Peninsula and Liaoning Peninsula have experienced Spring to summer gradually increased,fall again to reduce the process,with the seasons change significantly.The AOD of the Bohai Sea region is the highest in summer and lowest in winter,and the value is the same in spring and autumn.The AOD values of all seasons show a positive correlation with AQI values.(3)The actual annual change of AOD of circum-Bohai-Sea region represents the trend which is raising.It shows raising trend during 2000-2015 period and the slope rate is 0.084/10 a with the coefficient is 0.642.According to the seasons change tendency,the Spring one has a weak falling trend,and the summer one shows 2000-2011 period raising and 2011-2015 period falling trend.The autumn one keep rarely change tendency and the winter shows that the 2000-2012 period raising up fluctuate The summer one shows the maximum value and winter shows the minimum value and the value is the same in spring and autumn.In February and July it reaches peak and in May and December it falls trough value.The maximum appears in July and the minimum value appears in December.(4)The spatial and temporal distribution of FMF in the circum-Bohai-Sea region has a significant negative correlation with AOD.In the spatial distribution,the FMF values in the circum-Bohai-Sea region ranged from 0.1 to 1.0,The low values are located in the northwest of Shandong and the southeastern Hebei,where the population was relatively denser and more economically developed.However,Taihang Mountains and eastern Liaoning Province,the value of high-value area can reach the low value of more than 4 times.The overall FMF level presents that the value is low in the south and northwest area and high in the northwest.The annual average change of FMF around circum-Bohai-Sea region shows weakly raising tendency during2000-2015 period and the slope rate is 0.02/10 a..The FMF slope rate in circum-Bohai-Sea region ranges from-0.475 to 0.359/10 a.It indicates that the overall district has no obvious change.There are positive and negative value.The change scope is similar with AOD which indicates that there is positive relationship in the change of AOD and FMF.According to the data of aerosol optical thickness and topographic data,meteorological data,air pollution index data,population data,GDP data and vegetation index data,the correlation analysis and qualitative analysis,we have following conclusions:(1)Different aerosol types AOD value is consistent with corresponding meteorological data.The general rule is: AOD value is negatively correlated with air pressure and wind speed,and positively correlated with air temperature,relative humidity and precipitation.(2)According to the correlation analysis between AOD and air quality index,we find that the correlation between spring and summer is relatively high and the correlation between autumn and winter is relatively low,which shows that air quality index is significantly correlated with AOD data(3)Analyzing the AOD and the vegetation index in the circum-Bohai-Sea region qualitatively,it shows a negative correlation.(4)There is a positive correlation between population AOD and regional GDP for qualitative analysis.