- Xiang He: College of Geography Science, Nanjing Normal University, Nanjing 210023, China.
- Zhen-Shan Lin: College of Geography Science, Nanjing Normal University, Nanjing 210023, China.
In this paper,the generalized additive model (GAM) was introduced to analyze the interactive effects of the influencing factors on the change of PM concentration during 2013-2015 in Nanjing city.The results showed as follows:PM and its influencing factors appeared to follow normal distribution.There were strong correlations among the influencing factors,especially among the temperature (TEM),pressure (PRS) and water vapor pressure (VAP).For the single influencing factor GAM models of PM concentration,all influencing factors passed the significance test.Moreover,the equation fitting degrees of SO,CO,and NO were much higher.In the multiple influencing factors GAM models of PM concentration,the contribution of the SO,CO,NO,O,precipitation (PRE),wind and relative humidity (RHU) to the change of PM concentration was 73.9% with significant impacts on the change of PM concentration.Based on the diagnostic analysis of the effect of multi factors on the change of PM concentration,there were linear relationship between PM and SO,NO and wind,and non-linear relationship between PM and CO,O,PRE and RHU.The GAM models,which considered the interaction of SO respectively with CO,PRE and RHU,the interaction of CO respectively with NO,O,PRE,Wind and RHU,and the interaction of NO respectively with Wind、PRE and RHU,all passed the significance test (<0.01 or <0.05).The interaction of SO,CO and NO respectively with other factors such as meteorological factors had the most important influence on the change of PM concentration.At last,through the visualized three-dimensional map of the GAM models considering the interaction of the influencing factors on the PM concentration,the interactive effects of the influencing factors on PM concentration were quantitatively modeled.Our results demonstrated that GAM could be used to quantitatively analyze the interactive effect of the influencing factors on the change of PM concentration.Therefore,the research method is innovative and important for PM pollution and control.