Effect of Burning Straw in Open Air on CCN and Precipitation in Shanghai

Abstract

In this paper, the distribution characteristics of cloud condensation nuclei(CCN) and precipitation in Shanghai during the period of straw burning in the open air were analyzed by using the precipitation data, ground CCN data,K+concentration data and agricultural straw burning fire point data from 2009 to 2013 in Shanghai. The results showed that the daily distribution of CCN near the ground in Shanghai was single peak or multi peak, the concentration of CCN on the straw burning day was significantly higher than that on the non-burning day, and the later smoke flow of straw burning emission diffusion was easier to be activated into CCN than that in the early phase; the precipitation distribution in Shanghai during straw burning showed that the precipitation in summer harvest season was generally higher than that of autumn harvest and the precipitation frequency of summer harvest was significantly higher than that of autumn harvest. During the period of straw burning, there was mainly light rain in Shanghai, and the annual change was the "W" type of summer harvest and the "U" type of autumn harvest. In addition, through the correlation analysis of the days affected by straw burning and the precipitation in Shanghai for many years, it is found that the agricultural straw burning in open air has contributed to the formation of the light rain and the heavy rain in Shanghai but has a restraining effect on the moderate rain. It can be concluded that the straw burning in the open air not only affects the air quality, but also has a significant impact on the regional climate.

Keywords

• straw burning in the open air
• shanghai
• cloud condensation nuclei
• precipitation