Abstract:To explicitly investigate the influence of precipitation on visibility and PM2.5 concentration, minute scale observations of Hangzhou during 2014-2015 are used to comparatively analyze the distribution characteristics of visibility and PM2.5 concentration under different levels of precipitation, and, furthermore, the quantitative impacts of precipitation with different intensities on visibility and PM2.5 concentration are studied. The results indicate that the intensity and duration of precipitation can significantly modulate visibility and PM2.5 concentration. Consistent and stable rainfall are easy to trigger long low visibility scenario, and the sudden heavy precipitation is an important factor inducing the sharp decrease of visibility. With the rise of rainfall, the visibility changes from rapid decline to slow decline and there exists an inflection point. The removing effect of precipitation on PM2.5 concentration can be mediated by the intensity of rainfall and the PM2.5 concentration before raining. When there is modest/small rainfall, the removing effect usually occurs several time later. However, heavy precipitation is able to remove PM2.5 quickly. Basically, synchronous changes among precipitation, PM2.5 concentration and visibility can appear. Based on the two factors of precipitation intensity and PM2.5 concentration before raining, a quantitative statistical model reflecting the influence of rainfall on PM2.5 concentration is constructed with the non linear fitting technology, and the modeling results agree well with observations. Finally, the existing limitations and some scientific issues which need further exploring in the future are discussed.