Distinct Impacts of Light and Heavy Precipitation on PM_2.5 Mass Concentration in Beijing

Abstract

Using hourly observation data of precipitation and PM2.5 at 12 sites in Beijing from 2015 to 2017, this study investigates the impacts of different types of precipitation on PM2.5 mass concentration, along with the characteristics of precipitation and PM2.5. There were totally 91–123 precipitation events annually, 69.7–79.4% of which has precipitation amount less than 5 mm. By investigating the differences of PM2.5 mass concentration between 1 hr after and before the precipitation events, this study finds distinct impacts of different types of precipitation on PM2.5 mass concentration. For precipitation events with amount of 0.1–0.5 mm, PM2.5 mass concentration increased with precipitation amount with a rate of 0.85 μg/m3 per 0.1 mm. For precipitation events with amount of 0.5–10 mm, there was no clear relationship between precipitation amount and PM2.5 mass concentration. For precipitation events with amount larger than 10 mm, PM2.5 mass concentration decreased with precipitation amount with a rate of 0.17 μg/m3 per 1 mm. Further analysis shows that weak precipitation less than 10 mm increased PM10, and heavy precipitation larger than 10 mm decreased PM10. The aerosol amount also affects the response of PM2.5 to precipitation, with weak pollution prone to increase with precipitation and heavy pollution prone to decrease with precipitation. Likely mechanisms are discussed, which include the aerosol hygroscopic growth and gas‐particle conversion that increase aerosol amount and precipitation scavenging that decreases aerosol amount. Shortly, the mechanisms that increase (decrease) aerosol amount more probably dominate when precipitation is light (heavy).

Impact of Precipitation with Different Intensity on PM2.5 over Typical Regions of China

“…That is to say, with the increase of precipitation intensity, the removal effect changed from the negative removal process to the positive removal process. This finding is consistent with that found by Sun et al [21] When the precipitation intensity is low, the negative value of removal effects indicates that PM 2.5 mass concentration increases while the increased amount is generally less than 20%. A likely explanation is as follows.…”

“…However, they are still kept within the atmosphere. The mechanism in which the aerosols are really removed from the atmosphere is the dry and wet deposition [18][19][20][21]. The dry deposition is the process of direct deposition to the surface by the gravity of the particulate matters or by the absorption of other materials [22,23].…”

“…Taylor et al [34] and Andronache et al [35] found that the removal effect of precipitation on PM 2.5 is related to the size distribution of PM 2.5 . Sun et al [21] found that when the PM 2.5 mass concentration before precipitation is large, the removal effect of precipitation is more obvious.…”

Distinct Change of Supercooled Liquid Cloud Properties by Aerosols From an Aircraft‐Based Seeding Experiment

“…With more clouds and precipitation in south China (Z. Yang et al, 2020; Zhao, Chen, et al, 2019), there are sufficient water supply making this region suitable for the growth of rice, along with the warm temperature. In contrast, with limited precipitation and clouds in North China (Sun et al, 2019; Zhao, Chen, et al, 2019), irrigation is often necessary for the growth of agriculture. Associated with this, people hope that we could modify the clouds and precipitation so that we can decrease the impacts of drought to human society.…”

Evaluation of TMPA Satellite Precipitation in Driving VIC Hydrological Model over the Upper Yangtze River Basin

“…Therefore, accurate precipitation data are extremely important for water resource-related research. Currently, the main methods of obtaining precipitation data are the ground rain gauge, ground radar and space-borne passive radiometer [6][7][8]. Although the rain gauge is considered to be the standard for measuring precipitation, the gauge networks are unfortunately sparse or nonexistent in many remote areas of the world.…”