Abstract
Abstract. Many studies have investigated the impacts of aerosol on the intensity and amount of precipitation, but few have been done so regarding the impacts of aerosol on the start and peak times of precipitation. Using the high-resolution precipitation, aerosol, and meteorological data in the warm season of June–August from 2015 to 2020, this study investigates the influence of aerosol on the start and peak times of precipitation over three different regions, the North China Plain (NCP), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD). It shows that the period with the highest frequency of precipitation start time, defined as the frequent period (FP) of precipitation start time, is delayed and prolonged by aerosols in NCP, contributing to the similar durations of precipitation in NCP, YRD, and PRD. This study also shows that different types of aerosol (absorbing versus scattering) have caused different influences on the start and peak times of precipitation over the three study regions. The precipitation start time is 3 h advanced in NCP but 2 h delayed in PRD by aerosols during precipitation FP and shows no response to aerosol in YRD. Compared to stratiform precipitation, the convective precipitation is more sensitive to aerosol. The start and peak times of convective precipitation show similar responses to aerosols. This study further shows that the aerosol impacts on precipitation can vary with meteorological conditions. Humidity is beneficial to precipitation, which can advance the precipitation start and peak times and prolong the precipitation duration time. Correspondingly, the impacts of aerosol on start time of precipitation are significant under low humidity or weak low tropospheric stability conditions. The impacts of vertical wind shear (WS) on the start and peak times of precipitation are contrary to that of aerosols, resulting in the fact that WS inhibits the aerosol effects on precipitation.
Highlights
Aerosols can modify radiative energy balance, cloud physics, and precipitation and affect both weather and climate, bringing large uncertainties to weather forecast and climate assessment (Edenhofer and Seyboth, 2013; Tao et al, 2012)
This study investigates the influence of aerosol on the precipitation start and peak times over three different megacity regions using the high-resolution precipitation, aerosol, and meteorological data in summer (June–August) during the period from 2015 to 2020
We first examine the changes of precipitation start and peak times with aerosols over the North China Plain (NCP), Yangtze River Delta (YRD), and Pearl River Delta (PRD) regions
Summary
Aerosols can modify radiative energy balance, cloud physics, and precipitation and affect both weather and climate, bringing large uncertainties to weather forecast and climate assessment (Edenhofer and Seyboth, 2013; Tao et al, 2012). The aerosol can affect the cloud and precipitation by changing the radiation directly and by serving as cloud condensation nuclei (CCN) or ice nuclei (IN), which are referred to as radiative effect and microphysical effect (Garrett and Zhao, 2006; Wang et al, 2010; Fan et al, 2015; Chen et al, 2017; Liu et al, 2020; Zhao et al, 2020). The aerosols can scatter and absorb solar radiation, which can heat the atmosphere and cool the surface, stabilise the atmosphere, and suppress precipitation. Aerosols by absorbing solar radiation, can strengthen the evaporation of cloud and suppress the formation
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