Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

Abstract

Abstract. Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD) region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day) and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving -Weather Research and Forecasting (CR-WRF) model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI) exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16 % and 50 %, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day), but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

Observations of aerosol‐induced convective invigoration in the tropical east Atlantic

“…Since then others [e.g., Lin et al, 2006;Ten Hoeve et al, 2012] have also found evidence of higher cloud tops, enhanced heavy precipitation, and increased ice amounts in the same region. Similar evidence has also been found for convective invigoration (e.g., increased cloud tops, more frequent lightning, and heavier precipitation events) in polluted environments over the North Atlantic Ocean [Koren et al, 2005], in the southeast United States [Bell et al, 2008], and in China [Wang et al, 2011]. Wang et al [2009] analyzed both observational and modeling data and found evidence that smoke from biomass burning in Central America may lead to an enhancement of severe weather in the south central United States.…”

Persistent sulfate formation from London Fog to Chinese haze

“…It is well established, though, that sulfate (SO 4 2− ) is ubiquitous and is a key PM constituent in the atmosphere. Moreover, hygroscopic sulfate aerosols serve as efficient cloud condensation nuclei, affecting cloud formation, precipitation, and climate (4)(5)(6)(7)(8). A major fraction of regional acid deposition is attributed to the sulfate content that exerts debilitating effects on acid-sensitive ecosystems (9).…”

Elucidating severe urban haze formation in China

“…pollution | PM 2.5 | China | nucleation | secondary aerosols F ine particulate matter smaller than 2.5 μm (PM 2.5 ) represents a major environmental problem, degrading visibility, negatively affecting human health, and directly and indirectly impacting weather and climate (1)(2)(3)(4)(5). Aerosols can be directly emitted (primary) or formed through the gas-to-particle conversion process (secondary) in the atmosphere (6,7).…”