气候变化领域集成服务门户(CCPortal): Cloud condensation nuclei characteristics during the Indian summer monsoon over a rain-shadow region

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DOI	10.5194/acp-20-7307-2020
	Cloud condensation nuclei characteristics during the Indian summer monsoon over a rain-shadow region
	Jayachandran V.N.; Varghese M.; Murugavel P.; Todekar K.S.; Bankar S.P.; Malap N.; Dinesh G.; Safai P.D.; Rao J.; Konwar M.; Dixit S.; Prabha T.V.
发表日期	2020
ISSN	1680-7316
起始页码	7307
结束页码	7334
卷号	20 期号:12
英文摘要	Continuous aerosol and cloud condensation nuclei (CCN) measurements carried out at the ground observational facility situated in the rain-shadow region of the Indian subcontinent are illustrated. These observations were part of the Cloud Aerosol Interaction Precipitation Enhancement Experiment (CAIPEEX) during the Indian summer monsoon season (June to September) of 2018. Observations are classified as dry-continental (monsoon break) and wet-marine (monsoon active) according to the air mass history. CCN concentrations measured for a range of supersaturations (0.2 %-1.2 %) are parameterized using Twomey's empirical relationship. CCN concentrations at low (0.2 %) supersaturation (SS) were high (> 1000 cm-3) during continental conditions and observed together with high black carbon (BC ∼ 2000ngm-3) and columnar aerosol loading. During the marine air mass conditions, CCN concentrations diminished to ∼ 350 cm-3 at 0.3 % SS and low aerosol loading persisted (BC ∼ 800ngm-3). High CCN activation fraction (AF) of ∼D 0:55 (at 0.3 % SS) was observed before the monsoon rainfall, which reduced to ∼ D 0:15 during the marine air mass and enhanced to ∼ D 0:32 after that. There was mostly monomodal aerosol number size distribution (NSD) with a mean geometric mean diameter (GMD) of ∼ D 85 nm, with least (∼ D 9 %) contribution from nucleation mode (< 30 nm) particles persisted before the monsoon, while multimode NSD with ∼ D 19 % of nucleation mode particles was found during the marine air mass. Critical activation diameters (dcri) for 0.3 % SS were found to be about 72, 169, and 121 nm prior to, during, and after the marine conditions, respectively. The better association of CCN with aerosol absorption, and the concurrent accumulation mode particles during continental conditions, points to the possibility of aged (oxygenated) carbonaceous aerosols enhancing the CCN activity prior to the marine conditions. An enhancement in CCN concentrations and k values during the daytime along with absorption Ångström exponent was observed during the marine conditions. Best closure obtained using measured critical diameter and ammonium sulfate composition during continental conditions emphasizes the role of aged aerosols contributing to the accumulation mode, enhancing the CCN efficiency. The overestimation of CCN and less hygroscopicity of accumulation mode aerosols during the marine air mass indicate the role of size-dependent aerosol composition in CCN activity during the period. © 2020 Author(s).
语种	英语
scopus关键词	absorption; aerosol; air mass; ammonium sulfate; cloud condensation nucleus; concentration (composition); monsoon
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/247691
作者单位	Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, India
推荐引用方式 GB/T 7714	Jayachandran V.N.,Varghese M.,Murugavel P.,et al. Cloud condensation nuclei characteristics during the Indian summer monsoon over a rain-shadow region[J],2020,20(12).
APA	Jayachandran V.N..,Varghese M..,Murugavel P..,Todekar K.S..,Bankar S.P..,...&Prabha T.V..(2020).Cloud condensation nuclei characteristics during the Indian summer monsoon over a rain-shadow region.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(12).
MLA	Jayachandran V.N.,et al."Cloud condensation nuclei characteristics during the Indian summer monsoon over a rain-shadow region".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.12(2020).