气候变化领域集成服务门户(CCPortal): Aerosol influences on low-level clouds in the West African monsoon

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DOI	10.5194/acp-19-8503-2019
	Aerosol influences on low-level clouds in the West African monsoon
	Taylor J.W.; Haslett S.L.; Bower K.; Flynn M.; Crawford I.; Dorsey J.; Choularton T.; Connolly P.J.; Hahn V.; Voigt C.; Sauer D.; Dupuy R.; Brito J.; Schwarzenboeck A.; Bourriane T.; Denjean C.; Rosenberg P.; Flamant C.; Lee J.D.; Vaughan A.R.; Hill P.G.; Brooks B.; Catoire V.; Knippertz P.; Coe H.
发表日期	2019
ISSN	16807316
起始页码	8503
结束页码	8522
卷号	19 期号:13
英文摘要	Low-level clouds (LLCs) cover a wide area of southern West Africa (SWA) during the summer monsoon months and have an important cooling effect on the regional climate. Previous studies of these clouds have focused on modelling and remote sensing via satellite. We present the first comprehensive set of in situ measurements of cloud microphysics from the region, taken during June-July 2016, as part of the DACCIWA (Dynamics-aerosol-chemistry-cloud interactions in West Africa) campaign. This novel dataset allows us to assess spatial, diurnal, and day-to-day variation in the properties of these clouds over the region. LLCs developed overnight and mean cloud cover peaked a few hundred kilometres inland around 10:00 local solar time (LST), before clouds began to dissipate and convection intensified in the afternoon. Regional variation in LLC cover was largely orographic, and no lasting impacts in cloud cover related to pollution plumes were observed downwind of major population centres. The boundary layer cloud drop number concentration (CDNC) was locally variable inland, ranging from 200 to 840 cm-3 (10th and 90th percentiles at standard temperature and pressure), but showed no systematic regional variations. Enhancements were seen in pollution plumes from the coastal cities but were not statistically significant across the region. A significant fraction of accumulation mode aerosols, and therefore cloud condensation nuclei, were from ubiquitous biomass burning smoke transported from the Southern Hemisphere. To assess the relative importance of local and transported aerosol on the cloud field, we isolated the local contribution to the aerosol population by comparing inland and offshore size and composition measurements. A parcel model sensi- tivity analysis showed that doubling or halving local emissions only changed the calculated cloud drop number concentration by 13 %-22 %, as the high background meant local emissions were a small fraction of total aerosol. As the population of SWA grows, local emissions are expected to rise. Biomass burning smoke transported from the Southern Hemisphere is likely to dampen any effect of these increased local emissions on cloud-aerosol interactions. An integrative analysis between local pollution and Central African biomass burning emissions must be considered when predicting anthropogenic impacts on the regional cloud field during the West African summer monsoon. © 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License.
语种	英语
scopus关键词	aerosol; atmospheric chemistry; cloud microphysics; cloud radiative forcing; concentration (composition); diurnal variation; monsoon; remote sensing; West Africa
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/144308
作者单位	Centre for Atmospheric Science, School of Earth and Environmental Sciences, University of Manchester, Manchester, United Kingdom; National Centre for Atmospheric Science, University of Manchester, Manchester, United Kingdom; Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany; Institut für Physik der Atmosphäre, Johannes Gutenberg-Universität Mainz, Mainz, Germany; Laboratoire de Météorologie Physique, Université Clermont Auvergne, Clermont-Ferrand, France; CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France; School of Earth and Environment, University of Leeds, Leeds, United Kingdom; LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France; Wolfson Atmospheric Chemistry Laboratories, University of York, York, United Kingdom; National Centre for Atmospheric Science, University of York, York, United Kingdom; Department of Meteorology, University of Reading, Reading, United Kingdom; National Centre for Atmospheric Science, Leeds, U...
推荐引用方式 GB/T 7714	Taylor J.W.,Haslett S.L.,Bower K.,et al. Aerosol influences on low-level clouds in the West African monsoon[J],2019,19(13).
APA	Taylor J.W..,Haslett S.L..,Bower K..,Flynn M..,Crawford I..,...&Coe H..(2019).Aerosol influences on low-level clouds in the West African monsoon.Atmospheric Chemistry and Physics,19(13).
MLA	Taylor J.W.,et al."Aerosol influences on low-level clouds in the West African monsoon".Atmospheric Chemistry and Physics 19.13(2019).