Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign

doi:10.5194/acp-17-12617-2017

	Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign
	Cho, C (Cho, Chaeyoon)2; Kim, SW (Kim, Sang-Woo)2; Rupakheti, M (Rupakheti, Maheswar)3; Park, JS (Park, Jin-Soo)4; Panday, A (Panday, Arnico)5; Yoon, SC (Yoon, Soon-Chang)2; Kim, JH (Kim, Ji-Hyoung)2; Kim, H (Kim, Hyunjae)4; Jeon, H (Jeon, Haeun)4; Sung, M (Sung, Minyoung)4
刊名	ATMOSPHERIC CHEMISTRY AND PHYSICS
	2017
卷号	17 期号:20 页码:12617-12632
关键词	Black-carbon Light-absorption Nepal Himalaya Air Particles Region Dust
DOI	10.5194/acp-17-12617-2017
文献子类	Article
英文摘要	Particulate air pollution in the Kathmandu Valley has reached severe levels that are mainly due to uncontrolled emissions and the location of the urban area in a bowl-shaped basin with associated local wind circulations. The AERONET measurements from December 2012 to August 2014 revealed a mean aerosol optical depth (AOD) of approximately 0.30 at 675 nm during winter, which is similar to that of the post-monsoon but half of that of the pre-monsoon AOD (0.63). The distinct seasonal variations are closely related to regional-scale monsoon circulations over South Asia and emissions in the Kathmandu Valley. During the SusKat-ABC campaign (December 2012-February 2013), a noticeable increase in both aerosol scattering (sigma(s); 313 -> 577 Mm(-1) at 550 nm) and absorption (sigma(a); 98 -> 145 Mm(-1) at 520 nm) coefficients occurred before and after 4 January 2013. This can be attributed to the increase in wood-burned fires due to a temperature drop and the start of firing at nearby brick kilns. The sigma(s) value in the Kathmandu Valley was a factor of 0.5 lower than that in polluted cities in India. The sigma(a) value in the Kathmandu Valley was approximately 2 times higher than that at severely polluted urban sites in India. The aerosol mass scattering efficiency of 2.6 m(2) g(-1) from PM10 measurements in the Kathmandu Valley is similar to that reported in urban areas. However, the aerosol mass absorption efficiency was determined to be 11 m(2) g(-1) from PM10 measurements, which is higher than that reported in the literature for pure soot particles (7.5 +/- 1.2 m(2) g(-1)). This might be due to the fact that most of the carbonaceous aerosols in the Kathmandu Valley were thought to be mostly externally mixed with other aerosols under dry conditions due to a short travel time from their sources. The sigma(s) and sigma(a) values and the equivalent black carbon (EBC) mass concentration reached up to 757 Mm(-1), 224 Mm(-1), and 29 mu gm(-3) at 08:00 LST (local standard time), respectively but decreased dramatically during the daytime (09:00-18:00 LST), to one-quarter of the morning average (06:00-09:00 LST) due to the development of valley winds and an atmospheric bounder layer. The sigma(s) and sigma(a) values and the EBC concentration remained almost constant during the night at the levels of 410 Mm(-1), 130 Mm(-1), and 17 mu g m(-3), respectively. The average aerosol direct radiative forcings over the intensive measurement period were estimated to be -6.9 +/- 1.4 Wm(-2) (top of the atmosphere) and -20.8 +/- 4.6 W m(-2) (surface). Therefore, the high at-mospheric forcing (i.e., 13.9 +/- 3.6 Wm(-2)) and forcing efficiency (74.8 +/- 24.2 Wm(-2) tau(-1)) can be attributed to the high portion of light-absorbing aerosols in the Kathmandu Valley, as indicated by the high black carbon (or elemental carbon) to sulphate ratio (1.5 +/- 1.1).
学科主题	自然地理学
WOS研究方向	Meteorology & Atmospheric Sciences
语种	英语
WOS记录号	WOS:000413546200003
内容类型	期刊论文
源URL	[http://ir.itpcas.ac.cn/handle/131C11/7962]
专题	青藏高原研究所_图书馆
通讯作者	Kim, SW
作者单位	1.iGBu, Corona, CA 92882 USA. 2.Seoul Natl Univ, Sch Earth & Environm Sci, Seoul 08826, South Korea. 3.Inst Adv Sustainabil Studies, Berliner Str 130, D-14467 Potsdam, Germany. 4.Natl Inst Environm Res, Incheon 22689, South Korea. 5.Int Ctr Integrated Mt Dev, Kathmandu 44700, Nepal. 6.Natl Inst Meteorol Sci, Seogwipo 63568, South Korea. 7.Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Tibetan Environm Changes & Land Surface P, Beijing 100101, Peoples R China. 8.NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
推荐引用方式 GB/T 7714	Cho, C ,Kim, SW ,Rupakheti, M ,et al. Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign[J]. ATMOSPHERIC CHEMISTRY AND PHYSICS,2017,17(20):12617-12632.
APA	Cho, C .,Kim, SW .,Rupakheti, M .,Park, JS .,Panday, A .,...&Kim, SW.(2017).Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign.ATMOSPHERIC CHEMISTRY AND PHYSICS,17(20),12617-12632.
MLA	Cho, C ,et al."Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign".ATMOSPHERIC CHEMISTRY AND PHYSICS 17.20(2017):12617-12632.