气候变化领域集成服务门户(CCPortal): Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign

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DOI	10.5194/acp-17-12617-2017
	Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign
	Cho, Chaeyoon; Kim, Sang-Woo; Rupakheti, Maheswar; Park, Jin-Soo; Panday, Arnico; Yoon, Soon-Chang; Kim, Ji-Hyoung; Kim, Hyunjae; Jeon, Haeun; Sung, Minyoung; Bong Mann Kim; Hong, Seungkyu K.; Park, Rokjin J.; Rupakheti, Dipesh; Mahata, Khadak Singh; Praveen, Puppala Siva; Lawrence, Mark G.; Holben, Brent
通讯作者	Kim, SW (通讯作者)
发表日期	2017
ISSN	1680-7316
EISSN	1680-7324
起始页码	12617
结束页码	12632
卷号	17 期号:20
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).
关键词	BLACK-CARBON LIGHT-ABSORPTION NEPAL AIR REGION DUST
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS类目	Environmental Sciences ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000413546200003
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259087
推荐引用方式 GB/T 7714	Cho, Chaeyoon,Kim, Sang-Woo,Rupakheti, Maheswar,et al. Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign[J]. 中国科学院青藏高原研究所,2017,17(20).
APA	Cho, Chaeyoon.,Kim, Sang-Woo.,Rupakheti, Maheswar.,Park, Jin-Soo.,Panday, Arnico.,...&Holben, Brent.(2017).Wintertime aerosol optical and radiative properties in the Kathmandu Valley during the SusKat-ABC field campaign.ATMOSPHERIC CHEMISTRY AND PHYSICS,17(20).
MLA	Cho, Chaeyoon,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).