Observation of optical properties and sources of aerosols at Buddha’s birthplace, Lumbini, Nepal: environmental implications
- 864 Downloads
For the first time, aerosol optical properties are measured over Lumbini, Nepal, with CIMEL sunphotometer of the Aerosol Robotic Network (AERONET) program. Lumbini is a sacred place as the birthplace of Lord Buddha, and thus a UNESCO world heritage site, located near the northern edge of the central Indo-Gangetic Plains (IGP) and before the Himalayan foothills (and Himalayas) to its north. Average aerosol optical depth (AOD) is found to be 0.64 ± 0.38 (0.06–3.28) over the sampling period (January 2013–December 2014), with the highest seasonal AOD during the post-monsoon season (0.72 ± 0.44). More than 80% of the daily averaged AOD values, during the monitoring period, are above 0.3, indicating polluted conditions in the region. The levels of aerosol load observed over Lumbini are comparable to those observed at several heavily polluted sites in the IGP. Based on the relationship between AOD and Ångstrom exponent (α), anthropogenic, biomass burning, and mixed aerosols are found to be the most prevalent aerosol types. The aerosol volume-size distribution is bi-modal during all four seasons with modes centered at 0.1–0.3 and 3–4 μm. For both fine and coarse modes, the highest volumetric concentration of ~ 0.08 μm−3 μm−2 is observed during the post-monsoon and pre-monsoon seasons. As revealed by the single-scattering albedo (SSA), asymmetry parameter (AP), and refractive index (RI) analyses, aerosol loading over Lumbini is dominated by absorbing, urban-industrial, and biomass burning aerosols.
KeywordsAerosol optical depth Ångstrom exponent Indo-Gangetic Plain Lumbini Himalayas Nepal
Maheswar Rupakheti acknowledges the support provided by the Institute for Advanced Sustainability Studies (IASS) which is funded by the German Federal Ministry for Education and Research (BMBF) and the Brandenburg Ministry for Science, Research and Culture (MWFK). The authors acknowledge Christoph Cüppers and Michael Pahlke of the Lumbini International Research Institute (LIRI) for providing the space and power to run the instruments at the LIRI premises and Bhogendra Kathayat and Bhoj Raj Bhatta for their support in the operation of the site.
This study is supported by National Natural Science Foundation of China (41630754 and 41721091), Chinese Academy of Sciences (QYZDJ-SSW-DQC039) and the State Key Laboratory of Cryospheric Science (SKLCS-ZZ-2017). Dipesh Rupakheti is supported by CAS-TWAS President’s Fellowship for International PhD Students.
- Adhikary B, Carmichael GR, Tang Y, Leung LR, Qian Y, Schauer JJ, Stone EA, Ramanathan V, Ramana MV (2007) Characterization of the seasonal cycle of south Asian aerosols: a regional-scale modeling analysis. J Geophys Res 112(D22S22):1–22Google Scholar
- Choudhry P, Misra A, Tripathi S (2012) Study of MODIS derived AOD at three different locations in the Indo Gangetic Plain: Kanpur, Gandhi College and Nainital, Annales Geophysicae. Copernicus GmbH, pp. 1479–1493Google Scholar
- Ganguly D, Jayaraman A, Rajesh TA, Gadhavi H (2006) Wintertime aerosol properties during foggy and nonfoggy days over urban center Delhi and their implications for shortwave radiative forcing. J Geophys Res 111:1–15Google Scholar
- Gautam R, Hsu NC, Lau KM, Tsay SC, Kafatos M (2009) Enhanced pre-monsoon warming over the Himalayan-Gangetic region from 1979 to 2007. Geophys Res Lett 36:1–5Google Scholar
- Gautam R, Hsu NC, Tsay SC, Lau KM, Holben B, Bell S, Smirnov A, Li C, Hansell R, Ji Q, Payra S, Aryal D, Kayastha R, Kim KM (2011) Accumulation of aerosols over the Indo-Gangetic plains and southern slopes of the Himalayas: distribution, properties and radiative effects during the 2009 pre-monsoon season. Atmos Chem Phys 11:12841–12863CrossRefGoogle Scholar
- Kim M, Kim J, Jeong U, Kim W, Hong H, Holben B, Eck TF, Lim JH, Song CK, Lee S, Chung CY (2016) Aerosol optical properties derived from the DRAGON-NE Asia campaign, and implications for a single-channel algorithm to retrieve aerosol optical depth in spring from meteorological imager (MI) on-board the communication, ocean, and meteorological satellite (COMS). Atmos Chem Phys 16:1789–1808CrossRefGoogle Scholar
- Kumar V, Sarkar C, Sinha V (2016) Influence of post-harvest crop residue fires on surface ozone mixing ratios in the NW IGP analyzed using 2 years of continuous in situ trace gas measurements. J Geophys Res 121:3619–3633Google Scholar
- Marcq S, Laj P, Roger J, Villani P, Sellegri K, Bonasoni P, Marinoni A, Cristofanelli P, Verza G, Bergin M (2010) Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m asl). Atmos Chem Phys 10:5859–5872CrossRefGoogle Scholar
- Ramachandran S, Cherian R (2008) Regional and seasonal variations in aerosol optical characteristics and their frequency distributions over India during 2001–2005. J Geophys Res 113:1–16Google Scholar
- Sarkar C, Kumar V, Sinha V (2013) Massive emissions of carcinogenic benzenoids from paddy residue burning in north India. Curr Sci India 104:1703–1709Google Scholar
- Sigdel M, Ma Y (2015) Evaluation of future precipitation scenario using statistical downscaling model over humid, subhumid, and arid region of Nepal—a case study. Theor Appl Climatol 123:1–8Google Scholar
- Singh R, Dey S, Tripathi S, Tare V, Holben B (2004) Variability of aerosol parameters over Kanpur, northern India. J Geophys Res 109:1–14Google Scholar
- Singh A, Rajput P, Sharma D, Sarin MM, Singh D (2014) Black carbon and elemental carbon from postharvest agricultural-waste burning emissions in the indo-Gangetic plain. Adv Meteorol 2014:1–10Google Scholar
- Smirnov A, Holben B, Slutsker I, Giles D, McClain CR, Eck T, Sakerin S, Macke A, Croot P, Zibordi G (2009) Maritime aerosol network as a component of aerosol robotic network. J Geophys Res Atmos 114Google Scholar
- Stocker T, Qin D, Plattner G, Tignor M, Allen S, Boschung J, Nauels A, Xia Y, Bex B, Midgley B (2013) IPCC, 2013: climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate changeGoogle Scholar
- Tiwari S, Singh A (2013) Variability of aerosol parameters derived from ground and satellite measurements over Varanasi located in the Indo-Gangetic Basin. Aerosol Air Qual Res 13:627–638Google Scholar
- Wan X, Kang S, Li Q, Rupakheti D, Zhang Q, Guo J, Chen P, Tripathee L, Rupakheti M, Panday AK, Wang W, Kawamura K, Gao S, Wu G, Cong Z (2017) Organic molecular tracers in the atmospheric aerosols from Lumbini, Nepal, in the northern Indo-Gangetic Plain: influence of biomass burning. Atmos Chem Phys 17:8867–8885Google Scholar