Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications
Continuous ground-based observations of aerosols over the Himalayan region are highly beneficial in studying aerosol trends over the complex geographic terrain. This study presents the results from continuous long-term observations (2004–2016) of aerosols over a high-altitude site in the central Him...
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Frontiers Media S.A.
2022-06-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2022.851444/full |
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| author | Hema Joshi Hema Joshi Manish Naja Priyanka Srivastava Priyanka Srivastava Tarun Gupta Mukunda M. Gogoi S. Suresh Babu |
| author_facet | Hema Joshi Hema Joshi Manish Naja Priyanka Srivastava Priyanka Srivastava Tarun Gupta Mukunda M. Gogoi S. Suresh Babu |
| author_sort | Hema Joshi |
| collection | DOAJ |
| description | Continuous ground-based observations of aerosols over the Himalayan region are highly beneficial in studying aerosol trends over the complex geographic terrain. This study presents the results from continuous long-term observations (2004–2016) of aerosols over a high-altitude site in the central Himalayas – Nainital, quantifying multihued aspects of black carbon (BC) and columnar aerosol optical depth (AOD). The results reveal that BC and AOD have a positive trend of 23.04 ± 3.00 ng m−3 year−1 and 0.0076 ± 0.0003 year−1, respectively. Simultaneously, a positive trend of 0.0066 ± 0.0059 year−1 is observed in the Angstrom exponent, thus indicating an increase in anthropogenic aerosols. The satellite observations covering a broader region around Nainital also depicted increasing trends in AOD (0.0042–0.0074 year−1), absorbing aerosol optical depth (0.0001 ± 0.0001 year−1) and aerosol index (0.0131 ± 0.0019 year−1), along with a slight decline in single scattering albedo (−0.0004 year−1). These results suggest that aerosols of absorbing nature might have increased over this region in recent times. Investigation of the AOD ratio, obtained from aerosol vertical profiles, revealed an increasing trend in aerosol load below 1 km. The observed trends in aerosols are found to be associated with enhanced biomass burning activity, reflected in terms of the positive trend in fire count ∼38.65 ± 5.88 year−1 over the region. |
| first_indexed | 2024-04-13T19:41:21Z |
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| id | doaj.art-8940d4ed182940998d44924f272c5b44 |
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| language | English |
| last_indexed | 2024-04-13T19:41:21Z |
| publishDate | 2022-06-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Earth Science |
| spelling | doaj.art-8940d4ed182940998d44924f272c5b442022-12-22T02:32:54ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632022-06-011010.3389/feart.2022.851444851444Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and ImplicationsHema Joshi0Hema Joshi1Manish Naja2Priyanka Srivastava3Priyanka Srivastava4Tarun Gupta5Mukunda M. Gogoi6S. Suresh Babu7Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, IndiaDepartment of Civil Engineering, Indian Institute of Technology, Kanpur, IndiaAryabhatta Research Institute of Observational Sciences (ARIES), Nainital, IndiaAryabhatta Research Institute of Observational Sciences (ARIES), Nainital, IndiaDepartment of Physics and Astrophysics, University of Delhi, Delhi, IndiaDepartment of Civil Engineering, Indian Institute of Technology, Kanpur, IndiaSpace Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, IndiaSpace Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, IndiaContinuous ground-based observations of aerosols over the Himalayan region are highly beneficial in studying aerosol trends over the complex geographic terrain. This study presents the results from continuous long-term observations (2004–2016) of aerosols over a high-altitude site in the central Himalayas – Nainital, quantifying multihued aspects of black carbon (BC) and columnar aerosol optical depth (AOD). The results reveal that BC and AOD have a positive trend of 23.04 ± 3.00 ng m−3 year−1 and 0.0076 ± 0.0003 year−1, respectively. Simultaneously, a positive trend of 0.0066 ± 0.0059 year−1 is observed in the Angstrom exponent, thus indicating an increase in anthropogenic aerosols. The satellite observations covering a broader region around Nainital also depicted increasing trends in AOD (0.0042–0.0074 year−1), absorbing aerosol optical depth (0.0001 ± 0.0001 year−1) and aerosol index (0.0131 ± 0.0019 year−1), along with a slight decline in single scattering albedo (−0.0004 year−1). These results suggest that aerosols of absorbing nature might have increased over this region in recent times. Investigation of the AOD ratio, obtained from aerosol vertical profiles, revealed an increasing trend in aerosol load below 1 km. The observed trends in aerosols are found to be associated with enhanced biomass burning activity, reflected in terms of the positive trend in fire count ∼38.65 ± 5.88 year−1 over the region.https://www.frontiersin.org/articles/10.3389/feart.2022.851444/fullblack carbonaerosol optical depthtrendscarbonaceous aerosolsHimalayasbiomass burning |
| spellingShingle | Hema Joshi Hema Joshi Manish Naja Priyanka Srivastava Priyanka Srivastava Tarun Gupta Mukunda M. Gogoi S. Suresh Babu Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications Frontiers in Earth Science black carbon aerosol optical depth trends carbonaceous aerosols Himalayas biomass burning |
| title | Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications |
| title_full | Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications |
| title_fullStr | Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications |
| title_full_unstemmed | Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications |
| title_short | Long-Term Trends in Black Carbon and Aerosol Optical Depth Over the Central Himalayas: Potential Causes and Implications |
| title_sort | long term trends in black carbon and aerosol optical depth over the central himalayas potential causes and implications |
| topic | black carbon aerosol optical depth trends carbonaceous aerosols Himalayas biomass burning |
| url | https://www.frontiersin.org/articles/10.3389/feart.2022.851444/full |
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