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AGU: Journal of Geophysical Research, Atmospheres

 

Keywords

  • aerosol radiative forcing
  • Himalayan aerosols
  • atmospheric aerosols

Index Terms

  • Atmospheric Composition and Structure: Aerosols and particles
  • Atmospheric Composition and Structure: Biosphere/atmosphere interactions
  • Atmospheric Composition and Structure: Pollution: urban and regional
  • Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry
  • Atmospheric Composition and Structure: Radiation: transmission and scattering
Abstract
Cited By (14)
 

Abstract

Aerosol characteristics at a high-altitude location in central Himalayas: Optical properties and radiative forcing

P. Pant

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

P. Hegde

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

U. C. Dumka

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

Ram Sagar

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

S. K. Satheesh

Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, India

K. Krishna Moorthy

Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, India

Auromeet Saha

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

M. K. Srivastava

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, India

Collocated measurements of the mass concentrations of aerosol black carbon (BC) and composite aerosols near the surface were carried out along with spectral aerosol optical depths (AODs) from a high-altitude station, Manora Peak in central Himalayas, during a comprehensive aerosol field campaign in December 2004. Despite being a pristine location in the Shivalik Ranges of central Himalayas and having a monthly mean AOD (at 500 nm) of 0.059 ± 0.033 (typical to this site), total suspended particulate (TSP) concentration was in the range 15–40 μg m−3 (mean value 27.1 ± 8.3 μg m−3). Interestingly, aerosol BC had a mean concentration of 1.36 ± 0.99 μg m−3 and contributed ∼5.0 ± 1.3% to the composite aerosol mass. This large abundance of BC is found to have linkages to the human activities in the adjoining valley and to the boundary layer dynamics. Consequently, the inferred single scattering albedo lies in the range of 0.87 to 0.94 (mean value 0.90 ± 0.03), indicating significant aerosol absorption. The estimated aerosol radiative forcing was as low as −4.2 W m−2 at the surface, +0.7 W m−2 at the top of the atmosphere, implying an atmospheric forcing of +4.9 W m−2. Though absolute value of the atmospheric forcing is quite small, which arises primarily from the very low AOD (or the column abundance of aerosols), the forcing efficiency (forcing per unit optical depth) was ∼88 W m−2, which is attributed to the high BC mass fraction.

Received 15 October 2005; accepted 25 May 2006; published 14 September 2006.

Citation: Pant, P., P. Hegde, U. C. Dumka, R. Sagar, S. K. Satheesh, K. K. Moorthy, A. Saha, and M. K. Srivastava (2006), Aerosol characteristics at a high-altitude location in central Himalayas: Optical properties and radiative forcing, J. Geophys. Res., 111, D17206, doi:10.1029/2005JD006768.

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