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Proceedings Paper

Variability of aerosol optical depth and aerosol radiative forcing over Northwest Himalayan region
Author(s): Shaik Darga Saheb; Yogesh Kant; D. Mitra
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Paper Abstract

In recent years, the aerosol loading in India is increasing that has significant impact on the weather/climatic conditions. The present study discusses the analysis of temporal (monthly and seasonal) variation of aerosol optical depth(AOD) by the ground based observations from sun photometer and estimate the aerosol radiative forcing and heating rate over selected station Dehradun in North western Himalayas, India during 2015. The in-situ measurements data illustrate that the maximum seasonal average AOD observed during summer season AOD at 500nm ≈ 0.59±0.27 with an average angstrom exponent, α ≈0.86 while minimum during winter season AOD at 500nm ≈ 0.33±0.10 with angstrom exponent, α ≈1.18. The MODIS and MISR derived AOD was also compared with the ground measured values and are good to be in good agreement. Analysis of air mass back trajectories using HYSPLIT model reveal that the transportation of desert dust during summer months. The Optical Properties of Aerosols and clouds (OPAC) model was used to compute the aerosol optical properties like single scattering albedo (SSA), Angstrom coefficient (α) and Asymmetry(g) parameter for each day of measurement and they are incorporated in a Discrete Ordinate Radiative Transfer model, i.e Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) to estimate the direct short-wave (0.25 to 4 μm) Aerosol Radiative forcing at the Surface (SUR), the top-of-atmosphere (TOA) and Atmosphere (ATM). The maximum Aerosol Radiative Forcing (ARF) was observed during summer months at SUR ≈ -56.42 w/m2, at TOA ≈-21.62 w/m2 whereas in ATM ≈+34.79 w/m2 with corresponding to heating rate 1.24°C/day with in lower atmosphere.

Paper Details

Date Published: 6 May 2016
PDF: 9 pages
Proc. SPIE 9876, Remote Sensing of the Atmosphere, Clouds, and Precipitation VI, 98762M (6 May 2016); doi: 10.1117/12.2223641
Show Author Affiliations
Shaik Darga Saheb, Indian Institute of Remote Sensing (India)
Yogesh Kant, Indian Institute of Remote Sensing (India)
D. Mitra, Indian Institute of Remote Sensing (India)

Published in SPIE Proceedings Vol. 9876:
Remote Sensing of the Atmosphere, Clouds, and Precipitation VI
Eastwood Im; Raj Kumar; Song Yang, Editor(s)

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