Abstract
The aerosol optical properties have been investigated using the Raman lidar system for the month of November 2018 at the western Himalayan station of Palampur. Before deriving the optical properties, the lidar data has been applied with initial pre-processing such as Dead time correction, atmospheric noise correction, temporal and spatial averaging, range correction, gluing etc. The optical properties such as backscatter coefficient, extinction coefficient and linear depolarization ratio have been derived by using the inversion algorithm proposed by Fernald. The results show that the backscatter coefficient was found in the range from 9.00E-9 m−1sr−1 to 4.97E-6 m−1sr−1 and the extinction coefficient was found in the range from 3.16E-7m-1 to 1.74E-4m-1. The Linear depolarization ratio was in the range from 0.0179 to 0.621 with lower values at near heights suggesting the dominance of spherical particles at the lower heights. We have also observed a cloud layer at a height of 9.5 km to 12.1 km with high depolarization ratio during the observation period on 22/11/2018.
Highlights
The effects of atmospheric aerosols on climate have large uncertainties including their direct and indirect effects related to aerosol-cloud interactions
The climatic effects of aerosol depend on its physical, chemical and optical properties along with its vertical distribution. This enables the need of advanced lidar systems which can provide the optical and microphysical properties of aerosols with its vertical distribution [1]
The copolarized and cross polarized Mie channels of the lidar system provides the linear depolarization ratio which is an indicator of the shape of the aerosol/cloud particle
Summary
The effects of atmospheric aerosols on climate have large uncertainties including their direct and indirect effects related to aerosol-cloud interactions. The climatic effects of aerosol depend on its physical, chemical and optical properties along with its vertical distribution. We are presenting the measurement of aerosol vertical profiles in Palampur, Himachal Pradesh, India. The measurements are based on a Raman lidar which provides information on the vertical distribution of optical presence of aerosols and clouds. METHODOLOGY 2.1 Sampling Site A Raymetrics Raman Lidar system, LR111-D200 is installed at the National Physical Laboratory’s remote monitoring station at the campus of CSIRInstitute of Himalayan Bioresource Technology (IHBT), Palampur, Himachal Pradesh, India at an altitude of 1347 m above mean sea level to study the vertical profiles of physical and optical properties of aerosols and clouds. It is the first ground based lidar facility in the Western Himalayan region of India
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