Total Ozone Content Trend during the Last Decade over Western Indian Tropical Station i.e. Udaipur

Abhishek Saxena,Brij Mohan Vyas

doi:10.4236/ajcc.2016.52018

Abstract

This study focuses on multi-year change in Total Ozone Content (TOC) values measured simultaneously by ground based instrument, i.e., MICROTOPS-II sun photometer and space based TOMS satellite experiment during the last decade, i.e., the period from 2002 to 2009 in the outskirts of the semi-arid and semi-urban tropical region of Udaipur (24.6°N, 74°E; 580 m asl), India. The negative declining trend in TOC value has been detected about 2 DU/decade by using Linear Regression Analysis (LRA) of the monthly averaged TOC levels. The LRA presents the best statistically significant percentage level (p) of greater than 99%. From the comparison of present result with the observations reported over mid, high and polar latitude sites, long-term TOC variability from tropical site is found to be the lowest, followed by their intermediate range from 10 to 30 DU/ decade over mid latitude sites and the highest range from 30 to 50 DU/decade over high to polar latitude. In order to establish the possible linking of reduction in TOC level per decade with other stratospheric dynamic parameters and atmospheric UV aerosols parameter, inter-annual change in average monthly TOC level has shown a strong correlation coefficient (r) of the order of 0.73 (p > 99.9990) with the stratospheric temperature, followed by its observed lower r value of 0.25 (p = 99%) for stratospheric zonal wind and then a significant correlation (r = 0.17; p = 95%) for AI 300 nm (Aerosols Index 300 nm) parameter. The variation of monthly mean meridional wind component does not illustrate a statistically significant correlation (r = 0.13; p < 80%) with their respective multi-year change in mean monthly TOC values. The consequence of such reduction of TOC per decade may be identified as the result of expected enhancement in incident ground UV-radiation level. At the same time, the harmful influence of increasing the UV level seems to be counteracted and reduced with the evidence of observed higher level of AI at 300 nm as high as 3 in the summer months over selected tropical environmental site.

Highlights

Atmospheric ozone is one of the leading minor Earth chemical constituents as well as positive Earth’s atmospheric radiative forcing active species [1] [2]
Since stratospheric ozone concentrations share about more than 90% of the Total Ozone Content (TOC) amount in the Earth’s atmosphere, and it shields from dangerous solar incident UV radiation to our human being life on the Earth system
As such these atmospheric dynamics and UV absorption aerosol index parameters are especially considered in the course of the work in views of that tropical ozone concentration is predominantly governed through several mechanisms, i.e., photochemical, chemical and atmospheric dynamic transport processes or incident ground UV radiation level, aerosols, cloud and meteorological parameters, etc. [11] [23] [24]

Summary

Introduction

Atmospheric ozone is one of the leading minor Earth chemical constituents as well as positive Earth’s atmospheric radiative forcing active species [1] [2]. In order to capture the most possible causes of the ozone depletion level and their consequences on feasible enhancing of ground level reaching the dangerous solar UV-A and UV-B radiation band for human health, controlling the role of affecting the thermal structure of atmosphere etc., an attempt has been made in this paper to quantify the trend analysis of TOC variability on basis of averaged multiyear monthly TOC values over tropical station like Udaipur (24.6 ̊N, 74 ̊E; 580 m asl) along with to ascertain their inter-correlation between the declining trend of TOC with other new most relevant atmospheric parameters like Aerosols Index at 300 nm (AI 300 nm), stratospheric air temperature (AT, TC) at 30 mb, zonal wind velocity (V, m/s) and meridional wind velocity component (U, m/s) As such these atmospheric dynamics and UV absorption aerosol index parameters are especially considered in the course of the work in views of that tropical ozone concentration is predominantly governed through several mechanisms, i.e., photochemical, chemical and atmospheric dynamic transport processes or incident ground UV radiation level, aerosols, cloud and meteorological parameters, etc. As such these atmospheric dynamics and UV absorption aerosol index parameters are especially considered in the course of the work in views of that tropical ozone concentration is predominantly governed through several mechanisms, i.e., photochemical, chemical and atmospheric dynamic transport processes or incident ground UV radiation level, aerosols, cloud and meteorological parameters, etc. [11] [23] [24]

Data Analysis

Results

Findings

Conclusions