A study on the variations of mesospheric ozone over the Himalayan region using SABER long term dataset (2002-2017)

Muthukumaran Nandhini Devi

Shri Vishnu Engineering College for Women, Bhimavaram, West Godavri, Andhra Pradesh 534202.

Dr D.V. Phani Kumar

Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263002.

Abstract

It is known that the ozone layer in the stratosphere effectively blocks almost all solar radiation (Ultraviolet radiations) from reaching the Earth’s surface. Solar radiations are absorbed in the mesosphere and stratosphere by molecular oxygen (< 242 nm) and ozone (> 200 nm). Ozone in the lower atmosphere (troposphere) is toxic to human beings and many species of plant. It is, therefore, important to understand ozone variations in different atmospheric layers and study the atmospheric dynamics over different terrains including the Himalayan region. In this study, we, effectively, have utilized SABER measured ozone concentrations during a long-period (2002-2017) over the Himalayan Region, which lies between 25⁰ N and 35 ⁰ N (Latitude) and between 75 ⁰E to 85 ⁰E (Longitude), to study yearly variations and its anomalies. It is observed that the high and low ozone values of the order of 10 ppm (parts per million) and 1 ppm are observed in the stratosphere at regions of ~ 28-37 km and ~50-55km, respectively. Further, it is also observed that high and low ozone values of the order of 5 ppm and 0.5 ppm are observed in the mesosphere at regions of ~ 86-90 km and ~70-85km. Most importantly, the ozone concentrations during 2015 was observed to be enhanced at an altitude of around 25-34 km, and no such features could be seen in either 2014 or 2016 . Though we did not understand the possible physical mechanisms of these sudden and drastic variations of ozone concentrations particularly during 2014 and 2015, it is suspected that a low-altitude coupling mechanism (mesoscale) might have played a pivotal role to create such sudden and drastic changes in ozone concentrations. In order to understand these interesting and distinctive features, we are planning to verify ozone concentrations, succinctly, over different terrains /regions, using the available the same space-based remote sensing techniques (SABER).

Keywords: broadband emission radiometry, Dobson unit, chlorofluroarbons