Seasonal stratospheric intrusion of ozone in the upper troposphere over India

Abstract

The Model for Ozone and Related chemical Tracers-2 (MOZART-2) is used to examine the evolution of pollutant O₃ in the upper troposphere over the Indian region. Vertical profiles of ozone mixing ratio retrieved from Microwave Limb Sounder (MLS) aboard Earth Observing System (EOS) AURA satellite for the period 2005-2009 and Tropospheric Emission Spectrometer (TES) aboard (EOS) AURA for the period 2006-2007 has been analyzed. The satellite observations reveal the evidence of downward propagation of ozone (100-200 ppb) due to stratospheric intrusion during the winter and pre-monsoon seasons. The regular feature of enhancement of ozone in the upper troposphere over India is presented. Results obtained by the MOZART-2 simulations (for years 2000-2005) confirm the observations and indicate stratospheric intrusion of O3 during winter and pre-monsoon seasons. Observed enhanced O₃ mixing ratio in the upper troposphere is explained by, variation of Potential Vorticity (PV), tropopause pressure, relative humidity and CO-O₃ correlation.