Role of Long-range Transport, Downward Transport and Biomass Burning on the Tropospheric Ozone over the central Himalaya
Abstract
Tropospheric ozone is a secondary pollutant and plays crucial roles in determining air quality and climate change. It is also the primary source for the highly reactive OH radical, an atmospheric detergent. However, its chemistry and different processes controlling its variability over the tropical Asian region, particularly in South Asia, where anthropogenic emissions have increased rapidly in last few decades, are not well studied. Further, air pollution in the Himalayan region is being affected by deep convection and downward transport covering influence of global and regional air masses. In this reference, balloon-borne observations of ozone and meteorological parameters are being made from the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital (29.4 oN, 79.5 oE, 1793 m amsl) since 2011 to characterize vertical distribution of ozone in the central Himalayas. The seasonal distributions of tropospheric ozone profiles are studied for more than seven years and the effect of regional emissions, long range transport, and downward transport are investigated utilizing the FLEXPART Lagrangian model. Trajectory residence time and tracer-based NOx emissions are studied for different sectors (e.g. Arabian Sea, Africa, Europe etc.) including India and significant influence of long-range transport and local emissions have been observed. Higher variability in the tropospheric ozone profiles has been observed during winter and spring, which is primarily caused by frequent tropopause folding events and associated stratospheric intrusion. This is leading to 40-75% higher ozone in the tropopause altitude range of 14-16 km. Such high ozone events are also observed in the satellite observations (i.e. AIRS, MLS, IASI) and high resolution ERA5 PV distributions support the downward transport. Further, quantitative study of ozone transported from the stratosphere to the troposphere using FLEXPART model and white stripe features in radiance observations of geostationary satellite at 9.6 µm show highest ozone transport during winter and spring seasons. These results will be presented in detail.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA177.0007R
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0230 Impacts of climate change: human health;
- GEOHEALTH