Variations in tropospheric ozone driven by Rossby Wave Breaking events over the Indian subcontinent through Remote Sensing Retrievals

Rossby wave breaking (RWB) is a significant pathway for intrusion of stratospheric ozone into the troposphere. These events increase tropospheric ozone, which influences the greenhouse effect, atmospheric chemistry, and local ecosystems. As RWBs frequently affect the Indian subcontinent, a comprehensive study is required to understand the impact of RWB-induced ozone variations in the troposphere over the study region. To identify the RWB events, we used a contour searching algorithm and analyzed them for the period from 2004 to 2021 for Indian domain. Furthermore, we analyzed the anomalous ozone variability during the detected RWB event days using the CAMS global reanalysis (EAC4) and two independent satellite data sets, the Microwave Limb Sounder (MLS) and the Atmospheric Infrared Sounder (AIRS). Additionally, we utilized ground-based observations from the CPCB to examine the influence of RWB on the changes in surface ozone. The results of our study suggest that the CAMS reanalysis agrees well with the two independent satellite products, which provide a comprehensive understanding of ozone variability from various datasets. The upper-level potential vorticity anomaly allows ozone evolution to begin a few days before the strongest breaking time and intensify on the strongest day. Moreover, RWB enables the vertical intrusion of ozone down to 750 hPa, with variations observed from one case to another. Intrusion strength yields diverse tropospheric column increments (e.g., 190.5 ppbv at 100-150 hPa). Surface ozone response (850 hPa) to RWB correlates with intrusion intensity, resulting in 10-19 ppbv ozone anomalies. This could arise from the augmented tropospheric column ozone due to turbulent mixing. These findings deepen our understanding of RWB–related ozone variability and its impact on surface levels.