Deep Convective Influence on CO and CH4 Observed by Aircore in Northern Tibetan Plateau During Asian Summer Monsoon

Balloon-borne trace gas observations using aircore were conducted in August 2019 and 2020 at northern side of Tibetan Plateau (TP). Carbon monoxide (CO) and methane (CH4) are retrieved from surface to around 25 km under Tibetan Plateau (TP) and Iranian Plateau (IP) modes of Asian summer monsoon anticyclone (ASMA). Obvious increase of tropospheric tracers (CO and CH4) are shown in profiles at upper troposphere. CO reaches its maximum at around 360 K under IP mode and around 370 K under TP mode. The deep convection first hit close to tropopause in northern India and then follow the more center anticyclonic flow to transport to launch site under TP mode; while the deep convection intercept more edge anticyclonic flow and follow the jet stream to quickly transport to launch site under IP mode identified by the trajectory analyses and high-resolution observations of cloud tops from satellite. CH4 keeps its tropospheric value up to 400 K due to its extended photochemical lifetime. A unique structure of CH4 is its double peak at upper troposphere, lower peak (around 150hPa) is related to the fresh convection (around 6 days) and upper peak (around 100hPa) is associated with slow ascent of aged convective airmass mostly from Tibetan Plateau around one month ago. However, the upper peak CH4 mixing ratio on August 23rd is 50 ppb higher than the lower peak, different from other observed profiles, relatively fresh convection (around 16 days) is from southern Pakistan.