EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Exploring the ionic composition of the Asian Tropopause Aerosol Layer using medium duration balloon flights

Hazel Vernier1, Neeraj Rastogi2, Hongyu Liu3, Duncan Fairlie4, Amit Pandit3, Kristopher M. Bedka4, Anil Patel2, M. Venkat Ratnam5, B. Suneel Kumar6, Harish Gadhavi2, Frank G. Weinhold7, Gwenael Berthet1, and Jean-Paul Vernier3
Hazel Vernier et al.
  • 1Laboratory of Physics and Chemistry of the Environment, & Space, Atmospheric Science, France (
  • 2Physical Research Laboratory, Ahmedabad, India
  • 3National Institute of Aerospace, Hampton, VA, USA
  • 4NASA Langley Research Center, Hampton, VA, USA
  • 5National Atmospheric Research Laboratory, Gadanki, India
  • 6TIFR Balloon Facility, Hyderabad, India
  • 7Zürich, Switzerland

Satellite observations have revealed an enhanced aerosol layer near the tropopause over Asia during the summer monsoon, called the Asian Tropopause Aerosol Layer (ATAL). The chemical composition of the ATAL is investigated here using offline ionic analysis of aerosols collected with a balloon-borne impactor near the tropopause region over India onboard extended duration balloon flights in the summer of 2017 and winter 2018. We found NO3- and NO2- dominant among other ions with values ranging between 87-343 ng/m3 during the summer campaign. In contrast, SO4 levels were found above detection limit (>10 ng/m3) only in winter. In addition, we determined the origin of the air masses sampled during the flights through back trajectory analysis combined with convection. The results obtained therein were put into a context of large-scale transport and aerosol distribution with GEOS-Chem chemical transport model simulations. The first flight of summer 2017 sampled air mass within the Asian monsoon anticyclone (AMA), associated with smaller particle size found on stage 2 (particle size cut off > 0.15 microns) of the impactor, while the second flight sampled air mass at the edge of the AMA associated with larger particle size on stage 1 (particle size cut off between 2 and 0.5 microns). The sampled air masses in winter 2018 were affected by smoke from the Pacific Northwest fire event in Canada, which occurred 7 months prior to our campaign. Concentrations of SO42-, NH4+, and Ca2+ were enhanced. Overall, our results suggest that nitrogen- containing particles represent a large fraction of aerosols populating the ATAL in agreement with aircraft measurements during the StratoClim campaign. Furthermore, GEOS-chem model simulations suggest that lightning NOx emissions had a minimal impact on the production of nitrate aerosols sampled during the two flights. 

How to cite: Vernier, H., Rastogi, N., Liu, H., Fairlie, D., Pandit, A., Bedka, K. M., Patel, A., Ratnam, M. V., Kumar, B. S., Gadhavi, H., Weinhold, F. G., Berthet, G., and Vernier, J.-P.: Exploring the ionic composition of the Asian Tropopause Aerosol Layer using medium duration balloon flights, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2323,, 2021.