New insights into the effects of the Asian Summer Monsoon on the atmosphere
Scientists discovered that pollutants lofted from the surface by the monsoon system contribute to forming new particles at high altitudes at a regional scale, and that these particles grow to sizes where they can impact climate by scattering sunlight and modifying cloud properties. The effect can be either cooling or warming, depending on other factors such as where the particles travel to in the atmosphere and how they interact with clouds.
The Asian Summer Monsoon is a meteorological phenomenon whereby persistent convection over South, Southeast, and East Asia in summer lofts air from the surface to the upper troposphere and lower stratosphere, significantly enhancing concentrations of water vapour, trace gases and aerosols at these high altitudes.
The observations were made aboard the US NSF GV, one of two aircraft that took part in the Asian Summer Monsoon Chemical Climate Impacts Project ACCLIP, a joint National Aeronautics and Space Administration (NASA) and National Center for Atmospheric Research (NCAR) campaign based in the Republic of Korea.
The team measured the number, size and composition of aerosol particles and the concentrations of different gases in the atmosphere as they flew, and combined these data with models on different scales to show the formation and growth of small particles in the upper troposphere (around 12-14 km from the surface), the role of pollutants in these processes, and their impacts on climate.
Further information:
Research professor Christina Williamson, Finnish Meteorological Institute, puh. 050 479 4514
Email addresses are in the format: firstname.lastname@fmi.fi.
The scientific article is openly available in Nature Communications.
Reference: Williamson, C.J., Borrmann, S., Brauner, P. et al. Upper troposphere aerosol formation enhanced by monsoon lofted pollution. Nat Commun 17, 9672 (2026). https://doi.org/10.1038/s41467-026-75073-x
