Balloon observatories needed for future volcanic eruption observations

Abstract:

In situ and remote sensing observations will be crucial to understand the evolution of sulfate aerosol production, fine ash emissions, and growth and transport of stratospheric aerosols. After the last large eruption, of Mt. Pinatubo in 1991, satellite observations were inadequate to measure the vertical distribution of the thick tropical aerosol cloud or the evolution of the aerosol size distribution. Balloon observations were only taken at mid-latitudes long after the eruption. These observations are crucial to evaluate climate model simulations of volcanic eruptions, which are also being used for sunlight reflection climate intervention (geoengineering) studies. There have been four eruptions since Pinatubo with stratospheric injections of more than 1 Tg of SO₂, and there will certainly be other larger eruptions in the future. Climate modeling groups are ready to simulate the response to the next eruption, but they will need data to initialize and evaluate their simulations. While existing and future satellite observations will be important, airplanes may or may not be able to quickly respond, and ground-based lidar observatories, especially in the tropics are still sparse, one crucial missing piece of information can be provided by balloons. If we establish a network of balloon observatories, ideally spaced at 10° in latitude, with two on opposite sides of the world in each latitude band, using new, inexpensive instruments that measure particles, we can take regular observations every one or two months to establish background concentrations and to develop routine observational and analysis systems. Then we will be ready to launch much more frequently after the next large eruption, defined as more than 1 Tg of SO₂, as measured by OMI or another satellite system. This will allow detailed observations of the conversion of SO₂ to sulfate aerosols and the subsequent evolution of the aerosol size distribution. A proposed network and budget will be presented.