VolKilau: Volcano rapid response balloon campaign during the 2018 Kilauea eruption

After nearly 35 years of stable activity, the Kilauea volcanic system in Hawaii went through sudden changes in May 2018 with the emergence of 20 volcanic fissures along the Lower Eastern Rift Zone (LERZ), destroying 700 homes in Leilani Estates and forcing more than 2,000 people to evacuate. Elevated volcanic emissions lasted for several months between May and September 2018, leading to low visibility and poor air quality in Hawaii and across the western Pacific. The NASA-funded VolKilau mission was rapidly mounted and conducted between 11 and 18 June 2018 to (i) profile volcanic emissions with SO2 and aerosol measurements, (ii) validate satellite observations, and (iii) increase readiness for the next large volcanic eruption. Through a series of balloon-borne measurements with tethered and free-released launches, we measured SO2 concentration, aerosol concentration, and optical properties 60–80 km downwind from the volcanic fissures using gas sensors, optical particle counters, backscatter sondes, and an aerosol impactor. While most of the measurements made during the Kilauea eruption were ground based, the VolKilau mission represented a unique opportunity to characterize plume properties, constrain emission profiles, study early chemistry involving the conversion of SO2 into sulfuric acid, and understand the influence of water clouds in the removal of SO2. This unprecedented combination of measurements has significantly improved our team’s ability to assess the atmospheric and human impacts of a major event such as this