Volatile emissions during the 2021 Cumbre Vieja (La Palma) eruption integrating multiplatform atmospheric observations

Abstract. In a world increasingly impacted by climate change and natural hazards, atmospheric monitoring networks are essential for informed decision-making. During the 2021 La Palma eruption, we integrated surface and ground-based remote sensing measurements from global atmospheric network instruments, complemented by rapidly deployed sensors, to monitor volcanic gas emissions up to 140 km from the source. We used direct-sun measurements from low-resolution (EM27/SUN) and high-resolution (IFS-125HR) Fourier transform infrared (FTIR) spectrometers. On La Palma, the EM27/SUN was combined with a differential optical absorption spectroscopy (DOAS) instrument. We present new FTIR retrieval methods to derive the SO2, CO2, CO, HF, and HCl relative abundance in the plume from both low- and high-resolution solar absorption spectra. Using Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) data, we derived SO2 fluxes and estimated total emissions of 1.8 ± 0.2 Mt SO2, 19.4 ± 1.8 Mt CO2, 0.123 ± 0.005 Mt CO, 0.05 ± 0.01 Mt HCl, and 0.013 ± 0.002 Mt HF over the course of the eruption. These results are consistent with the mass balance derived from petrologic degassing estimates. This study demonstrates that high- and low-resolution FTIR and DOAS spectrometers, integrated within global monitoring networks, can provide quantitative constraints on volcanic gas composition and fluxes over large distances. Such capabilities are directly applicable to volcanic crisis monitoring, complementing dedicated networks, satellite observations and supporting improved assessments of volcanic impacts on the atmospheric composition at regional scales.