A cross-comparison of thermal infrared versus ultraviolet ground-based retrievals of SO2 masses during Strombolian explosions

Abstract

This study investigates sulfur dioxide (SO₂) emissions from Stromboli’s explosive activity using ground-based remote sensing techniques. We analyze the SO₂ mass derived from ultraviolet (UV) and thermal infrared (TIR) cameras, alongside explosion parameters and emitted products obtained from high-frequency thermal imaging. Our dataset (May 23–24, 2023) includes 49 explosions ranging from gas-dominated (Type 0) to bomb-dominated (Type 1) and ash-rich (Type 2). During non-explosive periods, UV and TIR SO₂ masses are generally comparable, whereas explosions show systematic TIR overestimation relative to UV. The TIR/UV deviation scales with plume temperature and eruption type, reflecting TIR sensitivity to thermal radiation and ash scattering, while UV retrievals remain largely temperature-independent. Our results emphasize the need for temperature-based corrections in TIR retrievals, and support integrated multi-sensor approaches for robust, real-time monitoring of volcanic gas emissions.