Remote CO, COS, CO2, SO2, HCl detection and temperature estimation of volcanic gas

Volcanic gas from an inaccessible fumarole at Aso volcano, Japan, was recently measured with a Fourier Transform InfraRed (FT‐IR) spectral radiometer. Absorption features of CO, COS, CO 2 , SO 2 , and HCl were identified in the volcanic plume spectra. This is the first time the five volcanic gas components are detected simultaneously by a remote technique. Based on the measured CO/CO 2 ratio of 2.6 × 10 −3 , the equilibrium temperature of the volcanic gas is estimated to be 750° ± 120°C.