Heidelberg 2015 – wissenschaftliches Programm
UP 13.11: Poster
Donnerstag, 26. März 2015, 10:45–19:45, G/Foyer
Radiative Transfer in Volcanic Plumes — •Katja Bigge, Nicole Bobrowski, Peter Lübcke, and Ulrich Platt — Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
Passive trace gas measurements such as Differential Optical Absorption Spectroscopy (DOAS) have been used to measure the gas contents of volcanic plumes for some time. SO2 is the most commonly measured gas and it plays an important role in volcanic processes and eruptions and in climate. Radiative transfer effects complicate these measurements and although this problem has been discussed already 30 years ago there is usually still no correction applied. However, the radiative transfer effects can cause over- and underestimation of retrieved gas fluxes in the order of tens of percent, or under certain conditions even lead to errors in the order of a magnitude, making current flux results inaccurate.
During a campaign at Etna, Italy, in July 2014, we measured SO2 fluxes simultaneously using two scanning DOAS instruments located at different distances from the plume, with the goal of determining the quantity of light dilution (underestimations of the flux) due to light not traversing the plume but entering the instruments. Additionally, we investigate some model estimations of the influence of the light dilution and multiple scattering inside the plume on our measurements using the Monte Carlo Radiative Transfer Model McArtim.