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UP: Fachverband Umweltphysik

UP 18: Meßtechnik (verschoben von Donnerstag 17:30)

UP 18.4: Vortrag

Freitag, 27. März 2015, 14:45–15:00, G/gHS

Improved determination of volcanic SO₂ emission rates from SO₂ camera images — •Angelika Klein, Nicole Bobrowski, Peter Lübcke, and Ulrich Platt — Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany

SO₂ cameras determine the SO₂ emissions of volcanoes with a high temporal and spatial resolution. The first step to obtain emission rates is to integrate the column amount of SO₂ in two different plume cross sections; combined with wind speed information this allows the determination of SO₂ fluxes. A popular method to determine the mean wind speed relies on estimating the time lag of the SO₂ signal derived for two cross sections of the plume at different distances downwind of the source by maximizing the cross correlation coefficient of the two signals.

Another method to obtain the wind speed is to use the optical flow technique to obtain a more detailed wind field in the plume from a series of SO₂ camera images. While the cross correlation method only gives the mean wind speed between the two cross sections of the plume, the optical flow technique determines the wind speed and direction for each pixel individually.

The two methods were applied to a data set taken at Etna, Italy in July, 2014 and will illustrate the differences between cross-correlation and the optical flow method. The influence of the wind direction on the flux determination will be discussed using this data set as an example. In addition we have a closer look into the possibility of wind direction determination from SO₂ camera images.