Automated sulfur dioxide gas measuring site using ultraviolet camer...
Top: Photograph of the SO2 camera installation when scientists tested the radio link to the Hawaiian Volcano Observatory (HVO). The camera is aimed at the plume emitting from the Overlook Crater, about 1.4 km away. Under typical trade wind conditions, the plume is blown to the southwest, thus moving from right to left in the imagery. The dashed line indicates the approximate field of view of the instrument. HVO is just off the image to the right. The photograph shows Mauna Loa's southern flank in the background. At a distance of more than 20 km, however, this feature is barely visible in the UV imagery even on the clearest of days because UV radiation is scattered significantly more efficiently on air molecules than visible light.
Bottom: Example of the imagery displayed at HVO on September 7, 2013 just after a transition between a passive and an active lava lake occurred at 11:21 HST (21:21 UTC). The color scale spans from 0 to 10,000 ppmm. The semicircle represents the closed path along which integration and derivation of the emission rate takes place. The rectangle indicates an area of the image that was found to be free of SO2 and is used for calculation of the differential optical. The small circle in the image center represents the field of view of the spectrometer built into the system.