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Department of Aerospace Engineering Sciences, University of Colorado, Boulder, USA
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- PublicationRestrictedDetection of plumes at Redoubt and Etna volcanoes using the GPS SNR method(2017-04-05)
; ; ; ; ; ; ; ; ; ; ; ; ; Detection and characterization of volcanic eruptions is important both for public health and aircraft safety. A variety of ground sensors are used tomonitor volcanic eruptions. Data fromthese ground sensors are subsequently incorporated into models that predict the movement of ash. Here amethod to detect volcanic plumes using GPS signals is described. Rather than carrier phase data used by geodesists, the method takes advantage of attenuations in signal to noise ratio (SNR) data. Two datasets are evaluated: the 2009 Redoubt Volcano eruptions and the 2013/2015 eruptions at Mt. Etna. SNR-based eruption durations are compared with previously published seismic, infrasonic, and radar studies at Redoubt Volcano. SNR-based plume detections from Mt. Etna are compared with L-band radar and tremor observations. To place these SNR observations from Redoubt and Etna in context, amodel of the propagation of GPS signals through bothwater/water vapor and tephra is developed. Neitherwater nor fine ash particles will produce the observed attenuation of GPS signals, while scattering caused by particles N1 cm in diameter potentially could.712 2 - PublicationRestrictedDesign and Preliminary Testing of the Volcanic Ash Plume Receiver NetworkThe presence of volcanic ash in the signal path between a GPS satellite and a ground-based receiver strongly correlates with a decrease in GPS signal strength. This effect has been seen in data collected from GPS sites located near active volcanoes; however, the sparse placement of existing GPS sites limits the applicability of this technique as an ash plume detection method to relatively few well-instrumented volcanoes. This deficiency has motivated the development of a low-cost distributed sensor system based on navigation-grade GPS receivers, which can take advantage of attenuated GPS signals to increase the quality and availability of real-time ash plume observations during an eruption. This GPS-based system has been designed specifically to meet remote sensing needs while operating autonomously in difficult conditions and minimizing on-site infrastructure requirements. Prototypes of this system have undergone long-term testing and the data collected from this testing have been used to develop the additional processing steps necessary to account for the different behavior of navigation grade GPS equipment compared to the geodetic equipment used at existing GPS sites.
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