Abstract
Abstract. A geometric technique is introduced to estimate the height of volcanic eruption columns using the generally discarded near-limb portion of geostationary imagery. Such oblique observations facilitate a height-by-angle estimation method by offering close-to-orthogonal side views of eruption columns protruding from the Earth ellipsoid. Coverage is restricted to daytime point estimates in the immediate vicinity of the vent, which nevertheless can provide complementary constraints on source conditions for the modeling of near-field plume evolution. The technique is best suited to strong eruption columns with minimal tilting in the radial direction. For weak eruptions with severely bent plumes or eruptions with expanded umbrella clouds the radial tilt/expansion has to be corrected for either visually or using ancillary wind profiles. Validation on a large set of mountain peaks indicates a typical height uncertainty of ±500 m for near-vertical eruption columns, which compares favorably with the accuracy of the common temperature method.
Highlights
Volcanic eruptions pose significant hazards to aviation, public health, and the environment (Martí and Ernst, 2005)
We presented a simple geometric technique that exploits the generally unused near-limb portion of geostationary fixed grid images to estimate the height of a volcanic eruption column
We demonstrated the technique using data from the Advanced Baseline Imager (ABI) instrument, which offers the highestresolution visible imagery and most accurate georegistration among current-generation geostationary imagers
Summary
Volcanic eruptions pose significant hazards to aviation, public health, and the environment (Martí and Ernst, 2005). In its simplest and still oft used single-channel form, the method determines plume height by matching the 11 μm BT to a temperature profile obtained from a radiosounding or a numerical forecast, assuming an opaque plume in thermal equilibrium with its environment. Both of these assumptions, can be invalid. Applicable near-real-time techniques, such as the satellite temperature method, are indispensable to support operations at volcanic ash advisory centers and mitigate aviation and health hazards. Our proof-of-concept study introduces a simple geometric technique to derive point estimates of eruption column height in the vicinity of the vent from side views of the plume captured in near-limb geostationary images. Nearly identical Advanced Himawari Imager (AHI) aboard the Himawari third-generation satellites
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