Earth Observation Data Group

Abstract:

Terrestrial volcanism has been one of the dominant geological forces shaping our planet since its earliest existence. Its associated phenomena, like atmospheric lightning and hydrothermal activity, provide a rich energy reservoir for chemical syntheses. Based on our laboratory simulations, we propose that on the early Earth volcanic activity inevitably led to a remarkable production of formic acid through various independent reaction channels. Large-scale availability of atmospheric formic acid supports the idea of the high-temperature accumulation of formamide in this primordial environment.

Abstract:

<p>Satellite remote sensing has been widely used to make measurements of sulphur dioxide (SO<sub>2</sub>) emissions from volcanoes. The Infrared Atmospheric Sounding Interferometer (IASI) is one such instrument that has been used to examine the emissions from large explosive eruptions.  Much less work has been done using IASI to study the emissions from smaller eruptions, non-eruptive degassing or anthropogenic sources, and similarly it is rarely used for examining long term trends in activity.  Now, when there are three IASI instruments in orbit and with over ten years of data, is the perfect opportunity to explore these topics. This study applied a ‘fast’ linear retrieval developed for IASI in Oxford, across the globe for a ten-year period. Global annual averages were dominated by the emissions from large eruptions (e.g. Nabro in 2011) but elevated signals could also be identified from smaller volcanic sources and industrial centres, suggesting the technique has promise for detecting lower level emissions. A systematic approach was then taken, rotating the linear retrieval output for each orbit at over 100 volcanoes worldwide, with the wind direction at the volcano’s vent, or in cases where the plume was emitted at a greater height, using the observed plume direction. This isolates the elevated signal downwind of the volcano. The rotated outputs were then averaged over monthly, annual and multi-annual time periods. Analysis of the upwind and downwind values establishes whether there is an elevated signal and its intensity. An inventory was then constructed from these observations which show how these emissions varied over a ten-year period. Trends in SO<sub>2 </sub>emission were compared against fluxes generated for the Ozone Monitoring Instrument (OMI) and the number of thermal anomalies detected by the MODVOLC algorithm developed for MODIS.  It was identified for example, that long term trends are more easily identified at high altitude volcanoes such as Popocatepetl, Sabancaya and Nevado del Ruiz. This is consistent with the idea that the instrument performs better in regions with lower levels of water vapour (e.g. above the boundary layer).</p>

Abstract:

<p>Precise knowledge of the location and height of the volcanic sulfur dioxide (SO<sub>2</sub>) plume is essential for accurate determination of SO<sub>2</sub> emitted by volcanic eruptions. So far, UV based SO<sub>2</sub> plume height retrieval algorithms are very time-consuming and therefore not suitable for near-real-time applications like aviation control. We have therefore developed the Full-Physics Inverse Learning Machine (FP_ILM) algorithm for extremely fast and accurate retrieval of volcanic SO<sub>2</sub> layer heights based on the UV satellite instruments Sentinel-5 Precursor/TROPOMI and MetOp/GOME-2.</p><p>In this presentation, we will present the FP-ILM algorithm and show results of the 2019 Raikoke eruption; a strong volcanic eruption which has emitted a huge ash cloud accompanied by more than 1300 DU of SO<sub>2</sub>, which could be detected  even two months after the end of eruptive event. We will also present first results of the recent Taal volcanic eruption on 13 January 2020 in Indonesia, which has injected a huge ash and SO<sub>2</sub> plume into the upper atmosphere, with plume heights of up to 20km. </p><p>The algorithm is developed in the framework of ESA's  "Sentinel-5p+ Innovation: SO<sub>2</sub> Layer Height project" (S5P+I: SO2 LH),  dedicated to the generation of an SO<sub>2</sub> LH product and its extensive verification with collocated ground- and space-born measurements.</p><p>The high-resolution UV spectrometer GOME-2 aboard the three EPS MetOp-A, -B, and –C satellites perform global daily atmospheric trace-gas measurements with a spatial resolution of  40x40km<sup>2</sup> at an overpass time of 8:30h local time. The UV spectrometer TROPOMI aboard the ESA Sentinel-5P satellite provides a much higher spatial resolution of currently 5.6x3.6km<sup>2</sup> per ground pixel, at an overpass time of 13:30h. In the future, also UV instruments aboard the Sentinel-4 (geostationary) and Sentinel-5 will complement the satellite-based global monitoring of atmospheric trace gases.</p>