The infrared spectral signature of volcanic ash determined from high-spectral resolution satellite measurements

info:eu-repo/semantics/publishe

Tracking, quantifying and profiling volcanic SO2 and aerosol using high spectral resolution infrared sounders

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Satellite Observations of Gravity Waves at the Stratospheric Speed Limit from the Hunga-Tonga Hunga Ha'apai Volcanic Eruption

International audienceOn 15th January 2022, a major volcanic eruption occurred between the islands of Hunga Tonga and Hunga Ha’apai (175.4W, 20.5S). Located under only a shallow depth of water, this submarine volcano launched an explosive plume of ash and flash-boiled water up through the ocean upwards into the atmosphere, with an explosive energy comparable to Krakatau in 1883. The explosion generated global-scale atmospheric waves that were detectable from the surface to the edge of space. This single event also sent shockwaves through the global research community, triggering upwards of several thousands of scientific studies. In this presentation, we focus on ultra-fast stratospheric gravity waves generated by the initial explosion that propagated over the entire Pacific region detected by satellite. We analyse brightness temperature perturbations in the 4.3 and 15 micron bands of the AIRS/Aqua, CrIS/Suomi-NPP, CrIS/JPSS-1, IASI/MetOp-B and IASI/MetOp-C instruments, supported by GOES radiance observations. An atmospheric "explosion time" of 04:28:48 UTC is calculated using surface pressure station anomalies and allows us to measure lower-bound propagation speeds of the leading atmospheric waves. Strikingly, we find not only a clear signal of the surface Lamb wave throughout the stratosphere travelling near the sound speed at 318 m/s, but also a leading gravity wave packet travelling at up to 275 m/s, with an apparent vertical depth greater than the depth of the atmosphere. This is, to our knowledge, one of the fastest gravity wave packets ever observed. These results are combined with airglow observations over Hawaii in the lower thermosphere to provide an independent estimate of phase speeds. Finally, analysis of small-scale gravity waves propagating in the ash plume reveal wave periods close to fastest possible oscillation speed near 5 mins. This event triggered gravity waves with speeds, scales and extents that are unprecedented in nearly 20 years of satellite observations, and will likely keep scientists busy for many years to come as we seek to understand the atmospheric response to this unique eruption

Satellite Observations of Gravity Waves at the Stratospheric Speed Limit from the Hunga-Tonga Hunga Ha'apai Volcanic Eruption

International audienceOn 15th January 2022, a major volcanic eruption occurred between the islands of Hunga Tonga and Hunga Ha’apai (175.4W, 20.5S). Located under only a shallow depth of water, this submarine volcano launched an explosive plume of ash and flash-boiled water up through the ocean upwards into the atmosphere, with an explosive energy comparable to Krakatau in 1883. The explosion generated global-scale atmospheric waves that were detectable from the surface to the edge of space. This single event also sent shockwaves through the global research community, triggering upwards of several thousands of scientific studies. In this presentation, we focus on ultra-fast stratospheric gravity waves generated by the initial explosion that propagated over the entire Pacific region detected by satellite. We analyse brightness temperature perturbations in the 4.3 and 15 micron bands of the AIRS/Aqua, CrIS/Suomi-NPP, CrIS/JPSS-1, IASI/MetOp-B and IASI/MetOp-C instruments, supported by GOES radiance observations. An atmospheric "explosion time" of 04:28:48 UTC is calculated using surface pressure station anomalies and allows us to measure lower-bound propagation speeds of the leading atmospheric waves. Strikingly, we find not only a clear signal of the surface Lamb wave throughout the stratosphere travelling near the sound speed at 318 m/s, but also a leading gravity wave packet travelling at up to 275 m/s, with an apparent vertical depth greater than the depth of the atmosphere. This is, to our knowledge, one of the fastest gravity wave packets ever observed. These results are combined with airglow observations over Hawaii in the lower thermosphere to provide an independent estimate of phase speeds. Finally, analysis of small-scale gravity waves propagating in the ash plume reveal wave periods close to fastest possible oscillation speed near 5 mins. This event triggered gravity waves with speeds, scales and extents that are unprecedented in nearly 20 years of satellite observations, and will likely keep scientists busy for many years to come as we seek to understand the atmospheric response to this unique eruption

Tracking, quantifying and profiling SO2 and volcanic aerosol using two high spectral infrared sounders - IASI and TES

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Tracking and quantifying volcanic SO2 with IASI, the September 2007 eruption at Jebel at Tair

In this paper we demonstrate the potential of the infrared Fourier transform spectrometer IASI in analysing volcanic eruptions, using the September 2007 eruption at Jebel at Tair as an illustrative example. Detailed radiative transfer calculations are presented, simulating IASI-like transmittance spectra for a variety of volcanic plumes. We analyse the sensitivity of IASI to SO 2 at different altitudes and demonstrate that IASI is in principle capable of sensing SO2 down to the surface. Using the brightness temperature difference of well chosen SO2 channels as a filter, we are able to track the plume of the Jebel at Tair eruption for 12 days, on a par with state of the art UV sounders. A method is presented for quickly estimating the altitude of a volcanic plume based on the relative intensities of the SO2 absorption lines. Despite recent advances, it is still very challenging to retrieve vertical profiles of SO2 from nadir viewing satellites. Currently the most accurate profiles in nadir are retrieved using backtracking of the plume with atmospheric transport models. Via full inverse retrievals using the optimal estimation method, we show the possibility of extracting medium coarse vertical profiles from IASI data. The retrieval allows us to present an evolution of the total mass of SO2 in the plume for the Jebel at Tair eruption. An analytical relation is derived between brightness temperature differences and concentrations, which fits the experimental data very well. The spectral range of IASI also allows retrieval of volcanic aerosols. In the initial plume of the Jebel at Tair eruption, volcanic aerosols were found in the form of ice particles, for which we derived particle sizes. © Author(s) 2008.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Tropospheric volcanic so2 mass and flux retrievals from satellite. The etna december 2018 eruption

The presence of volcanic clouds in the atmosphere affects air quality, the environment, climate, human health and aviation safety. The importance of the detection and retrieval of volcanic SO2 lies with risk mitigation as well as with the possibility of providing insights into the mechanisms that cause eruptions. Due to their intrinsic characteristics, satellite measurements have become an essential tool for volcanic monitoring. In recent years, several sensors, with different spectral, spatial and temporal resolutions, have been launched into orbit, significantly increasing the effectiveness of the estimation of the various parameters related to the state of volcanic activity. In this work, the SO2 total masses and fluxes were obtained from several satellite sounders—the geostationary (GEO) MSG-SEVIRI and the polar (LEO) Aqua/Terra-MODIS, NPP/NOAA20-VIIRS, Sentinel5p-TROPOMI, MetopA/MetopB-IASI and Aqua-AIRS—and compared to one another. As a test case, the Christmas 2018 Etna eruption was considered. The characteristics of the eruption (tropospheric with low ash content), the large amount of (simultaneously) available data and the different instrument types and SO2 columnar abundance retrieval strategies make this cross-comparison particularly relevant. Results show the higher sensitivity of TROPOMI and IASI and a general good agreement between the SO2 total masses and fluxes obtained from all the satellite instruments. The differences found are either related to inherent instrumental sensitivity or the assumed and/or calculated SO2 cloud height considered as input for the satellite retrievals. Results indicate also that, despite their low revisit time, the LEO sensors are able to provide information on SO2 flux over large time intervals. Finally, a complete error assessment on SO2 flux retrievals using SEVIRI data was realized by considering uncertainties in wind speed and SO2 abundance.SCOPUS: ar.jinfo:eu-repo/semantics/publishe