Sulfur dioxide layer height retrieval from Sentinel-5 Precursor/TROPOMI using FP_ILM

Abstract

Abstract. The accurate determination of the location, height, and loading of sulfur dioxide (SO2) plumes emitted by volcanic eruptions is essential for aviation safety. The SO2 layer height is also one of the most critical parameters with respect to determining the impact on the climate. Retrievals of SO2 plume height have been carried out using satellite UV backscatter measurements, but, until now, such algorithms are very time-consuming. We have developed an extremely fast yet accurate SO2 layer height retrieval using the Full-Physics Inverse Learning Machine (FP_ILM) algorithm. This is the first time the algorithm has been applied to measurements from the TROPOMI instrument onboard the Sentinel-5 Precursor platform. In this paper, we demonstrate the ability of the FP_ILM algorithm to retrieve SO2 plume layer heights in near-real-time applications with an accuracy of better than 2 km for SO2 total columns larger than 20 DU. We present SO2 layer height results for the volcanic eruptions of Sinabung in February 2018, Sierra Negra in June 2018, and Raikoke in June 2019, observed by TROPOMI.

Probabilistic retrieval of volcanic SO<sub>2</sub> layer height and cumulative mass loading using the Cross-track Infrared Sounder (CrIS)

“…As mentioned above, our strongest total column loading from the Raikoke cloud was 432 DU. This is significantly lower than the maximum detected by TROPOMI (> 900 DU, (Hedelt et al, 2019)), and several other UV-based methods (∼1000 DU, S. Carn, pers. comm.).…”

“…On 26 June, 2018 after a period of elevated seismicity, the onset of a major eruption at Sierra Negra was signaled by volcanic tremor at 19:40 UTC, producing an ash and SO 2 plume at 20:09 UTC (Carn et al, 2018;Vasconez et al, 2018;Hedelt et al, 2019). The first CrIS observation also occurred at 20:09 UTC from S-NPP, detecting SO 2 above the Sierra Negra on 3 adjacent…”

“…At approximately, 18:00 UTC on June 21, 2019 (4:00 AM local time), Raikoke volcano in the Kuril Islands erupted for the first time since 1924 (Sennert, 2019;Hedelt et al, 2019). The strongest pulses of the eruption rose to an altitude of approximately 13 km, forming an umbrella cloud which was quickly advected to the east by strong winds.…”

“…Krotkov et al, 2010;Carn et al, 2017;Li et al, 2017;Theys et al, 2013). More recently, efforts to improve UV methods have focused on high-cadence UV measurements made from the Deep Space Climate Observatory -Earth Polychromatic Imaging Camera (DSCOVR-EPIC) at the Earth-Sun (L1) Lagrange point (Carn et al, 2018) as well as high spatial resolution SO 2 loading and limited layer height measurements from the Tropospheric Monitoring Instrument (TROPOMI) (Theys et al, 2019;Hedelt et al, 2019). In the last decade, infrared sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) have provided additional SO 2 loading measurements and estimates of the layer altitude, providing significant added value to real-time monitoring of volcanic emissions as well as climatological analyses (Walker et al, 2011(Walker et al, , 2012Carboni et al, 2012Carboni et al, , 2016Clarisse et al, 2014;Bauduin et al, 2016).…”

“…SO 2 columns of > 900 DU (Hedelt et al, 2019 the support of the height PDF, the largest value of mean plus uncertainty occurs just below the upper end of the height PDF 11 https://doi.org/10.5194/amt-2020-41 Preprint. Discussion started: 27 February 2020 c Author(s) 2020.…”