The vertical distribution of volcanic SO<sub>2</sub> plumes measured by IASI

Abstract

Abstract. Sulfur dioxide (SO 2 ) is an important atmospheric constituent that plays a crucial role in many atmospheric processes. Volcanic eruptions are a significant source of atmospheric SO 2 and its effects and lifetime depend on the SO 2 injection altitude. The Infrared Atmospheric Sounding Interferometer (IASI) on the METOP satellite can be used to study volcanic emission of SO 2 using high-spectral resolution measurements from 1000 to 1200 and from 1300 to 1410 cm −1 (the 7.3 and 8.7 µm SO 2 bands) returning both SO 2 amount and altitude data. The scheme described in Carboni et al. (2012) has been applied to measure volcanic SO 2 amount and altitude for 14 explosive eruptions from 2008 to 2012. The work includes a comparison with the following independent measurements: (i) the SO 2 column amounts from the 2010 Eyjafjallajökull plumes have been compared with Brewer ground measurements over Europe; (ii) the SO 2 plumes heights, for the 2010 Eyjafjallajökull and 2011 Grimsvötn eruptions, have been compared with CALIPSO backscatter profiles. The results of the comparisons show that IASI SO 2 measurements are not affected by underlying cloud and are consistent (within the retrieved errors) with the other measurements. The series of analysed eruptions (2008 to 2012) show that the biggest emitter of volcanic SO 2 was Nabro, followed by Kasatochi and Grímsvötn. Our observations also show a tendency for volcanic SO 2 to reach the level of the tropopause during many of the moderately explosive eruptions observed. For the eruptions observed, this tendency was independent of the maximum amount of SO 2 (e.g. 0.2 Tg for Dalafilla compared with 1.6 Tg for Nabro) and of the volcanic explosive index (between 3 and 5).

Model simulations of the chemical and aerosol microphysical evolution of the Sarychev Peak 2009 eruption cloud compared to in situ and satellite observations

“…It is also consistent with retrievals from OMI (Theys et al, 2015) and MODIS (Realmuto and Berk, 2016). In contrast, the IASI retrievals reported in Carboni et al (2016) found that the transient SO 2 burden reached only up to 0.6 Tg SO 2 . We consider though that 0.9 Tg of SO 2 is the best estimate for the mass of SO 2 injected by the Sarychev eruption into the UTLS.…”

“…It is a spectrometer measuring infrared light spectra at nadir. Its primary goal is to assess temperature and water vapour content of the atmosphere, but it can also be used to retrieve the atmospheric concentrations of various gases, including SO 2 (Clarisse et al, 2008;Carboni et al, 2016). IASI provides global coverage twice a day, and its footprint ranges from circular (12 km diameter at nadir) to elliptical (up to 20 km by 39 km at the end of the swath).…”

“…We neglected the minor, low-altitude (inferior to 5 km) explosions reported on 11 and 16 June, and injected SO 2 continuously for a 24 h period on 15 June spread evenly between 11 and 15 km altitude a.s.l.. The timing of the SO 2 emissions is based on SO 2 satellite retrievals from IASI (Clarisse et al, 2012;Carn et al, 2016;Carboni et al, 2016), MODIS (MODerate-resolution Imaging Spectroradiometer; Rybin et al, 2011;Realmuto and Berk, 2016), and OMI (Ozone Monitoring Instrument; Theys et al, 2015), which all show that the majority of high altitude SO 2 was released on 15 June (and possibly in the early morning of 16 June). Haywood et al (2010) used a total injection mass of 1.2 Tg SO 2 , which was the SO 2 total mass value retrieved on 16 June with IASI.…”

“…Finally, there have also been recent advances in satellite observations of volcanic gases in the stratosphere. First, new retrievals now enable an improved estimation of SO 2 mass injected combined with estimates of plume height from IASI on the MetOp-A satellite (Clarisse et al, 2012;Carboni et al, 2016). Second, recent analysis of satellite data from the Microwave Limb Sounder (MLS) aboard the Aura satellite identifies that the Sarychev volcano co-injected HCl alongside SO 2 into the stratosphere (Carn et al, 2016).…”

“…), injecting SO 2 , ash, and also HCl to the stratosphere. The eruption was classified with a VEI of 4 (the volcanic eruptive index as defined in Newhall and Self (1982) is a logarithmic scale based on the volume of tephra ejected), and the main volcanic emission was injected into heights around 9-14 km as estimated from Infrared Atmospheric Sounding Interferometer (IASI) retrievals (Carn et al, 2016;Carboni et al, 2016). Remote sensing observations over Eureka, Canadian Arctic, showed volcanic aerosol layers from the tropopause up to 16-17 km 1 month after the eruption, that subsequently settled into a more homogeneous layer in the lower stratosphere (O'Neill et al, 2012).…”