Synoptic analysis of a decade of daily measurements of SO<sub>2</sub> emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change

Abstract

Abstract. Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the impact of the emission from sporadic or localized events to persistent or widespread processes of climatic and environmental importance. These observations provide information on volatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth's volcanic emission, particularly of sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurement of volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets. These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominate the total emission of volcanic SO2. Although space-based observations have provided this global insight into some aspects of Earth's volcanism, it still has important limitations. The magnitude and short-term variability of lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operational monitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the use of ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the beginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysis of measurements of SO2 flux and plume parameters obtained during the period March 2005 to January 2017 of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverse set of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style of eruptive activity. We find that passive volcanic degassing is by no means a stationary process in time and that large sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgets produced using short-term, sporadic observations. The use of a standard evaluation method allows for intercomparison between different volcanoes and between ground- and space-based measurements of the same volcanoes. The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. We also compare our results with those reported in the literature, providing ranges of variability in emission not accessible in the past. The open-access data repository introduced in this article will enable further exploitation of this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, and improved quantification of the prevalent tropospheric component of global volcanic emission. Datasets for each volcano are made available at https://novac.chalmers.se (last access: 1 October 2020) under the CC-BY 4 license or through the DOI (digital object identifier) links provided in Table 1.

The Extensive Parameters as a Tool to Monitoring the Volcanic Activity: The Case Study of Vulcano Island (Italy)

“…The NOVAC network was established with a project funded by the European Union in the period 2005-2010, thereafter, it continued to be maintained and expanded, thanks to resources supplied from the volcano observatories initially involved in the active project. The NOVAC community currently counts about 160 stations on 47 volcanoes in different regions of the world, now including Iceland, Philippines, Indonesia, Papua New Guinea and Montserrat [60]. The present work shows the updated results of the ground-based scanning DOAS network installed at Vulcano Island Italy in 2008 (Figures 1 and 4).…”

Open-vent volcanoes fuelled by depth-integrated magma degassing

“…It has also been shown that open-vent volcanoes are the most prodigious volcanic outgassers of volatiles into the atmosphere, worldwide (Andres and Kasgnoc 1998;Carn et al 2016). Additionally, extensive records of the outgassing fluxes of open-vent volcanoes from many decades of in situ measurements (Arellano et al 2021;Carn et al 2016;Carn et al 2017;Fioletov et al 2016) show that outgassing between eruptions dominates the volcanic gas budget (Allard 1997;Carn et al 2016;Carn et al 2017). Indeed, satellite-based global observations of SO 2 flux confirms that persistent, or passive, degassing accounts for ~ 90% of the global outgassing sulphur flux from volcanoes (Carn et al 2016;Carn et al 2017) and that most of the top 20 volcanic outgassers, as quantified from UV sensors total ozone mapping spectrometer (TOMS) and ozone mapping instrument (OMI), may be classified as 'open-vent' (Table S1; Fig.…”

Mobile and high-spectral-resolution Fabry–Pérot interferometer spectrographs for atmospheric remote sensing

“…with backpack sized instruments); and (4) instruments can be employed in autonomous, remote, and low-maintenance measurement networks (see e.g. Galle et al, 2010;Arellano et al, 2021). In practice, these points are substantial factors making scientific environmental observations feasible.…”