Synoptic analysis of a decade of daily measurements of SO₂ emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change

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.

Synoptic Analysis of a Decade of Daily Measurements of SO₂ Emission in the Troposphere from Volcanoes of the Global Ground-Based Network for Observation of Volcanic and Atmospheric Change

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 sulphur 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 spectrometers (ScanDOAS) 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 on 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 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-sensors validation, and improved quantification of the prevalent tropospheric component of global volcanic emission. Data sets for each volcano are made available at https://novac.chalmers.se, under license CC-BY 4, or through the DOI-links provided in Table 1.

Atmospheric change as a driver of change in the Canadian boreal zone1

Global anthropogenic emissions of greenhouse gases and hazardous air pollutants have produced broad yet regionally disparate changes in climatic conditions and pollutant deposition in the Canadian boreal zone (the boreal). Adapting boreal resource management to atmospheric change requires a holistic understanding and awareness of the ongoing and future responses of terrestrial and freshwater ecosystems in this vast, heterogeneous landscape. To integrate existing knowledge of and generate new insights from the broad-scale impacts of atmospheric change, we first describe historical and present trends (∼1980–2015) in temperature, precipitation, deposition of hazardous air pollutants, and atmospheric-mediated natural disturbance regimes in this region. We then examine their associations with ecosystem condition and productivity, biological diversity, soil and water, and the carbon budget. These associations vary considerably among ecozones and likely undergo further changes under the emerging risks of atmospheric change. We highlight the urgent need to establish long-term, boreal-wide monitoring for many key components of freshwater ecosystems to better understand and project the influences of atmospheric change on boreal water resources. We also formulate three divergent future scenarios of boreal ecosystems in 2050. Our scenario analysis reveals multiple undesirable changes in boreal ecosystem structure and functioning with more variable atmospheric conditions and frequent land disturbances, while continuing business-as-usual management of natural resources. It is possible, though challenging, to reduce unwanted consequences to ecosystems through management regimes focussed on socio-ecological sustainability and developing resilient infrastructure and adaptive resource-management strategies. We emphasize the need for proactive actions and improved foresight for all sectors of society to collaborate, innovate, and invest in anticipation of impending global atmospheric change, without which the boreal zone will face a dim future.

Entangled Trees and Arboreal Networks of Sensitive Environments

The article discusses how current mediated conditions change nature perception from a media study perspective. The article is based on different case studies such as the current sensation of atmospheric change through sensible media attached to trees which get published via Twitter, the meteorologist Amazonian Tall Tower Observatory and the use of gutta percha derived from tropical trees for the production of cables in the history of telegraphy. For analysing the examples, the perspective of »media as environments« is flipped to »environments as media«, because this focus doesn’t approach media from a networked and technological perspective primarily but makes productive the elemental character of basic »media« like air, earth and water