Review of “Detecting volcanic sulfur dioxide plumes in the Northern Hemisphere using the Brewer spectrophotometer, other networks, and satellite observations” by C.S. Zerefos et al.

Constraining emission inventories into chemistry-transport models (CTM) is essential. In addition to anthropogenic emissions, natural sources of pollutants must be considered. Among them, volcanoes are large emitters of gases, including sulfur dioxide (SO2), a volatile species, causing environmental and health issues.Volcanic SO2 emission inventories are usually integrated in global CTMs, in order to improve the modelling of chemical species in the atmosphere. Here, we use the model MOCAGE, developed at CNRM, which currently uses Andres & Krasgnoc&#8217;s inventory (1998); a temporal average of emission on some 40 volcanoes, monitored through the synergy of satellite data and surface remote sensing instruments, for 25 years (from 1970&#8217;s to 1997). However, this inventory is now quite old and is therefore no longer sufficiently accurate.Thanks to the development of new satellite observations, it has become possible to produce such inventories with an improved accuracy. The global coverage and higher sensitivity of these instruments has allowed to reference more emission sources (hard-to-access volcanoes, small eruptions or even passive degassing). Hence, a new inventory of Carn et al (2016,2017) based on satellite observations has been implemented in MOCAGE. Besides being recent (from 1978 up to 2015), it combines eruption and passive degassing over more than 160 volcanoes. Passive degassing fluxes are provided as annual averages and eruption fluxes as daily total quantities (in case of events). In addition, information on volcanoes vent altitude and eruptive plume heights is available, which has been used to better constraints the model.We focus our study at the global scale. The years 2013 and 2014 were chosen as the years with the lowest and highest total eruptive emissions respectively, in Carn's inventory. Thus, 2013 highlights mainly the impact of passive degassing, while 2014 provides additional information on eruptions.For each of the years studied, the sulfur species budget in MOCAGE simulation is increased when the inventory is updated and therefore the relative contribution of volcanic sulfur emissions is larger. We note the global increase in sulfur dioxide and sulfate aerosol burdens; an increase even more significant when the injection heights of the emissions are taken into account.

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Sensitivity of Summer Drying to Spring Snow-Albedo Feedback Throughout the Northern Hemisphere From Satellite Observations

IEEE Geoscience and Remote Sensing Letters ◽

10.1109/lgrs.2017.2764543 ◽

2017 ◽

Vol 14 (12) ◽

pp. 2345-2349 ◽

Cited By ~ 1

Author(s):

Xiaona Chen ◽

Shunlin Liang ◽

Yunfeng Cao

Keyword(s):

Northern Hemisphere ◽

Satellite Observations ◽

Albedo Feedback ◽

Snow Albedo

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Satellite Observations of AOD in 4 Northern Hemisphere Source Regions during the COVID-19 Pandemic

10.1002/essoar.10509416.1 ◽

2021 ◽

Author(s):

Sarah Elise Smith ◽

Mingfang Ting ◽

Yutian Wu ◽

Cheng Zheng

Keyword(s):

Northern Hemisphere ◽

Satellite Observations ◽

Source Regions

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First measurements of volcanic gas composition at Bagana volcano, Papua New Guinea

10.5194/egusphere-egu2020-10712 ◽

2020 ◽

Author(s):

Brendan McCormick Kilbride ◽

Emma Liu ◽

Kieran Wood ◽

Thomas Wilkes ◽

Ian Schipper ◽

...

Keyword(s):

Sulfur Dioxide ◽

Papua New Guinea ◽

Co2 Flux ◽

New Guinea ◽

Satellite Observations ◽

Molar Ratio ◽

Horizontal Distance ◽

Gas Composition ◽

Volcanic Gas ◽

Volcanic Gas Composition

Bagana volcano, Papua New Guinea, is among Earth&#8217;s youngest and most active volcanoes. Bagana typically exhibits multi-year episodes of lava extrusion, interspersed with pause periods characterised by strong passive degassing. Based on satellite-based observations, Bagana is the third ranked global source of volcanic sulfur dioxide over the past 15 years. Recent work based on global correlations between volcanic gas composition and magma trace element chemistry has predicted that it may be the fifth ranked global volcanic deep carbon source. However, this indirect estimate of Bagana&#8217;s potential carbon budget has yet to be ground-truthed by in-situ sampling.We visited Bagana in September 2019 and made the first measurements of the chemical composition of the volcano&#8217;s summit gas plume. We placed a miniaturized MultiGAS sensor array on board an unoccupied aerial system (UAS, or drone) and flew the sensors through the plume. Our aircraft flew beyond visual line of sight, reaching the gas plume from around 7 km horizontal distance and 2 km altitude below the summit. Such long-range UAS flights offer immense potential for studying gas emissions from such steep, active or remote volcanoes.Our MultiGAS flights found relatively low concentrations of both sulfur dioxide and carbon dioxide in the Bagana plume. Moreover, we made coincident remote sensing measurements of sulfur dioxide emissions using ground- and UAS-based ultraviolet spectroscopy and calculated SO2 fluxes of only ~400 tonnes per day. These are an order of magnitude below the typical fluxes inferred from satellite observations. Combining MultiGAS plume composition (CO2/SO2 molar ratio, mean ~3.4) and SO2 fluxes allow us to estimate Bagana&#8217;s CO2 flux into the atmosphere as only ~1360 t/d.Our interpretation of these results is that the volcano is presently in a low state of activity. From satellite observations, we note the cessation of the most recent extrusive episode several weeks prior to our field campaign. The lack of the anticipated strong passive degassing often observed by spaceborne UV sensors is likely a result of &#8220;scrubbing&#8221; in the volcanic edifice, where rising gases interact with groundwater, resulting in dissolution of sulfur species into the groundwater and perhaps precipitation of sulfur-bearing minerals into edifice fractures. As the volcano moves towards a future extrusive episode, we might anticipate the gradual drying out of the hydrothermal system and a shift towards more truly magmatic gas compositions. Our results show that short campaign measurements may not provide data which are representative of a volcano&#8217;s longterm behaviour and we suggest that caution is needed in using such data to calculate or extrapolate regional and global volatile emissions inventories.

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Improving retrieval of volcanic sulfur dioxide from backscattered UV satellite observations

Geophysical Research Letters ◽

10.1029/2008gl036036 ◽

2009 ◽

Vol 36 (3) ◽

pp. n/a-n/a ◽

Cited By ~ 39

Author(s):

Kai Yang ◽

Nickolay A. Krotkov ◽

Arlin J. Krueger ◽

Simon A. Carn ◽

Pawan K. Bhartia ◽

...

Keyword(s):

Sulfur Dioxide ◽

Satellite Observations

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Impact of northern hemisphere mid-latitude anthropogenic sulfur dioxide emissions on local and remote tropospheric oxidants

10.5194/acp-2020-1255 ◽

2021 ◽

Author(s):

Daniel M. Westervelt ◽

Arlene M. Fiore ◽

Colleen B. Baublitz ◽

Gustavo Correa

Keyword(s):

Sulfur Dioxide ◽

Northern Hemisphere ◽

Surface Ozone ◽

Sulfate Aerosol ◽

The Arctic ◽

Free Troposphere ◽

So2 Emissions ◽

Photolysis Rates ◽

The Us ◽

The Future

Abstract. The unintended consequences of reductions in regional anthropogenic sulfur dioxide (SO2) emissions implemented to protect human health are poorly understood. SO2 decreases began in the 1970s in the US and Europe and are expected to continue into the future, while recent emissions decreases in China are also projected to continue. In addition to the well documented climate effects (warming) from reducing aerosols, tropospheric oxidation is impacted via aerosol modification of photolysis rates and radical sinks. Impacts on the hydroxyl radical and other trace constituents directly affect climate and air quality metrics such as surface ozone levels. We use the Geophysical Fluid Dynamics Laboratory Atmospheric Model version 3 nudged towards National Centers for Environmental Prediction (NCEP) reanalysis wind velocities to estimate the impact of SO2 emissions from the United States, Europe, and China by differencing a control simulation with an otherwise identical simulation in which 2015 anthropogenic SO2 emissions are set to zero over one of the regions. Springtime sulfate aerosol changes occur both locally to the emission region and also throughout the Northern Hemispheric troposphere, including remote oceanic regions and the Arctic. The presence of sulfate aerosol strongly reduces hydroxyl (OH) and hydroperoxy (HO2) radicals by up to 10 % year-round throughout most of the troposphere north of 30° N latitude, the latter of which is directly removed via heterogeneous chemistry on aerosol surfaces, including sulfate, in the model. Regional SO2 emissions significantly increase nitrogen oxides (NOx) by about 5–8 % throughout most of the free troposphere in the Northern hemisphere by increasing the NOx lifetime as the heterogeneous sink on sulfate aerosol declines. Despite the NOx increases, tropospheric ozone decreases at northern mid-latitudes by 1–4 % zonally averaged and by up to 5 ppbv in surface air over China, as its response is dominated by the larger decreases (up to 2x) in HO2 and OH. Since 2015 anthropogenic SO2 emissions in China exceed those in the US or Europe, the oxidative response is greatest for the China perturbation simulation. Chemical effects of aerosols on oxidation (reactive uptake) dominate over radiative effects (photolysis rates), the latter of which are only statistically significant locally for the large perturbation over China. We find that the emissions decrease in China, which has yet to be fully realized, will have the largest impact on oxidants and related species in the Northern Hemisphere free troposphere compared to changes in Europe or the USA. Our results bolster previous calls for a multipollutant strategy for air pollution mitigation, to avoid the unintended consequence of aerosol removal leading to surface ozone increases that offset or mask surface ozone gains achieved by regulation of other pollutants, especially in countries where current usage of high-sulfur emitting fuels may be phased out in the future.

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