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Seasonal and diurnal patterns in the dispersion of SO2 from Mt. Nyiragongo
... The dominant natural source is the volcanic activity at Mt. Nyiragongo, located near the border separating the Democratic Republic of Congo and Rwanda. It is an active volcano that has the largest constant lava lake in the world located at its summit, and SO 2 is continuously degassed from it throughout the year (Dingwell et al., 2016;Pouclet and Bram, 2021). Consequently, the region around this mountain suffers the highest SO 2 pollution than any other region within East and Central Africa as shown in Fig. 1a. ...
... Their evaluation was made against OMI SO 2 observations. On a local scale, Landgren (2011) andDingwell et al. (2016) used the FLEXPART-WRF model to study the dispersion of SO 2 from this mountain. Both of them compared their simulations to observations taken by ground based Differential Optical Absorption Spectroscopy (DOAS) instruments. ...
... The results show that WRF-Chem overestimates the amount of SO 2 close to the volcano's vent. An earlier study by Dingwell et al. (2016) also found a similar overestimation bias. However, much further away from the volcano, WRF-Chem underestimates the SO 2 amount. ...
Mount Nyiragongo, an active volcano, is the most dominant natural source of sulfur dioxide (SO2) in Africa. While a number of studies have employed atmospheric models to simulate the dispersion of SO2 from this mountain, prior to this study, no attempt has been made to use deep learning to bias correct the model's estimates. Here, the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) was used to simulate massive SO2 plumes degassed from this mountain between September 2014 and August 2015. Satellite observations by the Ozone Monitoring Instrument (OMI) showed that the SO2 spread to over 500 km from the volcano site. A deep convolutional autoencoder algorithm (WRF-DCA) was then applied to reduce the bias that WRF-Chem showed against the OMI observations. Finally, the correction performance of WRF-DCA was compared with a conventional bias correction method, linear scaling (WRF-LS). The performance of WRF-Chem, WRF-DCA, and WRF-LS was analyzed using three metrics, that is, the normalized mean bias (NMB), the root mean square error (RMSE), and Pearson's correlation coefficient (R). The results showed that WRF-Chem overestimated SO2 at locations near the volcano site and underestimated SO2 at locations further away from the volcano site. It generated an overall average NMB of −0.61 against the OMI observations. Respectively, WRF-DCA and WRF-LS reduced this bias by an average of 0.25 (40.9%) and 0.21 (34.4%). Furthermore, although both methods also reduced the RMSE and improved the correlation, WRF-DCA consistently performed better than WRF-LS. This study demonstrates the advantage that deep learning can provide in estimating volcanic SO2 emissions.
... This is primarily because of the existence of an active volcano at Mt. Nyiragongo which is about 15 km from Goma. It is an open-vent volcano with a lava lake at the top and it continuously emits SO2 [36,37]. Overall, TRO-POMI observed higher SO2 column amounts than OMI. ...
... Nyiragongo is the dominant SO2 hotspot in the region, the overall decreasing trend is most likely associated with the processes going on within it. Arellano et al. [36] reported a decreasing trend in SO2 at this volcano and attributed it to degassed magma sinking down into the volcano's conduit. A further analysis of the CO vertical profile revealed significant trends at specific heights ( Figure 6 and Table 2). ...
The atmospheric chemistry constituents of nitrogen dioxide (NO2), sulphur dioxide (SO2) and carbon monoxide (CO) are associated with air pollution and climate change. In sub-Saharan Africa, a lack of sufficient ground-based and aircraft observations has, for a long time, limited the study of these species. This study thus utilized satellite observations as an alternative source of data to study the abundance of these species over the East African region. The instruments used included the Ozone Monitoring Instrument (OMI), the Atmospheric InfraRed Sounder (AIRS), and the TROPOspheric Monitoring Instrument (TROPOMI). An investigation of trends in the data series from 2005 to 2020 was carried out using the sequential Mann-Kendall test while the Pearson correlation coefficient was used to compare the data records of the instruments. The analysis revealed no trend in NO2 (p > 0.05), a decreasing trend in SO2 (p < 0.05), a decreasing trend (p < 0.05) in CO closer to the surface (850 hPa to 500 hPa) and an increasing trend (p < 0.05) in CO higher up in the atmosphere (400 hPa to 1 hPa). There is likely a vertical ascent of CO. The correlation between the instrument records was 0.54 and 0.77 for NO2 and CO, respectively. Furthermore, seasonal fires in the savanna woodlands were identified as the major source of NO2 and CO over the region, while cities such as Kampala, Nairobi, and Bujumbura and towns such as Dar es Salaam and Mombasa were identified as important NO2 hotspots. Similarly, the active volcano at Mt. Nyiragongo near Goma was identified as the most important SO2 hotspot.
... During the period April 2010eMarch 2011, a more detailed study of the local meteorology was conducted (Dingwell et al., 2016). Meteorological data with 0.75 deg resolution from the ERA reanalysis product was used as an input for the Weather Research and Forecasting (WRF) model. ...
... From the reported values of emission rate, and knowledge of the meteorological conditions, it is possible to estimate ground-level concentrations of the emitted gases at different distances downwind the crater. This study has been recently done by (Dingwell et al., 2016) for the SO 2 groundlevel concentration at the most important villages around Nyiragongo. It is also interesting to compare the record of long-term with past measurements of the bulk gas emission. ...
The activity of open-vent volcanoes with an active lava-lake, such as Nyiragongo, is characterized by persistent degassing, thus continuous monitoring of the rate, volume and fate of their gas emissions is of great importance to understand their geophysical state and their potential impact. We report results of SO2 emission measurements from Nyiragongo conducted between 2004 and 2012 with a network of ground-based scanning-DOAS (Differential Optical Absorption Spectroscopy) remote sensors. The mean SO2 emission rate is found to be 13 ± 9 kg s⁻¹, similar to that observed in 1959. Daily emission rate has a distribution close to log-normal and presents large inter-day variability, reflecting the dynamics of percolation of magma batches of heterogeneous size distribution and changes in the effective permeability of the lava lake. The degassed S content is found to be between 1000 and 2000 ppm from these measurements and the reported magma flow rates sustaining the lava lake. The inter-annual trend and plume height statistics indicate stability of a quiescently degassing lava lake during the period of study.
... During the period April 2010eMarch 2011, a more detailed study of the local meteorology was conducted ( Dingwell et al., 2016). Meteorological data with 0.75 deg resolution from the ERA reanalysis product was used as an input for the Weather Research and Forecasting (WRF) model. ...
... From the reported values of emission rate, and knowledge of the meteorological conditions, it is possible to estimate ground-level concentrations of the emitted gases at different distances downwind the crater. This study has been recently done by (Dingwell et al., 2016) for the SO 2 groundlevel concentration at the most important villages around Nyiragongo. It is also interesting to compare the record of long-term with past measurements of the bulk gas emission. ...
Mount Nyiragongo (3470 m a.s.l.) is an active stratovolcano of mafic composition located in the Virunga Mountains in the Democratic Republic of the Congo. It is considered as one of the most dangerous volcanoes in the world due to generation of voluminous and highly fluidized lava flows during historical eruptions and the proximity to densely inhabited areas. Nyiragongo volcano is also a source of prodigious gaseous emissions to the atmosphere during periods of both eruptive and non-eruptive activity. Documented records of the style, speciation, and magnitude of degassing from this volcano exist in the literature since three decades ago. These studies are mostly based on observations made during sporadic field campaigns or by satellite-borne sensors, owing to logistical constraints imposed by volcanic and political unrest. With the aim of strengthen the gas monitoring capabilities of Nyiragongo volcano, an automatic scanning spectroscopic (DOAS) system was installed in March 2004 in the Rusayo seismic station, 10 km from the volcano crater. This instrument is powered by solar panels and linked by radio telemetry to the Goma Volcanological Observatory. Combined with plume velocity data, this instrument provides near-to-real-time SO2 fluxes with a typical temporal resolution of 10 minutes during sunlight hours. In 2005 the instrument was upgraded and incorporated as part of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). Since 2005 three additional instruments has been installed, at 10 - 14 km distance W - SW of the crater, as part of the NOVAC project. We present the results of the measurements performed at Nyiragongo during the period March 2004-October 2009. Wind data has been obtained from the Weather Research and Forecasting (WRF) model based on data from the U.S. National Oceanic and Atmospheric Administration (NOAA) to account for the effect of local topography. A statistical analysis of the results and its relation with other volcanological observations is presented. This study emphasizes the importance of long-term and continuous gas monitoring to better understand the human and environmental effects of the persistent activity of this volcano.
... In concordance with our earlier vindication of the capacity of the PiSpec to accurately constrain cell SO 2 column amounts, via comparison with a USB2000 spectrometer (Wilkes et al., 2017), we suggest that the comparisons with NOVAC and DROAS data demonstrate the capability of the PiSpec to accurately retrieve volcanic SO 2 emission rates. Following the substantial contribution to volcano monitoring and research made by the NOVAC project in recent years (e.g., Galle et al., 2010;Lübcke et al., 2014;Granieri et al., 2015;Hidalgo et al., 2015;Dingwell et al., 2016;Aiuppa et al., 2018), we suggest that the low-cost self-built PiSpec could augment efforts to assess and mitigate volcanic hazards globally, by enabling further dissemination of DOAS measurement systems on active volcanoes. ...
Spectroscopy has been used to quantify volcanic gas emission rates, most commonly SO2, for a number of decades. Typically, commercial spectrometers costing 1000s USD are employed for this purpose. The PiSpec is a new, custom-designed, 3D-printed spectrometer based on smartphone sensor technology. This unit has ≈1 nm spectral resolution and a spectral range in the ultraviolet of ≈280–340 nm, and is specifically configured for the remote sensing of SO2 using Differential Optical Absorption Spectroscopy (DOAS). Here we report on the first field deployment of the PiSpec on a volcano, to demonstrate the proof of concept of the device’s functionality in this application area. The study was performed on Masaya Volcano, Nicaragua, which is one of the largest emitters of SO2 on the planet, during a period of elevated activity where a lava lake was present in the crater. Both scans and traverses were performed, with resulting emission rates ranging from 3.2 to 45.6 kg s−1 across two measurement days; these values are commensurate with those reported elsewhere in the literature during this activity phase (Aiuppa et al., 2018; Stix et al., 2018). Furthermore, we tested the PiSpec’s thermal stability, finding a wavelength shift of 0.046 nm/°C between 2.5 and 45°C, which is very similar to that of some commercial spectrometers. Given the low build cost of these units (≈500 USD for a one-off build, with prospects for further price reduction with volume manufacture), we suggest these units hold considerable potential for volcano monitoring operations in resource limited environments.
... Average monthly concentrations of SO 2 and SPM show markedly different characteristics. Consistent to research carried out for other volcanoes (Dingwell et al., 2016), SO 2 concentrations show seasonal changes. Proximal to the vent, SO 2 concentrations exhibit strong seasonality which is heavily dependent on the bearing from the volcano. ...
With the eruption of Eyjafjallajökull (Iceland) in 2010, interest in the transport of volcanic ash after moderate to major eruptions has increased with regards to both the physical and the emergency hazard management aspects. However, there remain significant gaps in the understanding of the long-term behaviour of emissions from volcanoes with long periods of activity. Mt. Sakurajima (Japan) provides us with a rare opportunity to study such activity, due to its eruptive behaviour and dense observation network. In the 6-year period from 2009 to 2015, the volcano was erupting at an almost constant rate introducing approximately 500 kt of ash per month to the atmosphere. The long-term characteristics of the transport and deposition of ash and SO2 in the area surrounding the volcano are studied here using daily surface observations of suspended particulate matter (SPM) and SO2 and monthly ashfall values.
Results reveal different dispersal patterns for SO2 and volcanic ash, suggesting volcanic emissions’ separation in the long-term. Peak SO2 concentrations at different locations on the volcano vary up to 2 orders of magnitude and decrease steeply with distance. Airborne volcanic ash increases SPM concentrations uniformly across the area surrounding the volcano, with distance from the vent having a secondary effect. During the period studied here, the influence of volcanic emissions was identifiable both in SO2 and SPM concentrations which were, at times, over the recommended exposure limits defined by the Japanese government, European Union and the World Health Organisation.
Depositional patterns of volcanic ash exhibit elements of seasonality, consistent with previous studies. Climatological and topographic effects are suspected to impact the deposition of volcanic ash away from the vent: for sampling stations located close to complex topographical elements, sharp changes in the deposition patterns were observed, with ash deposits for neighbouring stations as close as 5 km differing as much as an order of magnitude. Despite these effects, deposition was sufficiently approximated by an inverse power law relationship, the fidelity of which depended on the distance from the vent: for proximal to intermediate areas (<20 km), errors decrease with longer accumulation periods (tested here for 1–72 months), while the opposite was seen for deposition in distal areas (>20 km).
... The map in Fig. 9 is a qualitative estimation of the total area potentially impacted by phreatomagmatic ash deposits in the past and should hence not be interpreted as a probabilistic hazard map. Spatial extent of the deposits depends on the vent location, eruption intensity and duration, and wind direction which varies dominantly between NW and SSW in the area (Dingwell et al. 2016). These parameters will also control the emplacement of future deposits. ...
The Virunga Volcanic Province (VVP) represents the most active zone of volcanism in the western branch of the East African Rift System. While the VVP’s two historically active volcanoes, Nyamulagira and Nyiragongo, have built scoria cones and lava flows in the adjacent lava fields, several small phreatomagmatic eruptive centers lie along Lake Kivu’s northern shoreline, highlighting the potential for explosive magma-water interaction. Their presence in the densely urbanized Sake-Goma-Gisenyi area necessitates an assessment of their eruptive mechanisms and chronology. Some of these eruptive centers possess multiple vents, and depositional contacts suggest distinct eruptive phases within a single structure. Depositional facies range from polymict tuff breccia to tuff and loose lapilli, often impacted by blocks and volcanic bombs. Along with the presence of dilute pyroclastic density current (PDC) deposits, indicators of magma-water interaction include the presence of fine palagonitized ash, ash aggregates, cross-bedding, and ballistic impact sags. We estimate that at least 15 phreatomagmatic eruptions occurred in the Holocene, during which Lake Kivu rose to its current water level. Radiocarbon dates of five paleosols in the top of volcanic tuff deposits range between ∼2500 and ∼150 cal. year BP and suggest centennial- to millennial-scale recurrence of phreatomagmatic activity. A vast part of the currently urbanized zone on the northern shoreline of Lake Kivu was most likely impacted by products from phreatomagmatic activity, including PDC events, during the Late Holocene, highlighting the need to consider explosive magma-water interaction as a potential scenario in future risk assessments.
The reproducibility of surface wind and tracer transport simulations from high-resolution weather and transport models were studied over complex terrain in wintertime in Japan. The horizontal grid spacing was varied (5-km, 3-km, and 1-km grids), and radioactive cesium (Cs-137) from the Fukushima nuclear power plant was used as a tracer. Fukushima has complex terrain, such as mountains and valleys. The model results were validated by observations collected from the national networks of the automated meteorological data acquisition system and the hourly air pollution sampling system. The reproducibility depended on the model resolution, topographic complexity, and synoptic weather conditions. Higher model resolution led to higher reproducibility of surface winds, especially in mountainous areas when the Siberian winter monsoon was disturbed. In contrast, the model improvement was negligible or nonexistent over plain/coastal areas when the synoptic field was steady. The statistical scores of the tracer transport simulations often deteriorated due to small errors in the plume locations. However, the higher-resolution models advantageously performed better transport simulations in the mountainous areas because of the lower numerical diffusion and higher reproducibility of the mass flux. The reproducibility of the tracer distribution in the valley of the Fukushima mountainous region was dramatically improved with increasing model resolution. In the range of mesoscale model resolutions (commonly 1~10 km), it was concluded that a higher-resolution model is definitely recommended for tracer transport simulations over mountainous terrain.
Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the
free troposphere can significantly affect the Earth's radiation budget at
high latitudes yet the BC burden in these regions and the regional source
contributions are poorly constrained. Aircraft measurements of aerosol
composition in the European Arctic were conducted during the Aerosol–Cloud
Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic
troposphere featuring enhancements in CO and aerosol mass loadings, which
were chemically speciated into BC and non-refractory sulphate and organic
matter. FLEXPART-WRF simulations have been performed to evaluate the likely
contribution to the pollutants from regional ground sources. By combining
up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we
have been able to compare the contributions made to the observed pollution
layers from the sources of eastern/northern Asia (AS), Europe (EU) and North
America (NA). Over 90 % of the contribution to the BC was shown to arise
from non-OBB anthropogenic sources.
AS sources were found to be the major contributor to the BC burden,
increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng sm−3 (in standard air m3 at 273.15 K and 1013.25 mbar) and
55.8 ± 22.4 ng sm−3 in the middle and upper troposphere
respectively. AS plumes close to the tropopause (about 7.5–8 km) were also
observed, with BC concentrations ranging from 55 to 73 ng sm−3, which
will potentially have a significant radiative impact. EU sources influenced
the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng sm−3 but made a minor contribution to the upper troposphere due to the
relatively high latitude of the source region. The contribution of NA was
shown to be much lower at all altitudes with BC mean concentration of 20 ng sm−3. The BC transported to the Arctic is mixed with a non-BC volume
fraction representing between 90–95 % of the mass, and has a relatively
uniform core size distribution with mass median diameter 190–210 nm and
geometric standard deviation σg = 1.55–1.65 and this varied
little across all source regions. It is estimated that 60–95 % of BC is
scavenged between emission and receptor based on BC / ΔCO comparisons
between source inventories and measurement.
We show that during the springtime of 2013, the anthropogenic pollution
particularly from sources in Asia, contributed significantly to BC across
the European Arctic free troposphere. In contrast to previous studies, the
contribution from open wildfires was minimal. Given that Asian pollution is
likely to continue to rise over the coming years, it is likely that the
radiative forcing in the Arctic will also continue to increase.
Petroleum and dairy operations are prominent sources of gas-phase organic
compounds in California's San Joaquin Valley. It is essential to understand
the emissions and air quality impacts of these relatively understudied
sources, especially for oil/gas operations in light of increasing US
production. Ground site measurements in Bakersfield and regional aircraft
measurements of reactive gas-phase organic compounds and methane were part
of the CalNex (California Research at the Nexus of Air Quality and Climate
Change) project to determine the sources contributing to regional gas-phase
organic carbon emissions. Using a combination of near-source and downwind
data, we assess the composition and magnitude of emissions, and provide
average source profiles. To examine the spatial distribution of emissions in
the San Joaquin Valley, we developed a statistical modeling method using ground-based data and the
FLEXPART-WRF transport and meteorological model. We
present evidence for large sources of paraffinic hydrocarbons from petroleum
operations and oxygenated compounds from dairy (and other cattle)
operations. In addition to the small straight-chain alkanes typically
associated with petroleum operations, we observed a wide range of branched
and cyclic alkanes, most of which have limited previous in situ measurements
or characterization in petroleum operation emissions. Observed dairy
emissions were dominated by ethanol, methanol, acetic acid, and methane.
Dairy operations were responsible for the vast majority of methane emissions
in the San Joaquin Valley; observations of methane were well correlated with
non-vehicular ethanol, and multiple assessments of the spatial distribution
of emissions in the San Joaquin Valley highlight the dominance of dairy
operations for methane emissions. The petroleum operations source profile
was developed using the composition of non-methane hydrocarbons in unrefined
natural gas associated with crude oil. The observed source profile is
consistent with fugitive emissions of condensate during storage or
processing of associated gas following extraction and methane separation.
Aircraft observations of concentration hotspots near oil wells and dairies
are consistent with the statistical source footprint determined via our
FLEXPART-WRF-based modeling method and ground-based data. We quantitatively
compared our observations at Bakersfield to the California Air Resources
Board emission inventory and find consistency for relative emission rates of
reactive organic gases between the aforementioned sources and motor vehicles
in the region. We estimate that petroleum and dairy operations each
comprised 22% of anthropogenic non-methane organic carbon at Bakersfield
and were each responsible for 8–13% of potential precursors to ozone.
Yet, their direct impacts as potential secondary organic aerosol (SOA)
precursors were estimated to be minor for the source profiles observed in
the San Joaquin Valley.
Soil moisture strongly controls the surface fluxes in mesoscale numerical
models, and thereby influences the boundary layer structure. Proper
initialization of soil moisture is therefore critical for faithful
simulations. In many applications, such as air quality or process studies,
the model is run for short, discrete periods (a day to a month). This paper
describes one method for soil initialization in these cases – self-spinup. In
self-spinup, the model is initialized with a coarse-resolution operational
model or reanalysis output, and run for a month, cycling its own soil
variables. This allows the soil variables to develop appropriate spatial
variability, and may improve the actual values. The month (or other period)
can be run more than once if needed.
The case shown is for the Boundary Layer Late Afternoon and Sunset
Turbulence experiment, conducted in France in 2011. Self-spinup adds spatial
variability, which improves the representation of soil moisture patterns
around the experiment location, which is quite near the Pyrenees Mountains.
The self-spinup also corrects a wet bias in the large-scale analysis. The
overall result is a much-improved simulation of boundary layer structure,
evaluated by comparison with soundings from the field site.
Self-spinup is not recommended as a substitute for multi-year spinup with an
offline land data assimilation system in circumstances where the data sets
required for such spinup are available at the required resolution.
Self-spinup may fail if the modeled precipitation is poorly simulated. It is
an expedient for cases when resources are not available to allow a better
method to be used.
Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the free troposphere can significantly affect the Earth's radiation budget at high latitudes yet the BC burden in these regions and the regional source contributions are poorly constrained. Aircraft measurements of aerosol composition in the European Arctic were conducted during the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic troposphere featuring enhancements in CO and aerosol mass loadings, which were chemically speciated into BC and non-refractory sulphate and organic matter. FLEXPART-WRF simulations have been performed to evaluate the likely contribution to the pollution from regional ground sources. By combining up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we have been able to compare the contributions made to the observed pollution layers from the sources of eastern/northern Asia (AS), Europe (EU) and North America (NA). Over 90% of the contribution to the pollution was shown to arise from non-OBB anthropogenic sources.
AS sources were found to be the major contributor to the BC burden, increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng s m−3 and 55.8 ± 22.4 ng s m−3 in the middle and upper troposphere respectively. AS plumes close to the tropopause (about 7.5–8 km) were also observed, with BC concentrations ranging from 55 to 73 ng s m−3, which will potentially have a significant radiative impact. EU sources influenced the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng s m−3 but made a minor contribution to the upper troposphere due to the relatively high latitude of the source region. The contribution of NA was shown to be much lower at all altitudes with BC mean concentration of 20 ng s m−3. The BC transported to the Arctic is mixed with a non-BC volume fraction representing between 90–95% of the mass, and has a relatively uniform core size distribution with mass median diameter 190–210 nm and geometric standard deviation σg = 1.55–1.65 and this varied little across all source regions. It is estimated that 60–95% of BC is scavenged between emission and receptor based on BC/ΔCO comparisons between source inventories and measurement.
We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to BC across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.
Volcanoes are well known as an impressive large natural source of trace elements into the troposphere. Etna (Italy) and Nyiragongo (D.R. Congo) are two stratovolcanoes located in different geological settings, both characterized by persistent passive degassing from their summit craters. Here, we present some results on trace element composition in volcanic plume emissions, atmospheric bulk deposition (rainwater) and their uptake by the surrounding vegetation, with the aim to compare and identify differences and similarities between these two volcanoes. Volcanic emissions were sampled by using active filter-packs for acid gases (sulfur and halogens) and specific teflon filters for particulates (major and trace elements). The environmental impact of the volcanogenic deposition in the area surrounding of the crater rims was investigated by using different sampling techniques: bulk rain collectors' gauges were used to collect atmospheric bulk deposition, and biomonitoring was carried out to collect gases and particulates by using en-demic plant species. The estimates of the trace element fluxes confirm that Etna and Nyiragongo are large sources of metals into the atmosphere, especially considering their persistent state of passive degassing. The large amount of emitted trace elements is clearly reflected on the chemical composition of rainwater collected at the summit areas both for Etna and Nyiragongo. Moreover, the biomonitoring results highlight that bioaccumulation of trace elements is extremely high in the proximity of the crater rim and decreases with the distance from the active craters.
Soil moisture strongly controls the surface fluxes in mesoscale numerical models, and thereby influences the boundary layer structure. Proper initialization of soil moisture is therefore critical for faithful simulations. In many applications, such as air quality or process studies, the model is run for short, discrete periods (a day to a month). This paper describes one method for soil initialization in these cases, self-spinup. In self-spinup, the model is initialized with a coarse-resolution operational model or reanalysis output, and run for a month, cycling its own soil variables. This allows the soil variables to develop appropriate spatial variability, and may improve the actual values. The month (or other period) can be run more than once if needed. The case shown is for the Boundary Layer Late Afternoon and Sunset Turbulence experiment, conducted in France in 2011. Self-spinup adds spatial variability, which improves the representation of soil moisture patterns around the experiment location, which is quite near the Pyrenees Mountains. The self-spinup also corrects a wet bias in the large-scale analysis. The overall result is a much-improved simulation of boundary layer structure, evaluated by comparison with soundings from the field site. Self-spinup is not recommended as a substitute for multi-year spinup with an offline land data assimilation system in circumstances where the data sets required for such spinup are available at the required resolution. Self-spinup may fail if the modeled precipitation is poorly simulated. It is an expedient for cases when resources are not available to allow a better method to be used.
The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu.
The number concentrations and size distributions of aerosol particles >0.3 μm diameter were measured at the summit of Mount Etna and up to 10 km downwind from the degassing vents during July and August 2004. Aerosol number concentrations reached in excess of 9 × 106 L−1 at summit vents, compared to 4–8 × 104 L−1 in background air. Number concentrations of intermediate size particles were higher in emissions from the Northeast crater compared to other summit crater vents, and chemical composition measurements showed that Northeast crater aerosols contained a higher mineral cation content compared to those from Voragine or Bocca Nuova, attributed to Strombolian or gas puffing activity within the vent. Downwind from the summit the airborne plume was located using zenith sky ultraviolet spectroscopy. Simultaneous measurements indicated a coincidence of elevated ground level aerosol concentrations with overhead SO2, demonstrating rapid downward mixing of the plume onto the lower flanks of the volcano under certain meteorological conditions. At downwind sites the ground level particle number concentrations were elevated in all size fractions, notably in the 2.0–7.5 μm size range. These findings are relevant for assessing human health hazard and suggest that aerosol size distribution measurements may aid volcanic risk management.
A revised approach to cloud microphysical processes in a commonly used bulk microphysics parameterization and the importance of correctly representing properties of cloud ice are discussed. Several modifications are introduced to more realistically simulate some of the ice microphysical processes. In addition to the assumption that ice nuclei number concentration is a function of temperature, a new and separate assumption is developed in which ice crystal number concentration is a function of ice amount. Related changes in ice microphysics are introduced, and the impact of sedimentation of ice crystals is also investigated. In an idealized thunderstorm simulation, the distribution of simulated clouds and precipitation is sensitive to the assumptions in microphysical processes, whereas the impact of the sedimentation of cloud ice is small. Overall, the modifications introduced to microphysical processes play a role in significantly reducing cloud ice and increasing snow at colder temperatures and slightly increasing cloud ice and decreasing snow at warmer temperatures. A mesoscale simulation experiment for a heavy rainfall case indicates that impact due to the inclusion of sedimentation of cloud ice is not negligible but is still smaller than that due to the microphysics changes. Together with the sedimentation of ice, the new microphysics reveals a significant improvement in high-cloud amount, surface precipitation, and large-scale mean temperature through a better representation of the ice cloud-radiation feedback.
The word “mazuku” in Swahili means “evil wind”. It corresponds to lowland (depressions) where carbon dioxide is released and, being heavier than air, accumulates at high – often lethal – concentrations (10 vol.% of CO2 in atmosphere can be considered as the deadly threshold, even for a short time exposure). Mazuku are abundant in Goma and surrounding areas and particularly in the area south of the large volcanic edifices of Nyiragongo and Nyamulagira volcanoes located in the most eastern part of DR Congo, W branch of the East African Rift System (EARS). Our extensive field surveys have indicated that mazuku are concentrated within to and around the densely populated city of Goma close to the N shores of Lake Kivu, mainly near fault or fissure networks. At a more local scale, depressions allowing CO2-rich gas accumulation are created by lava flow superposition, lava tunnels or cavity collapses, or directly associated with open fractures. People are killed by mazuku every year. Given political and social unrest coupled with the current important demographic and urban growths around Goma, the risks associated to mazuku are increasing accordingly. Mazuku are currently the most important natural risk in terms of human loss for the area and there is an urgent need for further research, more systematic mapping and monitoring of mazuku and for appropriate risk management to be implemented. This paper summarizes the current scientific knowledge on mazuku as well as new advances and a preliminary risk assessment performed recently in the frame of the GORISK project.
[1] Existing studies of the composition of volcanic plumes generally interpret the presence of sulfate aerosol as the result of comparatively slow oxidation of gaseous SO2. We report here new observations from Masaya Volcano, Nicaragua, which demonstrate that sulfate aerosol may also be emitted directly from volcanic vents. Simultaneous aerosol and gaseous S, Cl, and F compounds were collected at the rim of the passively degassing crater in May 2001. Mean concentrations of SO42−, Cl−, and F− within the plume were 83, 1.2, and 0.37 μg m−3, respectively (fine aerosol fraction 2.5 μm). The aerosols were highly acidic, with estimated pH of
Satellite remote sensing data presents an important tool to map and analyze airborne volcanic ash, both spa-tially and temporally. However, such data only represents an instant in time. To supplement the satellite data and to forecast plume and cloud movement, volcanic ash transport and dispersion models are used. Mount Redoubt Volcano erupted in March and April 2009 with 19 detected events. By analyzing events 5 and 19, we show how satellite data can be used in combination with PUFF and the Weather Research and Forecast model with online Chemistry (WRF-Chem). WRF-Chem has been combined and initialized with a volcanic eruption model. PUFF as well as WRF-Chem show a good assessment of the plume characteristics compared to the satellite data. Especially for event 19, we observed a very close match between WRF-CHEM and satellite data, where PUFF showed an offset of the predicted plume.
ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF.
Uncertainties in simulating the seasonal mean atmospheric water cycle in Equatorial East Africa are quantified using 58 one-year-long
experiments performed with the Weather Research and Forecasting model (WRF). Tested parameters include physical parameterizations
of atmospheric convection, cloud microphysics, planetary boundary layer, land-surface model and radiation schemes, as well
as land-use categories (USGS vs. MODIS), lateral forcings (ERA-Interim and ERA40 reanalyses), and domain geometry (size and
vertical resolution). Results show that (1) uncertainties, defined as the differences between the experiments, are larger
than the biases; (2) the parameters exerting the largest influence on simulated rainfall are, in order of decreasing importance,
the shortwave radiation scheme, the land-surface model, the domain size, followed by convective schemes and land-use categories;
(3) cloud microphysics, lateral forcing reanalysis, the number of vertical levels and planetary boundary layer schemes appear
to be of lesser importance at the seasonal scale. Though persisting biases (consisting of conditions that are too wet over
the Indian Ocean and the Congo Basin and too dry over eastern Kenya) prevail in most experiments, several configurations simulate
the regional climate with reasonable accuracy.
KeywordsWRF–Regional climate modeling–Water cycle–East Africa–Rainfall
One-third of the world's population burn organic material such as wood, dung or charcoal (biomass fuel) for cooking, heating and lighting. This form of energy usage is associated with high levels of indoor air pollution and an increase in the incidence of respiratory infections, including pneumonia, tuberculosis and chronic obstructive pulmonary disease, low birthweight, cataracts, cardiovascular events and all-cause mortality both in adults and children. The mechanisms behind these associations are not fully understood. This review summarises the available information on biomass fuel use and health, highlighting the current gaps in knowledge.
A severe windstorm downstream of Mnt. Öræfajökull in Southeast Iceland is simulated on a grid of 1 km horizontal resolution by using the PSU/NCAR MM5 model and the Advanced Research WRF model. Both models are run with a new, two equation planetary boundary layer (PBL) scheme as well as the ETA/MYJ PBL schemes. The storm is also simulated using six different micro-physics schemes in combination with the MYJ PBL scheme in WRF. Output from a 3 km MM5 domain simulation is used to initialise and drive both the 1 km MM5 and WRF simulations. Both models capture gravity-wave breaking over Mnt. Öræfajökull, while the vertical structure of the lee wave differs between the two models and the PBL schemes. The WRF simulated downslope winds, using the MYJ PBL scheme, are in good agreement with the strength of the observed downslope windstorm, whilst using the new two equation scheme surface winds are considerably less than observed winds. The MM5 simulated surface winds, with the new two equation model, are in better agreement with observations than when using the ETA scheme. Micro-physics processes are shown to play an important role in the formation of downslope windstorms and lifting of the upslope isotherm layer from mountain height to about 1.3 times the mountain height leads to a significant increase in the downslope windstorm.
We report the first combined measurements of the composition and flux of gas emitted from Nyiragongo volcano by ground-based remote-sensing techniques. Ultraviolet spectroscopic measurements made in May/June 2005 and January 2006 indicate average SO2 emission rates of 38 kg s−1 and 23 kg s−1, respectively. Open-path Fourier transform infrared spectroscopic measurements obtained in May/June 2005, January 2006, and June 2007 indicate average molar proportions of 70, 24, 4.6, 0.87, 0.26, 0.11, and 0.0016% for H2O, CO2, SO2, CO, HCl, HF, and OCS, respectively. The composition of the plume was remarkably similar in 2005, 2006, and 2007, with little temporal variation in proportions of CO2, SO2, and CO, in particular, on the scale of seconds or days or even between the three field campaigns that span a period of 24 months. This stability persisted despite a wide range of degassing behaviors on the surface of the summit crater's lava lake (including discrete strombolian bursts and lava fountains) and variations in the SO2 emission rate. We explain these observations by a regime of steady state degassing in which bubbles nucleate and ascend in chemical equilibrium with the convecting magma. Short-term (seconds to minutes) temporal fluctuations in the SO2–HCl–HF composition were observed, and these are attributed to shallow degassing processes. Published Q02017 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive JCR Journal
In January 2002, Nyiragongo volcano erupted 14–34 × 106 m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion of the fracture system and that later erupted from the southern part. These observations are confirmed by new 238U and 232Th series radioactive disequilibria data, which show the presence of three different phases during the eruption. The lavas first erupted (T1) were probably supplied by a residual magma batch from the lava lake activity during 1994–1995. These lavas were followed by a fresh batch erupted from fissure vents as well as later (May–June 2002) from the central crater (T2). Both lava batches reached the surface via the volcano's central plumbing system, even though a separate flank reservoir may also have been involved in addition to the main reservoir. The final phase (T3) is related to an independent magmatic reservoir located much closer (or even beneath) the city of Goma. Data from the January 2002 eruption, and for similar activity in January 1977, suggest that the eruptive style of the volcano is likely to change in the future, trending toward more common occurrence of flank eruptions. If so, this would pose a significant escalation of volcanic hazards facing Goma and environs, thus requiring the implementation of different volcano-monitoring strategies to better anticipate where and when future eruptions might take place. published B09202 3.6. Fisica del vulcanismo JCR Journal
The atmospheric composition over the Amazon forest during the wet season is simulated with a one-dimensional photochemical model for the planetary boundary layer (PBL) extending from the ground to 2000-m altitude. The model is constrained and evaluated using observations from the Amazon Boundary Layer Experiment 2B field expedition. Results indicate that only about 20 percent of NO(x) emitted by soils is exported to the atmosphere above the forest canopy. The balance is deposited to vegetation before leaving the canopy layer. The small NO(x) flux that escapes from the canopy is nevertheless sufficient to account for the low NO concentrations observed in the PBL. Soil emission can account for only a portion of NO(y) observed over the forest. Organic nitrates of nonbiogenic origin likely account for the balance of NO(y). Enhancements of CO observed in the PBL appear to reflect direct emission of CO by the forest ecosystem. Concentrations of O3 in the PBL are regulated largely by transport from aloft and deposition to the canopy, with little net influence from photochemistry. Ozone is photochemically produced immediately above the forest where NO concentrations are relatively high, but is photochemically consumed in the upper portion of the PBL.
Numerous modifications to the Kain-Fritsch convective parameterization have been implemented over the last decade. These modifications are described, and the motivating factors for the changes are discussed. Most changes were inspired by feedback from users of the scheme (primarily numerical modelers) and interpreters of the model output (mainly operational forecasters). The specific formulation of the modifications evolved from an effort to produce desired effects in numerical weather prediction while also rendering the scheme more faithful to observations and cloud-resolving modeling studies.
In this study, radiation doses and lifetime attributable health risk to the members of public in a 40-km impact zone around the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) were assessed for the airborne releases that occurred during 11–31 March 2011 from the loss of coolant accident associated with the east Japan earthquake and tsunami event. High-resolution simulations with FLEXPART-WRF Lagrangian particle dispersion model were made using available source term estimates for four significant isotopes (Cs134, Cs137, I131, Xe133). Radiation risk models were adopted to estimate the health risk for leukemia, breast, thyroid, and all solid cancers using simulated distributed lifetime organ doses. The simulations indicate occurrence of hotspots in the spatial activity deposition and radiation dose distribution with high values in the northwest and south-southwest land sectors in a 40-km radius. Large activity depositions (106 to 108 Bq/m2 of Cs137 between 12 and 31 March 2011) and external air doses (10 to 100 μSv/h) are simulated in the above sectors. The simulated air dose rates are found to match with observed doses at 85 % of the monitor stations within a factor of 5. It is estimated that the groundshine and ingestion dose are the principal contributors of the effective dose. Simulated average effective dose during the first year of exposure varied as ~150 mSv in the first few kilometers to 2 mSv at 40 km. The risk incidence was estimated to be high for infants compared to the children and adult age group for all types of cancers. The first 0–20-km range of the FDNPP is characterized with high risk for all types of cancers, for example, 10 to 20 in 10,000 adults for leukemia. The analysis shows that the immediate implementation of countermeasures of evacuation in the 0–20-km zone, sheltering in the 20–40-km zone, and food restrictions by Japan actually reduced significant health risks to the population living near FDNPP. Simulated yearly distribution of total dose indicates that people of evacuated zone can be rehabilitated in about 16 years in the 5–10-km area and 7 years in the 10–20-km area with minimum risk, whereas the near reactor zone of 0–5 km and areas along the plume footprint up to 20 km in the northwest sector of FDNPP require special attention and reclamation measures for rehabilitation. This study demonstrates a total simulation-based approach for estimating the radiation risk for the Fukushima case and helps to assess the time attainment of low risk for inhabitation of the people in the affected areas.
Petroleum and dairy operations are prominent sources of gas-phase
organic compounds in California's San Joaquin Valley. Ground site
measurements in Bakersfield and aircraft measurements of reactive
gas-phase organic compounds were made in this region as part of the
CalNex (California Research at the Nexus of Air Quality and Climate
Change) project to determine the sources contributing to regional
gas-phase organic carbon emissions. Using a combination of near-source
and downwind data, we assess the composition and magnitude of emissions
from these prominent sources that are relatively understudied compared
to motor vehicles We also developed a statistical modeling method with
the FLEXPART-WRF transport and meteorological model using ground-based
data to assess the spatial distribution of emissions in the San Joaquin
Valley. We present evidence for large sources of paraffinic hydrocarbons
from petroleum extraction/processing operations and oxygenated compounds
from dairy (and other cattle) operations. In addition to the small
straight-chain alkanes typically associated with petroleum operations,
we observed a wide range of branched and cyclic alkanes that have
limited previous in situ measurements or characterization in emissions
from petroleum operations. Observed dairy emissions were dominated by
ethanol, methanol, and acetic acid, and methane. Dairy operations were
responsible for the vast majority of methane emissions in the San
Joaquin Valley; observations of methane were well-correlated with
non-vehicular ethanol, and multiple assessments of the spatial
distribution of emissions in the San Joaquin Valley highlight the
dominance of dairy operations for methane emissions. The good agreement
of the observed petroleum operations source profile with the measured
composition of non-methane hydrocarbons in unrefined natural gas
associated with crude oil suggests a fugitive emissions pathway during
petroleum extraction, storage, or processing with negligible coincident
methane emissions Aircraft observations of emission hotspots from
operations at oil wells and dairies are consistent with the statistical
source footprint determined via transport modeling and ground-based
data. At Bakersfield, petroleum and dairy operations each comprised
22-23% of anthropogenic non-methane organic carbon and were each
responsible for ~12% of potential precursors to ozone, but their direct
impacts as potential SOA precursors were estimated to be minor. A
comparison with the California Air Resources Board emission inventory
supports the current relative emission rates of reactive organic gases
from these sources in the region.
The step-mountain eta model has shown a surprising skill in forecasting severe storms. Much of the credit for this should be given to the Betts and Miller (hereafter referred to as BM) convection scheme and the Mellor-Yamada (hereafter referred to as MY) planetary boundary layer (PBL) formulation. However, the eta model was occasionally producing heavy spurious precipitation over warm water, as well as widely spread light precipitation over oceans. In addition, the convective forcing, particularly the shallow one, could lead to negative entropy changes. As the possible causes of the problems, the convection scheme, the processes at the air-water interface, and the MY level 2 and level 2.5 PBL schemes were reexamined. A major revision of the BM scheme was made, a new marine viscous sublayer scheme was designed, and the MY schemes were retuned. The deep convective regimes are postulated to be characterized by a parameter called “cloud efficiency.” The relaxation time is extended for low cloud effic...
Airborne measurements of gases and aerosols from the recently activated volcanic vents on Mt. Baker were made on March 27 and June 30, 1975. The total rates of emission of gaseous sulfur on these two days were estimated to be 0.35 and 1.3 kg sâ»Â¹, respectively. The latter rate is comparable to the largest single, industrial source of sulfur in the Pacific Northwest. A significant increase in the emission of sub-micron aerosols was also observed between March 27 and June 30. Small aerosol particles are produced in the plume of effluents, probably by gas-to-particle conversion, at a rate of about 2 x 10¹ⷠsâ»Â¹. However, the concentrations of cloud condensation nuclei and ice nuclei in the plume are comparatively small. Aerosols in the plume, greater than about 1 ..mu..m in diameter, consist predominantly of Al, Si, S, K and Ca. Some of the aerosols which were collected in the plume on June 30 might have been Pele's hairs, which are a sign of new magmatic activity.
Chemical composition of rainwater is strictly related to atmosphere scavenging. Active degassing volcanoes release acid gases and solid particulate in the surrounding environment. Nyiragongo Volcano (DRC) is characterized by a high degassing activity from an active lava lake hosted within the crater. Chemistry of rainwater in the area is clearly dependent on the influence of the volcanic plume, especially at the rim of the Nyiragongo summit crater. Rainwater collected from this zone has pH values as low as 2, high salinity (EC 28–1800 μS/cm), and high contents of F− and Cl− (up to 193 and 270 ppm, respectively), NH4+ (up to 146 ppm) and SO42 − ions (up to 340 ppm) relative to worldwide rainwater. The chemical composition of rainwater after interaction with the volcanic plume tends to shift towards the condensable fraction of fumarolic fluids discharged from the summit crater. Rainwater acidified by the volcanic plume also removes metals from particulate suspended in the atmosphere, thus undergoing metal enrichment. Displacement of the Nyiragongo volcanic plume by predominantly westward-directed wind causes “natural” contamination of rainwater collected for drinking purposes in villages located on the western flank of the volcano. Rainwater falling in urban centers located S–SE of the Nyiragongo Volcano is not usually affected by the rain–plume interactions which strictly depends on wind directions. However, areas of possible contamination by the volcanic plume might create a further emergency and critical situations on top of an already existing severe humanitarian crisis. Rainwater is the principal drinking water supply in the Nyiragongo area, thus the geochemical monitoring of rainwater quality is of great importance to mitigate the hazard of natural contamination of this fundamental resource for the local communities.
Numerous modifications to the Kain Fritsch convective parameterization have been implemented over the last decade. These modifications are described, and the motivating factors for the changes are discussed. Most changes were inspired by feedback from users of the scheme (primarily numerical modelers) and interpreters of the model output (mainly operational forecasters). The specific formulation of the modifications evolved from an effort to produce desired effects in numerical weather prediction while also rendering the scheme more faithful to observations and cloud-resolving modeling studies.
The step-mountain eta model has shown a surprising skill in forecasting severe storms. Much of the credit for this should be given to the Betts and Miller (hereafter referred to as BM) convection scheme and the Mellor-Yamada (hereafter referred to as MY) planetary boundary layer (PBL) formulation. However, the eta model was occasionally producing heavy spurious precipitation over warm water, as well as widely spread light precipitation over oceans. In addition, the convective forcing, particularly the shallow one, could lead to negative entropy changes. As the possible causes of the problems, the convection scheme, the processes at the air-water interface, and the MY level 2 and level 2.5 PBL schemes were reexamined. A major revision of the BM scheme was made, a new marine viscous sublayer scheme was designed, and the MY schemes were returned. The MY level 2.5 turbulent kinetic energy (TKE) is initialized from above in the PBL, so that excessive TKE is dissipated at most places during the PBL spinup. The method for calculating the MY level 2.5 master length scale was rectified. To demonstrate the effects of the new schemes for the deep convection and the viscous sublayer, tests were made using two summer cases: one with heavy spurious precipitation, and another with a successful 36-h forecast of a tropical storm. The new schemes had dramatic positive impacts on the case with the spurious precipitation. The results were also favorable in the tropical storm case. The developments presented here were incorporated into the eta model in 1990. The details of further research will be reported elsewhere. The eta model became operational at the National Meteorological Center, Washington, D.C., in June 1993. 60 refs., 8 figs.
This paper presents the global project Network for Observation of Volcanic and Atmospheric Change (NOVAC), the aim of which is automatic gas emission monitoring at active volcanoes worldwide. Data from the network will be used primarily for volcanic risk assessment but also for geophysical research, studies of atmospheric change, and ground validation of satellite instruments. A novel type of instrument, the scanning miniaturized differential optical absorption spectroscopy (Mini-DOAS) instrument, is applied in the network to measure volcanic gas emissions by UV absorption spectroscopy. The instrument is set up 5-10 km downwind of the volcano under study, and typically two to four instruments are deployed at each volcano in order to cover different wind directions and to facilitate measurements of plume height and plume direction. Two different versions of the instrument have been developed. Version I was designed to be a robust and simple instrument for measurement of volcanic SO2 emissions at high time resolution with minimal power consumption. Version II was designed to allow the best possible spectroscopy and enhanced flexibility in regard to measurement geometry at the cost of larger complexity, power consumption, and price. In this paper the project is described, as well as the developed software, the hardware of the two instrument versions, measurement strategies, data communication, and archiving routines. As of April 2009 a total of 46 instruments have been installed at 18 volcanoes worldwide. As a typical example, the installation at Tungurahua volcano in Ecuador is described, together with some results from the first 21 months of operation at this volcano. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in text query field) Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
On January 2, 2010 the Nyamuragira volcano erupted lava fountains extending up to 300m vertically along an ∼1.5km segment of its southern flank cascading ash and gas on nearby villages and cities along the western side of the rift valley. Because rain water is the only available potable water resource within this region, volcanic impacts on drinking water constitutes a major potential hazard to public health within the region. During the 2010 eruption, concerns were expressed by local inhabitants about water quality and feelings of physical discomfort (e.g. nausea, bloating, indigestion, etc.) after consuming rain water collected after the eruption began. We present the elemental and ionic chemistry of drinking water samples collected within the region on the third day of the eruption (January 5, 2010). We identify a significant impact on water quality associated with the eruption including lower pH (i.e. acidification) and increases in acidic halogens (e.g. F(-) and Cl(-)), major ions (e.g. SO(4)(2-), NH(4)(+), Na(+), Ca(2+)), potentially toxic metals (e.g. Al(3+), Mn(2+), Cd(2+), Pb(2+), Hf(4+)), and particulate load. In many cases, the water's composition significantly exceeds World Health Organization (WHO) drinking water standards. The degree of pollution depends upon: (1) ash plume direction and (2) ash plume density. The potential negative health impacts are a function of the water's pH, which regulates the elements and their chemical form that are released into drinking water.
We present the first application of a multi-stage impactor to study volcanic particle emissions to the troposphere from Masaya volcano, Nicaragua. Concentrations of soluble SO4
2–,Cl–, F–, NO3
–, K+, Na+,NH4
+, Ca2+ and Mg2+ were determined in 11 size bins from 0.07 m to >25.5 m. The near-source size distributions showed major modes at 0.5m (SO4
2–, H+,NH4
+); 0.2 m and 5.0 m (Cl–) and 2.0–5.0 m(F–). K+ and Na+ mirrored the SO4
2– size-resolvedconcentrations closely, suggesting that these were transported primarily asK2SO4 and Na2SO4 in acidic solution, while Mg2+ andCa2+ presented modes in both m and >1 m particles. Changes in relative humidity were studied by comparing daytime (transparent plume) and night-time (condensed plume) results. Enhanced particle growth rates were observed in the night-time plume as well as preferential scavenging of soluble gases, such as HCl, by condensed water. Neutralisation of the acidic aerosol by background ammonia was observed at the crater rim and to a greater extent approximately 15 km downwind of the active crater. We report measurements of re-suspended near-source volcanic dust, which may form a component of the plume downwind. Elevated levels ofSO4
2–, Cl–, F–,H+, Na+, K+ and Mg2+ were observed around the 10 m particle diameter in this dust. The volcanic SO4
2– flux leaving the craterwas 0.07 kg s–1.
Methods for estimating the dry deposition velocities of atmospheric gases in the U.S. and surrounding areas have been improved and incorporated into a revised computer code module for use in numerical models of atmospheric transport and deposition of pollutants over regional scales. The key improvement is the computation of bulk surface resistances along three distinct pathways of mass transfer to sites of deposition at the upper portions of vegetative canopies or structures, the lower portions, and the ground (or water surface). This approach replaces the previous technique of providing simple look-up tables of bulk surface resistances. With the surface resistances divided explicitly into distinct pathways, the bulk surface resistances for a large number of gases in addition to those usually addressed in acid deposition models (SO2,O3, NOx and HNO3) can be computed, if estimates of the effective Henry's Law constants and appropriate measures of the chemical reactivity of the various substances are known. This has been accomplished successfully for H2O2, HCHO, CH3CHO (to represent other aldehydes), CH3O2H (to represent organic peroxides), CH3C(O)O2H, HCOOH (to represent organic acids), NH3, CH3C(O)O2NO2 and HNO2. Other factors considered include surface temperature, stomatal response to environmental parameters, the wetting of surfaces by dew and rain, and the covering of surfaces by snow. Surface emission of gases and variations of uptake characteristics by individual plant species within the landuse types are not considered explicitly.
Nicaragua comprises seven historically active volcanoes (Cosigüina, San Cristobal, Telica, Cerro Negro, Momotombo, Masaya, and Concepcion), five of which are in a state of continuous degassing. Published measurements of the atmospheric dispersion of continuous emissions from Nicaraguan volcanoes, the chemical and aerosol microphysical modifications of the released gases and aerosols, and related acid deposition and impacts on the environment cover only short periods of time. We applied a three-dimensional atmosphere-chemistry/aerosol numerical model over Central America focussing on Nicaraguan volcanic emissions for month long simulation periods during the dry and wet seasons of 2003. The model is able to reproduce observed monthly precipitation and wind speed throughout the year 2003. Model results for near surface SO2 concentrations and SO2 dry deposition fluxes around Masaya volcano are in very good agreement with field measurements. During the dry season, oxidation of SO2 to sulphate plays only a minor role downwind of the Nicaraguan volcanoes and over the Pacific Ocean, whereas SO2 released from Arenal and Poas in Costa Rica is oxidised to sulphate much faster and closer to the volcanoes due to higher humidity and cloud water availability. During the wet season, more variable wind conditions lead to reduced dispersion of SO2 over the Pacific Ocean and increased dispersion inland. The availability of liquid water in the atmosphere favours sulphate formation close to the Nicaraguan volcanoes via aqueous phase oxidation and represents another limitation for the dispersion of SO2. Strong precipitation removes sulphate quickly from the atmosphere by wet deposition. Atmospheric SO2 concentrations and in particular dry deposition close to the volcanoes show a pronounced diurnal cycle.
- A G Allen
- C Oppenheimer
- M Ferm
- P J Baxter
- L A Horrocks
- B Galle
- A J S Mcgonigle
- H J Duffell
Allen, A. G., Oppenheimer, C., Ferm, M., Baxter, P. J.,
Horrocks, L. A., Galle, B., McGonigle, A. J. S., Duffell,
H. J., 2002. Primary sulfate aerosol and associated emissions from Masaya volcano, Nicaragua. Journal of Geophysical Research: Atmospheres 107 (D23), ACH 5 1–8.
- O Rögnvaldsson
- J.-W Bao
- H Augústsson
- H Olafsson
Rögnvaldsson, O., Bao, J.-W., ´
Augústsson, H., ´
Olafsson,
H., 2008. Downslope windstorm in Iceland – WRF/MM5
795
model comparison. Atmos. Chem. Phys. 8, 6437–6468.
- J.-C Komorowski
- D Tedesco
- M Kasereka
- P Allard
- P Papale
- O Vaselli
- J Durieux
- P Baxter
- M Halbwachs
- M Akumbe
- B Baluku
- P Briole
- M Ciraba
- J.-C Dupin
- O Etoy
- D Garcin
- H Hamaguchi
- N Houli E
- K S Kavotha
- A Lemarchand
- J Lockwood
- N Lukaya
- G Mavonga
- M De Michele
- S Mpore
- K Mukambilwa
- F Munyololo
- C Newhall
- J Ruch
- M Yalire
- M Wafula
Komorowski, J.-C., Tedesco, D., Kasereka, M., Allard, P., Papale, P., Vaselli, O.,
Durieux, J., Baxter, P., Halbwachs, M., Akumbe, M., Baluku, B., Briole, P.,
Ciraba, M., Dupin, J.-C., Etoy, O., Garcin, D., Hamaguchi, H., Houli e, N.,
Kavotha, K.S., Lemarchand, A., Lockwood, J., Lukaya, N., Mavonga, G., de
Michele, M., Mpore, S., Mukambilwa, K., Munyololo, F., Newhall, C., Ruch, J.,
Yalire, M., Wafula, M., 2003. The january 2002 flank eruption of Nyiragongo
volcano (Democratic Republic of Congo): chronology, evidence for a tectonic rift
trigger, and impact of lava flows on the city of Goma. Acta Vulcanol. 15 (1e2),
27e62.
Human health and vulnerability in the Nyiragongo volcano crisis at Goma
- P Baxter
- P Allard
- M Halbwachs
- J.-C Komorowski
- A Woods
- A Anica
Baxter, P., Allard, P., Halbwachs, M., Komorowski, J.-C.,
Woods, A., Anica, A., 2003. Human health and vulnerability in the Nyiragongo volcano crisis at Goma, Demo-690
Nyamuragira eruptive event: Implications for essential potable water resources
- E Cuoco
- D Tedesco
- R J Poreda
- J C Williams
- S D Francesco
- C Balagizi
- T H Darrah
Cuoco, E., Tedesco, D., Poreda, R. J., Williams, J. C.,
Francesco, S. D., Balagizi, C., Darrah, T. H., 2013b. Im-710
pact of volcanic plume emissions on rain water chemistry
during the January 2010 Nyamuragira eruptive event: Implications for essential potable water resources. Journal of
Hazardous Materials 244-245, 570-581.
Investigation into magma degassing at Nyiragongo volcano, Democratic Republic of the Congo
- G M Sawyer
- S A Carn
- V I Tsanev
- C Oppenheimer
- M Burton
Sawyer, G. M., Carn, S. A., Tsanev, V. I., Oppenheimer,
C., Burton, M., Feb. 2008. Investigation into magma degassing at Nyiragongo volcano, Democratic Republic of
the Congo. Geochemistry, Geophysics, Geosystems 9 (2),
800
1-17.
volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo
F., 2007. January 2002 volcano-tectonic eruption of Nyiragongo volcano, Democratic Republic of Congo. Journal
of Geophysical Research: Solid Earth 112 (B9).