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This dataset included the fire emission, plume, and air quality observation for the 2020 US Giga Fire. The fire emissions productis from the 0.1 degree daily blended Global Biomass Burning Emissions Product from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) (GBBEPx V3, Zhang, et al., 2012, 2019). The plume height information is from theMulti-angle Imaging SpectroRadiometer(MISR) Plume Height project (Diner et al., 1998;Nelson et al., 2013; Val Martin et al., 2018). The atmospheric optical depth (AOD) data isVIIRS Enterprise AOD from Suomi-NPP (Zhang et al., 2016; Kondragunta et al., 2017).VIIRS AOD Thesurface PM2.5 observation is from AirNow measurements. Time period: Aug, 1st, 2020-Sep, 30th, 2020 Please cite: Li, Y.,Tong, D.,Ma, S.,Zhang, X.,Kondragunta, S.,Li, F., &Saylor, R.(2021).Dominance of wildfires impact on air quality exceedances during the 2020 record-breaking wildfire season in the United States.Geophysical Research Letters,48, e2021GL094908.https://doi.org/10.1029/2021GL094908 &nbsp

This dataset included the fire emission, plume, and air quality observation for the 2020 US Giga Fire. The fire emissions product is from the 0.1 degree daily blended Global Biomass Burning Emissions Product from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) (GBBEPx V3, Zhang, et al., 2012, 2019). The plume height information is from the Multi-angle Imaging SpectroRadiometer (MISR) Plume Height project (Diner et al., 1998; Nelson et al., 2013; Val Martin et al., 2018). The atmospheric optical depth (AOD) data is VIIRS Enterprise AOD from Suomi-NPP (Zhang et al., 2016; Kondragunta et al., 2017). VIIRS AOD The surface PM2.5 observation is from AirNow measurements. Time period: Aug, 1st, 2020-Sep, 30th, 2020 Please cite: Li, Y., Tong, D., Ma, S., Zhang, X., Kondragunta, S., Li, F., & Saylor, R. (2021). Dominance of wildfires impact on air quality exceedances during the 2020 record-breaking wildfire season in the United States. Geophysical Research Letters, 48, e2021GL094908. https://doi.org/10.1029/2021GL094908, {"references":["Kondragunta, S., Laszlo, I., Ma, L., JPSS Program Office: NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Aerosol Optical Depth and Aerosol Particle Size Distribution Environmental Data Record (EDR) from NDE. [NOAA-20 dataset]. NOAA National Centers for Environmental Information. NOAA Natl. Cent. Environ. Inf 2017.","Li, Y., Tong, D., Ma, S., Zhang, X., Kondragunta, S., Li, F., & Saylor, R.: Dominance of wildfires impact on air quality exceedances during the 2020 record-breaking wildfire season in the United States. Geophysical Research Letters, 48, e2021GL094908. https://doi.org/10.1029/2021GL094908, 2021.","Nelson, D.L., Garay, M.J., Kahn, R.A., and Dunst, B.A.: Stereoscopic Height and Wind Retrievals for Aerosol Plumes with the MISR INteractive eXplorer (MINX). Remote Sens. 5, 4593-4628, doi:10.3390/rs5094593, 2013.","Val Martin, M., Kahn, R. A., and Tosca, M. G.: A Global Analysis of Wildfire Smoke Injection Heights Derived from Space-Based Multi-Angle Imaging. Remote Sensing, 2018, 10, 1609; doi:10.3390/rs1010, 2018.","Zhang, H., Kondragunta, S., Laszlo, I., Liu, H., Remer, L. A., Huang, J., Superczynski, S., and Ciren, P. (2016), An enhanced VIIRS aerosol optical thickness (AOT) retrieval algorithm over land using a global surface reflectance ratio database, J. Geophys. Res. Atmos., 121, 10,717– 10,738, doi:10.1002/2016JD024859.","Zhang, X., Kondragunta, S., Ram, J., Schmidt, C., & Huang, H.-C.: Near-real-time global biomass burning emissions product from geostationary satellite constellation. Journal of Geophysical Research: Atmospheres, 117(D14). https://doi.org/10.1029/2012JD017459, 2012.","Zhang, X., Kondragunta, S., Da Silva, A., Lu, S., Ding, H., Li, F., & Zhu, Y.: The blended global biomass burning emissions product from MODIS and VIIRS observations (GBBEPx) version 3.1, https://www.ospo.noaa.gov/Products/land/gbbepx/docs/GBBEPx_ATBD.pdf, 2019."]}

PURPOSE: To determine whether mask-induced redirected exhaled air through the superior mask gap contacts multiuse eyedrop bottles during drop administration and the efficacy of interventions to reduce such exposure. SETTING: Academic ophthalmology center. DESIGN: Interventional analysis. METHODS: Schlieren airflow imaging was taken of an examinee wearing frequently used face masks and enacting common clinical scenarios-with and without manual occlusion of the superior mask gap and/or neck extension-and maximum visible vertical breath plume height was quantified. Bottle height during eyedrop administration was measured for 4 ophthalmologists during instillation to 8 eyes of 4 subjects. RESULTS: Breath plume height (mean ± SD 275.5 ± 16.3 mm) was significantly greater than mean bottle height (13.9 ± 4.7 mm; P < .01). Plume height was reduced with manual mask occlusion vs without (P < .01) and was also lower than mean bottle height with manual mask occlusion (P < .01) but not in the absence of occlusion (P < .01). Neck extension alone did not adequately redirect liberated breath to prevent contact with a bottle. CONCLUSIONS: Exhaled air liberated from commonly worn patient face masks was able to contact multiuse eyedrop bottles during eyedrop administration. These findings have important patient safety implications during the coronavirus disease 2019 pandemic and with other respiratory pathogens because these multiuse bottles could potentially serve as vectors of disease. Occlusion of the superior mask gap significantly reduces breath contamination and should be strongly considered by eyecare providers during drop administration in eye clinics.

We present here a computational study of turbulent forced plume released in a varying density environment. The buoyancy frequency N ∞ and the Richardson number ( Ri ) considered in this study are 0.4 s - 1 and 0.1, respectively. The Unsteady Reynold-Averaged Navier-Stokes simulations are conducted to evaluate the capabilities of different turbulence models. First, a grid independence study is performed to finalize the grid parameters. Then, simulations were performed using various k-e turbulence models. The passive scalar contours reveal that the plume reaches a maximum height before it spreads laterally. The velocity contours for the standard k-e model were compared with a reported experimental study and a good agreement is observed. The mean centerline vertical velocity profile throughout the plume height is compared using different k-e turbulence models and similar trends are observed for different turbulence models. Overall, we observed that all the variants of k-e turbulence models capture the macroscale physics accurately, however, the r.m.s. error is the least for the standard k-e model when compared with the reported experimental study.

The Copernicus Atmosphere Monitoring Service (CAMS), operated by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission, provides daily analyses and 5-day forecasts of atmospheric composition, including forecasts of volcanic sulphur dioxide (SO2) in near-real time. CAMS currently assimilates total column SO2 retrievals from the GOME-2 instruments on MetOp-B and -C and the TROPOMI instrument on Sentinel-5P which give information about the location and strength of volcanic plumes. However, the operational TROPOMI and GOME-2 retrievals do not provide any information about the height of the volcanic plumes and therefore some prior assumptions need to be made in the CAMS data assimilation system about where to place the resulting SO2 increments in the vertical. In the current operational CAMS configuration, the SO2 increments are placed in the mid-troposphere, around 550 hPa or 5 km. While this gives good results for the majority of volcanic emissions, it will clearly be wrong for eruptions that inject SO2 at very different altitudes, in particular exceptional events where part of the SO2 plume reaches the stratosphere. A new algorithm, developed by DLR for GOME-2 and TROPOMI and optimized in the frame of the ESA-funded Sentinel-5P Innovation–SO2 Layer Height Project, the Full-Physics Inverse Learning Machine (FP_ILM) algorithm, retrieves SO2 layer height from TROPOMI in NRT in addition to the SO2 column. CAMS is testing the assimilation of these data, making use of the NRT layer height information to place the SO2 increments at a retrieved altitude. Assimilation tests with the TROPOMI SO2 layer height data for the Raikoke eruption in June 2019 show that the resulting CAMS SO2 plume heights agree better with IASI plume height retrievals than operational CAMS runs without the TROPOMI SO2 layer height information and that making use of the additional layer height information leads to improved SO2 forecasts than when using the operational CAMS configuration. By assimilating the SO2 layer height data the CAMS system can predict the overall location of the Raikoke SO2 plume up to 5 days in advance for about 20 days after the initial eruption.

Insights into the 9 December 2019 eruption of Whakaari/White Island from analysis of TROPOMI SO2 imagery., Small, phreatic explosions from volcanic hydrothermal systems pose a substantial proximal hazard on volcanoes, which can be popular tourist sites, creating casualty risks in case of eruption. Volcano monitoring of gas emissions provides insights into when explosions are likely to happen and unravel processes driving eruptions. Here, we report SO2 flux and plume height data retrieved from TROPOMI satellite imagery before, during, and after the 9 December 2019 eruption of Whakaari/White Island volcano, New Zealand, which resulted in 22 fatalities and numerous injuries. We show that SO2 was detected without explosive activity on separate days before and after the explosion, and that fluxes increased from 10 to 45 kg/s ~40 min before the explosion itself. High temporal resolution gas monitoring from space can provide key insights into magmatic degassing processes globally, aiding understanding of eruption precursors and complementing ground-based monitoring.

Using a three-dimensional fluid dynamic model for eruption cloud dynamics, we present numerical simulations of the development of a volcanic eruption column and umbrella cloud formed during the 13 February 2014 eruptions of Mount Kelud, Indonesia. The model used in this study quantitatively reproduces the observed data and, in particular, the plume height and the horizontal expansion level and rate of the umbrella cloud. The simulation results suggest that on the basis of the plume height and structures and the horizontal expansion level of the umbrella cloud the mass eruption rate (MER) for the 2014 Kelud eruptions was 3 × 107 to 4 × 107 kg s− 1. On the basis of the horizontal expansion rate of the umbrella cloud, on the other hand, the estimated MER was 1 × 108 kg s− 1. The difference between these two estimates implies the strong diffusion in the umbrella cloud or the efficient entrainment of ambient air by eruption column.

We report on experiments of turbulent particle-laden plumes descending through a stratified environment. We show that provided the characteristic plume speed $(B_{0}N)^{1/4}$ exceeds the particle fall speed, where the plume buoyancy flux is $B_{0}$ and the Brunt–Väisälä frequency is $N$, then the plume is arrested by the stratification and initially intrudes at the neutral height associated with a single-phase plume of the same buoyancy flux. If the original fluid phase in the plume has density equal to that of the ambient fluid at the source, then as the particles sediment from the intruding fluid, the fluid finds itself buoyant and rises, ultimately intruding at a height of about $0.58\pm 0.03$ of the original plume height, consistent with new predictions we present based on classical plume theory. We generalise this result, and show that if the buoyancy flux at the source is composed of a fraction $F_{s}$ associated with the buoyancy of the source fluid, and a fraction $1-F_{s}$ from the particles, then following the sedimentation of the particles, the plume fluid intrudes at a height $(0.58+0.22F_{s}\pm 0.03)H_{t}$, where $H_{t}$ is the maximum plume height. This is key for predictions of the environmental impact of any material dissolved in the plume water which may originate from the particle load. We also show that the particles sediment at their fall speed through the fluid below the maximum depth of the plume as a cylindrical column whose area scales as the ratio of the particle flux at the source to the fall speed and concentration of particles in the plume at the maximum depth of the plume before it is arrested by the stratification. We demonstrate that there is negligible vertical transport of fluid in this cylindrical column, but a series of layers of high and low particle concentration develop in the column with a vertical spacing which is given by the ratio of the buoyancy of the particle load and the background buoyancy gradient. Small fluid intrusions develop at the side of the column associated with these layers, as dense parcels of particle-laden fluid convect downwards and then outward once the particles have sedimented from the fluid, with a lateral return flow drawing in ambient fluid. As a result, the pattern of particle-rich and particle-poor layers in the column gradually migrates upwards owing to the convective transport of particles between the particle-rich layers superposed on the background sedimentation. We consider the implications of the results for mixing by bubble plumes, for submarine blowouts of oil and gas and for the fate of plumes of waste particles discharged at the ocean surface during deep-sea mining.

Biofilm formation is a dynamic process that leads to mature communities over time. Despite a general knowledge of biofilm community formation and the resultant limitations of antibiotic therapy, there is a paucity of data describing specific plume heights, surface coverage and rates of maturation. Furthermore, little is published on the effect that the broth medium might have on the degree of biofilm maturation. In this study, three strains of methicillin-resistant Staphylococcus aureus (MRSA) (USA300, USA400 and a clinical isolate) were grown in brain heart infusion broth (BHI) or tryptic soy broth (TSB). Following growth, SEM images were captured for 3-D analysis to assess plume height. TSB produced significantly higher plume heights of USA300 and USA400 compared to BHI. Broth type was less influential on the clinical isolate. The data indicate that broth type and time may be important factors to consider when assessing maturation and plume height formation of MRSA biofilms.

We herein propose an alternative model for deformation caused by an eruption at Sakurajima, which has been previously interpreted as being due to a Mogi-type spherical point source beneath Minami-dake. On November 13, 2017, a large explosion with a plume height of 4200 m occurred at Minami-dake. During the 3 min following the onset of the explosion (November 13, 2017, 22:07–22:10 (Japan standard time (UTC + 9); the same hereinafter), phase 1, a large strain with changes up to 120 nstrain was detected at the Arimura observation tunnel (AVOT) located approximately 2.1 km southeast from the Minami-dake crater. After the peak of the explosion (November 13, 2017, 22:10–24:00), phase 2, a large deflation was detected at every monitoring station due to the continuous Strombolian eruption. Subsidence toward Minami-dake was detected at five out of six stations, whereas subsidence toward the north of Sakurajima was detected at the newly installed Komen observation tunnel (KMT), located approximately 4.0 km northeast from the Minami-dake crater. The large strain change at AVOT as well as small tilt changes at all stations and small strain changes at the Harutayama observation tunnel (HVOT) and KMT during phase 1 can be explained by a very shallow deflation source beneath Minami-dake at 0.1 km below sea level (bsl). For phase 2, a deeper deflation source beneath Minami-dake at a depth of 3.3 km bsl was found in addition to the shallow source beneath Minami-dake, which turned inflation after the deflation that occurred during phase 1. However, this model cannot explain the tilt change of KMT. Adding a spherical deflation source beneath Kita-dake at a depth of 3.2 km bsl can explain the tilt and strain change at KMT and the other stations. The Kita-dake source was also found in a previous study of long-term ground deformation. Not only the deeper Minami-dake sourceMD, but also the Kita-dake source deflated due to the Minami-dake explosion.

We analyze seismic tremor recorded during eruptive activity over the course of the 2016–2017 eruption of Bogoslof volcano, Alaska. Only regional recordings of the tremor wavefield exist for Bogoslof, making it a challenge to place the recordings in context with other eruptions that are normally captured by local seismic data. We apply a technique of time-frequency polarization analysis to three-component seismic data to reveal the wavefield composition of Bogoslof eruption tremor. We find that at regional distances, the tremor is dominated by P-waves in the band from 1.5 to 10 Hz. Using this information, along with an enriched Bogoslof earthquake catalog, we obtain estimates of average reduced displacement (DR) for eruption tremor during 25 of the 70 Bogoslof events. DR reaches as high as approximately 40 cm2 for two of the major events, similar to other VEI~3 eruptions in Alaska. Overall, average reduced displacement displays a weak correlation to plume height during the first half of the 9-month-long eruption sequence, with a few notable exceptions. The two events with the highest DR values also generated measurable eruption tremor at very-long-periods (VLP) between 0.05 and 0.15 Hz.

Publisher's version (útgefin grein), Meaningful forecasting of the atmospheric concentration and ground accumulation of volcanic ash during explo-sive eruptions requires detailed knowledge of the eruption source parameters. However, due to the large uncer-tainties in observations and limitations of current models used to make inferences from these, monitoring anongoing eruption and quantifying the mass eruption rate in real-time is a considerable challenge. Within theEU supersite project“FutureVolc”, an integrated approach has been applied to develop a quasi-autonomousmulti-parameter system, denoted“REFIR”, for monitoring volcanic eruptions in Iceland and assessing the erup-tion massflow rate by inverting the plume height information and taking account of these uncertainties. REFIRhas the capability to ingest and process streaming plume-height data provided by a multitude of ground basedsensors, including C–and X-band radars and web-cam based plume height tracking systems. These observationaldata are used with a suite of plume models that also consider the current wind and other atmospheric conditions,providing statistically assessed best estimates of plume height and mass eruption rate. Provided instrumentaldata is available, near real-time estimates are obtained (the delay corresponding to the scan rate of data-providing instruments, presently of the order of minutes). Using the Hekla 2000, and Eyjafjallajökull 2010 erup-tions in Iceland, the potential of REFIR is demonstrated and discussed through application to three scenarios. Thesystem has been developed to provide maximumflexibility. A setup script assists the user in adapting to localconditions, allowing implementation of REFIR for any volcanic eruption site worldwide. REFIR is designed to beeasily upgradable, allowing future extension of monitoring networks, learning from new events, and incorpora-tion of new technologies and model improvements. This article gives an overview of the basic structure, modelsimplemented, functionalities and the computational techniques of REFIR., The development of REFIR has been part of the FUTUREVOLC supersite project and was funded by the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308377. TD's work was also funded by the project EVER-EST, as part of the EU's Horizon 2020 research and innovation programme under grant agreement no 674907.

Stromboli volcano has a persistent activity that is almost exclusively explosive. Predominated by low intensity events, this activity is occasionally interspersed with more powerful episodes, known as major explosions and paroxysms, which represent the main hazards for the inhabitants of the island. Here, we propose a machine learning approach to distinguish between paroxysms and major explosions by using satellite-derived measurements. We investigated the high energy explosive events occurring in the period January 2018–April 2021. Three distinguishing features are taken into account, namely (i) the temporal variations of surface temperature over the summit area, (ii) the magnitude of the explosive volcanic deposits emplaced during each explosion, and (iii) the height of the volcanic ash plume produced by the explosive events. We use optical satellite imagery to compute the land surface temperature (LST) and the ash plume height (PH). The magnitude of the explosive volcanic deposits (EVD) is estimated by using multi-temporal Synthetic Aperture Radar (SAR) intensity images. Once the input feature vectors were identified, we designed a k-means unsupervised classifier to group the explosive events at Stromboli volcano based on their similarities in two clusters: (1) paroxysms and (2) major explosions. The major explosions are identified by low/medium thermal content, i.e., LSTI around 1.4 °C, low plume height, i.e., PH around 420 m, and low production of explosive deposits, i.e., EVD around 2.5. The paroxysms are extreme events mainly characterized by medium/high thermal content, i.e., LSTI around 2.3 °C, medium/high plume height, i.e., PH around 3330 m, and high production of explosive deposits, i.e., EVD around 10.17. The centroids with coordinates (PH, EVD, LSTI) are: Cp (3330, 10.7, 2.3) for the paroxysms, and Cme (420, 2.5, 1.4) for the major explosions.

Syneruptive gas flux time series can, in principle, be retrieved from satellite maps of SO 2 collected during and immediately after volcanic eruptions, and used to gain insights into the volcanic processes which drive the volcanic activity. Determination of the age and height of volcanic plumes are key prerequisites for such calculations. However, these parameters are challenging to constrain using satellite-based techniques. Here, we use imagery from OMI and GOME-2 satellite sensors and a novel numerical procedure based on back-trajectory analysis to calculate plume height as a function of position at the satellite measurement time together with plume injection height and time at a volcanic vent location. We applied this new procedure to three Etna eruptions (12 August 2011, 18 March 2012 and 12 April 2013) and compared our results with independent satellite and ground-based estimations. We also compare our injection height time-series with measurements of volcanic tremor, which reflects the eruption intensity, showing a good match between these two datasets. Our results are a milestone in progressing towards reliable determination of gas flux data from satellite-derived SO 2 maps during volcanic eruptions, which would be of great value for operational management of explosive eruptions.

In December 2016, the unmonitored Bogoslof volcano unexpectedly began erupting, producing at least 70 explosions over the next 8.5 months. Roughly half of the explosions were preceded by observable short-term precursory activity, defined here as seismic activity ending within 30 min of the explosion onset or an earthquake swarm ending within a few hours before the explosion onset. Five different types of precursors were noted during the Bogoslof eruption: non-swarm earthquakes, earthquake swarms, rapid rate events, tremor, and chromatic tremor. Most of the precursors that were detectable by the nearby seismic networks (> 45 km away) occurred during the first 3 months of the eruption, with nearly all precursory earthquake swarms occurring during this period. A hydrophone deployed ~ 7 km northeast of the summit for the last 3 months of the eruption detected weaker activity that was not recorded by the more distant seismic networks. We describe the observed precursors and discuss their inter-relations. Overall, the precursors seem indicative of processes occurring throughout the volcanic system and suggest possible changes in the system during the eruption. We then compare the short-term precursors with explosion parameters, such as plume height, duration, and occurrence of lightning, to look for relations that may provide more insight into the eruption dynamics and subsurface processes and help to further improve forecasting. We find no obvious relations between any of the precursor or explosion parameters, suggesting that their use in forecasting eruption characteristics at Bogoslof is limited.

Height of plumes generated during explosive volcanic eruptions is commonly used to estimate the associated eruption intensity (i.e., mass eruption rate; MER). In order to quantify the relationship between plume height and MER, we performed a parametric study using a three-dimensional (3D) numerical model of volcanic plumes for different vent sizes. The results of five simulations indicate that the flow pattern in the lower region of the plume systematically changes with vent size, and hence, with MER. For MERs 7 kg s − 1 , the flow in the lower region has a jet-like structure (the jet-like regime). For MERs > 10 8 kg s − 1 , the flow shows a fountain-like structure (the fountain-like regime). The flow pattern of plumes with 4 × 10 7 kg s − 1 8 kg s − 1 shows transitional features between the two flow regimes. Within each of the two flow regimes, the plume height increases as the MER increases, whereas plume heights remain almost constant or even decrease as MER increases in the transitional regime; as a result, the jet-like and fountain-like regimes show distinct relationships of plume height and MER. The different relationships between the two regimes reflect the fact that the efficiency of entrainment of ambient air in the jet-like regime is substantially lower than that in the fountain-like regime. It is suggested that, in order to estimate eruption intensity from the observed plume heights, it is necessary to take the different flow regimes depending on MER into account.

ADAP (Automatic Detection of Ash Plume) software intended for automatic detection of the seismic signals accompanying ash emission at the active volcanoes is designed and introduced. This software also calculates the height of the ash plume in real time and automatically sends information on the detected hazardous ash emissions by e-mail and SMS to scientists on duty. The reliability of the program is estimated at 70%. The program has no current analogues.

The 2010 Eyjafjallajokull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash transport forecast in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs to be run with Eruption Source Parameters (ESP) such as plume height and mass eruption rate as input, and with data assimilation techniques to continuously improve the initial conditions of the forecast. Reliable and accurate ash measurements are crucial for providing a successful ash clouds advice. In this paper, simulated aircraft-based measurements, as one type of volcanic ash measurements, will be assimilated into a transport model to identify the potential benefit of this kind of observations in an assimilation system. The results show assimilating aircraft-based measurements can significantly improve the state of ash clouds, and further providing an improved forecast as aviation advice. We also show that for advice of aeroplane flying level, aircraft-based measurements should be preferably taken from this level to obtain the best performance on it. Furthermore it is shown that in order to make an acceptable advice for aviation decision makers, accurate knowledge about uncertainties of ESPs and measurements is of great importance.

The anticipated material captured from a flythrough of Europa’s putative plumes is investigated using a simple model. With parameters appropriate to observed constraints (plume height 100–200 km, column mass 1E20 H2O molecules/m2, originating in a liquid water exposure), bacterial cells of ∼10 μm could be lofted even to the plume tops, but no particles larger than 2 mm will be lofted above ∼2 km, a likely lower limit on feasible altitude. Intercepted mass densities of 1E−5 to 1E−3 kg/m2 are calculated. With a small in-situ sampler at the lowest altitudes a few hundred cells might be captured if the liquid is as abundant in biota as the richest environments on Earth, but statistically less than 1 cell for Vostok waters, a Europa analog. The imperative for a large collection area is noted. The likelihood of capturing at least a single cell, with a log-uniform prior of cell abundances, is proposed as a science value metric for different flyby altitudes.

In the wake of the June 2011 Nabro eruption, large stratospheric plumes were observed by several instruments up to altitudes of 21 km, much higher than initial reported injection heights. It has been debated whether deep convection associated with the Asian Summer Monsoon anticyclone played a vital role in the vertical transport of the plume. Here we present a new and fast SO2 height retrieval algorithm for observations of the Infrared Atmospheric Sounding Interferometer (IASI). A comprehensive validation with forward trajectories and coincident CALIOP measurements is presented which indicates an accuracy better than 2 km for plumes below 20 km and SO2 columns up to the 1 DU level. We use this new product to analyse the Nabro eruption. Our findings indicate an initial plume located mainly between 15 and 17 km for which the lower parts underwent in succession rapid descent and uplift, within the Asian Monsoon anticyclone circulation, up to the stable thermal tropopause between 16 and 18 km, from where it slowly ascended further into the stratosphere. Evidence is presented that emissions in the first week of the eruption also contributed to the stratospheric sulfur input. This includes a second eruption between 15 and 17 km on the 16th and continuous emissions in the mid-troposphere of which some were also entrained and lifted within the anticyclonic circulation.

Atmospheric shock waves induced by explosive volcanic eruptions can provide valuable information about eruption characteristics. Shock waves are manifested as pressure-density gradients that can be remotely observed with relatively little noise. Field measurements of expanding shock waves can be directly recorded by pressure transducers or imaged under the proper illumination and atmospheric conditions. In this paper, an open-ended shock tube was used to generate weak shock waves in the laboratory that are representative of explosive volcanic eruptions. They indicate that strong shock wave theory can be used for modeling moderate volcanic eruptions. Based on that finding, we use strong shock theory to estimate the sudden explosive energy released from several explosive eruptions. Our energy calculations are well correlated with total energy estimates derived from plume height or erupted mass.

During the sub-plinian eruptions of Mt. Shinmoedake (Japan) on 26–27 January 2011 a significant amount of ash was emitted into the atmosphere, destroying thousands of hectares of farm land, causing air traffic disruption, and forcing the closure of four railroad lines located around the volcano. In this work, a retrospective analysis of these eruptive events is presented, exploiting the high temporal resolution of the Japanese Multi-functional Transport Satellites (MTSAT) data to study thermal volcanic activity, to identify and track volcanic ash, and to determine the cloud-top height, inferring information about eruption features and space-time evolution. We show that a strong and sudden increase in the thermal signal occurred at Mt. Shinmoedake as a consequence of above mentioned eruptive events, generating hot spots timely detected by the RST VOLC algorithm for the first time implemented here on data provided by geostationary satellites. This study also shows that the emitted ash plume, identified by means of the RST ASH algorithm, strongly fluctuated in altitude, reaching a maximum height around 7.4 km above sea level, in agreement with information provided by the Tokyo VAAC. The plume heights derived in this work, by implementing the widely accepted cloud-top temperature method, appear also compatible with the values provided by independent weather radar measurements, with the main differences characterizing the third sub-plinian event that occurred in the afternoon of 27 January. The estimates of discharge rate, the temporal trend of ash affected areas, and the results of thermal monitoring reported in this work seem to indicate that the third sub-plinian event was the least intense. In spite of some limitations, this study confirms the potential of Japanese geostationary satellites in effectively monitoring volcanoes located in the West Pacific region, providing continuous information also about such critical parameters of ash clouds as the plume height. Such information is useful not only for driving numerical models, forecasting ash dispersion into the atmosphere, but also for characterizing eruption features and dynamics.

This impact of heat rejection on cooling tower plume dispersion was studied in this paper by applied SACTI (Seasonal Annual Cooling Tower Impact) model. In order to analyze the impact of heat rejection (HR), we set five scenarios including observed, HR decrease 5% (HR-5) and 10% (HR-10), and increase 5% (HR+5) and 10% (HR+10). Results showed that plume length frequency, plume height frequency and plume radius frequency will present different variation trend when heat rejection increase and decrease scenarios. On the whole, the plume character parameter will decrease as heat rejection decrease, but will increase as heat rejection increasing.

The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the Terra satellite acquires imagery at 275-m resolution at nine angles ranging from 0deg (nadir) to 70deg off-nadir. This multi-angle capability facilitates the stereoscopic retrieval of heights and motion vectors for clouds and aerosol plumes. MISR's operational stereo product uses this capability to retrieve cloud heights and winds for every satellite orbit, yielding global coverage every nine days. The MISR INteractive eXplorer (MINX) visualization and analysis tool complements the operational stereo product by providing users the ability to retrieve heights and winds locally for detailed studies of smoke, dust and volcanic ash plumes, as well as clouds, at higher spatial resolution and with greater precision than is possible with the operational product or with other space-based, passive, remote sensing instruments. This ability to investigate plume geometry and dynamics is becoming increasingly important as climate and air quality studies require greater knowledge about the injection of aerosols and the location of clouds within the atmosphere. MINX incorporates features that allow users to customize their stereo retrievals for optimum results under varying aerosol and underlying surface conditions. This paper discusses the stereo retrieval algorithms and retrieval options in MINX, and provides appropriate examples to explain how the program can be used to achieve the best results.

The SACTI model (Seasonal Annual Cooling Tower Impact) as the environmental impact assessment of cooling tower was applied in this paper, which was used to simulate the plume characters under different kinds of relative humidity. The three kinds of relative humidity were 70%, 80% and 90% and it was analyzed that the plume character under these three kinds of relative humidity. Results showed that the plume length, plume height and plume radius will present different change trend when relative humidity changed. Additionally, the plume dispersion character in different seasons presented obviously variations and the different wind direction also play important role in prediction of cooling tower plume dispersion.

Wind speed was an important impact factor when simulating the cooling tower plume dispersion. The SACTI model was selected in this paper and this model was used to predict the plume dispersion character discharging from cooling tower under normal operation and three different kinds of wind speeds. The three kinds of wind speeds were 2 m/s, 4 m/s and 6 m/s and it was analyzed that the plume character under these three wind speeds. Results showed that the plume length, plume height and plume radius will present different change trend when wind speed changed.

The SACTI model (Seasonal Annual Cooling Tower Impact) as the environmental impact assessment of cooling tower was applied in this paper, which was used to simulate the plume characters under different cooling tower heights. The results showed that the plume length, plume height and plume radius presented noticeable differences with variances of different distances and wind directions under different cooling tower heights. The comparisons of differences of plume characters indicated that the relative change of plume length frequency displayed obvious decreased trend with increased distance when distance was greater than 500m, and that of plume height frequency appeared parabolic curve with increased distance. The relative change of plume radius frequency expressed totally descended trend.

© 2016 by the American Association for the Advancement of Science; all rights reserved. The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America.The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array.The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data.We propose that the time-varying relationship at Pavlof arose from changes in the tremor source related to volcanic vent erosion.This relationship may improve estimates of volcanic emissions and characterization of eruption size and intensity.

The intensity is important for comparing eruptions. Remote-sensing data allow investigators to quickly estimate Volcanic Explosivity Index (VEI), an indicator for the intensity of an eruption. The volume of volcanic products and plume height, which can be determined by satellite data, are two major variables used to estimate VEI. Sarychev Peak has been one of the most active volcanoes on Kuril Islands. Most recently it repeated its violent eruptions in June 2009. The volume of volcanic products in Matua Island discharged from Sarychev Peak was estimated, and there was a 0.08 km 3 difference between ASTER and PRISM DEM Data. The plume height was estimated as high as 10 km using ASTER images. The 2009 Sarychev Peak eruptions is rated as VEI “3” based on the measured ejecta volume and the plume height calculated in our analysis, but this did not take into account the volcanic products deposited in the sea. If this volume was considered, the VEI should have been “4”. Satellite remote-sensing is a powerful tool to estimate VEI quickly, even for a volcano on an inaccessible remote island.

Volcanic infrasound from explosive eruptions is detectable at distances up to 1000 s of km and is often recorded on the International Monitoring System (IMS) infrasound network. Though infrasound produced by individual volcanoes has previously been studied, more general relationships between infrasound characteristics and eruption parameters remain unclear. Therefore, using a dataset comprising 110 events at 39 globally distributed volcanoes, we assess the ability of the IMS to monitor remote volcanoes and investigate whether volcanic infrasound exhibits consistent trends across a range of eruption styles and intensities. Acoustic pressure amplitude and frequency content of the volcanic infrasound were measured, and acoustic energy was also calculated. These were compared, along with the maximum distance of detection for each event, to the maximum plume height reported for the event, which was used as a proxy for event intensity. Of the events investigated 62% were detected by at least one infrasound station. The maximum distance at which an event was detected generally increased with the plume height, and infrasound produced during the eruption of Manam, PNG in January 2005, which produced a plume which rose over 20 km above the summit, was detected at a distance of 10,671 km. Total acoustic energy and acoustic pressure amplitude (corrected for geometrical spreading) increased with plume height, whilst the lowest frequency present in the volcanic infrasound decreased. Additionally, relationships seen between infrasound characteristics and eruption plume height indicate that analyses of this data alone could constrain vital estimates of plume heights for otherwise un-observed eruptions. Taken together these findings indicate that if made available for this purpose in the future, the IMS infrasound network could complement existing monitoring techniques by detecting and characterising eruptions at remote volcanoes which often have no local monitoring networks.

The 2006 eruption of Augustine Volcano, Alaska, began with an explosive phase comprising 13 discrete Vulcanian blasts. These events generated ash plumes reaching heights of 3–14 km. The eruption was recorded by a dense geophysical network including a pressure sensor located 3.2 km from the vent. Infrasonic signals recorded in association with the eruptions have maximum pressures ranging from 13–111 Pa. Eruption durations are estimated to range from 55–350 s. Neither of these parameters, however, correlates with eruption plume height. The pressure record, however, can be used to estimate the velocity and flux of material erupting from the vent, assuming that the sound is generated as a dipole source. Eruptive flux, in turn, is used to estimate plume height, assuming that the plume rises as a buoyant thermal. Plume heights estimated in this way correlate well with observations. Events that exhibit strongly impulsive waveforms are underestimated by the model, suggesting that flow may have been supersonic.

The largest error in determining volcanic gas fluxes using ground based optical remote sensing instruments is typically the determination of the plume speed, and in the case of fixed scanning instruments also the plume height. We here present a newly developed technique capable of measuring plume height, plume speed and gas flux using one single instrument by simultaneously collecting scattered sunlight in two directions. The angle between the two measurement directions is fixed, removing the need for time consuming in-field calibrations. The plume height and gas flux is measured by traversing the plume and the plume speed is measured by performing a stationary measurement underneath the plume. The instrument was tested in a field campaign in May 2005 at Mt. Etna, Italy, where the measured results are compared to wind fields derived from a meso-scale meteorological model (MM5). The test and comparison show that the instrument is functioning and capable of estimating wind speed at the plume height.

The European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Avi­ ation Hazards, was introduced after the eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 to facilitate the development of an optimal End­to­End System for Volcanic Ash Plume Monitoring and Predic­ tion. The Eyjafjallajökull plume drifted towards Europe and caused major disruptions of European air traffic for several weeks affecting the everyday life of millions of people. The limitations in volcanic plume monitoring and prediction capabilities gave birth to this observational system which is based on comprehensive satellite­derived ash plume and sulphur dioxide [SO2] level estimates, as well as a widespread validation using supplementary satellite, aircraft and ground­based measurements. Inter­comparison of the volcanic total SO2 column and plume height observed by GOME­2/Metop­A and IASI/Metop­A are shown before, during and after the Eyjaf­ jallajökull 2010 eruptions as well as for the 2011 Grímsvötn eruption. Co­located ground­based Brewer Spectro­ photometer data extracted from the World Ozone and Ultraviolet Radiation Data Centre for de Bilt, the Nether­ lands, are also compared to the different satellite estimates. Promising agreement is found for the two different types of instrument for the SO2 columns with linear regression coefficients ranging around from 0.64 when comparing the different instruments and 0.85 when comparing the two different IASI algorithms. The agree­ ment for the plume height is lower, possibly due to the major differences between the height retrieval part of the GOME2 and IASI algorithms. The comparisons with the Brewer ground­based station in de Bilt, The Nether­ lands show good qualitative agreement for the peak of the event however stronger eruptive signals are required for a longer quantitative comparison.

In this paper, we reconstruct the vertical profile of volcanic ash emissions by assimilating satellite data and ground‐based observations using a modified trajectory‐based 4D‐Var (Trj4DVar) approach. In our previous work, we found that the lack of vertical resolution in satellite ash column data can result in a poor estimation of the injection layer where the ash is emitted into the atmosphere. The injection layer is crucial for the forecast of volcanic ash clouds. To improve estimation, Trj4DVar was implemented, and it has shown increased performance in twin experiments using synthetic observations. However, there are some cases with real satellite data where Trj4DVar has difficulty in obtaining an accurate estimation of the injection layer. To remedy this, we propose a modification of Trj4DVar, test it with synthetic twin experiments, and evaluate real data performance. The results show that the modified Trj4DVar is able to accurately estimate the injection height (location of the maximal emission rate) by incorporating the plume height (top of the ash plume) and mass eruption rate data obtained from ground‐based observations near the source into the assimilation system. This will produce more accurate emission estimations and more reliable forecasts of volcanic ash clouds. Also provided are two strategies on the preprocessing and proper use of satellite data.

In this study two neural networks were implemented in order to emulate a retrieval model and to estimate the sulphur dioxide (SO 2 ) columnar content and plume height from volcanic eruption. ANNs were trained using all IASI channels in TIR as inputs, and the corresponding values of SO 2 content and height of plume obtained using the Oxford SO 2 retrievals as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajokull volcano (Iceland) occured in 2010 and to three IASI images of the Grimsvotn volcanic eruption that occurred in May 2011, in order to evaluate the networks for a different eruption. The results of validation, both for Eyjafjallajokull and Grimsvotn independent datasets, provided RMSE values between neural network outputs and targets lower than 20 DU for SO 2 total column and 200 mb for plume height, therefore demonstrating the feasibility to estimate SO 2 values using a neural network approach, and its importance in near real time monitoring activities, owing to its fast application. Concerning the validation carried out with neural networks on images from the Grimsvotn eruption, the RMSE of the outputs remained lower than the Standard Deviation (STD) of targets, and the neural network underestimated retrieval only where target outputs showed different statistics than those used during the training phase.

Observations from ground-based observatories and with the Galileo spacecraft suggest that the flares from the SL9 impacts resulted from ejecta falling back onto Jupiter in ballistic plumes. This explanation is supported by comparing the plume height as a function of time in HST images with the flare light curve. We show that the rotational temperature of CO in the shock from the R impact rose from less than 2000 K near the beginning of the main flare to about 5000 K at its end. This behavior agrees with a simple physical model of ballistic plumes with a mean molecular weight indicating they are 50% or more jovian air. Alternate models involving formation of molecules at the original impact site, or formation of dust grains to initiate the flare, are inconsistent with these measurements. The energy is emitted primarily as a hot continuum, supporting the possibility that finely divided dust grains are heated in the reentry shock and emit to create the flare. Scaling such models to the energy of the K/T event supports proposals that ballistic plumes were responsible for the global disaster associated with it.

A series of 69 × 15 min trajectories of the plume from a direct-cooled, 360 MW(e) power station have been measured with a rapid-scanning Lidar to downwind distances of 3 km; the measurements were made in August and September 1993 in eastern England. The results indicate that, in sunny conditions, buoyant rise is halted when plume elements start to impinge on the top of the boundary layer. By contrast, the Briggs “break-up” model, according to which plume rise ceases when the plume is broken up by ambient turbulence, failed to predict the distribution of observed final plume heights. It is concluded that in U.K. conditions buoyant rise is likely to be limited by the depth of the boundary layer. Several methods of estimating the depth of the boundary layer from Lidar measurements are discussed. The initial plume rise at Staythorpe was similar to the plume rise at other inland power stations.

Preliminary 2D/3D numerical simulations were carried out for the penetration of 1-km bodies in the Jovian atmosphere and the subsequent rise and collapse of the erupted plumes. A body that crushed at a stagnation point pressure of 5 kbar produced a plume that rose to 800 km. Evolution of the shape of the calculated plume corresponds rather well to the plumes observed by HST. A crescent-shaped lobe centered on the “backfire” azimuth was produced by lateral flow during plume collapse. The plumes observed on Jupiter rose about 4 times higher, and their rise and fall times were about twice those in this calculation. Plume height is a sensitive function of the distribution of energy along the entry path; a very low-strength body will disintegrate higher along the penetration path and will produce a higher plume.

We show that in the diffusive combustion of turbulent underexpanded gas jets the geometric dimensions of the plume are directly associated with the gas flowrate, and we propose a technique for evaluating the flowrate of the burning gushers that arise in the case of well accidents on the basis of the diffusive plume height.

[1] The eruption of the Eyjafjallajokull volcano, Iceland, in April and May 2010 caused unprecedented disruptions of European air traffic showing that timely monitoring of volcanic ash and SO2 dispersion as well as the corresponding plume heights are important for aviation safety. This paper describes the observations of SO2 and BrO columns in the eruption plume and the determination of the SO2 plume height using the GOME-2 satellite instrument. During the eruptive period in May 2010, SO2 total columns of up to ∼20 DU and BrO columns of ∼7.7 × 1013 molec/cm2 were detected. The BrO/SO2 ratio estimated from the GOME-2 observations of the Eyjafjallajokull eruption varies from 1.1 × 10−4 to 2.1 × 10−4. The SO2 plume heights estimated from the GOME-2 observations on 5 May range from 8–13 km and mostly agree within 1–3 km with visual observations, radar data and modeling results. Furthermore, the GOME-2 SO2 observations are compared with in situ measurements of the DLR Falcon aircraft on 17 and 18 May 2010 and with Brewer instruments at Valentia, Ireland and Hohenpeissenberg, Germany. The SO2 columns derived from the Falcon profile measurements range from 0.6–4.7 DU and the comparison with the GOME-2 measurements shows a good agreement, mainly within 1 DU. The Brewer observations at Hohenpeissenberg also agree well with the GOME-2 measurements with a daily average SO2 column of ∼1.3 DU during the overpass of the SO2 cloud on 18 May, whereas the Brewer instrument at Valentia shows up to 50% higher SO2 columns (∼8 DU) on 11 May.

[1] During the 2010 eruption of Eyjafjallajokull, improvements were made to the modeling procedure at the Met Office, UK, enabling peak ash concentrations within the volcanic cloud to be estimated. In this paper we describe the ash concentration forecasting method, its rationale and how it evolved over time in response to new information and user requirements. The change from solely forecasting regions of ash to also estimating peak ash concentrations required consideration of volcanic ash emission rates, the fraction of ash surviving near-source fall-out, and the relationship between predicted mean and local peak ash concentrations unresolved by the model. To validate the modeling procedure, predicted peak ash concentrations are compared against observations obtained by ground-based and research aircraft instrumentation. This comparison between modeled and observed peak concentrations highlights the many sources of error and the uncertainties involved. Despite the challenges of predicting ash concentrations, the ash forecasting method employed here is found to give useful guidance on likely ash concentrations. Predicted peak ash concentrations lie within about one and a half orders of magnitude of the observed peak concentrations. A significant improvement in the agreement between modeled and observed values is seen if a buffer zone, accounting for positional errors in the predicted ash cloud, is used. Sensitivity of the predicted ash concentrations to the source properties (e.g., the plume height and the vertical distribution of ash at the source) is assessed and in some cases, seemingly minor uncertainties in the source specification have a large effect on predicted ash concentrations.

Applications of environmental aerodynamics, namely pedestrian level winds and dispersion of pollutants in the building environment, are discussed with particular emphasis to suitable engineering design issues and practices. Both experimental and computational approaches are presented with reference to particular case studies.

15 December 1989 was never going to be an entirely ordinary day for Captain Karl van der Elst and the rest of the crew of a KLM Royal Dutch Airlines Boeing 747, operating Flight 867 from Amsterdam to Tokyo, via a fuel stop in Anchorage, Alaska. The reason for the peculiarity of the flight lay about 100 miles to the southwest of Anchorage, in the shape of 10197 feet high volcano Mount Redoubt, which had been erupting for the last 36 hours or so. A number of airlines operating in the area had already decided that discretion was the better part of valor and had suspended their flights [133], but others, including the KLM crew, were proceeding on the assumption that, if necessary, they would be able to alter their approach routes into Anchorage such that they would avoid the plume emerging from the Alaskan volcano. As their flight plan envisaged a broad daylight arrival to their stopover destination, they were expecting to be able to see the ash cloud and take evasive action accordingly, also guided by any radar-based updates received from air traffic control.

Volcanic plumes can be hazardous to aircraft. A correlation between plume height and ground deformation during an eruption of Grimsvotn Volcano, Iceland, allows us to peer into the properties of the magma chamber and may improve eruption forecasts.

Hazardous chemicals escape to the environment by a number of anthropogenic activities. Air pollution has both acute and chronic effects on human health, affecting a number of different systems and organs. Ghazaouet city homes a Metallurgical company (En-Metanof) producing zinc by pyrometallurgical process. This coastal city, in which winds are of NW and NE directions, is surrounded by cliffs. The soil and atmospheric environments in the area of the city are polluted by SO2 gases and aerosols issued by the main stack of the plant.

Flow visualizations show that the buoyant plume above a line heat source in thermally stable stratified air has a vortex pair and a swaying motion. The stable stratification suppresses the plume height, increases the swaying amplitude, and generates a vortex pair near the plume front. The plume pattern changes into fumigation flow, the mushroom plume, the plume with the maximum amplitude of the swaying motion, and the plume with a glasseslike vortex pair, with increase of the heat rate. These four kinds of plume pattern do not occur in unstratified air and therefore characterize the plume in the stable stratification.