Investigation on flight level contamination using volcanic SO2 plume and cloud top height satellite products

2021 ◽  
Author(s):  
Klaus Sievers ◽  
Hugues Brenot ◽  
Nicolas Theys ◽  
Cathy Kessinger
Keyword(s):  
Warning System ◽  
Volcanic Plume ◽  
Strong Impact ◽  
Volcanic Emissions ◽  
Volcanic Cloud ◽  
Flight Level ◽  
Volcanic Emission ◽  
Cruise Flight ◽  
Control Service ◽  
Hyperspectral Sensor

<p>Volcanic emission is a major risk for air traffic. Flying through a volcanic cloud can have a strong impact on engines (damage caused by ash and/or sulphur dioxide – SO<sub>2</sub>) and persons. The knowledge of the height of the volcanic plume is indeed essential for pilots, airlines and passengers.</p><p>In this presentation, we study recent volcanic emissions to illustrate the difficulty for obtaining information about the height of the SO<sub>2</sub> plume in a form relevant to aviation. Our study uses satellite data products. We consider SO<sub>2</sub> layer height from TROPOMI (UV-vis hyperspectral sensor on board S5P, a polar orbiting platform), as shown by SACS (Support to Aviation Control Service), combined with cloud top observations (from the same sensors or from geostationary broadband imagers) to determine the minimum SO<sub>2</sub>-cloud height. This is a validation which is of interest to aviation.</p><p>The flight level, not the km, is the measure, the unit for expressing height during cruise flight used on board by the pilots to ensure safe vertical separation between aircraft, despite natural local variations in atmospheric air pressure and temperature. Thus, it is critical to provide the corresponding SO<sub>2</sub> contamination expressed as flight levels. Our study will focus on this conversion that is one item currently being developed in the frame of ALARM H2020 project (https://alarm-project.eu) and SACS early warning system (https://sacs.aeronomie.be) in the creation of NetCDF alert products.</p>

scholarly journals Passive degassing at Nyiragongo (D.R. Congo) and Etna (Italy) volcanoes

2015 ◽  
Vol 57 ◽  
Author(s):  
Sergio Calabrese ◽  
Sarah Scaglione ◽  
Silvia Milazzo ◽  
Walter D'Alessandro ◽  
Nicole Bobrowski ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Major And Trace Elements ◽  
Trace Element Composition ◽  
Bulk Deposition ◽  
Volcanic Plume ◽  
Strong Impact ◽  
Volcanic Emissions ◽  
Endemic Plant ◽  
The Impact

<p>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-pack for acid gases (sulfur and halogens) and specific teflon filters for particulates (major and trace elements). The impact of the volcanogenic deposition in the 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 technique was carried out to collect gases and particulates by using endemic 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 has a strong impact on the close surrounding of both volcanoes. This is clearly reflected by in 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.</p>

The Effect of using a New Parameterization of Nucleation in the WRF-Chem model on the Cluster Formation Rate and Particle Number Concentration in a Passive Volcanic Plume

2021 ◽  
Author(s):  
Somayeh Arghavani ◽  
Clémence Rose ◽  
Sandra Banson ◽  
Céline Planche ◽  
Karine Sellegri
Keyword(s):  
Particle Number ◽  
Cluster Formation ◽  
Formation Rate ◽  
Number Concentration ◽  
Cloud Formation ◽  
Scale Model ◽  
Volcanic Plume ◽  
Particle Number Concentration ◽  
Microphysics Scheme ◽  
Volcanic Emission

&lt;p&gt;Volcanic eruption is one of the main natural sources of atmospheric particles. In particular, evidence of New Particle Formation (NPF) from volcanic emission is reported in previous studies (Boulon et al., 2011; Sahyoun et al., 2019), which also suggests an essential role of sulfuric acid in this process. In addition, Rose et al. (2019) highlighted a significant contribution of the particles formed in the volcanic plume of the piton de la Fournaise to the budget of potential CCN at the Ma&amp;#239;do observatory, located ~40 km from the vent of the volcano. Therefore, it is predicted that the number and size of the cloud droplets, cloud growing and precipitation processes might be affected by the frequency of occurrence and characteristics of volcanically induced NPF in both local and regional scales, because volcanic plumes can extend far from the vent and even lower heights under the influence of the wind field and atmospheric dispersion.&amp;#160;&lt;/p&gt;&lt;p&gt;Following the study of Planche et al. (2020), the effect of using the New Parameterization of Nucleation (NPN) derived from the measurements performed in the passive volcanic emission plume of Etna (37.748&amp;#730; N, 14.99&amp;#730; E; Italy) (Sahyoun et al., 2019) in the WRF-Chem model (Weather Research and Forecasting Model coupled with Chemistry) is assessed, with a specific focus on the cluster formation rate and particle number concentration including CCN. In particular, results obtained with the NPN are compared to the predictions obtained with the default model settings, and further with observations.&lt;/p&gt;&lt;p&gt;In the next step, the resulting aerosol fields will be used to further evaluate the influence of the newly formed and grown particles on cloud formation and properties in a 3D cloud-scale model using a detailed microphysics scheme (DESCAM; Flossmann and Wobrock, 2010; Planche et al. 2010; 2014) .&amp;#160;&lt;/p&gt;

Volcanic ash detection and retrievals using SLSTR. Test case: 2019 Raikoke  eruption

2021 ◽  
Author(s):  
Ilaria Petracca ◽  
Davide De Santis ◽  
Stefano Corradini ◽  
Lorenzo Guerrieri ◽  
Matteo Picchiani ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Volcanic Ash ◽  
Thermal Infrared ◽  
Integrated Approach ◽  
Effective Radius ◽  
Volcanic Plume ◽  
Transfer Model ◽  
Volcanic Cloud

&lt;p&gt;When an eruption event occurs it is necessary to accurately and rapidly determine the position and evolution during time of the volcanic cloud and its parameters (such as Aerosol Optical Depth-AOD, effective radius-Re and mass-Ma of the ash particles), in order to ensure the aviation security and the prompt management of the emergencies.&lt;/p&gt;&lt;p&gt;Here we present different procedures for volcanic ash cloud detection and retrieval using S3 SLSTR (Sentinel-3 Sea and Land Surface Temperature Radiometer) data collected the 22 June at 00:07 UTC by the Sentinel-3A platform during the Raikoke (Kuril Islands) 2019 eruption.&lt;/p&gt;&lt;p&gt;The volcanic ash detection is realized by applying an innovative machine learning based algorithm, which uses a MultiLayer Perceptron Neural Network (NN) to classify a SLSTR image in eight different surfaces/objects, distinguishing volcanic and weather clouds, and the underlying surfaces. The results obtained with the NN procedure have been compared with two consolidated approaches based on an RGB channels combination in the visible (VIS) spectral range and the Brightness Temperature Difference (BTD) procedure that exploits the thermal infrared (TIR) channels centred at 11 and 12 microns (S8 and S9 SLSTR channels respectively). The ash volcanic cloud is correctly identified by all the models and the results indicate a good agreement between the NN classification approach, the VIS-RGB and BTD procedures.&lt;/p&gt;&lt;p&gt;The ash retrieval parameters (AOD, Re and Ma) are obtained by applying three different algorithms, all exploiting the volcanic cloud &amp;#8220;mask&amp;#8221; obtained from the NN detection approach. The first method is the Look Up Table (LUT&lt;sub&gt;p&lt;/sub&gt;) procedure, which uses a Radiative Transfer Model (RTM) to simulate the Top Of Atmosphere (TOA) radiances in the SLSTR thermal infrared channels (S8, S9), by varying the aerosol optical depth and the effective radius. The second algorithm is the Volcanic Plume Retrieval (VPR), based on a linearization of the radiative transfer equation capable to retrieve, from multispectral satellite images, the abovementioned parameters. The third approach is a NN model, which is built on a training set composed by the inputs-outputs pairs TOA radiances vs. ash parameters. The results of the three retrieval methods have been compared, considering as reference the LUT&lt;sub&gt;p&lt;/sub&gt; procedure, since that it is the most consolidated approach. The comparison shown promising agreement between the different methods, leading to the development of an integrated approach for the monitoring of volcanic ash clouds using SLSTR.&lt;/p&gt;&lt;p&gt;The results presented in this work have been obtained in the sphere of the VISTA (Volcanic monItoring using SenTinel sensors by an integrated Approach) project, funded by ESA and developed within the EO Science for Society framework [https://eo4society.esa.int/projects/vista/].&lt;/p&gt;

scholarly journals Comparison of operational satellite SO<sub>2</sub> products with ground-based observations in northern Finland during the Icelandic Holuhraun fissure eruption

2015 ◽  
Vol 8 (6) ◽  
pp. 2279-2289 ◽  
Author(s):  
I. Ialongo ◽  
J. Hakkarainen ◽  
R. Kivi ◽  
P. Anttila ◽  
N. A. Krotkov ◽  
...  
Keyword(s):  
Air Quality ◽  
Satellite Data ◽  
A Priori ◽  
Exceptional Case ◽  
Fissure Eruption ◽  
Volcanic Plume ◽  
Volcanic Emissions ◽  
Ozone Monitoring Instrument ◽  
The Difference ◽  
Total Column

Abstract. This paper shows the results of the comparison of satellite SO2 observations from OMI (Ozone Monitoring Instrument) and OMPS (Ozone Mapping Profiler Suite) with ground-based measurements during the Icelandic Holuhraun fissure eruption in September 2014. The volcanic plume reached Finland on several days during the month of September. The SO2 total columns from the Brewer direct sun (DS) measurements in Sodankylä (67.42° N, 26.59° E), northern Finland, are compared to the satellite data. The operational satellite SO2 products are evaluated for high latitude conditions (e.g. large solar zenith angle, SZA). The results show that the best agreement can be found for lowest SZAs, close-to-nadir satellite pixels, cloud fraction below 0.3 and small distance between the station and the centre of the pixel. Under good retrieval conditions, the difference between satellite data and Brewer measurements remains mostly below the uncertainty on the satellite SO2 retrievals (up to about 2 DU at high latitudes). The satellite products assuming a priori profile with SO2 predominantly in the planetary boundary layer give total column values with the best agreement with the ground-based data. The analysis of the SO2 surface concentrations at four air quality stations in northern Finland shows that the volcanic plume coming from Iceland was located very close to the surface. This is connected to the fact that this was a fissure eruption and most of the SO2 was emitted into the troposphere. This is an exceptional case because the SO2 volcanic emissions directly affect the air quality levels at surface in an otherwise pristine environment like northern Finland. The time evolution of the SO2 concentrations peaks during the same days when large SO2 total column values are measured by the Brewer in Sodankylä and enhanced SO2 signal is visible over northern Finland from the satellite maps. Thus, the satellite retrievals were able to detect the spatiotemporal evolution of the volcanic plume as compared to the surface observations. Furthermore, direct-broadcast SO2 satellite data (from both OMI and OMPS instruments) are compared for the first time against ground-based observations.

scholarly journals A volcanic hazard demonstration exercise to assess and mitigate the impacts of volcanic ash clouds on civil and military aviation

2019 ◽  
Author(s):  
Marcus Hirtl ◽  
Delia Arnold ◽  
Rocio Baro ◽  
Hugues Brenot ◽  
Mauro Coltelli ◽  
...  
Keyword(s):  
Traffic Management ◽  
Volcanic Eruptions ◽  
Route Optimization ◽  
Volcanic Plume ◽  
Case Scenario ◽  
Ensemble Techniques ◽  
Current State ◽  
Aviation Hazards ◽  
Volcanic Cloud ◽  
Flight Cancellations

Abstract. Volcanic eruptions comprise one of the most important airborne hazards for aviation. Although significant events are rare, they have a very high impact. The current state of tools and abilities to mitigate aviation hazards associated with an assumed volcanic cloud was tested within an international demonstration exercise. Experts in the field assembled at the Schwarzenberg barracks in Salzburg, Austria, in order to simulate the sequence of procedures for the volcanic case scenario of an artificial eruption of Etna volcano in Italy. The scope of the exercise ranged from the detection of the assumed event to the issuance of early warnings. Volcanic emission concentration charts were generated applying modern ensemble techniques. The exercise products provided an important basis for decision making for aviation traffic management during a volcanic eruption crisis. By integrating the available wealth of data, observations and modelling results directly into a widely used flight planning software, it was demonstrated that route optimization measures could be implemented effectively. With timely and rather precise warnings available, the new tools and processes tested during the exercise demonstrated vividly that a vast majority of flights could be conducted despite a volcanic plume widely dispersed within a high-traffic airspace over Europe. The resulting number of flight cancellations was minimal.

Self-limiting atmospheric lifetime of environmentally reactive elements in volcanic plumes

2020 ◽  
Author(s):  
Evgenia Ilyinskaya ◽  
Emily Mason ◽  
Penny Wieser ◽  
Lacey Holland ◽  
Emma Liu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Atmospheric Dispersion ◽  
Chemical Species ◽  
Volcanic Plume ◽  
Emission Rates ◽  
Volcanic Emissions ◽  
Metal Pollutants ◽  
Volcanic Plumes ◽  
Pollutant Concentrations ◽  
Cadmium And Lead

&lt;p&gt;Volcanoes are a large global source of almost every element, including ~20 environmentally reactive trace elements classified as metal pollutants (e.g. selenium, cadmium and lead). Fluxes of metal pollutants from individual eruptions can be comparable to total anthropogenic emissions from large countries such as China.&lt;/p&gt;&lt;p&gt;The 2018 Lower East Rift Zone eruption of K&amp;#299;lauea, Hawaii produced exceptionally high emission rates of major and trace chemical species compared to other basaltic eruptions over 3 months (200 kt/day of SO&lt;sub&gt;2&lt;/sub&gt;; Kern et al. 2019). We tracked the volcanic plume from vent to exposed communities over 0-240 km distance using in-situ sampling and atmospheric dispersion modelling. This is the first time that trace elements in volcanic emissions (~60 species) are mapped over such distances. In 2019, we repeated the field campaign during a no-eruption period and showed that volcanic emissions had caused 3-5 orders of magnitude increase in airborne metal pollutant concentrations across the Island of Hawai&amp;#8217;i.&lt;/p&gt;&lt;p&gt;We show that the volatility of the elements (the ease with which they are degassed from the magma) controls their particle-phase speciation, which in turn determines how fast they are depleted from the plume after emission. Elements with high magmatic volatilities (e.g. selenium, cadmium and lead) have up to 6 orders of magnitude higher depletion rates compared to non-volatile elements (e.g. magnesium, aluminium and rare earth metals).&lt;/p&gt;&lt;p&gt;Previous research and hazard mitigation efforts on volcanic emissions have focussed on sulphur and it has been assumed that other pollutants follow the same dispersion patterns. Our results show that the atmospheric fate of sulphur, and therefore the associated hazard distribution, does not represent an accurate guide to the behaviour and potential impacts of other species in volcanic emissions. Metal pollutants are predominantly volatile in volcanic plumes, and their rapid deposition (self-limited by their volatility) places disproportionate environmental burdens on the populated areas in the immediate vicinity of the active and, in turn, reduces the impacts on far-field communities.&lt;/p&gt;&lt;p&gt;Reference: Kern, C., T. Elias, P. Nadeau, A. H. Lerner, C. A. Werner, M. Cappos, L. E. Clor, P. J. Kelly, V. J. Realmuto, N. Theys, S. A. Carn, AGU, 2019; https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/507140.&lt;/p&gt;

scholarly journals Reactive bromine chemistry in Mount Etna's volcanic plume: the influence of total Br, high-temperature processing, aerosol loading and plume–air mixing

2014 ◽  
Vol 14 (20) ◽  
pp. 11201-11219 ◽  
Author(s):  
T. J. Roberts ◽  
R. S. Martin ◽  
L. Jourdain
Keyword(s):  
High Temperature ◽  
Volcanic Plume ◽  
Plume Dispersion ◽  
Emission Flux ◽  
Volcanic Aerosol ◽  
Model Simulations ◽  
Aerosol Loading ◽  
Initial Rise ◽  
Air Mixing ◽  
Volcanic Emission

Abstract. Volcanic emissions present a source of reactive halogens to the troposphere, through rapid plume chemistry that converts the emitted HBr to more reactive forms such as BrO. The nature of this process is poorly quantified, yet is of interest in order to understand volcanic impacts on the troposphere, and infer volcanic activity from volcanic gas measurements (i.e. BrO / SO2 ratios). Recent observations from Etna report an initial increase and subsequent plateau or decline in BrO / SO2 ratios with distance downwind. We present daytime PlumeChem model simulations that reproduce and explain the reported trend in BrO / SO2 at Etna including the initial rise and subsequent plateau. Suites of model simulations also investigate the influences of volcanic aerosol loading, bromine emission, and plume–air mixing rate on the downwind plume chemistry. Emitted volcanic HBr is converted into reactive bromine by autocatalytic bromine chemistry cycles whose onset is accelerated by the model high-temperature initialisation. These rapid chemistry cycles also impact the reactive bromine speciation through inter-conversion of Br, Br2, BrO, BrONO2, BrCl, HOBr. We predict a new evolution of Br speciation in the plume. BrO, Br2, Br and HBr are the main plume species near downwind whilst BrO and HOBr are present further downwind (where BrONO2 and BrCl also make up a minor fraction). BrNO2 is predicted to be only a relatively minor plume component. The initial rise in BrO / SO2 occurs as ozone is entrained into the plume whose reaction with Br promotes net formation of BrO. Aerosol has a modest impact on BrO / SO2 near-downwind (< ~6 km, ~10 min) at the relatively high loadings considered. The subsequent decline in BrO / SO2 occurs as entrainment of oxidants HO2 and NO2 promotes net formation of HOBr and BrONO2, whilst the plume dispersion dilutes volcanic aerosol so slows the heterogeneous loss rates of these species. A higher volcanic aerosol loading enhances BrO / SO2 in the (> 6 km) downwind plume. Simulations assuming low/medium and high Etna bromine emissions scenarios show that the bromine emission has a greater influence on BrO / SO2 further downwind and a modest impact near downwind, and show either complete or partial conversion of HBr into reactive bromine, respectively, yielding BrO contents that reach up to ~50 or ~20% of total bromine (over a timescale of a few 10 s of minutes). Plume–air mixing non-linearly impacts the downwind BrO / SO2, as shown by simulations with varying plume dispersion, wind speed and volcanic emission flux. Greater volcanic emission flux leads to lower BrO / SO2 ratios near downwind, but also delays the subsequent decline in BrO / SO2, and thus yields higher BrO / SO2 ratios further downwind. We highlight the important role of plume chemistry models for the interpretation of observed changes in BrO / SO2 during/prior to volcanic eruptions, as well as for quantifying volcanic plume impacts on atmospheric chemistry. Simulated plume impacts include ozone, HOx and NOx depletion, the latter converted into HNO3. Partial recovery of ozone occurs with distance downwind, although cumulative ozone loss is ongoing over the 3 h simulations.

scholarly journals Near crater observations of gas and aerosols variability at Mount Etna during the EPL-RADIO and EPL-REFLECT measurement campaigns.

2021 ◽  
Author(s):  
Suzanne Crumeyrolle ◽  
Marion Ranaivombola ◽  
Tjarda Roberts ◽  
Chiara Giorio ◽  
Giusseppe Salerno ◽  
...  
Keyword(s):  
Low Cost ◽  
Health Hazard ◽  
Regional Climate ◽  
Chemical Properties ◽  
Inorganic Ions ◽  
Mount Etna ◽  
Volcanic Plume ◽  
Local Health ◽  
Volcanic Emissions ◽  
Short Period

&lt;p&gt;During the EPL (Etna Plume Lab) campaigns occurring in 2017 (EPL-RADIO) and 2019 (EPL-REFLECT),&amp;#160; gas&amp;#160; and aerosol measurements were performed&amp;#160; at Mount Etna (Sicily, Italy) to better assess the role of volcanic aerosols on both regional climate system and local health hazard. Gas related to volcanic emissions (such as SO2, H2S and others) were measured with low cost sensors (Alphasense) and HCl/SO2 ratio was validated in comparison to FTIR measurements. Aerosol physical and chemical properties were measured using low-cost Optical Particle Counters (OPCN2 from Alphasense) and filter measurements dedicated to organic acids, inorganic ions, soluble metals and total metals. During the EPL-REFLECT campaign, in-situ measurements were performed during: 1) the hike up, 2) a 2-hours period in the close vicinity of the Bocca Nuova crater, 3) the hike down and 4) in Milo (city on the flank of the Etna). Moreover, few OPCs were left unattended at the Bocca Nuova crater for two full days.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Gas abundances at the crater-rim ranged from a few to 10&amp;#8217;s ppmv SO2, with correlation to PM. The analysis of the 2 days measurements highlights a clear diurnal variation of aerosol size distributions. Indeed, at sunrise the total number and mass concentration is rapidly increasing from 15mg/m3 to 125mg/m3 in less than 2 hours. The variation of PM1/PM10 ratio shows a constant trend throughout the day except during a short period of time associated with high wind speeds. These results suggest that most aerosols are emitted through degassing and conversion of precursor gases to particles.&lt;/p&gt;&lt;p&gt;Moreover, analysis of aerosol samples collected on filters showed a change in metal solubility from the samples collected at the crater and the samples collected after atmospheric transport in Milo. This may indicate that the volcanic plume underwent processing in the aqueous phase during transport.&lt;/p&gt;

scholarly journals Passive Earth Observations of Volcanic Clouds in the Atmosphere

Atmosphere ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 199 ◽  
Author(s):  
Fred Prata ◽  
Mervyn Lynch
Keyword(s):  
Spatial Information ◽  
Physical Models ◽  
Optical Parameters ◽  
Cloud Detection ◽  
Volcanic Emissions ◽  
Temporal Behaviour ◽  
Statistical Measures ◽  
Volcanic Clouds ◽  
Infrared Measurements ◽  
Volcanic Cloud

Current Earth Observation (EO) satellites provide excellent spatial, temporal and spectral coverage for passive measurements of atmospheric volcanic emissions. Of particular value for ash detection and quantification are the geostationary satellites that now carry multispectral imagers. These instruments have multiple spectral channels spanning the visible to infrared (IR) wavelengths and provide 1 × 1 km2 to 4 × 4 km2 resolution data every 5–15 min, continuously. For ash detection, two channels situated near 11 and 12 μ m are needed; for ash quantification a third or fourth channel also in the infrared is useful for constraining the height of the ash cloud. This work describes passive EO infrared measurements and techniques to determine volcanic cloud properties and includes examples using current methods with an emphasis on the main difficulties and ways to overcome them. A challenging aspect of using satellite data is to design algorithms that make use of the spectral, temporal (especially for geostationary sensors) and spatial information. The hyperspectral sensor AIRS is used to identify specific molecules from their spectral signatures (e.g., for SO2) and retrievals are demonstrated as global, regional and hemispheric maps of AIRS column SO2. This kind of information is not available on all sensors, but by combining temporal, spatial and broadband multi-spectral information from polar and geo sensors (e.g., MODIS and SEVIRI) useful insights can be made. For example, repeat coverage of a particular area using geostationary data can reveal temporal behaviour of broadband channels indicative of eruptive activity. In many instances, identifying the nature of a pixel (clear, cloud, ash etc.) is the major challenge. Sophisticated cloud detection schemes have been developed that utilise statistical measures, physical models and temporal variation to classify pixels. The state of the art on cloud detection is good, but improvements are always needed. An IR-based multispectral cloud identification scheme is described and some examples shown. The scheme is physically based but has deficiencies that can be improved during the daytime by including information from the visible channels. Physical retrieval schemes applied to ash detected pixels suffer from a lack of knowledge of some basic microphysical and optical parameters needed to run the retrieval models. In particular, there is a lack of accurate spectral refractive index information for ash particles. The size distribution of fine ash (1–63 μ m, diameter) is poorly constrained and more measurements are needed, particularly for ash that is airborne. Height measurements are also lacking and a satellite-based stereoscopic height retrieval is used to illustrate the value of this information for aviation. The importance of water in volcanic clouds is discussed here and the separation of ice-rich and ash-rich portions of volcanic clouds is analysed for the first time. More work is required in trying to identify ice-coated ash particles, and it is suggested that a class of ice-rich volcanic cloud be recognized and termed a ‘volcanic ice’ cloud. Such clouds are frequently observed in tropical eruptions of great vertical extent (e.g., 8 km or higher) and are often not identified correctly by traditional IR methods (e.g., reverse absorption). Finally, the global, hemispheric and regional sampling of EO satellites is demonstrated for a few eruptions where the ash and SO 2 dispersed over large distances (1000s km).

scholarly journals Real time retrieval of volcanic cloud particles and SO<sub>2</sub> by satellite using an improved simplified approach

2016 ◽  
Vol 9 (7) ◽  
pp. 3053-3062 ◽  
Author(s):  
Sergio Pugnaghi ◽  
Lorenzo Guerrieri ◽  
Stefano Corradini ◽  
Luca Merucci
Keyword(s):  
Sulfur Dioxide ◽  
Atmospheric Model ◽  
Volcanic Plume ◽  
Volcanic Area ◽  
Simplified Approach ◽  
Mt Etna ◽  
Plume Temperature ◽  
Volcanic Cloud ◽  
Preliminary Preparation ◽  
The Mean

Abstract. Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a volcanic cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the volcanic cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the volcanic cloud. This new version takes into account the layer of atmosphere above the cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the volcanic cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajökull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajökull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajökull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.

Sign in / Sign up

Export Citation Format

Share Document