preliminary sensitivity study of eruption source parameters for operational volcanic ash cloud transport and dispersion models a case study of the august 1992 eruption of the crater peak vent mount spurr alaska abstract ash clouds are one of the major hazards that result from volcanic eruptions once an eruption is reported volcanic ash transport and dispersion vatd models are used to forecast the location of the ash cloud these models require source parameters to describe the ash column for initialization these parameters include eruption cloud height and vertical distribution particle size distribution and start and end time of the eruption further if downwind concentrations are needed the eruption mass rate and or volume of ash need to be known upon notification of an eruption few constraints are typically available on many of these source parameters recently scientists have defined classes of eruption types each with a set of pre defined eruption source parameters esp we analyze the august 18 1992 eruption of the crater peak vent at mount spurr alaska which is the example case for the medium silicic eruption type we have evaluated the sensitivity of two of the esp the grain size distribution gsd and the vertical distribution of ash on the modeled ash cloud hysplit and puff vatd models are used to simulate the ash clouds from the different sets of source parameters we use satellite data processed through the reverse absorption method as reference for computing statistics that describe the modeled to observed comparison with the grain size distribution the three options chosen 1 an estimated distribution based on past eruption studies 2 a distribution with finer particles and 3 the national oceanic and atmospheric administration hysplit gsd have little effect on the modeled ash cloud for the initial vertical distribution both linear uniform concentration throughout the vertical column and umbrella shapes were chosen for hysplit the defined umbrella distribution no ash below the umbrella apparently underestimates the lower altitude portions of the ash cloud and as a result has a worse agreement with the satellite detected ash cloud compared to that with the linear vertical distribution for this particular eruption the puff model with a poisson function to represent the umbrella cloud gave similar results as for a linear distribution both having reasonable agreement with the satellite detected cloud further sensitivity studies of this eruption as well as studies using the other source parameters are needed

an evaluation of volcanic cloud detection techniques during recent significant eruptions in the western ring of fire we examined recent volcanic cloud events in the western pacific and indonesian area to validate the performance of remote sensing techniques used to support the international airways volcano watch iavw five events were considered during which eruptions from eight volcanoes injected ash into the upper troposphere or lower stratosphere for one of the eruptions at miyakejima japan at least five aircraft encountered volcanic ash clouds and the cost to three operators alone exceeded us 12 000 000 in aircraft repairs diversions and lost operating time we performed reverse absorption and pattern analysis using gms 5 vissr modis and avhrr data and we examined toms so2 and aerosol index data surface based observations pilot reports and dispersion model output our results verify that the introduction of reverse absorption using the geostationary gms 5 platform significantly enhanced our capacity to monitor volcanic ash clouds in the region in one case we tracked an eruption cloud for approximately 80 h the primary impediment to remote monitoring is the presence of overlying cloud or substantial amounts of ice within the volcanic clouds toms data showed success in identifying volcanic clouds during these conditions but was limited by the infrequency of observations more effective future operation of the iavw relies on developing complementary methods of volcanic cloud remote sensing and greatly increasing the amount and quality of available surface and air observations including observations of precursor activity an understanding of the likely future limitations of remote sensing techniques will aid in the refining of iavw procedures

uncertainty in two channel infrared remote sensing retrievals of a well characterised volcanic ash cloud this work provides a sensitivity study of a two channel passive infrared remote sensing retrieval of effective radius and optical depth using the spinning enhanced visible and infrared imager with channels centred at 10 8 and 12 0 m and a look up table approach to calculate mass column loading the retrieval is applied to images of two ash clouds from the 2010 eyjafjallajokull eruption on 6 and 13 may 2010 the 2010 eruption of eyjafjallajokull is well characterised especially in terms of the airborne volcanic ash which allows the relative uncertainties to be investigated within the realms of observation and reasonable approximation the parameters investigated are as follows refractive index surface temperature cloud top temperature ash bulk density and in particular the uncertainties related to the spread of the ash particle size distribution in terms of the geometric standard deviation of a lognormal particle size distribution the lack of constraint on particle size distribution is shown to cause the largest uncertainty in retrieved mass column loading for the 6 may and 13 may ash cloud a review of measured in situ size distributions of airborne particles is presented with justification for the choice of a lognormal size distribution for the 2010 eyjafjallajokull eruption

three dimensional volcanic aerosol dispersal a comparison between multiangle imaging spectroradiometer misr data and numerical simulations 1 the three dimensional reconstruction of volcanic plumes is a central goal to enhance our understanding on dispersal processes in this paper we use data from the multiangle imaging spectroradiometer misr on board nasa s terra spacecraft combined with a stereo matching retrieval procedure we show the potential of misr in capturing important features of volcanic plumes like column height optical depth type and shape of the finest particles of two highly explosive eruptions occurring on mount etna in 2001 and 2002 this work tests how tephra dispersal models reconstruct the 3 d shape of volcanic clouds we compare misr data with fall3d an eulerian model for the transport and deposition of volcanic ash and aerosols coupled with the weather research and forecasting mesoscale meteorological model agreement between simulations and misr data is good regarding both events although it could be improved by increasing the accuracy of the meteorological data a better constraint on volcanological input parameters like the height of the eruptive column and improving our understanding of processes such as aggregation phenomena and volcanic cloud microphysics

impact on volcanic ash detection caused by the loss of the 12 0 μm split window band on goes imagers abstract geostationary operational environmental satellite goes imager and sounder data were evaluated to determine the potential effects of volcanic ash detection without the use of a 12 m infrared ir band on goes m 12 through q a period of at least 10 years principal component analysis pca images with and without 12 m ir data were compared subjectively for six weak to moderate eruptions using pattern recognition techniques and objectively by determining a false detection rate parameter goes sounder data were also evaluated in a few instances to assess any potential contributions from the new 13 3 m imager band results indicated that during periods of daylight there was little apparent difference in the quality of ir detection without the 12 m ir likely due to a maximum in solar reflectance of silicate ash in a shortwave ir swir band centered near 3 9 m at night when swir reflectance diminished the ash detection capability appeared to be significantly worse evidenced by increased ambiguity between volcanic ash and meteorological clouds or surface features the possible effects of this degradation on aviation operations are discussed the new 13 3 m ir band on goes has the capability to help distinguish ash from cirrus clouds but not from low level clouds consisting of water droplets multi spectral data from higher resolution polar orbiting satellites may also be used to supplement analyses from lower resolution goes for long lived ash cloud events the advanced very high resolution radiometer avhrr and moderate resolution imaging spectroradiometer modis instruments appear to be the best options in accomplishing this with additional satellite missions becoming available later in the decade in summary it will still be possible to observe and track significant volcanic ash clouds in the goes m through q era 2003 2012 without the benefit of 12 m ir data but with some degradation that will be most significant at night

integrated satellite observations of the 2001 eruption of mt cleveland alaska abstract satellite data were the primary source of information for the eruption of mt cleveland alaska on 19 february and 11 and 19 march 2001 multiple data sets were used pre syn and post eruption to mitigate the hazard and determine an eruption chronology the 19 february eruption was the largest of the three resulting in a volcanic cloud that formed an arc over 1000 km long moved to the ne across alaska and was tracked using satellite data over more than a 50 h period the volcanic cloud was concurrently detected on the goes avhrr and modis data at various times and their respective signals compared all three sensors detected a cloud that had a very similar shape and position but there were differences in their areal extent and internal structural detail goes data showed the largest volcanic cloud in terms of area probably due to its oblique geometry modis bands 31 and 32 which are comparable to goes and avhrr thermal infrared wavelengths were the least effective single channels at detecting the volcanic cloud of those investigated modis bands 28 29 31 and 32 modis bands 28 and 29 detected the largest volcanic clouds that could easily be distinguished from weather clouds of the split window data modis bands 29 minus band 32 detected the largest cloud but the band 31 minus band 32 data showed the volcanic cloud with the most internal structural detail the puff tracking model accurately tracked the movement and predicted the extent and shape of this complex cloud even into areas beyond satellite detection numerous thermal anomalies were also observed during the eruption on the twice daily avhrr data and the high spatial resolution landsat data the high resolution radarsat data showed that the avhrr thermal anomalies were due to lava and debris flow features and a newly formed fan along the west coast of the island field observations and images from a hand held forward looking infrared radiometer flir showed that the flow features were a a lava debris flows and a warm debris fan along the west coast real time satellite data were the primary tool used to monitor the eruption track changes and to mitigate hazards high resolution data even though coverage is infrequent were critical in helping to identify volcanic processes and to compile an eruption chronology

improved space borne detection of volcanic ash for real time monitoring using 3 band method abstract for over 25 years thermal infrared data supplied by satellite based sensors are used to detect and characterize volcanic ash clouds using a commonly accepted method the 2 band reverse absorption technique this method is based on a two channel difference model using the opposite extinction features of water ice and ash particles at 11 and 12 m wavelengths although quite efficient with the supervision of a user this method shows however some limitations for reliable automated detection of volcanic ash in a real time fashion here we explore a method dedicated to the operational monitoring of volcanic ash that combines the 11 12 m brightness temperature difference btd11 12 with a second brightness temperature difference between channels 8 7 m and 11 m btd8 7 11 we first achieve a detailed microphysics analysis of different atmospheric aerosols volcanic ash water ice sulfuric acid mineral dust using optical properties e g extinction efficiency single scattering albedo and asymmetry parameter calculated by mie theory and showing that btd8 7 11 can be particularly efficient to remove most of artifacts then we tested this method for eight different eruptions between 2005 and 2011 from six different volcanoes mount etna piton de la fournaise karthala soufriere hills eyjafjallajokull and grimsvotn using data from the spinning enhanced visible and infrared imager seviri on board meteosat second generation msg geostationary satellite we show that between 95 6 and 99 9 of ash contaminated pixels erroneously identified by the btd11 12 method i e artifacts were detected and removed by the 3 band method for all eruptions the 3 band method shows a high and constant reliability having a false alarm rate in the range 0 002 0 08 hence allowing operational implementation for automated detection in case of a volcanic crisis

simulated volcanic ash imagery a method to compare name ash concentration forecasts with seviri imagery for the eyjafjallajokull eruption in 2010 1 during volcanic eruptions that eject ash into the atmosphere volcanic ash advisory centers issue statements on the forecast dispersion of the ash so that the aviation industry can manage airspace to avoid aircraft encountering volcanic ash observations such as those from satellites are compared with the forecasts from an atmospheric dispersion model to assess the quality of the ash forecasts a method has been developed to enable like with like comparison between satellite imagery of volcanic ash and simulated imagery using the forecast ash concentration data from an atmospheric dispersion model the ash concentration and numerical weather prediction data are used as inputs to a radiative transfer model to simulate radiances simulated satellite images are created from these simulated radiances here spinning enhanced visible and infrared imager volcanic ash images based on infrared brightness temperatures for the eyjafjallajokull eruption in 2010 are simulated in addition to providing a useful tool for forecasters in a volcanic ash advisory center the simulated images can be used to aid the understanding of how the ash affects the satellite imagery and also the physical properties of the ash

investigating the use of the saharan dust index as a tool for the detection of volcanic ash in seviri imagery abstract despite the similar spectral signatures of ash and desert dust relatively little has been done to explore the application of dust detection techniques to the problem of volcanic ash detection the saharan dust index sdi is routinely implemented for dust monitoring at some centres and could be utilised for volcanic ash detection with little computational expense thereby providing a product that forecasters already have some familiarity with to complement the suite of existing ash detection tools we illustrate one way in which the index could be implemented for the purpose of ash detection by applying it to three scenes containing volcanic ash from the 2010 eyjafjallajokull eruption iceland and the 2011 eruption of puyehue chile it was also applied to an image acquired over etna in january 2011 where a volcanic plume is clearly visible but is unlikely to contain any ash these examples demonstrate the potential of the sdi as a tool for ash monitoring under different environmental and atmospheric conditions in addition to presenting a valuable qualitative product to aid monitoring this work includes a quantitative assessment of the detection skill using a manually constructed expert ash mask the optimum implementation of any technique is likely to be dependent on both atmospheric conditions and on the properties of the imaged ash which is often unknown in a real time situation here we take advantage of access to a truth rarely available in a real time situation and calculate an ash mask based on the optimum threshold for the specific scene which is then used to demonstrate the potential of the sdi the sdi mask is compared to masks calculated from a simplistic implementation of the more traditional split window method again exploiting our access to the truth to set the most appropriate threshold for each scene and to a probabilistic method that is implemented without reference to the truth and which provides useful insights into the likely cloud ash contamination of each pixel since the sensitivity of the sdi and split window methods to the tailored thresholds was not tested such tailoring is unlikely to be possible in a real situation this study presents the maximum anticipated skill for the sdi in the context of the maximum skill anticipated for the split window method although both are likely to be lower in a real time situation the results for the sdi are comparable to those of the other methods with a true skill score of 80 02 for the eyjafjallajokull night time scene compared to 88 81 and 46 63 for the split window and probabilistic method respectively and 90 06 for the eyjafjallajokull day time scene compared to 97 61 and 56 96 for the puyehue image the sdi resulted in a true skill score of 74 85 while the split window approach achieved 99 62 these results imply that the sdi which is already implemented operationally at some centres for dust detection could be a useful complement to existing ash monitoring techniques

improving volcanic ash cloud detection by a robust satellite technique abstract automated and reliable satellite based techniques are strongly required for volcanic ash cloud detection and tracking in fact volcanic ash clouds pose a serious hazard for air traffic and the synoptic and possibly frequent coverage offered by satellites can provide exciting opportunities for monitoring activities as well as for risk mitigation purposes a new avhrr based technique for improved automatic detection of volcanic clouds by means of multi temporal analysis of historical long term satellite records has been recently proposed the technique basically rests on the robust avhrr techniques rat approach which is an innovative strategy of satellite data analysis devoted to a former characterisation of the measured signal in terms of expected value and natural variability and a further recognition of signal anomalies by an automatic unsupervised change detection step in this work an extension of this method to nighttime observations is presented by using thermal infrared information coming from avhrr bands centred approximately at 3 5 11 0 and 12 0 m results achieved for two recent eruptive events of mount etna occurred in may 2000 and in july 2001 seem to be encouraging showing clear improvements in terms of ash detection sensitivity as well as in terms of false alarms reduction the technique performance is also evaluated by comparison with the traditional split window brightness temperature difference method this exercise revealed a general improvement obtained by the proposed approach even though some common problems still remain unsolved the main merits of such an approach are its intrinsic self adaptability to different environmental natural observational conditions and its natural exportability also to different satellite sensors the results here presented show the benefits of such a technique especially when different observational conditions time of pass seasonal period atmospheric moisture solar illumination volcanic cloud composition satellite angles of view etc are considered the future prospects also in terms of possible operational scenarios coming from the implementation of such an approach on the new generation of satellite sensors like for example seviri aboard meteosat second generation platform are also discussed

remote observations of eruptive clouds and surface thermal activity during the 2009 eruption of redoubt volcano abstract volcanoes often erupt explosively and generate a variety of hazards including volcanic ash clouds and gaseous plumes these clouds and plumes are a significant hazard to the aviation industry and the ground features can be a major hazard to local communities here we provide a chronology of the 2009 redoubt volcano eruption using frequent low spatial resolution thermal infrared tir mid infrared mir and ultraviolet uv satellite remote sensing data the first explosion of the 2009 eruption of redoubt volcano occurred on march 15 2009 utc and was followed by a series of magmatic explosive events starting on march 23 utc from march 23 april 4 2009 satellites imaged at least 19 separate explosive events that sent ash clouds up to 18 km above sea level asl that dispersed ash across the cook inlet region in this manuscript we provide an overview of the ash clouds and plumes from the 19 explosive events detailing their cloud top heights and discussing the variations in infrared absorption signals we show that the timing of the tir data relative to the event end time was critical for inferring the tir derived height and true cloud top height the ash clouds were high in water content likely in the form of ice which masked the negative tir brightness temperature difference btd signal typically used for volcanic ash detection the analysis shown here illustrates the utility of remote sensing data during volcanic crises to measure critical real time parameters such as cloud top heights changes in ground based thermal activity and plume cloud location

simulations of tephra dispersal from the 1991 explosive eruptions of hudson volcano chile abstract the 1991 explosive eruptions of hudson volcano in southern chile produced 2 7 km 3 dense rock equivalent of basalt and trachyandesite tephra during the period august 8 15 the initial basaltic phase phase i august 8 9 produced a maximum column height of 12 km above sea level asl and tephra fallout was directed to the north and northeast by the prevailing winds the paroxysmal trachyandesitic phase phase ii august 12 15 involved at least three separate events with a maximum 18 km high asl eruption column inferred from satellite temperature data during the initial 24 h of this phase the plume was advected almost directly south before swinging towards the east as the wind changed direction the plume was ultimately directed to the southeast and stayed relatively fixed at this bearing for the remainder of the eruption these temporal variations in the main dispersal direction during the earlier stages of the phase ii eruption produced a much wider overall deposit than would be expected from a plume with a relatively fixed transport direction e g latter stages of phase ii the lagrangian ash tracking model puff was utilized to simulate the 1991 explosive eruptions and was able to successfully reproduce the aerial distribution and temporal evolution of the plumes the optimal agreement between the observed and simulated plumes occurs when the highest concentration of ash particles coincides with the tropopause a height that is typically lower than the maximum observed column heights for the 1991 eruptions gravitational settling of the laterally spreading umbrella region e g pinatubo 1991 may result in the concentration of ash at this level this may account for differences in column height estimates between ground or satellite based and lithic based models the plume associated with the paroxysmal phase august 12 15 1991 produced a multilayered deposit composed of alternating layers of fine ash and pumice lapilli the highly stratified nature of the fall deposit is likely the result of multiple eruptive events coupled with a time varying wind field a strongly changing wind direction that occurred during the earlier stages of the paroxysmal eruption could have produced variations in the dominant grain size being deposited between fine ash and pumice lapilli during individual eruptive sequences

active erosion deposition cycles in the hyperarid atacama desert of northern chile 10be 21 ne abstract there is significant debate over the rates and types of fluvial activity at the plio pleistocene boundary in the hyperarid atacama desert of chile to quantify fluvial processes and help resolve this debate we measure terrestrial cosmogenic nuclide tcn 10 be and 21 ne concentration depth profiles in three settings representing a chronosequence 1 a late pliocene alluvial fan representative of major regional deposits 2 a modern active channel and 3 an adjacent low terrace inset into the pliocene alluvium late pliocene deposits that are widely preserved in the region contain tcn profiles consistent with relatively rapid stripping of upland sediment at the plio pleistocene boundary deposits inset into these late pliocene features record cut and fill cycles that rework sediment throughout the quaternary the tcn profile in the modern channel is best explained by sediment aggradation at 2 1 m myr 1 during the last 250 000 yr similarly the adjacent low terrace sediments contain tcn concentration profiles consistent with aggradation of 2 0 m myr 1 over a period of 250 000 750 000 yr prior to the last 250 000 yr of stability in summary depth profiles of two tcns provide constraints on the rates of sediment deposition sources of sediment and transport history as well as the subsequent exposure conditions of the sediment following deposition our results are consistent with early quaternary initiation of hyperaridity for the region during the quaternary winter precipitation events experienced at our sites latitude 241s drive active erosion deposition cycles the northward migration of the subtropical front during quaternary glacial cycles may have enhanced precipitation at 241s leading to more active fluvial processes during cooler periods

improved prediction and tracking of volcanic ash clouds abstract during the past 30 years more than 100 airplanes have inadvertently flown through clouds of volcanic ash from erupting volcanoes such encounters have caused millions of dollars in damage to the aircraft and have endangered the lives of tens of thousands of passengers in a few severe cases total engine failure resulted when ash was ingested into turbines and coating turbine blades these incidents have prompted the establishment of cooperative efforts by the international civil aviation organization and the volcanological community to provide rapid notification of eruptive activity and to monitor and forecast the trajectories of ash clouds so that they can be avoided by air traffic ash cloud properties such as plume height ash concentration and three dimensional ash distribution have been monitored through non conventional remote sensing techniques that are under active development forecasting the trajectories of ash clouds has required the development of volcanic ash transport and dispersion models that can calculate the path of an ash cloud over the scale of a continent or a hemisphere volcanological inputs to these models such as plume height mass eruption rate eruption duration ash distribution with altitude and grain size distribution must be assigned in real time during an event often with limited observations databases and protocols are currently being developed that allow for rapid assignment of such source parameters in this paper we summarize how an interdisciplinary working group on eruption source parameters has been instigating research to improve upon the current understanding of volcanic ash cloud characterization and predictions improved predictions of ash cloud movement and air fall will aid in making better hazard assessments for aviation and for public health and air quality

the explosive eruption of soufriere hills volcano montserrat west indies 17 september 1996 on 17 september 1996 the soufriere hills volcano started a 9 hour period of dome collapse involving 11 7 106 m dre of lava after 2 5 hours of quiescence a sustained explosive eruption began estimated eruption parameters are plume height at least 11 3 km and a maximum of 15 km 180 m s for launch velocities of ballistic clasts peak explosion pressure of 27 5 mpa magma water contents of 2 5 5 magma discharge rates from 2300 to 4300 m s ejecta volume of 3 2 0 9 106 m dre ejecta consists of pumice 1160 kg m higher density vesiculated ejecta 1300 to 2000 kg m dense glassy clasts 2600 kg m breccias cut by tuffisite veins and hydrothermally altered lithics the ejecta are interpreted as a conduit assemblage with evacuation of the conduit down to depths of about 3 to 5 km the eruption was triggered by unloading of a gas pressurised conduit due to dome collapse

a multi sensor plume height analysis of the 2009 redoubt eruption abstract during an explosive volcanic eruption accurately determining the height of a volcanic plume or cloud is essential to accurately forecast its motion because volcanic ash transport and dispersion models require the initial plume height as an input parameter the direct use of satellite infrared temperatures for height determination one of the most commonly employed methods at the alaska volcano observatory often does not yield unique solutions for height this result is documented here for the 2009 eruption of redoubt volcano satellite temperature heights consistently underestimated the height of ash plumes in comparison to other methods such as ground based radar and multi angle imaging spectroradiometer misr stereo heights for ash plumes below the tropopause increasing transparency of a plume begins to affect the accuracy of simple temperature height retrievals soon after eruption with decreasing opacity plume temperature heights become increasingly inaccurate comparison with dispersion models and aircraft gas flight data confirms that radar and misr stereo heights are more accurate than basic satellite temperature heights even in the cases in which satellite temperature results appeared to be relatively accurate e g for plumes below the tropopause a mixed signal of plume and ground radiation still presented an issue for almost every event studied this was true regardless of the fact that a band differencing method was used to remove presumably translucent pixels the data presented here make a strong case for the use of data fusion in volcano monitoring as there is a need to confirm satellite temperature heights with other height data if only basic satellite temperature heights are available for a given eruption then these heights must be considered with a significant margin of error

ascent dynamics of large phreatomagmatic eruption clouds the role of microphysics 1 we examine the impact of abundant surface water interaction on the development of volcanic clouds from large scale 108 kg s 1 magma phreatomagmatic eruptions presenting the first 2 d large eddy simulations of wet volcanic plumes that incorporate the effects of microphysics the active tracer high resolution atmospheric model was forced with field derived inputs from an exceptionally large phreatomagmatic eruption the 27 ka oruanui supereruption taupo volcano new zealand surface water contents were varied from 0 to 40 wt for eruptions with equivalent magma eruption rates of 1 3 108 and 1 1 109 kg s 1 our findings confirm that increased surface water has a pronounced impact on column stability leading to transitional column behavior and hybrid clouds resulting from simultaneous ascent of material from stable columns and pyroclastic density currents pdcs contrary to the suggestion of previous workers however abundant surface water does not systematically lower the spreading level or maximum height of volcanic clouds owing to vigorous microphysics assisted lofting of pdcs the simulated behavior and ash cloud dimensions provide a close match to field evidence from the oruanui case study cloud heights from the collapsing eruption columns also show a notable sensitivity to changes in the altitude of the tropopause while ambient humidity primarily impacts the abundance of airborne hydrometeors particularly ice associated with the volcanic clouds general relationships between eruption style meteorological conditions and the resulting vertical profiles of volcanic emissions outlined here could also be adapted for use in operational volcanic ash forecasting and deposit reconstruction techniques already in existence

observations of mt etna volcanic ash plumes in 2006 an integrated approach from ground based and polar satellite noaa avhrr monitoring system abstract mt etna in sicily italy is one of the world s most frequent emitters of volcanic plumes during the last ten years etna has produced copious tephra emission and fallout that have damaged the inhabited and cultivated areas on its slopes and created serious hazards to air traffic recurrent closures of the catania international airport have often been necessary causing great losses to the local economy recently frequent episodes of ash emission lasting from a few hours to days occurred from july to december 2006 necessitating a look at additional monitoring techniques such as remote sensing the combination of a ground monitoring system with polar satellite data represents a novel approach to monitor etna s eruptive activity and makes etna one of the few volcanoes for which this surveillance combination is routinely available in this work ash emission information derived from an integrated approach based on comparing ground and noaa avhrr polar satellite observations is presented this approach permits us to define the utility of real time satellite monitoring systems for both sporadic and continuous ash emissions using field data visible observations collection of tephra samples and accounts by local inhabitants the duration and intensity of most of the tephra fallout events were evaluated in detail and in some cases the order of magnitude of the erupted volume was estimated the ground data vs satellite data comparison allowed us to define five different categories of etna volcanic plumes according to their dimensions and plume height taking into account wind intensity using frequent and good quality satellite data in real time this classification scheme could prove helpful for investigations into a possible correlation between eruptive intensity and the presence and concentration of ash in the volcanic plume the development and improvement of this approach may constitute a powerful warning system for civil protection thus preventing unnecessary airport closures

near real time volcanic ash cloud detection experiences from the alaska volcano observatory volcanic eruptions produce ash clouds which are a major hazard to population centers and the aviation community within the north pacific nopac region there have been numerous volcanic ash clouds that have reached aviation routes others have closed airports and traveled for thousands of kilometers being able to detect these ash clouds and then provide an assessment of their potential movement is essential for hazard assessment and mitigation remote sensing satellite data through the reverse absorption or split window method is used to detect these volcanic ash clouds with a negative signal produced from spectrally semi transparent ash clouds single channel satellite is used to detect the early eruption spectrally opaque ash clouds volcanic ash transport and dispersion vatd models are used to provide a forecast of the ash clouds future location the alaska volcano observatory avo remote sensing ash detection system automatically analyzes satellite data of volcanic ash clouds detecting new ash clouds and also providing alerts both email and text to those with avo however there are also non volcanic related features across the nopac region that can produce a negative signal these can complicate alerts and warning of impending ash clouds discussions and examples are shown of these non volcanic features and some analysis is provided on how these features can be discriminated from volcanic ash clouds finally there is discussion on how information of the ash cloud such as location particle size and concentrations could be used as vatd model initialization these model forecasts could then provide an improved assessment of the clouds future movement

estimation of the 2002 mount etna eruption cloud radiative forcing from meteosat 7 data abstract on 27th october 2002 after 15 months of small activity the mount etna located on the island of sicily italy 37 73 n 15 00 e erupted undergoing one of its most vigorous eruptions in years during a few days europe s highest and most active volcano hurled lava and spewed significant amounts of ash and trace gases into the atmosphere the smoke and ash plume originating from the volcano stretched from the sicily to the north african coast the plume from the volcano has been identified and tracked using half hourly meteosat 7 visible infrared and water vapor imagery in order to estimate the radiative forcing produced by the introduction of the volcanic cloud in a previously clear sky our results indicate that while the volcanic cloud has introduced a well discernable radiative perturbation the magnitude of the shortwave volcanic forcing appears in the range of the one introduced by large clouds above the mediterranean sea by contrast the perturbation generated in the longwave spectrum at the top of the atmosphere is larger than the one introduced by large meteorological clouds

aster watches the world s volcanoes a new paradigm for volcanological observations from orbit onboard nasa terra spacecraft is one of the most sophisticated earth observing instruments ever flown the advanced spaceborne thermal emission and reflection radiometer aster created as part of a joint project between the japanese ministry of economy trade and industry and nasa this instrument consists of three independent bore sighted telescopes with 14 channels in the visible near infrared and thermal infrared regions capable of being pointed up to 22 5 off nadir in addition there is an additional backward looking visible channel telescope for stereo photogrammetric observations the spatial resolutions are 15 m pixel in the visible 30 m pixel in the near ir and 90 m pixel at thermal wavelengths and the swath width is 60 km aster instrument offers unprecedented opportunities for observing volcanoes and their activity from low earth orbit it is the purpose of this short paper to introduce aster to the volcanological community highlight its capabilities advantages and limitations and to show some examples of aster data and related analyses we will also explain how users can readily access aster data

estimation of optimal dispersion model source parameters using satellite detections of volcanic ash in this paper we demonstrate how parameters describing the geometry of the volcanic ash source for a particular volcanic ash dispersion model hysplit may be inferred by the use of satellite data and multiple trial simulations the areas of space likely to be contaminated by ash are identified with the aid of various remote sensing techniques and polygons are drawn around these areas as they would be in an operational setting dispersion model simulations are initialized either by a cylindrical source or a specified ash distribution depending on the context parameters of interest such as the base and top height diameter and optimal release time of the cylindrical source or the height of the specified ash distribution are inferred by forming a parameter grid and running multiple simulations for each parameter grid point value optimal values of the parameter values are identified by calculating spatial correlations between the model simulations and observations we demonstrate that the methodology can be used to correctly infer various model parameters and improves volcanic ash forecasts in various eruption case studies

reducing discrepancies in ground and satellite observed eruption heights abstract the plume height represents a crucial piece of evidence about an eruption feeding later assessment of its size character and potential impact and feeding real time warnings for aviation and ground based populations there have been many observed discrepancies between different observations of maximum plume height for the same eruption a comparison of maximum daily height estimates of volcanic clouds over indonesia and papua new guinea during 1982 2005 shows marked differences between ground and satellite estimates and a general tendency towards lower height estimates from the ground without improvements in the quality of these estimates reconciled among all available methods warning systems will be less effective than they should be and the world s record of global volcanism will remain hard to quantify examination of particular cases suggests many possible reasons for the discrepancies consideration of the satellite and radar cloud observations for the 1991 pinatubo eruptions shows that marked differences can exist even with apparently good observations the problem can be understood largely as a sampling issue as the most widely reported parameter the maximum cloud height is highly sensitive to the frequency of observation satellite and radar cloud heights also show a pronounced clumping near the height of the tropopause and relative lack of eruptions reaching only the mid troposphere reinforcing the importance of the tropopause in determining the eruption height in convectively unstable environments to reduce the discrepancies between ground and satellite estimates a number of formal collaboration measures between vulcanological meteorological and aviation agencies are suggested

early evolution of a stratospheric volcanic eruption cloud as observed with toms and avhrr this paper is a detailed study of remote sensing data from the total ozone mapping spectrometer toms and the advanced very high resolution radiometer avhrr satellite detectors of the 1982 eruption of el chichon mexico the volcanic cloud atmosphere interactions in the first four days of this eruption were investigated by combining ultraviolet retrievals to estimate the mass of sulfur dioxide in the volcanic cloud krueger et al 1995 with thermal infrared retrievals of the size optical depth and mass of fine grained 1 10 m radius volcanic ash wen and rose 1994 our study provides the first direct evidence of gravitational separation of ash from a stratospheric gas rich plinian eruption column and documents the marked differences in residence times of volcanic ash and sulfur dioxide in volcanic clouds the eruption column reached as high as 32 km carey and sigurdsson 1986 and was injected into an atmosphere with a strong wind shear which allowed for an observation of the separation of sulfur dioxide and volcanic ash the upper more sulfur dioxide rich part of the cloud was transported to the west in the stratosphere while the fine grained ash traveled to the south in the troposphere the mass of sulfur dioxide released was estimated at 7 1 109 kg with the mass decreasing by approximately 4 1 day after the peak the mass of fine grained volcanic ash detected was estimated at 6 5 109 kg amounting to about 0 7 of the estimated mass of the ash which fell out in the mapped ash blanket close to the volcano over the following days 98 of this remaining fine ash was removed from the volcanic cloud and the effective radius of ash in the volcanic cloud decreased from about 8 m to about 4 m

the millennium eruption of hekla in february 2000 the 18th historic eruption of hekla started on 26 february 2000 it was a short lived but intense event emitting basaltic andesitic 55 5 wt sio2 pyroclastic fragments and lava during the course of the eruption monitoring was done by both instruments and direct observations together providing unique insight into the current activity of hekla during the 12 day eruption a total of 0 189 km3 dre of magma was emitted the eruptive fissure split into five segments the segments at the highest altitude were active during the first hours while the segments at lower altitude continued throughout the eruption the eruption started in a highly explosive manner giving rise to a subplinian eruptive column and consequent basaltic pyroclastic flows fed by column collapses after the explosive phase reached its maximum the eruption went through three more phases namely fire fountaining strombolian bursts and lava effusion in this paper we describe the course of events of the eruption of hekla and the origin of its magma and then show that the discharge rate can be linked to different style of eruptive activity which are controlled by fissure geometry we also show that the eruption phases observed at hekla can be linked with inferred magma chamber overpressure prior to the eruption

thermal infrared remote sensing of volcanic emissions using the moderate resolution imaging spectroradiometer the volcanological community has a powerful new tool in the spaceborne moderate resolution imaging spectroradiometer modis which from its synoptic perspective provides satellite imagery of every volcano on earth every 2 days modis has the spectral characteristics to be able to utilise previously developed retrievals that quantify volcanic ash ice sulfates and sulfur dioxide using their thermal infrared 8 12 am transmission signature in this paper we present a detailed description of the methodologies based within the thermal infrared region that are being applied to modis data modis data for two eruptions hekla iceland and cleveland alaska are presented to show results from the ice ash and so2 retrieval schemes we look at current problems with the retrievals used to quantify volcanic emissions detail recent developments within the field that can be applied to modis data and suggest areas where improvements need to be made in the future published by elsevier b v

overview of the eruption of soufriere hills volcano montserrat 18 july 1995 to december 1997 the onset of phreatic volcanic activity at the soufriere hills volcano montserrat on 18 july 1995 followed a three year period of heightened volcano seismic activity beneath the island phreatic explosions gave way to continuous eruption of juvenile andesitic magma in the form of a lava dome on or around 15 november 1995 magma production rate has varied leading to changes in eruptive style an explosive eruption on 17 september 1996 followed a period of enhanced dome growth and large scale gravitational collapses from its eastern flank increasing dome volume led to stressing and overtopping of the confining crater walls to the southwest north and west during early 1997 sustained high magma production rate since june 1997 has led to three periods of major gravitational dome collapses followed by vulcanian explosive eruptions dome growth re started immediately after the cessation of the latest of these explosive phases in october 1997 and continues as of december 1997

identifying eruptive sources of drifting volcanic ash clouds using back trajectory modeling of spaceborne thermal infrared data a new approach is presented for determining the source region of disconnected volcanic ash clouds using a combination of orbital thermal infrared tir image data hysplit generated backward trajectories and spatial geostatistics interpolated surfaces derived from the tir data are created to find the most likely ash cloud travel path and the potential source volcanoes identified from that path the ability to use backward trajectories to determine the ash cloud source region will become an important triggering tool to target high spatial resolution orbital sensors which normally rely on thermal anomalies for new targeting during cases where thermal anomalies are not present or masked by meteorological cloud ash cloud detection and predicted source location become more important image data from several well documented past eruptions are presented to validate and determine the overall accuracy of this technique because this is seen as a limited range source region validation tool the ash clouds examined were 1000 km from their source vent the approach and analysis are deemed successful if 80 of the model results produce one or more trajectories that pass within 60 km of the source volcano this methodology could be improved further with the ability to determine the cloud location more accurately using higher image data frequency and most importantly greater accuracy in determining the cloud height in the atmosphere

failures in detecting volcanic ash from a satellite based technique abstract immediate and accurate detection of airborne volcanic ash is an operational imperative of the aviation industry especially jet aircraft ash encounters place passengers aboard these aircraft at severe risk and significantly impact via forced rerouting both the safety and profit margins of freight carriers due to their limited fuel supply moreover the airlines can suffer high economic costs for repair and replacement of equipment operational detection and tracking of volcanic ash by most national weather services has relied heavily on a split window differencing technique of thermal longwave infrared channels on currently operational satellites unfortunately prior work on volcanic ash detection has not emphasized the dynamical interaction between the erupting volcano and the effects of overlying atmospheric water vapor phreatic and phreatomagmatic water sources six volcanic ash eruptions from around the globe were chosen for study because they have wide variation in ambient atmospheric water vapor available ground and surface water and different magma types results show that the present differencing technique is not uniformly effective in properly classifying volcanic ash pixels in the satellite scene and often falsely interprets meteorological clouds as volcanic ash clouds and conversely moreover it is not always a robust early detector an operational aviation requirement seasonal variability in global integrated atmospheric water vapor coupled with the geographical distribution of currently active volcanoes suggests the concerns discussed herein with regard to six specific eruptions have applicability to the global aviation industry operational implications are discussed and a strategic proposal is presented on necessary steps to improve detection

anatomy of 1986 augustine volcano eruptions as recorded by multispectral image processing of digital avhrr weather satellite data eighteen digital avhrr advanced very high resolution radiometer data sets from noaa 6 and noaa 9 polar orbiting satellites recorded between 27 march and 7 april 1986 depict the eruptive activity of augustine volcano located 280 km sw of anchorage alaska the synoptic view resolution of either 1 1 or 4 4 km frequent coverage often twice a day and multispectral coverage five bands 0 58 0 68 0 72 1 1 3 55 3 93 10 5 11 3 and 11 5 12 5 m makes the avhrr broadly applicable to analyzing explosive eruption clouds the small scale of the augustine activity column heights of 2 13 km and eruption rates of 2x106 8x107 metric tonnes day facilitated intensive multispectral study because the plumes generally covered areas within the 550x550 km area of one easily manipulated image field hourly ground weather data and twice daily radiosonde measurements from stations surrounding the volcano plus numerous volcanological observations were made throughout the eruption providing important ground truth with which to calibrate the satellite data the total erupted volume is estimated to be at least 0 102 km3 the pattern of changing eruption rates determined by satellite observations generally correlate with more detailed estimates of explosion magnitudes multispectral processing techniques were used to distinguish eruption clouds from meteorological clouds variable weather during the augustine eruption offered an opportunity to test various trial algorithms a ratio between thermal ir channels four and five served to delineate the ashbearing eruption plumes from ordinary clouds future work is needed to determine whether the successful multispectral discrimination is caused by wavelength dependent variable emission of silicate ash or reflects a spectral role of sulfuric acid aerosol in the plume

charnockites and granites of the western adirondacks new york usa a differentiated a type suite abstract granitic rocks in the west central adirondack highlands of new york state include both relatively homogeneous charnockitic and hornblende granitic gneisses cg that occur in thick stratiform bodies and elliptical domes and heterogeneous leucogneisses lg that commonly are interlayered with metasedimentary rocks major and trace element geochemical analyses were obtained for 115 samples including both types of granitoids data for cg fail to show the presence of more than one distinct group based on composition most of the variance within the cg sample population is consistent with magmatic differentiation combined with incomplete separation of early crystals of alkali feldspar plagioclase and pyroxenes or amphibole from the residual liquid ti fe mg ca p sr ba and zr decrease with increasing silica while rb and k increase within cg the distinction between charnockitic orthopyroxene bearing and granitic gneisses is correlated with bulk chemistry the charnockites are consistently more mafic than the hornblende granitic gneisses although forming a continuum with them the leucogneisses while generally more felsic than the charnockites and granitic gneisses are otherwise geochemically similar to them the data are consistent with the lg suite being an evolved extrusive equivalent of the intrusive cg suite both cg and lg suites are metaluminous to mildly peraluminous and display an a type geochemical signature enriched in fe k ce y nb zr and ga and depleted in ca mg and sr relative to i and s type granites rare earth element patterns show moderate lree enrichment and a negative eu anomaly throughout the suite the geochemical data suggest an origin by partial melting of biotite and plagioclase rich crustal rocks emplacement occurred in an anorogenic or post collisional tectonic setting probably at relatively shallow depths deformation and granulite facies metamorphism with some partial melting followed during the ottawan phase of the grenville orogeny yielding the present migmatitic granitic and charnockitic gneisses

transport of atmospheric water vapor by volcanic eruption columns contrary to assumptions often made in the literature explosive volcanic eruptions are capable of transporting significant amounts of water into the stratosphere in addition to the magmatic water component atmospheric water vapor is entrained by the column at lower levels a theoretical model for the conservation of mass momentum and thermal energy of four separate components dry air water vapor liquid condensates and solid particles is used to determine the extent of atmospheric water redistribution we examine the effects of water vapor condensation on dynamical characteristics and ambient water vapor transport a simple technique is presented for deriving canonical forms for the complex system of ordinary differential equations governing the column components solutions of this model are presented that show the influence of different volcanic boundary conditions and a range of ambient water vapor distributions on transport of the buoyant column we show that the water component vapor liquid of small eruption columns rising through a wet atmosphere is dominated by entrained water whereas larger columns are dominated by the magmatic water this is due in part to the proportionately smaller entrainment surface area in relation to the control volume for the larger columns we also show that a maintained column with an initial mass flux of 2 7 108 kg s 1 erupted into a wet atmosphere would inject 96 mt of water vapor into the stratosphere over 24 hours comparable to the annual input from methane oxidation or 100 midlatitude thunderstorms this increase may accelerate the conversion of simultaneously erupted volcanic so2 into sulfuric acid

analyses of in situ airborne volcanic ash from the february 2000 eruption of hekla volcano iceland 1 a mcdonnell douglas dc 8 nasa research aircraft inadvertently flew into an airborne volcanic ash plume from the 26 february 2000 eruption of hekla volcano filter samples from the aircraft were compared with normal use and pristine clean filters using sem energy dispersive x ray spectrometer and nicolet ftir spectrophotometer analyses these analyses confirm that the dc 8 encountered airborne volcanic ash from hekla volcano this result is supported by independent onboard heated aerosol observations at the time of the encounter the analyses further demonstrate the ambiguous nature of the dual band thermal ir split window method for detecting volcanic ash from the point of view of aviation safety they also highlight the utility of in situ aircraft filter based observations of volcanic aerosols for scientific purposes

satellite and ground observations of the june 2009 eruption of sarychev peak volcano matua island central kuriles after 33 years of repose one of the most active volcanoes of the kurile island arc sarychev peak on matua island in the central kuriles erupted violently on june 11 2009 the eruption lasted 9 days and stands among the largest of recent historical eruptions in the kurile island chain satellite monitoring of the eruption using moderate resolution imaging spectroradiometer meteorological agency multifunctional transport satellite and advanced very high resolution radiometer data indicated at least 23 separate explosions between 11 and 16 june 2009 eruptive clouds reached altitudes of generally 8 16 km above sea level asl and in some cases up to 21 km asl clouds of volcanic ash and gas stretched to the north and northwest up to 1 500 km and to the southeast for more than 3 000 km for the first time in recorded history ash fall occurred on sakhalin island and in the northeast sector of the khabarovsky region russia based on satellite image analysis and reconnaissance field studies in the summer of 2009 the eruption produced explosive tephra deposits with an estimated bulk volume of 0 4 km3 the eruption is considered to have a volcanic explosivity index of 4 because the volcano is remote there was minimal risk to people or infrastructure on the ground aviation transport however was significantly disrupted because of the proximity of air routes to the volcano