V32A-01 INVITED 10:20h
Remote Sensing Studies of Kilauea volcano, Hawaii, as an Aid to Understanding Volcanic Processes on Mars, Venus and Io
By virtue of the near-continuous activity, relatively safety of the eruptions, and excellent field access within a U.S. National Park, extensive testing of new field, airborne and orbital remote sensing data sets has taken place at Kilauea, Hawaii, over the last 20 years. Here I review the important role that such studies of Kilauea have had in understanding volcano morphology and eruption processes on Mars, Venus and Io. Many types of remote sensing data have been collected over Kilauea that have direct planetary analogs. Two space shuttle radar missions (SIR-B and SIR-C) had Kilauea as a primary target, and there have been three deployments of the TOPSAR airborne radar (1993, 1996, and 2000) to Hawaii. These data have been used to understand the radar scattering properties of lava flows on Venus, as well as assessing the importance of multi-incidence angle and look-direction radar data for structural mapping. Topographic mapping of Kilauea caldera by an airborne lidar was conducted at 1 m/pixel in 2004 to facilitate the analysis of the topography of lava flows, vents and fractures at a scale that is not possible using MOLA data for Mars, but may be relevant when data are studied from the Mars Express stereo camera or the HiRISE instrument on MRO. Thermal studies of active lava flows and the Kupianaha lava lake provide insights into effusive volcanism on Io. Not only can the dynamics of Ionian lava lakes (e.g., Loki Patera) be studied, but also on-going work with MODIS and GOES satellite data for Kilauea are being used to understand lava flow and vent dynamics as they may relate to the resurfacing mechanism(s) of Io. Comparison of data acquisition for on-going Mars missions and Kilauea also show similarities in the approach to planetary and terrestrial volcanology. Systematic imaging of Kilauea volcano at increasingly high spatial resolution (for both multispectral and topographic mapping) continues to be of value for planetary analogs and technique development. Multispectral image data for Kilauea were first concentrated around the summit area, and MOC data were initially targeted for caldera floor and walls of Martian calderas. Now, high resolution ($<$10 m/pixel) data have been collected for almost all of Kilauea, and comparable data for all of Olympus and Ascraeus Montes calderas have been obtained by THEMIS VIS instrument. Extensive THEMIS coverage for the flanks of these and other Martian volcanoes is now revealing valuable information on the structure of the Martian shield volcanoes and the diversity of lava flows, thereby justifying a closer comparison with volcanic landscapes seen in the field in Hawaii.
V32A-02 10:35h
Flow Emplacement Styles and Flow Rates From Flow Margin and Channel Topography: Examples From Terrestrial Field and Martian Altimetry Data
Basaltic volcanism is the predominant volcanic mode for the terrestrial planets, and constraining basaltic emplacement styles and rates is key in estimating regional resurfacing rates, eruption durations, etc. In this study, we combine field and remote sensing data to constrain emplacement styles and eruption rates. For field approaches, we examine differential GPS topography profiles across terrestrial Eastern Snake River Plains (ESRP) basaltic flow margins to see if 1) flow surface type (e.g. pahoehoe. a'a, blocky, platy ) can be approximately determined from flow topography, 2) if flow emplacement modes (sheet flow, channel flow, tube flow, slow toe advance, etc.) can be constrained from topography and 3) model the apparent flow rate from the topography based on apparent flow emplacement mode. For remote sensing comparisons, we sample martian flows using Mars Orbiter Laser Altimeter (MOLA) , THEMIS (Thermal Emission Imaging System) and MOC (Mars Orbiter Camera) data. The MOLA profile data helps constrain emplacement styles with comparative flow margin topography and whole-flow cross-section profiles to detect tubes and channels. The THEMIS and MOC data are used in concert with MOLA data to constrain flow surface types. For the ESRP areas so far, the sub-meter sampling of flow margin profiles does constrain emplacement style (pahoehoe toe field, pahoehoe inflated, block pahoehoe, a'a), and that GPS channel topography yields good topographic constraints for flow rate modeling. In comparison, martian emplacement styles need both topography and images to adequately constrain flow surface type analogs due to the larger sampling spacing of the topography. However, many of the tube and channel flows are sufficiently large that the MOLA topography is sufficient for good flow rate modeling and constraints, and we find that ESRP calculated flow rates are quite similar to Cerberus region flow rates for Mars.
V32A-03 10:50h
A Multisensor Approach to the Remote Sensing of Volcanic Emissions
NASA$^{'}$s series of Earth Observing System satellites present remote sensing volcanologists with a potent suite of instruments for the study of volcanic emissions. In this presentation we focus on applications of data acquired with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Atmospheric Infrared Sounder (AIRS), Moderate-Resolution Imaging Spectrometer (MODIS), and Multiangle Imaging SpectroRadiometer (MISR). The volcanic emission products of interest are sulfur dioxide, silicate ash, and sulfate aerosols. The ASTER, MODIS, AIRS, and MISR data are applied to studies of the sulfur dioxide, ash, and aerosol emissions associated with recent eruptions of Mount Etna. The measurements provided by these instruments are complimentary. ASTER collects visible and near-infrared (VNIR), short-wave infrared (SWIR), and thermal infrared (TIR) radiance measurements at (nadir) spatial resolutions of 15, 30, and 90 m, respectively. MODIS collects radiance measurements in 32 spectral channels between the VNIR and TIR. The majority of these measurements are acquired at a (nadir) spatial resolution of 1 km. There are MODIS instruments on two EOS platforms, providing daily coverage of the Earth at non-Tropical latitudes. AIRS collects radiance measurements in over 2300 spectral channels between the SWIR and TIR, with a (nadir) spatial resolution of approximately 17 km. MISR acquires multispectral VNIR radiance measurements at nine distinct viewing angles through the simultaneous use of nine nadir, fore, and aft-viewing cameras. The spatial resolution of the nadir scene and the red channels of the off-nadir scenes is 275 m. The remaining off-nadir scenes have a spatial resolution of 1100 m. The high spatial resolution of ASTER data allows us to detect volcanic emissions at low concentrations, making ASTER the primary instrument for monitoring passive emissions of sulfur dioxide. The comprehensive spectral, spatial, and temporal coverage provided by MODIS make these data the most versatile for the study of volcanic sulfur dioxide, ash, and aerosol emissions. The high spectral resolution of AIRS data permits unambiguous identification of sulfur dioxide, ash, and aerosol and facilitates the estimation of the quantities of these materials. In addition, AIRS data are used to map the 3D distributions of atmospheric temperature and water vapor. MISR data are used to derive estimates of aerosol optical depth, cloud-top altitude, wind direction, and wind speed. Volcanic plumes and clouds exhibit apparent displacement, known as parallax or disparity, in the off-nadir views relative to the nadir view. These disparities are a function of the altitude of these features as well as wind-induced motion during the seven-minute period required to obtain a suite of fore- and aft-viewing scenes over a given point on the Earth's surface.
V32A-04 11:05h
Estimating the height of volcanic plumes from the 15 micron CO2 band
This paper investigates the use of CO$_{2}$ slicing approach to determine the height of volcanic plumes. Monitoring of plumes resulting from volcanic eruptions from a satellite orbit can provide good temporal resolution for detecting and tracking the plumes. Algorithms to detect the presence of volcanic plumes have been developed that are based on spectral signatures resulting from the presence of suspended matter particulates that arise from differential scattering, absorption and/or emission of the plume constituents. Spectral measurements at 11 and 12 $\mu$m have been successful at detecting these aerosols. Additional spectral measurements at 7.3 and 8.5 $\mu$m have helped with the detection of plumes containing dust and SO$_{2}$. Estimates of plume height have been made from satellites. One method uses the brightness temperature of a infrared window channel, which can work well in the case of thick plums. Another approach is to use shadows to estimate height. In this paper we investigate the use of the 15 micron CO$_{2}$ band. The CO$_{2}$ slicing algorithm has successfully retrieved cloud top pressure for over three decades. The method was developed to overcome errors in the height retrievals of partially cloudy fields of view and optically thin clouds. The method relies on the strong temperature sensitivity of the 15 $\mu$m CO$_{2}$ band and the well-mixed nature of carbon dioxide. Theoretically, the same approach can be used to estimate the height of an aerosol plume, provided that emissivity differences in the plume are accounted for in the retrieval. The strengths and weaknesses of this approach will be discussed.
V32A-05 11:20h
On The Potential Of A Robust, Satellite Data Analysis Strategy For Monitoring And Mitigation Of The Volcanic Hazard.
In recent years, satellite remote sensing has been increasingly used as an useful tool for volcanic features monitoring. Several techniques have been proposed for quite a large set of applications devoted to the study of active volcanic systems. Recently, a robust approach (RAT - Robust AVHRR Techniques) has been proposed, in order to try to improve our observational capabilities, both in terms of volcanic features detection sensitivity and of false alarms avoidance. The aim of this work is to try to emphasize the capabilities of such an approach, especially from the point of view of a possible operational implementation at global scale and in whatever observational/environmental conditions. The potential of RAT in identifying, in a timely manner, possible pre-eruptive anomalous signs which might announce impending events, is discussed as well. The method robustness as well as its intrinsic exportability to different satellite/sensor systems, will permit its implementation on the present Spinning Enhanced Visible and InfraRed Imager (SEVIRI), aboard Meteosat Second Generation (MSG) platform, which is going to guarantee improved spectral (12 observation bands) and temporal (15 minutes of observational frequency) resolutions, particularly required if an operational scenario is aimed at.
V32A-06 11:35h
Lava Lakes on Jupiter's Moon Io
Jupiter's moon Io is the most volcanically active body in the Solar System. The Galileo spacecraft spent nearly 8 years in orbit around Jupiter, making several close passes of Io and obtaining numerous observations in visible and IR wavelengths that have led to a new view of how magma erupts on Io's surface. We now know of at least 166 active volcanic centers on Io's surface and that three major eruption styles exist: long lava flows, violent fire fountaining and explosive events, and lava lakes confined within Io's many patera. Paterae - features defined as irregular craters, or complex craters with scalloped edges - are the most ubiquitous volcanic construct on Io's surface and are interpreted as calderas or pit craters. Galileo infrared observations have shown that many paterae are volcanically active and that activity is often confined to the interior. We use observations from Galileo's Near-Infrared Mapping Spectrometer (NIMS, spanning the wavelength range 1-5 microns) to examine the distribution of thermal emission at several paterae, how the thermal emission has varied with time, and the implications for eruption styles on Io. Several paterae viewed at high spatial resolution by NIMS reveal greater thermal emission around the edges, which can be explained as the crust of a lava lake breaking up against the caldera or crater walls, similar to what has been observed at lava lakes on Earth. Comparisons between the NIMS data and images obtained by Galileo's camera support the lava lake interpretation at these paterae. However, Io's largest patera, Loki, appears to behave differently from a typical terrestrial lava lake: in terms of lava production rates, eruption frequencies and thermal output, Loki is most similar to a superfast spreading mid-ocean ridge on Earth. Identifying eruption styles on Io is important for constraining resurfacing rates and interior models. Large lava flows and explosive eruptions producing giant plumes have been identified on Io, but our results indicate that lava lakes within calderas are likely the common style of activity. Ionian lava lakes appear to be long-lived, lasting from years to a decade or more. Persistent lava lake activity has important implications for how Io is resurfaced, and also for Io's interior, as it suggests open systems with ready access to magma.
V32A-07 11:50h
Volumetric Fluxes From Volcanoes on Io and Earth: a Comparison.
Two bodies in the Solar System exhibit high-temperature active volcanism: Earth and Io. Different styles of activity are seen on both planets but a telling point is that in low-spatial-resolution data (corresponding to the bulk of available and foreseeable data of Io) similar styles of effusive and explosive volcanism yield similar mass and flux densities. For example, a square meter of an active pahoehoe flow on Io looks very similar to a square meter of an active pahoehoe flow on Earth. If, from observed thermal emission as a function of wavelength and change in thermal emission with time, the eruption style of an ionian volcano can be constrained, estimates of volumetric fluxes can be made and compared with terrestrial volcanoes using techniques derived for analysing terrestrial remotely-sensed data. In this way we find that ionian volcanoes generally differ from their terrestrial counterparts only in areal extent, with Io volcanoes covering larger area (at least when compared with contemporary terrestrial activity). There is an exception to this rule: Io outbursts eruptions have enormous implied volumetric fluxes, greater than any contemporary terrestrial eruption. This work was carried out at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA. AGD is supported by the NASA PG&G Program.
V32A-08 INVITED 12:05h
The synergy of field and satellite-based thermal infrared observations for volcanic surfaces
Thermal infrared (TIR) surface observations of Earth and Mars have added to a wealth of information for volcanoes and their eruptive products. Much of this information comes from quantitative data extraction algorithms developed using Earth-based data as analogs. Effects such as compositional mixing, non-isothermal surfaces at the pixel scale, and surface coatings are all are being explored with terrestrial data to better understand similar information being returned from other planetary surfaces. One of the most difficult environments for which to examine many of these complications is that of active silicic volcanoes. Intermediate to silicic volcanoes with active lava domes commonly present an emitting target that is highly non-isothermal, typically obscured by some amount of volcanic plume, and can be areally mixed (i.e., fumarolic sublimates, vesiculated textures, petrologic variations). Although active silicic systems are not a factor on Mars, they provide an excellent algorithm development opportunity. One such example is the presence of non-isothermal elements on the surface. Integrated, these produce a non-linear composite of emitted energy that ultimately results in large errors where attempting to extract an accurate emissivity spectrum. This situation arises over active cold lava domes with a small areal abundance of very hot cracks, and on the surface of Mars, which commonly has a small fraction of warm rocks surrounded by colder dust. Data returned from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) of several volcanoes in the Kamachaka region of Russia have been examined. These data captured various states of eruption, flow deposition, and passive states. In addition, ground- and airborne-based FLIR images have been collected to provide a small-scale spatial context. It was found that thermal anomalies varied significantly over time on the active domes and clearly show the onset of new phases of activity as well as the semi-quiescent hydrothermal background. However, many of the aforementioned complications are also present. New models for accurate spectral retrievals have been developed, which further refine the extraction of accurate emissivity from temperature in TIR radiance data. Results have an impact on the spectral analysis of the reconstructed emissivity to better quantify the chemistry and texture of the erupted material. Such approaches could easily be adapted for TIR data acquired over volcanic units on other planetary surfaces.