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For several years, the University of Costa Rica, NASA Centers (e.g., JPL, ARC, GSFC/WFF, GRC) & NASA contractors-partners have made regular in situ measurements of aerosols & gases at Turrialba Volcano in Costa Rica, with aerostats (e.g., tethered balloons & kites), & free-flying fixed wing UAVs (e.g., Dragon Eye, Vector Wing 100, DELTA 150), at altitudes up to 12.5Kft ASL within 5km of the summit. Onboard instruments included gas detectors (e.g., SO2, CO2), visible & thermal IR cameras, air samplers, temperature pressure & humidity sensors, particle counters, & a nephelometer. Deployments are timed to support bimonthly overflights of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the NASA Terra satellite (26 deployments to date). In situ observations of dilute plume SO2 concentrations (~1-20ppmv), plume dimensions, and associated temperature, pressure, & humidity profiles, validate detailed radiative transfer-based SO2 retrievals, as well as archive-wide ASTER band-ratio SO2 algorithms. Our recent UAV-based CO2 observations confirm high concentrations (e.g., ~3000ppmv max at summit jet), with 1000-1500ppmv flank values, and essentially global background CO2 levels (400ppmv) over distal surroundings. Transient Turrialba He detections (up to 20ppmv) were obtained with a small (~10kg) airborne mass spectrometer on a light aircraft—a UAV version (~3kg) will deploy there soon on the UCR DELTA 500. Thus, these platforms, though small (most payloads <500gm), can perform valuable systematic measurements of potential eruption hazards, as well as of volcano processes. Because they are economical, flexible, and effective, such platforms promise unprecedented capabilities for researchers and responders throughout Central and South America, undertaking volcanic data acquisitions uniquely suited to such small aircraft in close proximity to known hazards, or that were previously only available using full-sized manned aircraft. This work was carried out, in part, at the Jet Propulsion Laboratory of the California Institute of Technology under NASA contract. We are grateful to the Universidad de Costa Rica, the NASA Airborne Science and Earth Surface & Interior Programs, the Dirección General de Aeronáutica Civil de Costa Rica, and FH Düsseldorf for their support.
Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.
Volcanoes emit particles (silicates and sulphate aerosol) and gases (e.g., water and sulphur dioxide) which influence the radiative balance of the atmosphere. The rate at which sulphur dioxide oxidises to sulphate aerosol is poorly constrained and measurements of downwind abundance are required to quantify the rate at which this process occurs.
During July and November 2011, a series of measurements were performed in emissions from Etna Volcano, Sicily, using the University of Applied Sciences (Dusseldorf) research aircraft. Both in situ and remote sensing instrumentation was simultaneously deployed to quantify the down-wind characteristics of gases and particles in the plume emitted by the volcano. In situ particle characteristics were measured using a Grimm 1.109 optical particle counter (microparticles 0.25-32 microns) and Grimm 1320 diffusion electrometer (nanoparticles 25-300 nanometers). Column abundance of sulphur dioxide was measured using a vertically-pointing differential optical absorption spectrometer (DOAS). These measurements were compared to horizontal pathlength-integrated measurements of sulphur dioxide from the Airborne Volcanic Imaging Object Detector (AVOID).
Down-wind plume dispersion was discriminated through a series of aircraft transects below and through the volcanic plume. The emissions contained large amounts of nanoparticles relative to microparticles, which reflects gas-phase nucleation of sulphate aerosol. The AVOID system discriminated horizontal layering of volcanic aerosol at altitudes of up to 12,000 ft from a detection range of >50 km. Plume boundaries were discriminated using a combination of the in situ and DOAS measurements in order to compare to the pathlength-integrated measurements from AVOID.