V44A-01 INVITED
Ground-Based Infrared and Ultra-Violet Imaging of Volcanic Gases and Particles
Monitoring the emissions from volcanoes can be done effectively and in a quantitative manner using advanced imaging technology in the infrared and ultra-violet. Infrared cameras exploit relatively cheap microbolometer arrays with low noise and high capture rates to permit identification of particulate and gaseous emissions up to 5-10 km away during the day and night. UV systems utilize CCD arrays with high quantum efficiencies and capabilities of measuring SO2 flux rates during the daytime. The retrieval of particle microphysics and gas amounts from these cameras is described and some results from monitoring volcanoes in South America and the Pacific are presented. It is suggested that fused systems which incorporate imaging cameras with high- spectral resolution spectrometers and FT-IRs hold great promise for the future of ground-based volcano monitoring.
V44A-02
Development of a Mass Spectrometer-based Instrument for Volcanic Gas Monitoring
We have developed and field tested an instrument that is capable of acquiring multiple-species gas chemistry data at active volcanoes and hydrothermal systems. The current prototype consists of a quadrupole mass spectrometer, a series of pumps, valves and control/data logging electronics housed in a corrosion-resistant container. We tested the instrument at the summit of Kilauea volcano in March, 2006, collecting time-series data from a 96°C fumarole (Sulphur Banks) at 15 minute intervals for nearly 3 days. Two temperature probes were utilized, a thermocouple placed in the gas stream and a thermistor which recorded ambient air temperatures inside the instrument housing. Of these, the thermistor produced the more reliable trace, as the thermocouple pegged near 45°C shortly after reaching the fumarole gas composition. This composition was indicated by sharp drops in the instrument response for N2, O2, Ar, and water vapor, and increases in CO2 and SO2 at about 6.5 hours elapsed time. The two most obvious gas/temperature trends in this brief time-series are: (1) sharp discontinuities caused by two of the standard "Giggenbach" bottle sampling interludes (despite some care given not to vent the gas line to atmosphere); and (2) two distinct types of thermal events. The two sampling interruptions caused decreases in temperature, and caused the responses of CO2, N2, O2, Ar and water vapor and the ratio of CO2/He to rise sharply. This appears consistent with contamination by cooler ambient air enriched in CO2 relative to normal air (solfatara air). The two types of thermal events are similar in that both generally show enrichments of SO2 and He, and decreases in CO2/He, whereas the last, much hotter event displays increases in CO2, N2, O2, Ar, and water vapor, in contrast to decreases in these gases during the two former events. The last thermal event correlates with a brief dry period on 17 March, after a previous week of almost continuous rainfall. An interesting increase in the HD/H2 ratio suggests either HD-enriched H2 gas or water vapor was introduced during the last thermal event, which is consistent with a fumarole influenced by evaporated, boiling water and atmospheric gases at depth. During our tests we have discovered several problematic issues that need to be overcome if the instrument is to be deployed for extended periods of time (months to years) in harsh and remote locations of active volcanoes. One of the main obstacles is the large amount of water vapor in fumaroles and the need for keeping that water out of the mass spectrometer. We have successfully achieved this using a series of traps and a condenser that still allow the other species to enter the instrument. Related problems are loss of some of the reactive gases within the instrument and/or traps and the precipitation of elemental sulfur in the pre-mass spec inlet system. Another issue that we are currently addressing is the relatively high power consumption of the instrument and condenser.
V44A-03
First Experiences Using Small Unmanned Aerial Vehicles for Volcano Observation in the Visible Range
Many of the most active volcanoes in the world are located in Middle and South America. While permanently
installed sensors for seismicity give reliable supervision of volcanic activities, they lack the possibility to
determine occurrence and extent of surface activities. Both from the point of science and civil protection, visible
documentation of activities is of great interest. While satellites and manned aircraft already offer many
possibilities, they also have disadvantages like delayed or poor image data availability or high costs.
The Institute of Aerospace Systems of the Technical University of Braunschweig, in collaboration with the spin-off
company Mavionics, developed a family of extremely small and lightweight Unmanned Aerial Vehicles (UAV), with
the smallest aircraft weighting only 550~g (19~ounces) at a wing span of 50 cm (20~inch). These aircraft
are operating completely automatically, controlled by a highly miniaturized autopilot system. Flight mission is
defined by a list of GPS waypoints using a conventional notebook. While in radio range, current position and
status of the aircraft is displayed on the notebook and waypoints can easily be changed by the user. However,
when radio connection is not available, the aircraft operates on its on, completing the flight mission automatically.
This greatly increases the operating range of the system.
Especially for the purpose of volcano observation in South America, the aircraft Carolo~P330 was developed,
weighting 5~kg (11~pounds) at a wing span of 3.3~m ( 11~ft). The whole system can be easily carried by car
and the electric propulsion system avoids handling of flammable liquids. The batteries can be recharged in the
field. Carolo~P330 has an endurance of up to 90~minutes at a flight speed of 25~m/s, giving it a maximum
range of 67 km (41~miles). It was especially designed to operate under harsh conditions. The payload is a
digital still camera, which delivers aerial images with a resolution of up to 8~megapixel.
On a field campaign in 2005, the performance of the system was evaluated at the two active Ecuadorian
volcanoes Cotopaxi and El~Reventador. After hand-launch at Mt. Cotopaxi, the autopilot brought the aircraft up to
7,000~m above sea level (starting from a plateau on 4,500~m a.s.l.), with temperatures around the freezing point.
At El~Reventador active lava flows were documented in the tropical montane rain forest. Since the position and
attitude of the aircraft is recorded within the autopilot system, the single aerial images can be referenced
automatically after the flight to form a mosaic of images. The whole processing chain from mission planning to
image mosaic takes less than half a day.
Besides the technical details of this cost-effective remote sensing system, the results of the measurement
campaign in 2005 will be presented. An outlook will discuss the installation of other payload for thermal imaging
or air sampling.
http:www.mavionics.de
V44A-04 INVITED
NOVAC - Network for Observation of Volcanic and Atmospheric Change, First Installations and Results
The NOVAC project, funded by European Union, was started in October 2005 with the aim to establish a global
network of stations for the quantitative measurement of volcanic gas emissions. The network is based on a novel
type of instrument, the Scanning Dual-beam mini-DOAS. Primarily the instruments will be used to provide new
parameters in the toolbox of observatories for gas emission estimates, geophysical research and hazard
assessment. In addition, data are exploited for other scientific purposes, e.g. global estimates of volcanic gas
emissions, regional to global statistical analysis, and studies of atmospheric chemistry. In particular large scale
validation of satellite measurements of volcanic gas emissions will be possible, bringing spaceborne
observation volcanoes a significant step forward.
The Scanning Dual-beam Mini-DOAS instrument is capable of real-time automatic, unattended measurement of
the total emission fluxes of SO2 and BrO from a volcano with better then 5 minutes time resolution during
daylight. The high time-resolution of the data enables correlations with other geophysical data, e.g. seismicity,
thus significantly extending the information available for real-time hazard assessment and research. By
comparing high time resolution gas emission data with emissions from neighboring volcanoes on different
geographical scales, or with other geophysical events (earthquakes, tidal waves) mechanisms of volcanic forcing
may be revealed. The spectra recorded by the instrument will also be used to derive data that complement
global observation networks related to climate change and stratospheric ozone depletion research.
The consortium encompasses observatories of 20 volcanoes from five continents, including some of the most
active and strongest degassing volcanoes in the world.
The project will be presented as well as first results from the recent installations on San Cristobal, Masaya,
Tungurahua and Galeras volcanoes.
http:www.novac-project.eu
V44A-05
A Survey of Volcanic Degassing in the Americas Since 2004
The Ozone Monitoring Instrument (OMI) on NASA's Aura satellite is the first space-based instrument providing
daily measurements of sulfur dioxide (SO¬2) in the lower troposphere and boundary layer. We use these
daily observations, plus monthly and annual averages of OMI SO2 data, to assess the magnitude and
variability of SO2 emissions from passive volcanic degassing in the Americas since September 2004. To
properly assess the magnitude of non-eruptive degassing, any signal due to drifting eruption clouds must first be
removed from the long-term averages. We derive a first-order evaluation of emission strengths from the
maximum value of the average SO2 vertical column density (VCD) measured close to sources. Emissions
from well-known volcanic SO2 sources such as Kilauea, Popocatépetl, Masaya, Tungurahua, Láscar and
Soufrière Hills are clearly identified. We also note elevated SO2 VCDs close to the remote Lastarria
volcano (Chile), with an ambiguous source that could be magmatic degassing and/or combustion of preexisting
sulfur deposits. Several SO2 anomalies are collocated with copper smelters in Peru and Chile, indicating
significant anthropogenic SO2 emissions in this region. Measurements of SO2 emissions from
Anatahan (CNMI) and Ubinas (Peru) demonstrate OMI's ability to identify and monitor episodic degassing at
remote volcanoes. Detailed evaluation of relative source strengths requires accurate knowledge of the air mass
factor (AMF) used in SO2 retrievals and of local dispersion processes. The AMF depends on several
parameters including the SO2 vertical distribution, cloud fraction, aerosol loading, surface reflectivity, ozone
column amount and satellite viewing geometry. Efforts to model and correct for the AMF dependence will be
discussed. OMI measurements are an effective and economical tool for daily quantification of SO2
emissions and surveys such as could be incorporated into regularly updated assessments of global volcanic
and anthropogenic SO2 production.
http:so2.umbc.edu/omi
V44A-06
Volcanic Ash fall Impact on Vegetation, Colima 2005
An ash sampling network was established arround Colima Volcano in 2005. Ash fall was sampled on the North, Northeast, East, Southeast, South, Southwest and West of the volcano. Samples were analyzed for ash components, geochemistry and leachates. Ash fall ocurred on April (12), May (10, 23), June (2, 6, 9, 10, 12, 14), July (27), September (27), October (23) and November (24). Most of the ash is made of andesitic dome-lithics but shows diferences in crystal, juvenile material and lithic content. In May, some samples contained grey and dark pumice (scoria). Texture varies from phi >4 to phi 0. Leachate concentration were low: SO4 (7.33-54.19) Cl- (2.29-4.97) and F- (0.16-0.37). During 2005, Colima Volcano's ash fall rotted some of the guava and peach fruits and had a drying effect on spearment and epazote plants. Even these small ash amounts could have hindered sugar cane and agave growth.
V44A-07
A Comparison of Ultraviolet and Thermal Infrared SO2 Retrievals of a Near-Pure SO2 Plume
Volcanic plumes are composed of various amounts of silicate ash, ice, SO42-, SO2 and other gases, all of which vary in abundance and have specific transmission signatures within the TIR. Overlaps in their absorption and scattering features, specifically silicate ash, may lead to overestimates of SO2 unless corrected. The 8.6 μ m SO2 algorithm was developed for passive degassing plumes with little to no silicate ash. Prior to an ash-correction, the capabilities of the 8.6 μ m SO2 algorithm for large SO2 plumes need to be established by comparing it to a well documented technique. In this study, we compare near-coincidental data from the UV Earth Probe Total Ozone Mapping Spectrometer (EP TOMS) and TIR MODerate resolution Imaging Spectroradiometer (MODIS) of a near-pure SO2 plume from the Al-Mishraq State sulfur plant fire on 29 June 2003 and provide an ash-free end member for future SO2 ash-correction studies. On 24 June 2003 a fire started at the Al-Mishraq State sulfur plant near Mosul, Iraq and lasted for approximately one month. On 29 June, EP TOMS and MODIS images were acquired at 0752 and 1010 UTC respectively. A previous EP TOMS retrieval estimated the plume contained 102 kt SO2 compared to the 138 kt detected by MODIS based on the 8.6 μ m retrieval. The resampling of the MODIS-based retrieval to the coarser spatial resolution of EP TOMS results in a decrease in the MODIS total mass by 9%. Overall, the agreement between the retrieval techniques on a pixel scale is minimal and ranges between 10% to greater than 90% with no discernable spatial pattern. The low agreement between the two retrievals is likely the result of differences in spatial resolution of the EP TOMS and MODIS measurements, sensitivity of the SO2 estimates to atmospheric absorption and scattering and solar illumination, variations in plume height with distance from the fire and time of data acquisition.
V44A-08
Automated Detection of Volcanic Thermal Anomalies: Detailed Analysis of the 2004 - 2005 Mt. Etna, Italy Eruption
Use of thermal infrared satellite data to detect, characterize and track volcanic thermal emissions is an appealing method for monitoring volcanoes for a number of reasons. It provides a synoptic perspective, with satellites sensors such as AVHRR and MODIS allowing global coverage at-least 4 times/day. At the same time, direct reception of calibrated digital data in a standard and stable format allows automation, enabling near-real time analysis of many volcanoes over large regions, including volcanoes where other geophysical instruments are not deployed. In addition, extracted thermal data can be use to convert to heat and volume flux estimates/time series. The development of an automated algorithm to detect volcanic thermal anomalies using thermal satellite data was first attempted over a decade ago (VAST). Subsequently several attempts have been made to create an effective way to automatically detect thermal anomalies at volcanoes using such high-temporal resolution satellite data (e.g. Okmok, MODVOLC and RAT). The underlying motivation has been to allow automated, routine and timely hot spot detection for volcanic monitoring purposes. In this study we review four algorithms that have been implemented to date, specifically: VAST, Okmok, MODVOLC and RAT. To test how VAST and MODVOLC performed we tested them on the 2004 - 2005 effusive eruption of Mount Etna (Sicily, Italy). These results were then compared with manually detected and picked thermal anomalies. Each algorithm is designed for different purposes, thus they perform differently. MODVOLC, for example, must run efficiently, up to 4 times a day, on a full global data set. Thus the number of algorithm steps are minimal and the detection threshold is high, meaning that the incidence of false positives are low, but so too is its sensitivity. In contrast, VAST is designed to run on a single volcano and has the added advantage of some user input. Thus, a greater incidence of false positives occurs, but more subtle anomalies are detected.