|EOS IDS Volcanology Team General Introduction|
The impact of volcanoes on the Earth system was dramatically demonstrated by the eruption in 1991 of Mt. Pinatubo (Philippines), and in 1994 by activity at Rabaul volcano (Papua New Guinea). Mt. Pinatubo has had a near-global effect via the introduction of 20 to 30 megatons of sulfur dioxide and aerosols into the atmosphere, and represents the second largest eruption this century - second only to Mt. Katmai (Alaska) in 1912. The materials injected into the stratosphere by Mt. Pinatubo circled the Earth in only 3 weeks, and covered about 42 percent of the Earth's surface after only 2 months. Atmospheric models suggest that a global cooling of 0.5 degrees centigrade took place after the year after the eruption. In Papua New Guinea, the hazards associated with volcanoes was clearly demonstrated by the unexpected eruption of Rabaul volcano, which caused 30,000 people to be hastily evacuated hours before over a meter of ash was deposited in parts of the town of Rabaul!
The degassing history of a lava flow or an eruption plume may have a major effect on the local or hemispheric climate, depending on the rate of eruption, the magma chemistry, and preeruption storage characteristics of the magma. Through the analysis of ongoing eruptions, data from EOS surface imagers and atmospheric instruments are expected to significantly improve the understanding of how volcanoes work, volcanic hazards, and the short-term effects that eruptions have on weather and climate.
This Interdisciplinary Science Investigation's objectives are three-fold: 1) To understand the physical processes associated with volcanic eruptions; 2) to investigate the manner by which sulfur dioxide, water vapor, carbon dioxide, and other volcanic gases are injected into the troposphere and stratosphere; and 3) to place the diverse volcanic eruptions into the context of the regional tectonic setting of the volcano.
The major activity of the Team is the development of robust algorithms that enable us to routinely study volcanic phenomena and their impact on the atmosphere. This includes a wide range of investigations, from the development of SO2 retrievals using UV and thermal infrared data, the mapping of topography and topographic change using radar interferometry, the analysis of the particle size distribution and gas content of volcanic eruption clouds, and the analysis of the temperature distribution within active lava flows. Code is also being developed that will automatically detect a new eruption and, in the case of a thermal alarm, distinguish an eruption from a forest fire or other hotspot, thereby enabling event detection to be routinely conducted worldwide. Field programs that test the ability of remote sensing instruments to make quantitative measurements of volcanic phenomena, and the validation of satellite observations made at visible, infrared, and microwave wavelengths also comprise much of our on-going research.
Use of Satellite Data:
This Interdisciplinary Investigation will draw heavily on many of the EOS sensors, combining high spatial resolution images of near-vent activity and daily regional low-resolution views of volcanic thermal anomalies and eruption plume dispersal. ASTER and MODIS will be used for temperature measurements of active lava flows and eruption plumes. TES, MLS, MISR, EOSP, and SAGE III will be used to study the dispersal of different volcanic gases and aerosols. ASTER and orbital radars (RADARSAT 2, ENVISAT's ASAR) will be used for high resolution topographic mapping of volcanoes and the analysis of ground deformation due to intrusions and eruptions. MODIS, GLAS and MISR will be used to determine the height of eruption plumes and their three-dimensional shape, and these measurements will be compared to AIRS atmospheric temperature data in order to investigate eruption-plume dynamics.
Before the EOS satellites are launched, the team is using analog data sets from existing instruments, including AVHRR, ERS-1, HIRS, UARS MLS, SIRC / X-SAR, TOMS, TIMS, and TOPSAR. The radar data sets from ERS-1, SIR-C / X-SAR, and TOPSAR provide baseline topography for individual volcanoes which can be compared to future EOS digital elevation models derived from MISR and ASTER. Different orbital radar instruments are being used to gain experience in studying temporal changes on volcanoes. ERS-1 and SIR-C / X-SAR data are also being used develop experience in handling large volumes of data and in working with on-going missions. HIRS is used as an analog for MODIS and TIMS is an aircraft instrument similar to the mid-infrared portion of ASTER, and is being used both for temperature studies as well as the development of algorithms for mapping tropospheric SO2. Different versions of TOMS have been flown on satellites since 1978 and have been routinely used to estimate amounts of SO2 released by volcanic eruptions. The MLS on UARS (Upper Atmosphere Research Satellite) is providing experience in the interpretation of daily global maps of SO2 that start 3 months after the eruption of Pinatubo.
In order to observe eruptions while they are in progress, this EOS investigation will contribute significantly to the development of a near-real-time response capability. Automatically-generated alarms for hot lava flows will be produced continuously from the MODIS data stream. Such a capability is expected to be of benefit to numerous other studies of transient phenomena, particularly forest fires. Higher order data sets that document the characteristics of specific eruptions, the dispersal of eruption plumes, and the geology of individual volcanoes will be the primary archival products. These products will be transferred to the EOS Data and Information System (EOSDIS) and also maintained locally for access by the volcanology community at large.
Participation in Field Programs:
The Volcanology IDS Team is heavily involved in several field programs related to the analysis of the 15 International Decade Volcanoes, as well as on-going studies of other active volcanoes around the world. We helped organize Decade Volcano Workshops at Santa Maria (Guatemala) and have a workshop planned at Taal (Philippines) in late 1995. Planning is underway to collaborate with the Japanese in the study of Mt. Unzen (Japan) and Mauna Loa (Hawaii). We have also experimented with the use of FTIR and thermal IR sensors to monitor SO2 and HCl at Mount Etna (Sicily). In 1993, we ran the NASA aircraft deployment to Kamchatka (E. Russia) to map some of the volcanoes and perform gas studies. These programs are multidisciplinary, involving the measurement of volcanic gases, surface temperatures, ground deformation, and topography. Mapping using satellite and aircraft data is also conducted in the Andes of Chile and the Galapagos Islands, while synoptic radar data are employed to study volcanoes in the Alaska/Aleutian arc.
There are several EOS IDS Teams. Most are focussed on studying the oceans, atmosphere, biogeochemical cycles, and hydrology. Only 2 are focussed on geologic processes (our Volcanology Team and the team of Bryan Isacks at Cornell: Climate, Erosion and Tectonics in the Andes and Other Mountain Systems). Dr. Ghassem Asrar (the EOS Program Scientist) presented the following list as the role of the EOS IDS teams (January 11, 1994, at the EOS-IWG meeting):
Further information on the science strategy can be found in the book: G. Asrar and J. Dozier, 1994, EOS: Science Strategy for the Earth Observing System, American Institute of Physics, 119 pp.