Volcanologist/igneous petrologist, PhD 1984 Princeton University; Research Scientist at JPL
1989-present. Remote sensing of volcanic plumes, infrared remote sensing of volcanic rocks, lava
flows on Earth and Mars.
Sample Images Radiative transfer simulations (16K image)
Uppermost curve shows the simulation of a down-looking satellite observation of a background
atmosphere. Next (partly overlapping) curve shows the same background, perturbed by the presence
of a sulfur dioxide plume at 12 km altitude (SO2 concentration = 0.3 atm cm). SO2 absorption
features are apparent at wavelengths of 7.3 and 8.7 micrometers. Lowermost curve shows the effect
of water droplets (optical depth 1.5, cirrus-type size distribution) within the SO2 plume. Symbols
indicate the brightness temperatures that would be measured by the HIRS/2 infrared channels. An SO2 detection algorithm has been
developed for HIRS/2, after analysis of many radiative
transfer simulations like these shown here. This SO2 alarm is based upon the sensitivity of the
7.3 micrometer channel to SO2 and thresholds set on the differences in brightness temperature
between various HIRS/2 channels. This alarm has been tested
with HIRS/2 observations of the 1980 Mount St. Helens and
1979 Sierra Negra eruptions. We will use a similar alarm algorithm for MODIS to detect large SO2 anomalies.
H2S transmission spectrum (5K image)
This plot shows the transmission of a 1.5 atm cm column of H2S gas. The absorption line data used
to generate this plot is from the HITRAN database over the 6.3 to 10 micrometer wavelength range,
and new estimates (Bykov et al. reference given below) covering 1.3 to 4.2 micrometers. This data
is being used to simulate measurements of volcanic H2S by
AIRS and TES at different viewing angles. H2S is roughly
50 times less absorbing than SO2 in the mid-infrared. Only extremely large quantities will be
detected by EOS instruments (At 40 degrees off nadir, the detection limit is about 0.2 atm cm H2S
for TES, and about 0.8 atm cm H2S for AIRS) [1 atm cm H2S = 30 tons H2S per km2].
Pre-launch EOS activities
Develop and test an SO2 alarm for MODIS, using
HIRSobservations of plumes.
Run radiative transfer simulations of infrared
observations of volcanic plumes and learn how to identify different types of plume characteristics
from AIRS and TES
Study the radiative effects of SO2, ash, and aerosols in the first few months after the eruption of El Chichon.
Determine capabilities for AIRS and
MODIS to detect and measure H2S.
EOS mission activities
Automatically detect SO2 anomalies in the MODIS data stream.
Use radiative transfer modelling to infer characteristics
of aerosols, volcanic gases, and ash in volcanic plumes observed by MODIS,
AIRS, TES, and ASTER.
Study maps of SO2, HCl, OCS, CO, H2S, HF, HCl/SO2, HCl/HF
near volcanic vents to monitor changes in volcanic activity and determine patterns of behavior.
Some recent related publications
Brown, LR, JA Crisp, D Crisp, OV Naumenko, MA Smirnov,
LN Sinitsa, and A Perrin (1998) The absorption spectrum of H2S between 2150 and 4260 cm-1:
Analysis of the positions and intensities in the first [2v2, v1, and v3] and second [3v2, v1+v2
and v2+v3] triad regions, J. Molec. Spectroscopy, 188: 148-174.
Pieri, DC, J Crisp, and AB Kahle (1995) Observing
volcanism and other transient phenomena with ASTER, Jour. Rem. Sens. Soc. Japan, 15(2): 56-61.
Gerstell, M.F., J. Crisp, and D. Crisp (1995)
Radiative forcing of the stratosphere by SO2 gas, silicate ash, and H2SO4 aerosols shortly after
the 1982 eruptions of El Chichon, J. Climate, 8: 1060-1070.