HR: 11:05h
AN: V32A-04    [Abstracts]
TI: Estimating the height of volcanic plumes from the 15 micron CO2 band
AU: Richards, M
EM: msrichards2@wisc.edu
AF: CIMSS UW-Madison, 1225 West Dayton St., Madison, WI 53706
AU: * Ackerman, S A
EM: stevea@ssec.wisc.edu
AF: CIMSS UW-Madison, 1225 West Dayton St., Madison, WI 53706
AU: Feltz, W
EM: waynef@ssec.wisc.edu
AF: CIMSS UW-Madison, 1225 West Dayton St., Madison, WI 53706
AB: 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.
DE: 0305 Aerosols and particles (0345, 4801)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting