Computer Science
Scientific paper
Jan 1993
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993phdt........19j&link_type=abstract
PhD Dissertation, Michigan Univ. Ann Arbor, MI United States
Computer Science
Carbon Dioxide, Far Infrared Radiation, Ice, Mars Atmosphere, Mars Surface, Water, Ice Clouds, Infrared Spectra, Brightness Temperature, Emissivity, Optical Thickness, Radiative Transfer, Refractivity, Infrared Spectrometers, Surface Temperature
Scientific paper
Ices in the atmospheres and on the surfaces of planets are thought to play important roles in the evolution and stability of planetary atmospheres. In this dissertation the capability of far infrared spectral observations to determine planetary ice composition was investigated. Thin film transmission spectra of crystalline (Ic) and amorphous H2O ice and crystalline CO2 deposited on a silicon substrate were measured in the laboratory by a Fourier transform spectrometer and used to calculate the refractive indices at temperatures of 77 to 150 K over the range 50-500 cm-1. The refractive index data were compared with previously published data and generally agreed well to within the approximately 20% experimental error. The chief source of error was due to uncertainty in film thickness, determined by fitting channel spectra with a theoretical transmission model. The derived refractive indices were incorporated into a radiative transfer model used to study the far infrared properties of cloud and surface ices on Mars. Thin midlatitude H2O ice clouds with typical integrated ice amounts of approximately 0.5 pr micrometer have vertical far infrared optical depths of the order of 10-4, making their detection difficult. However, cloud models based on Viking observations of the polar regions produced observable spectral features (Delta T less than or equal to 8 K) in calculated spectra near 225 cm-1. The presence of a CO2 ice haze lowered the apparent surface brightness temperature by 10-20 K. Theoretical emission by CO2 frost shows strong spectral contrast of approximately 20-30 K near the lattice absorption bands in solid CO2. In the weakly absorbing interband region, CO2 frost emissivity is approximately 0.4 increasing to approximately 0.7 with the incorporation of small amounts (0.1-1.0%) of dust or water ice. H2O frost exhibits poor spectral contrast in this region with an emissivity close to unity. Far infrared observations of Martian polar condensates and CO2 frost by a conventional satellite-based instrument in earth orbit may be feasible but would require a collecting aperture greater than or equal to 15 m to achieve adequate spatial resolution. Interferometric techniques involving one or more satellites is theoretically capable of achieving the high spatial resolution required for far infrared planetary observations.
No associations
LandOfFree
Laboratory and theoretical study of the far infrared spectra of Martian ices does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Laboratory and theoretical study of the far infrared spectra of Martian ices, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Laboratory and theoretical study of the far infrared spectra of Martian ices will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1264236