Applications of an Energy Transfer Model to Three Problems in Planetary Regoliths: The Solid-State Greenhouse, Thermal Beaming, and Emittance Spectra

Several problems of interest in planetary infrared remote sensing are investigated using a new radiative-conductive model of energy transfer in regoliths: the solid-state greenhouse effect, thermal beaming, and reststrahlen spectra. The results of the analysis are as follows: (1) The solid-state greenhouse effect is self-limiting to a rise of a few tens of degrees in bodies of the outer solar system. (2) Non-Lambertian directional emissivity can account for only about 20% of the observed thermal beaming factor. The remainder must have another cause, presumably surface roughness effects. (3) The maximum in a reststrahlen emissivity spectrum does not occur exactly at the Christiansen wavelength where, by definition, the real part of the refractive index equals one, but rather at the first transition minimum in reflectance associated with the transition from particle scattering being dominated by volume scattering to that dominated by strong surface scattering. The transparency feature is at the second transition minimum and does not require the presence of a second band at longer wavelength for its occurance. Subsurface temperature gradients have only a small effect on emissivity bands.

[1]  W. Irvine,et al.  Monochromatic phase curves and albedos for the lunar disk. , 1973 .

[2]  R. W. Shorthill,et al.  The sunlit lunar surface , 1972 .

[3]  James E. Conel,et al.  Infrared emissivities of silicates: Experimental results and a cloudy atmosphere model of Spectral emission from condensed particulate mediums , 1969 .

[4]  F. Fanale,et al.  The effect of volume phase changes, mass transport, sunlight penetration, and densification on the thermal regime of icy regoliths , 1990 .

[5]  B. Jakosky,et al.  Near‐surface thermal gradients and their effects on mid‐infrared emission spectra of planetary surfaces , 1994 .

[6]  B. Hapke.  A model of radiative and conductive energy transfer in planetary regoliths , 1996 .

[7]  Bruce Hapke,et al.  An Experimental Study of Light Scattering by Large, Irregular Particles , 1995 .

[8]  William M. Irvine,et al.  Infrared optical properties of water and ice spheres , 1968 .

[9]  J. Spencer.  A rough-surface thermophysical model for airless planets , 1990 .

[10]  D. Matson,et al.  Thermal effects of insolation propagation into the regoliths of airless bodies , 1986 .

[11]  W. Sinton.  CHAPTER 11 – Temperatures on the Lunar Surface , 1961 .

[12]  D. Morrison,et al.  Radiometry of asteroids , 1979 .

[13]  Graham R. Hunt,et al.  Emission spectra of particulate silicates under simulated lunar conditions , 1970 .

[14]  F. Wooten,et al.  Optical Properties of Solids , 1972 .

[15]  John W. Salisbury,et al.  Measurements of thermal infrared spectral reflectance of frost, snow, and ice , 1994 .

[16]  B. Hapke.  Theory of reflectance and emittance spectroscopy , 1993 .

[17]  D. Matson,et al.  Solid-state greenhouse and their implications for icy satellites , 1989 .

[18]  Emil Wolf,et al.  Principles of Optics: Contents , 1999 .

[19]  John W. Salisbury,et al.  Thermal infrared directional emissivity of powdered quartz , 1995 .

[20]  D. A. Kleinman,et al.  Infrared Lattice Bands of Quartz , 1961 .

[21]  John W. Salisbury,et al.  Thermal infrared (2.5–13.5 μm) spectroscopic remote sensing of igneous rock types on particulate planetary surfaces , 1989 .

[22]  Richard J. Rudy,et al.  A refined “standard” thermal model for asteroids based on observations of 1 Ceres and 2 Pallas , 1986 .

[23]  J. Salisbury,et al.  Thermal‐infrared remote sensing and Kirchhoff's law: 1. Laboratory measurements , 1993 .