Dependence of Mercurian Atmospheric Column Abundance Estimations on Surface-Reflectance Modeling

University of Arizona, Lunar and Planetary Laboratory, Tucson, Arizona, 85721
Icarus (Impact Factor: 3.04). 07/1997; 128(1):75-82. DOI: 10.1006/icar.1997.5725


Column abundance estimates of sodium, and analogously, potassium, in Mercury's exosphere are strongly correlated to the surface reflection model used to calibrate the spectral data and the surface reflection model incorporated into the atmospheric radiative transfer solution. Depending on the surface reflection model parameters used, there can be differences in calibration factors of up to ±30% and differences in estimated column abundance of up to ±35%. Although the surface reflectance may not be used in the calibration of spacecraft measurements, the interaction between the reflected surface light and the atmospheric brightness remains important.

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Available from: Deborah L Domingue, Jan 22, 2014
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    • "). For spectral images of excellent seeing and higher spatial resolution, it will be necessary to account for changing surface albedo beneath the slit in the absolute calibration of the slit sectors before conversion of emission DNs to column abundances (Domingue et al., 1997). Table 3 shows g-factors, Rr, and calibration factors for the three spectra presented in this paper. "
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    ABSTRACT: Analysis of three spectra of the exosphere of Mercury in the Na-D lines are presented. Spectra were secured with the high-resolution spectrograph (SARG) of the 3.5 M Telescopio Nazionale Galileo (TNG, located on the Roque de los Muchachos, Canaries) on the evenings of August 23 and 24, 2002. Spectra have resolution ; the slit length was 26.7”. The Na column abundances range from 4.3 to with the highest abundances being close to the illuminated limb. Our observations at true anomaly angles (TAA) from 171°to 174°show the traces of the emission lines to be strongly peaked at the illuminated limb, supportive of recent modeling that shows thermal desorption to be a strong factor in determining the distribution of Na about the planet.
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