RETRIEVAL OF ATMOSPHERIC TEMPERATURES IN THE MARTIAN PLANETARY BOUNDARY-LAYER USING UPWARD-LOOKING INFRARED-SPECTRA

We present an algorithm for the retrieval of temperature in the planet ary boundary layer (lowest few kilometers) of the martian atmosphere u sing upward-looking infrared spectra from a Mars lander. Temperature p rofiles retrieved from an orbiting or passing spacecraft do not have a dequate vertical resolution to provide significant information within the planetary boundary layer. By using spectra taken from a surface la nder looking upward toward zenith, and by transforming to a vertical c oordinate that ''stretches out'' the atmosphere just above the surface where the contribution to the observed radiation peaks, we find that an efficient algorithm can be formulated with adequate vertical resolu tion to successfully retrieve temperature profiles that exhibit the ma jor features of the diurnal cycle of planetary boundary layer temperat ures. We expect that this technique can be extended to simultaneously retrieve the opacity, and possibly the scattering properties, of atmos pheric aerosols as well. Although no upward-looking martian infrared s pectra yet exist, demonstration of the abilities of a lander-based inf rared spectrometer is important for the planning of future missions to Mars. (C) 1996 Academic Press, Inc.