  We present a concept for using a polarization sensitive multispectral lidar
to map the seasonal distribution and exchange of volatiles among the reservoirs
of the Martian surface and atmosphere.
  The LIDAR instrument will be a multi-wavelength, altitude-resolved, active
near-infrared (NIR, with 10 bands around 1.6 microns) instrument to measure the
reflected intensity and polarization of backscattered radiation from planetary
surfaces and atmospheres. The proposed instrument would be ideally suited for a
mission to Mars to comprehensively investigate the nature and seasonal
distributions of volatiles and aerosols. The investigation would include the
abundance of atmospheric dust and condensed volatiles, surface and
cloud/aerosol grain sizes and shapes, ice and dust particle microphysics and
also variations in atmospheric chemistry during multiple overflight local times
throughout polar night and day.
  Such an instrument would be ideal for mapping and detection of recently
detected CO2 frost phenomena and H2O and CO2 precipitation events in the polar
regions of Mars. Herein we discuss the applicability of this instrument to
detect and map sublimation/deposition 'mode flips' recently discovered by Brown
et al. (2016) using the CRISM passive infrared sensor on Mars Reconnaissance
Orbiter.
