Mro-Crism 2006-2008 Martian Cloud Map Retrievals.
D. R. Klassen, (Klassen@Rowan.Edu), B. D. West, Rowan University, New Jersey, Usa.

Introduction
There In An Inherent Difficulty In The Visible Wavelength
(Vis) And Near-Infrared (Nir) When One Moves From A
Technique Of Tracking Cloud Positions And Getting Semiquantitative Relative Thicknesses To Retrieving Full Optical Depth Measurements That Is Much Less Problematic
In Other Wavebands Such As Ultraviolet (Uv) And Thermal Infrared (Tir); Namely In The Vis-Nir One Needs
To Properly Characterize The Intrinsic Surface Reflectance
In Order To Complete The Radiative Transfer Modeling.
Since The Spectra Are Not Easily Separable Into Surface
And Aerosol Components, There Are Two Primary Techniques One Can Use To Get An Approximate Surface Spectrum: Find Your Region Of Interest On Another Day You
Believe To Be Free Of Cloud Cover And Use The Retrieved
Spectrum As The Surface, Or Find Another “Nearby” Region
In The Same Image That Appears To Be Similar Enough To
Your Region Of Interest And Appears Free Of Cloud Cover
And Use That Spectrum As The Surface Proxy. Neither Of
These Is Usable If One Is Going To Scale Up The Cloud Measurements To The Entire Globe Of Mars. Additionally, The
First Idea Requires That The Surface Reflectance Remain Relatively Static In Time While The Second Requires Surface
Reflectance To Vary Slowly Across A Scene Of Interest.