VALIDATING THE BANDFIELD SURFACE ROUGHNESS MODEL USING NOVEL THEMIS ROTO DATA: APOLLINARIS MONS IN A NEW LIGHT
A series of ROTO data centered around Apollinaris Mons were acquired at local true solar times from 18:00h -19:00h, solar longitudes from 38°- 47°, incidence angles from 94°-102°, and emission angles from -31°to 33°. Using these eight observations, BT differences were examined. Observations show temperature asymmetry about the -2 roll angle (effectively nadir) with the lowest temperatures recorded at the highest magnitude emission angles. Negative roll angles, highlighting western facing slopes, show higher overall temperatures than the positive roll angles of similar magnitude. This corresponds to warmer western facing slopes that had previously been illuminated by the setting sun. BT variations between THEMIS bands 3 and 9 indicate the range of temperatures within the region of study. Band 3 BT are always greater than band 9 BT, indicating the presence of sub-pixel anisothermality.
By combining the KRC thermal model and a modified Bandfield surface roughness model, simulated BT data are used to quantify this sub-pixel anisothermality. Maximizing emission angle observations with variable look angles provides a more complete view of surface features, improving previous estimates of RMS and Θ-bar roughness by Bandfield (2009).