Spectral indices R987/814 (A) and BD440 for EQ6 (B; 8:40 pm), with color maps scaled to the ranges in Fig. 2. There is much less diversity in R987/814 than in the EQ3 data (Figs. 2 and 3). High inertia (coarser) materials emit most strongly at night and little geographic correlation is visible, suggesting that variation in this parameter in the daytime data is due primarily to differences in the relative abundance of fine particulates. BD440 shows geographic trends comparable to those in EQ3 (Figs. 2 and 3), revealing that this band depth is partially decoupled from the characteristics that lead to variation in R987/814. See Fig. A.7 for error maps.