“…Measurements in the 200-315 nm region were found to be most useful for PMC analysis because of the absence of earth albedo effects. Further studies using subsets of the MSX data have investigated PMC altitudes, transpolar structure, latitude variations, and particle size distributions (Carbary et al, 1999(Carbary et al, , 2000(Carbary et al, , 2001(Carbary et al, , 2002.…”