Figure 2. a) MODIS RGB composite image on 5 September 2006 where the red (R) channel is the brightness temperature difference (BTD) between the 12 and 11 μm bands, the green (G) channel is the 0.65 μm band, and the blue (B) channel is the BTD between the 11 and 8.5 μm bands. The overpasses east of the data gap occur around 1355 UTC and the overpasses west of the gap occur around 1530 UTC. The three CALIPSO transects in this domain on 5 September are in black while the NAMMA DC-8 flight path is along the red line. The blue section of the red line indicates an ascent profile from about 1155 to 1220 UTC and the blue triangle on the eastern extent of the flight path is the location of a descent profile from about 1340 to 1405 UTC. NCEP reanalysis wind data at 700 hPa is shown by the black vectors. b) The measured size distribution from the APS instrument during the ascent profile of the DC-8 aircraft where the mean radius is 0.598 and the geometric standard deviation is 1.565. The UHSAS capable of measuring very fine particle size distributions was not operating during the DC-8 flight path on 5 September which explains the absence of particles with radii less than about 0.3 μm.
