Figure 4. a-b) GOCART and MODIS τ at 532 nm across the region on 19 August 2006. The angstrom exponent is used to calculate the τ at 532 nm for MODIS and GOCART since they do not provide a τ at 532 nm directly. The MODIS is unable to show a complete spatial distribution of τ across the region due to cloud covered pixels causing a low confident retrieval of τ which we disregard by using the QA-weighted τ parameter. c) The combined MODIS and GOCART τ maps on the WRF-Chem grid where MODIS provides the τ values for a large portion of the main dust storm region while GOCART provides the τ values for the regions with dense cloud cover evident. d) τ at 532 nm on the WRF-Chem grid but for the τ calculations based strictly on the CALIPSO 5 km extinction profiles (i.e. τcalipso). The τ scale for all the panels is located at the bottom.