Please work on improving the introduction section of the paper per the suggestion below

In their reply, the authors argue that they "do not have better knowledge of the research algorithms that use chemistry transport models for aerosol properties. And we do not have a reference to this research work either". The following references are listed for authors to consider, with a hope to make the introduction part complete and stronger.

Drury, E., D. J. Jacob, J. Wang, R. J. D. Spurrs, and K. Chance, Improved algorithm for MODIS satellite retrievals of aerosol optical depths over land, J. Geophys. Res., 113, D16204, doi:10.1029/2007JD009573, 2008.

Drury, E., D. J. Jacob, R. J. D. Spurr, J. Wang, Y. Shinozuka, B. E. Anderson, A. D. Clarke, J. Dibb, C. McNaughton, and R. Weber, Syntehsis of satellite (MODIS), aircraft (ICARTT), and surface (IMPROVE, EPA-AQS, AERONET) aerosol observations over North America to improve MODIS aerosol retrievals and constrain surface aerosol concentration and sources, J. Geophys. Res., D14204, 2010.

Wang, J., X. Xu, R. Spurr, Y. Wang, and E. Drury, Improved algorithm for MODIS satellite retrievals of aerosol optical thickness over land in dusty atmosphere:Implications for air quality monitoring in China, Remote Sensing of Environment, 114, 2575-2583, 2010.