AMS = American Millitary Standard?

And FA-AMS = ?

Context:
Total mass concentration (in micrograms per cubic meter) and mass fractions of nonrefractory inorganic species and organic components in submicrometer aerosols measured with the AMS at multiple surface locations in the Northern Hemisphere (21). The organic components were obtained with FA-AMS methods (3, 15"17). In some studies, the FA-AMS methods identified one OOA factor, whereas in other locations, two types, SV-OOA and LV-OOA, were identified. HOA is a surrogate for urban primary OA, and Other OA includes primary OAs other than HOA that have been identified in several studies, including BBOA. (Inset) Distributions of O:C for the OA components identified at the different sites, calculated according to (18). http://www.sciencemag.org/cgi/content/full/326/5959/1525