Table 2.

Datasets used in this study.

EARTH OBSERVATION DATA, MODEL, AND TOOL	PRODUCT (NAME AND RESOLUTION)	VARIABLES	RELATION TO PM2.5 ABUNDANCE
NASA GMAO GEOS 5	MERRA	Thirty-eight surface layer and land surface variables are used, including the height of the planetary boundary layer, precipitation, the surface humidity, wind speed, temperature, and density	Factors related to the production, dispersion, or removal of boundary layer PM2.5
MERRA 1979 to present	2/3° × 1/2° (Lat., Long.)
SeaWIFS 1997–2010	Deep Blue 0.5° × 0.5°	Aerosol optical depth, angstrom exponent, single scattering albedo, viewing geometry, illumination geometry, surface reflectivity, and assorted flags	Measure of total aerosol abundance in a vertical atmospheric profile
MODIS Terra & Aqua 2000–present 2002–present	MOD04 MYD04 Collection 5.1 10 km × 10 km	Deep Blue and Standard retrievals of aerosol optical depth, viewing geometry, illumination geometry, surface reflectivity, and assorted flags	Measure of total aerosol abundance in a vertical atmospheric profile
MODIS 2000–present	MCD43C3 0.05° × 0.05°	Seven wavelength band surface reflectance	Related to surface sources of PM2.5 and AOD biases
MODIS 2000–present	MCD45A1 500 m	Gridded burned area product, which contains burning and quality information on a per-pixel basis	Fires are a major source of PM2.5

Abbreviations: AOD, aerosol optical depth; GMAO, global modeling and assimilation office; MERRA, modern-era retrospective analysis for research and applications; MODIS, moderate resolution imaging spectroradiometer; SeaWIFS, sea-viewing wide field-of-view sensor.