Aerosols include, but are not limited to, smoke, dust, sand, volcanic ash, sea spray, polar stratospheric clouds, and smog. Although cloud particles can be considered as a particular type of aerosol, it is conventional to put them in a separate category.

Liquid water clouds are defined as distinct optically thick particulate features composed of droplets. Cirrus clouds are defined as visible, or sub-visible particulate layers (either natural, or man-made, such as contrails), which reside in the upper troposphere/lower stratosphere and are composed of water ice crystals with sizes ranging from several micrometers to a millimeter.

The Glory Aerosol Polarimetry Sensor (APS) is the only instrument currently capable of making measurements that can distinguish various species of aerosols.

1. The global distribution of natural and anthropogenic aerosols (black carbons, sulfates, etc.) with accuracy and coverage suf- ficient for reliable quantification of:
  + the aerosol effect on climate
  + the anthropogenic component of the aerosol effect
  + the potential secular trends in the aerosol effect caused by natural and anthropogenic factors

2. The direct impact of aerosols on the radiation budget and its natural and anthropogenic components

3. The effect of aerosols on clouds (lifetime, microphysics, and precipitation) and its natural and anthropogenic components

4. Investigate the feasibility of improved techniques for the measurement of black carbon and dust absorption to provide more accurate estimates of their contribution to the climate forcing function

APS DATA

APS threshold science requirements and science goals are characterized in following sections and described in terms of the specific data products. These data products, sometimes referred to as Environmental Data Records (EDRs), are:

For threshold science requirements

1. Aerosol optical thickness
2. Aerosol particle size
3. Aerosol refractive index, single-scattering albedo, and shape
4. Cloud optical thickness
5. Cloud particle size distribution

For science goals

1. Single scattering albedo derived from the ocean glint
2. Single-scattering albedo derived from the 412 nm aerosol differential absorption technique
3. Aerosol optical thickness derived from APS-VIIRS combined inversion
4. Fraction of fine mode aerosol derived from APS-VIIRS combined inversion Aerosols are defined as suspensions of liquid droplets or solid particles in the atmosphere.