Introduction
NASA maintains programs which continuously monitor atmospheric parameters using remote sensing satellites. A summary of the NASA Aerosol programs can be found here. There are two instruments which are used, MISR (Multi-angle Imaging SpectroRadiometer) and MODIS (Moderate-resolution Imaging Spectroradiometer). MODIS provides a wide band, low resolution spectroscopic view of the earth's surface and can "see" the entire planet every 1-2 days. MISR has a higher resolution, and "sees" the entire planet less frequently, but at a higher resolution.
Accessing the data
There are a variety of "levels" at which data can be retrieved. Level 1 corresponds to raw, calibrated instrument data. Level 2 is data which has been derived from level 1 data, and consists of cloud and aerosol optical depth information. Level 3 corresponds to global concatenated datasets, showing cloud/aerosol distribution over the planet surface.
Access portals
Atmospheric Science Data Center (ASDC)
ASDC coordinates the collection, processing, and distribution of NASA Earth Science data and is the entry point for access to all earth science datasets
Aerosol Measurement and Processing Sytem (AMAPS)
AMAPS provides convenient tools which provide access to aerosol data from MODIS and MISR. It provides a tool which allows a user to specify a specific location on the planet by latitude and longitude, and will provide all MISR between a specified time interval which cover this area. There are two methods to specify the location , either through uploading a text file, URL version (useful for batch operation) or through browser text input
Data pool
Provides FTP access to recently produced data, in a .HDF file format. This data must be post processed using supplied software. It appears that to retrieve specific Aerosol data from the .HDF files, a compatible GIS environment (eg.IDL) must be utilized.
Data order tool
Provides access to all MIDC data, filtered spatially and temporally, in separate .HDF files for the entire measurement campaign. Again, post processing of the .HDF file is required to read individual site Aerosol information.