Aerosol Robotic Network (AERONET)
AERONET is a ground-based aerosol monitoring network and data archive supported by NASA's Earth Observing System and expanded by federation with many non-NASA institutions. Data from this collaboration provides near real-time observations of aerosols.
[AERONET Web Site]

An AERONET sun-sky scanning spectral radiometer at McMurdo Dry Valleys, Antarctica.

FLUXNET
FLUXNET integrates measurements of carbon dioxide, water vapor, and energy fluxes and associated site vegetation, hydrologic, and meteorological characteristics. The collection of data from around the world aids research on understanding how carbon, water, and nutrient cycles of terrestrial ecosystems respond to environmental and climatic changes.
[FLUXNET Web Site]