The CERES experiment is one of the highest priority scientific satellite instruments developed for NASA's Earth Observing System (EOS). CERES products include both solar-reflected and Earth-emitted radiation from the top of the atmosphere to the Earth's surface. Cloud properties are determined using simultaneous measurements by other EOS instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS). Analyses of the CERES data, which build upon the foundation laid by previous missions such as the Earth Radiation Budget Experiment (ERBE), will lead to a better understanding of the role of clouds and the energy cycle in global climate change.

      CALIPSO was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. NASA Langley Research Center is leading the mission and is providing overall project management, systems engineering, payload mission operations, data validation, processing and archival. The Centre National d'Etudes Spatiales (CNES) is providing a PROTEUS spacecraft, the imaging infrared radiometer (IIR), payload-to-spacecraft integration and spacecraft mission operations. CALIPSO was developed through collaboration between NASA and the French space agency, CNES.

      The HSRL instrument is an innovative technology that is similar to radar; however, with lidar, radio waves are replaced with laser light. Lidar allows researchers to see the vertical dimension of the atmosphere, and the advanced HSRL makes measurements that can even distinguish among different aerosol types and their sources. The HSRL technique takes advantage of the spectral distribution of the lidar return signal to discriminate aerosol and molecular signals and thereby measure aerosol extinction and backscatter independently. It measures aerosol backscatter and depolarization at 532 and 1064 nm and aerosol extinction at 532 nm.

      Vaporized water is an invisible gas that is present everywhere in the atmosphere. The distribution of atmospheric water vapor is of fundamental importance to weather and climate, atmospheric radiation studies, global hydrological cycle and atmospheric chemistry. The LASE program was initiated as an effort to produce an autonomous system for measuring water vapor levels from airborne and spaceborne platforms using LIDAR technology.

      LITE is a three-wavelength backscatter lidar developed by NASA Langley Research Center that flew on the Space Shuttle Discovery in September of 1994.

      The LiDAR group at NASA Langley Research Center has been developing and applying advanced lidar systems to a broad range of atmospheric investigations. These activities have included the development and application of airborne Differential Absorption LiDAR (DIAL) systems for studies of ozone, water vapor, aerosols and clouds.

      The SAGE II mission provided the scientific community with a long-term, global depiction of the distribution of aerosol, ozone, water vapor and nitrogen dioxide. The data provide unique and crucial input to the understanding of global, seasonal to interannual variability in climate and, in particular, trends in stratospheric ozone.

      SAGE III's role was to provide global, long-term measurements of key components of the Earth's atmosphere. The most important of these are the vertical distribution of aerosols and ozone from the upper troposphere through the stratosphere.