The Earth's climate is a dynamic system influenced by interactions between land, water, and atmosphere. To better measure and understand specific climate changes, international agencies, through the Committee on Earth Observation Satellites (CEOS), have agreed to provide satellite-based multi-decadal climate information products covering terrestrial, oceanic, and atmospheric domains at regional and global scales. Some of these products, known as Climate Data Records (CDRs), are time-series observational data of sufficient length, consistency, and continuity to record effects of climate change. Examples of CDRs include calibrated radiances, surface reflectance, and surface temperature.
Essential Climate Variables (ECVs) are derived in part from CDRs, and address the following terrestrial categories: River Discharge; Water Use; Groundwater; Lake and Reservoir Levels and Volumes; Snow Cover; Glaciers and Ice Caps; Permafrost; Land Surface Albedo; Land Cover; Absorbed Photosynthetically Active Radiation; Leaf Area Index, Biomass; and Fire Disturbance. CDRs and Terrestrial ECVs are parameters derived from systematic long-term measurements collected by satellite and aircraft platforms as well as in situ observation networks.
The U.S. Geological Survey (USGS) is the steward of the most comprehensive satellite data record of the global land masses, and a participating member of CEOS. The USGS Landsat archive goes back to 1972, providing a valuable time series of observations that can be used to document changes to the Earth's terrestrial environment resulting from natural processes and human activities. The initial focus will be on developing CDR and ECV products from Landsat thematic mapper (TM) and enhanced thematic mapper plus (ETM+) data due to the spectral coverage and calibration history of these instrument records.
USGS is undertaking the development of the following ECVs: global 30 meter land cover; burned area (surrogate for fire disturbance); dynamic surface water extent (proxy for lake variables); and snow covered area (a component of snow and ice cover).
