For the past several years, the Land Remote Sensing Program has sponsored the development of Landsat science products referred to as climate data records (CDRs) and essential climate variables (ECVs) to support scientific research and applications associated with the study of long-term trends in natural or human-induced changes to the Earth’s land surface. These products include atmospherically corrected surface reflectance and surface temperature, burned area, dynamic surface water extent, fraction of snow covered area, and aboveground biomass. The development of the science data processing algorithms is undertaken through collaboration among scientists from multiple USGS Science Centers, NASA (Goddard Space Flight Center and the Jet Propulsion Laboratory), University of Maryland, and the Rochester Institute of Technology. The goal is to generate these science products from the historical record of Landsat data dating back to 1982 corresponding to the beginning of the Landsat 4 Thematic Mapper (TM) measurements through the present Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI) data and into the future.
The combined daily data acquisition rates by Landsat 7 and 8 today is 1,200 scenes per day, which is the highest in the history of the program. In addition, the Landsat Global Archive Consolidation (LGAC) activity is increasing the amount of historical data in the archive through the repatriation of data downlinked to the International Cooperator network. This means that the temporal depth and density of the Landsat archive, particularly over the conterminous United States, provides the opportunity to apply time series analysis of geophysical and biophysical properties of the land surface to study seasonal, interannual, and decadal variability. Through the development of dense multitemporal “data stacks,” scientists can now compare contemporaneous observations with historical trends to assess landscape resiliency and vulnerability to change associated with natural processes, land management policies, and land use practices.
In fiscal year 2016 the development of these Landsat science products has made significant progress. Landsat surface reflectance products can be generated on a routine basis for anywhere in the world. Burned area and dynamic surface water extent products have been generated on a provisional basis from Landsat TM and ETM+ data and have been provided to stakeholders for evaluation and feedback, and by the end of the fiscal year the science processing algorithms will be updated to accommodate processing of OLI data. A Landsat surface temperature product is currently undergoing evaluation by select investigators and is expected to be available on a provisional basis in early 2017. Prototype fractional snow cover and aboveground biomass products have also been successfully demonstrated.
Illustration of a “data stack” comprised of seamless mosaics of Landsat 8 Operational Land Imager (OLI) surface reflectance data for the conterminous United States.