Regent's Professor Emeritus University of Montana Missoula, Montana, United States
Planning for the NASA Earth Observing System (EOS) began in 1981, the mission was approved by Congress in 1990, and the first multi-sensor satellite launch occurred in December 1999. Until EOS, satellite imagery was primarily used as a digital aerial photograph of landcover, or for ecosystems a simple spectral index of Normalized Difference Vegetation Index. I proposed in 1988 a suite of advanced biophysical variables for terrestrial ecology. First I proposed leaf area index (LAI) a canopy structural variable that can be derived from spectral data, that ecologists had used for years. I also proposed daily evapotranspiration (ET) a key hydrologic canopy variable and then annual net primary production (NPP) the foundation of terrestrial carbon cycles. The ET and NPP algorithms relied on both satellite data and ancillary daily meteorology to, in effect, drive a simple canopy gas exchange model at 1km spatial resolution for 120 million km2, a huge processing task for the computers of the day. I was selected for the MODIS Science Team, a position I still have. Additionally, I proposed using the satellite data not as a simple digital photograph, but as an input into geo-spatial ecosystem and biospheric models, a novel idea at the time. We published the first georeferenced color image of regional ET and NPP of a 1200km2 watershed in Montana in the journal Ecology in 1989. We now have a 40+ yr record of global evapotranspiration and net primary production, using my algorithms both for the EOS and reprocessing earlier satellite NDVI. Global climate models used these global datasets for model development, testing and validation of their land submodels. Daily evapotranspiration provides a critical look at regional water balance and drought conditions. NPP quantifies trends in agriculture and grazing production, and more generally the health of the terrestrial biosphere. These global measures are continuing with new NASA and NOAA satellites.
