NASA's Pathfinder data set programme: land surface parameters

Abstract

The Pathfinder data set concept was initiated by the Earth Observing System (EOS) Program Office at the National Aeronautics and Space Administration (NASA) Headquarters to address how existing satellite-derived data sets could be used for global change research prior to the availability of EOS data. They are denned as long time-series satellite data sets capable of stable calibration which can be reprocessed using a community-consensus set of algorithms In October 1990 NASA and the National Oceanic and Atmospheric Administration (NOAA) initiated a joint Pathfinder program. Data from three NOAA and one Defense Meteorological Satellite Program (DMSP) instruments have been designated as Pathfinders under this activity. In addition to this joint effort, NASA has also initiated a Pathfinder development effort for data from both Landsat and the Scanning Multichannel Microwave Radiometer (SMMR) flown on NASA's Nimbus-7 satellite The AVHRR Pathfinder was the first set of projects to be initiated. Because the data have distinct disciplinary user heritages and expertise associated with the atmosphere, ocean, and land, three separate Science Working Groups were formed to recommend and comment on all stages of data set design and development. One of these groups is the AVHRR Land Pathfinder Science Working Group. Additionally, low resolution land surface parameters will be produced by the SSM/1 and SMMR Pathfinder projects. A Global 1 km Data Set Project, in the spirit of Pathfinder and partially funded with NASA Pathfinder funding, was begun in October 1991 and began collecting data continuously on a daily basis on 1 April 1992 One of the goals of Pathfinder data set production, to make available consistent long-time series data sets for global change research, has encouraged substantial interdisciplinary use of the data, and therefore consideration of problems of data fusion or integration. Work in producing the Pathfinder data sets has exposed important technical problems which scientists encounter impeding interuse of data sets. Presently, an experiment involving scientists and systems engineers working with several Pathfinder data sets is exploring possible solutions to some of these technical problems.