NASA PATHFINDER DATA SET PROGRAM - LAND-SURFACE PARAMETERS

The Pathfinder data set concept was initiated by the Earth Observing S ystem (EOS) Program Office at the National Aeronautics and Space Admin istration (NASA) Headquarters to address how existing satellite-derive d data sets could be used for global change research prior to the avai lability of EOS data. They are defined as long time-series satellite d ata 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 joi nt Pathfinder program. Data from three NOAA and one Defense Meterologi cal Satellite Program (DMSP) instruments have been designated as Pathf inders under this activity. In addition to this joint effort, NASA has also initiated a Pathfinder development effort for data from both Lan dsat and the Scanning Multichannel Microwave Radiometer (SMMR) flown o n 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, a nd land, three separate Science Working Groups were formed to recommen d and comment on all stages of data set design and development. One of these groups is the AVHRR Land Pathfinder Science Working Group. Addi tionally, low resolution land surface parameters will be produced by t he SSM/I 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 continuo usly on a daily basis on 1 April 1992. One of the goals of Pathfinder data set production, to make available consistent long-time series dat a sets for global change research, has encouraged substantial interdis ciplinary 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 i mpeding interuse of data sets. Presently, an experiment involving scie ntists and systems engineers working with several Pathfinder data sets is exploring possible solutions to some of these technical problems.