ing contingency plans for inevitable initial difficulties with the ECS; and (2) the DAAC should develop a clearer vision for serving the needs of its scientific and, potentially much more numerous, applications users. This vision should include a plan for meeting the challenges of the EOS era, including major increases in data volume and product diversity, a broader user community, and concomitant increased complexity of user services.

INTRODUCTION

The EDC DAAC was created in 1992 to manage data from Landsat 7 and other land remote sensing instruments. It is located within the EROS Data Center, which has been managing land processes data for two decades, but its holdings and operations are separate from those of the USGS. The creation of the EDC DAAC signaled a shift in the focus of the Landsat program. Previous Landsat satellites served primarily the applications community, a very large user group that is likely to increase substantially if data become available at lower cost and in near real time. Landsat 7, on the other hand, has been incorporated into the EOS program as a science instrument, and scientists will be the DAAC's highest-priority users (Box 5.1). However, the demands on the system will likely still be driven by the applications users.

When it was formed, the EDC DAAC did not acquire any heritage data sets. Its data sets, which are few in number but relatively large in size, include the Global 1-Kilometer Advanced Very High-Resolution Radiometer (AVHRR), Landsat Pathfinder, and the digital elevation model Global 30 Arc-Second Elevation Data Set (GTOPO30).

In the EOS AM-1 era, the DAAC will manage data from Landsat 7 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). It will also receive Moderate-Resolution Imaging Spectroradiometer (MODIS) data from the GSFC DAAC and will distribute and possibly process MODIS land products. Data from these instruments, which are scheduled to be launched in 1999, will increase the volume of holdings by a factor of 20, from 9 TB to nearly 200 TB per year (Box 5.1).

To prepare for these data streams, the DAAC has requested an additional 50 ECS contractors (there are 38 ECS contractors at the DAAC in FY 1998), and it has begun readiness exercises. The DAAC has tested the algorithms for processing ASTER data and appears to be ready for the ASTER data stream. This is to be credited in large part to the ASTER instrument team, which was extremely diligent in porting its processing codes to the DAAC and testing them extensively. Readiness for MODIS will depend, in part, on the GSFC DAAC and the MODIS science team; at the time of the review, the schedule and products from the MODIS science team were still uncertain, and only limited tests of the algorithms had been completed.

Delays in the delivery of the ECS and uncertainties about its capabilities



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