Review of NASA’s Distributed Active Archive Centers (1999)
Chapter: 3 Goddard Space Flight Center DAAC
J.-BERNARD MINSTER, Chair, Scripps Institution of Oceanography, La Jolla, California
FERRIS WEBSTER, Vice Chair, University of Delaware, Lewes
SYDNEY LEVITUS, NOAA National Oceanographic Data Center, Silver Spring, Maryland
RICHARD S. LINDZEN, Massachusetts Institute of Technology, Cambridge
TERENCE R. SMITH, University of California, Santa Barbara
JOHN R.G. TOWNSHEND, University of Maryland, College Park
The Goddard Space Flight Center (GSFC) DAAC is the largest of the EOSDIS DAACs. It manages a variety of data sets related to climate, the biosphere, and the upper atmosphere, and it will also process, disseminate, and archive data from the flagship EOS instrument, the Moderate Resolution Imaging Spectroradiometer (MODIS). The DAAC understands its role and is doing a good job with its current data sets. However, the large data volumes and complex algorithms of the MODIS data stream present a significant challenge to the DAAC, and the panel’s main recommendation is that the DAAC continue to focus its efforts on preparing for the AM-1 platform, and particularly the MODIS instrument.
The GSFC DAAC was created in 1993 to archive and distribute data related to climate change, atmospheric dynamics, global biosphere, hydrology, and upper atmospheric chemistry (Box 3.1). Its roots are in the NASA Climate Data System and the Pilot Land Data System. The first data sets archived by the DAAC included data collected by the Total Ozone Mapping Spectrometer (TOMS) and the Nimbus-7 Coastal Zone Color Scanner (CZCS). Today the DAAC manages data sets from a variety of missions and experiments, supports the Goddard Data Assimilation Office, and also manages some of the hydrology holdings of the Marshall Space Flight Center DAAC, which was closed in 1997. With a staff of 114 and current holdings of 4 TB, the GSFC DAAC is one of the largest DAACs in the EOSDIS system.
In the EOS AM-1 era, DAAC holdings will increase in size by a factor of 500 (Box 3.1). The Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) and Tropical Rainfall Measuring Mission (TRMM) instruments, which have already been launched, will produce 65 TB of data, and MODIS, which will be launched in early 1999, will produce nearly 2,000 TB. To prepare for these large data streams, the DAAC is staffing up. Approximately 40 EOSDIS Core System (ECS) contractors have been added to process MODIS data, and about 12 permanent staff have been added to manage DAAC operations. The average budget for the DAAC, which includes DAAC personnel and functions, civil servants, ECS contractors, and ECS-supplied hardware, is about $15 million per year.
Managing the enormous MODIS data stream poses daunting managerial and technological challenges for the GSFC DAAC. Of most concern is whether the information system, particularly the ingest system, can be scaled up to accommodate increasing loads (see “Technology,” below). To prepare for the new data streams, the DAAC will start “day-in-the-life” exercises and operations rehearsals several months before launch. As of June 1998, the ECS was still not ready for day-in-the-life exercises, but so far, it has been sufficient to test the science algorithms. Delays in the launch of the EOS satellites will provide additional preparation time.
The Panel to Review the GSFC DAAC held its formal site visit on October 20–21, 1997. To ensure that its report and recommendations reflect recent developments, several panel members visited the DAAC again in June 1998. The following report is based on findings from both visits and e-mail discussions with DAAC managers in July and September 1998.
Even before the launch of TRMM and AM-1, the GSFC DAAC has been managing and distributing numerous data sets of substantial size. These include in particular the Advanced Very High-Resolution Radiometer (AVHRR) and the
BOX 3.1. Vital Statistics of the GSFC DAAC
History. The GSFC DAAC was created in 1993 out of the NASA Climate Data System and the Pilot Land Data System. Its holdings go back to 1978.
Host Institution. NASA Goddard Space Flight Center in Greenbelt, Maryland.
Disciplines Served. Atmospheric science and hydrology; data are available on the chemistry of the upper atmosphere, global biosphere, atmospheric dynamics, and climatology.
Mission. To maximize NASA’s investment benefits by providing data and services that enable its customers to fully realize the scientific and educational potential of data and information from the Earth Science Enterprise.
Holdings. The DAAC holds 4 TB of heritage data sets and anticipates receiving more than 2000 TB of data from the AM-1 platform.
Users. There were 12,216 unique users in FY 1997, based on log-in addresses.
Staff. In FY 1998 the DAAC had 74 staff (9 of them civil servants) and 40 ECS contractors.
Budget. Approximately $9.2 million in FY 1998 (including DAAC costs and ECS-provided hardware, software, and personnel), increasing to $17 million in FY 2000.
Television and Infrared Observation Satellite Operational Vertical Sounder (TOVS) Pathfinder data sets, which have been used extensively by EOS investigators to prepare for the processing of AM-1 data (Box 3.2). These holdings consist primarily of imagery and remotely sensed data, and constitute one of the best resources available to date to support research on the atmosphere and global climate change. Figure 3.1, for example, illustrates changes in the size of the ozone hole, as detected by several remote sensing instruments, whose data are managed by the GSFC DAAC.