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Assessment of the Usefulness and Availability of NASA’s Earth and Space Science Mission Data
BOX 1.3Applications of Earth Science Archives
Archived data have proven to be extremely important for investigations of changes in the Earth’s atmosphere, oceans, and land cover. Examples include:
Global ocean surface topography has been measured by Ocean Topography Experiment (TOPEX)/Poseidon, a joint NASA-French Space Agency mission, since October 1992. The unprecedented accuracy (2 cm) and precision (4 mm) of the data allowed sea-level change in the Pacific to be monitored and predicted during the large 1997–1998 El Niño event.1 El Niño events disrupt the ocean-atmosphere system in the tropical Pacific, with global consequences for weather and climate. Analysis of TOPEX data has also augmented coastal tide gauge records, revealing a long-term global mean sea-level rise of 3.2 mm/yr, which can be completely explained by the thermal expansion of seawater. The relationship of the Pacific Decadal Oscillation to El Niño events or its effect on fisheries, coral bleaching, or ocean eddies has yet to be determined, owing to the relative shortness of the TOPEX data record. Such questions may be addressed as the current Jason-1 mission extends the record of sea-surface height another decade.
Establishing the magnitude and causes of greenhouse warming requires access to accurate data over as long a period as possible. Harries and others recently used satellite interferometry data from NASA and Japan to compare the outgoing long-wave radiation spectra from the Earth in 1970 and 1997.2 They showed experimental evidence of “a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” Their investigations were hampered by the poor quality of older data tapes, which had deteriorated over time.3 Considerable effort was required to rescue the data and make them usable, illustrating the importance of routine migration of data to new media and working with archived data to ensure their long-term scientific value.
C.Cabanes, A.Cazenave, and C. Le Provost, 2001, Sea level changes from TOPEX/Poseidon altimetry for 1993– 1999, and warming of the southern oceans, Geophysical Research Letters, v. 28, p. 9–12.
J.E.Harries, H.E.Brindley, P.J.Sagoo, and R.J.Bantges, 2001, Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature, v. 410, p. 355–357.
Richard Goody, Professor Emeritus, Harvard University, personal communication to J.Purdom, fall 2001.
THE CHANGING PARADIGM FOR NASA
With the adoption of the scientific goals of the Earth Science and Space Science Enterprises, NASA can no longer be viewed primarily as a technology-demonstration agency. Instead, NASA has defined itself as a knowledge-generating agency, with missions at the front end of the information pipeline. NASA data are a national resource; the stewardship and exploitation of NASA data are necessarily a national responsibility. The care of the data, including the tasks of archiving and distribution, must be accomplished so as to maximize knowledge enhancement, scientific impact, and discovery potential. The chapters following describe and evaluate the strategies adopted by NASA to date and make recommendations to enhance the usefulness and accessibility of the growing databases obtained from NASA missions.