• Absolute incident and reflected solar irradiances define solar forcing, which constitutes the fundamental long-term record of net energy received by the Earth system. Benchmark observations of total solar irradiance and spectrally resolved solar irradiance to an accuracy of 0.03 percent referenced to NIST standards are required to elucidate the origin of climate change. The incident component ties solar output to an absolute scale,44 and the reflected component defines the quantitative impact of spatially resolved changes in snow cover, sea ice, aerosol properties, and land use on the flux of energy returned to space.45

The committee recommends that NASA, NOAA, and other agencies as appropriate accelerate efforts to create a sustained, robust, integrated observing system that includes at a minimum an essential baseline of climate observations, including atmospheric temperature and water vapor, spectrally resolved Earth radiances, and incident and reflected solar irradiance.

Climate Data Records and NPOESS

The NRC and others have recommended that NOAA embrace its new mandate to understand climate variability and change by asserting national leadership in applying new approaches to generate and manage satellite climate data records (CDRs), developing new community relationships, and ensuring the long-term accuracy of satellite data records.46 Climate data records are time series measurements of sufficient length and accuracy to determine climate variability and change. NOAA has stated its intention to use NPOESS to create CDRs.47 However, the production, distribution, and stewardship of long-term climate records and the associated systematic testing and improvement of climate forecasts cannot be accomplished through the current NPOESS program or its data system architecture. As discussed above, baseline climate observations will be required, other satellite data records will have to be incorporated, and biases will have to be removed through testing for systematic errors on-orbit using independent techniques pinned to NIST absolute standards. These tasks will be sufficiently complex that a climate data and information system (a “Climate Central”) will be needed, analogous to the operational weather prediction centers for environmental data records.48 The Climate Central would benefit from having its own advisory council with international participation; moreover, the U.S.-funded Climate Central could become a node within an international virtual Climate Central. An associated data analysis and research program is also needed. The CCSP and Global Earth Observation initiatives provide a possible manage-

44  

National Research Council, Solar Influences on Global Change, National Academy Press, Washington, D.C., p. 1, 1994; Intergovernmental Panel on Climate Change, Climate Change 1994, Radiative Forcing of Climate Change and an Evaluation of the IPCC 1992 IS92 Emission Scenarios, J.T. Houghton, L.G. Meira Filho, J.P. Bruce, H. Lee, B.A. Callander, and E.F. Haites, eds., Cambridge University Press, Cambridge, 1995; R.C. Wilson, “Total Solar Irradiance Trend in Solar Cycles 21 and 22,” Science 277:1963-1965, 1997.

45  

National Research Council, Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties, The National Academies Press, Washington, D.C., p. 112, 2005.

46  

National Research Council, Climate Data Records from Environmental Satellites: Interim Report, The National Academies Press, Washington, D.C., 2004. See also congressional testimony of Dr. Mark Abbott at <http://www.house/gov/science/hearings/ets02/jul24/abbott.htm>.

47  

See <http://projects.osd.noaa.gov/NDE/pub-docs/NDE-1PgDescript.pdf> and NOAA’s 2003 white paper plan to create CDRs at <http://cimss.ssec.wisc.edu/itwg/groups/climate/Creating_CDRs_from_NOAA_Satellites_White_Pager_18_Aug.pdf>.

48  

A.M. Goldberg, Environmental Data Production and Delivery for NPOESS, The MITRE Corporation, Work performed under NOAA contract 50-SPNA-9-00010; see <http://www.mitre.org/work/tech_papers/tech_papers_02/goldberg_environmental/goldberg_environmental.pdf>.



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