FIGURE 1.1.1 Relative contributions of different Earth observing systems to accuracy in the European Centre for Medium Range Weather Forecasts (ECMWF) weather forecast model, a numerical model that runs out to 10 days that is used by NOAA in developing operational forecasts. The percentage contribution to the reduction of forecast error, which is a measure of errors in temperature, pressure, water vapor, and wind over the entire atmosphere, is shown for each observational system for the period September to December 2008. This measure is a robust indicator of the contribution to the overall accuracy of forecasts of high-impact weather phenomena such as hurricanes, tornadic and winter storms, floods and droughts, and heat and cold waves. The top five observing systems are (1) microwave sounders from satellites, (2) an infrared sounder on the Infrared Atmospheric Sounding Interferometer, (3) the Atmospheric Infrared Sounder (AIRS), (4) aircraft measurements of temperature, winds, and humidity, and (5) Global Positioning Satellite radio occultation sounders on the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) and other satellites. Thus four out of five of the top contributors to forecast accuracy are satellite systems, and all are currently operating beyond their design lifetimes. NOTE: IASI, the Infrared Atmospheric Sounding Interferometer, first launched in 2006 on the nominal 5-year-lifetime METOP-A, is also included on METOP-B, scheduled for launch in May 2012. SOURCE: Courtesy of European Centre for Medium Range Weather Forecasts.


The end result of these efforts was a proposed set of activities that included space missions to be undertaken by NASA and NOAA, as well as supporting and complementary in situ and suborbital programs, programs for sensor and technology development, a robust research and analysis program, and a data analysis, archive, and dissemination program to exploit the enormous quantities of raw data that would result from these activities. The breadth and balance of the 2007 survey’s recommendations were both intentional and essential, because increased knowledge of the entire, interconnected Earth system, not just a comprehensive understanding of just one or two of its components, is a primary goal.

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