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--> 1 Introduction The potential benefits of satellite observations for monitoring current weather patterns and for forecasting weather were recognized soon after the first Earth-orbiting satellites were launched in the late 1950s. Several research and operational programs were initiated in the United States by both military and civilian agencies. The TIROS-1 (television and infrared observation satellite) experimental weather satellite was launched on April 1, 1960. As described in Chapter 3, the National Weather Service (NWS) has made daily operational use of satellite data since 1966. Over the intervening years, improvements in sensing instruments and in processing and disseminating data have expanded the utility and importance of satellites in NWS operations. Today the NWS uses satellite data in a great variety of its products. These range from daily inputs to global forecast models, the near-real-time tracking of hurricanes and severe storms, the mapping of snow cover, and the determination of temperature and water vapor content of the atmosphere to the provision of animated cloud images we have all come to expect on daily television news programs. NOAA, other government agencies, research organizations (including academia), and private organizations also use NOAA satellite data and derived information for many purposes. Some examples are: developing specialized forecasts for agriculture, construction, transportation and other applications; developing weather depictions for television broadcasts (mostly private sector) measuring sea-surface temperatures for marine activities and monitoring and predicting climate (governments, private sector, research) using multispectral imaging of the atmosphere and land surfaces to detect and monitor forest fires (governments, private sector); global drought
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--> watch (governments); global mapping of vegetation, precipitable water, snow and ice coverage, reflectance and brightness temperature to monitor changes in climate (governments, research); land use planning (governments, private sector) forecasting sea ice, predicting snow melt, etc., for managing water resources, forecasting floods, improving marine navigation (governments, private sector, research) monitoring ozone in the atmosphere for impact on climate and health (governments, research) monitoring solar activity to warn of the impact on terrestrial communications, electric power distribution, and high-altitude aircraft and space flights (governments, private sector, research) receiving and relaying emergency beacon signals in support of search and rescue services (cooperative program of Canada, France, Russia, and the United States; governments, private sector) collecting and relaying ocean, land, and atmospheric data from a wide variety of automatic observing devices to central locations; broadcasting processed satellite data to relatively low cost receivers (governments, private sector, academia, research) Beginning in 1989 some of these services were threatened when one of the two geostationary operational environmental satellites (GOES-6) failed. Earlier, in 1986, the GOES-G, planned as a replacement, had been lost on launch. The United States was left with a single satellite, GOES-7, to provide imaging until the next replacement was launched. The replacement satellite, the first of a new design, was delayed because of development problems, so no immediate additional satellite was available. Fortunately, the National Oceanic and Atmospheric Administration (NOAA) was able to obtain the use of a European geostationary meteorological satellite (METEOSAT) to provide coverage over the eastern United States and the Atlantic Ocean, and the threatened outage was avoided. NOAA has planned satellite programs to provide replenishment satellites through about 2010 (see Chapter 4). To provide some confidence that the planning is adequate to preclude future outages, in January 1995 NOAA requested that the National Research Council's (NRC) National Weather Service Modernization Committee (NWSMC) provide a report on “the adequacy of planned NOAA geostationary and polar satellite coverage in terms of system continuity and backup.” Accordingly, a panel was formed to gather data and prepare a draft report for analysis, review, and development of a final consensus report by the NWSMC. The panel was composed of three members of the NWSMC; the former study director, serving as an advisor; and the current study director, serving ex officio. Three of the panelists have extensive experience in various satellite programs; three are meteorologists; three are members of the National Academy of
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--> Engineering; and three are experienced users of satellite sensing data. All four panel members have several years of experience working with NWS programs. In carrying out its tasks, the panel arranged five formal briefings with NOAA/NWS. They spoke with NOAA personnel involved in the procurement, production, and operational phases of the satellite programs and with NWS personnel who use satellite data for monitoring the weather and for developing numerical models used to produce daily weather forecasts. Lists of topics discussed at these meetings are contained in the Appendix. The panel met several more times to consolidate information, develop conclusions and recommendations, and produce draft reports for consideration by the NWSMC. In responding to its charge (see Preface), the NWSMC limited its investigation to the evaluation of the NOAA satellite programs as currently planned (see tables 4-3 and 4-4). These programs include the GOES and polar-orbiting operational environmental satellite (POES) programs presently on contract; a planned (but not yet contracted) block of four additional GOES satellites; one or more supplementary polar orbiting satellites provided by the European Space Agency; and the planned National Polar-orbiting Operational Environmental Satellite System (NPOESS) program.1 NPOESS is a follow-on program to the POES program and is a joint effort of NOAA, the Department of Defense (DOD), and the National Aeronautics and Space Administration (NASA). These programs are expected to provide weather satellite coverage for about a decade following the phase-in of the first NPOESS satellite, which is planned for 2008. Only preliminary plans exist beyond 2008. The committee made no attempt to evaluate the impact of incorporating improved sensors, new technology, or other factors that are not included in planned programs.2 However, the committee does recognize the importance of these other factors, particularly the long lead time required for developing and integrating new sensors and other new technology. This lead time must be taken into account when planning follow-on replenishment programs for environmental satellites. The historical background of the current satellite program, including the history of satellites used by NOAA, is covered in Chapter 2. Chapter 3 discusses the significance of the satellite data and products used by the NWS as a basis for evaluating the number of operational satellites needed. Studies of the availability of satellites to meet the needs of the NWS, the various factors that affect availability, predictions of future satellite performance, and the adequacy of the existing and planned satellites to provide reasonable assurance of continuity of observations are discussed in Chapter 4. References and a list of acronyms follow Chapter 4, and topics discussed during the several briefings are included in the Appendix. 1 The NWSMC has not investigated the DOD Defense Meteorological Satellite Program (DMSP), except peripherally as it relates to the proposed NPOESS program and as a backup to POES. 2 The NWSMC plans to evaluate improved sensors and new technology as part of a future study for NOAA.
Representative terms from entire chapter: