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Severe Space Weather Events–Understanding Societal and Economic Impacts: A Workshop Report SPACE WEATHER INFRASTRUCTURE Space weather services in the United States are provided primarily by NOAA’s SWPC and the U.S. Air Force’s (USAF’s) Weather Agency (AFWA), which work in close partnership to address the needs of their civilian and military user communities, respectively. The SWPC draws on a variety of data sources, both space- and ground-based, to provide forecasts, watches, warnings, alerts, and summaries as well as operational space weather products to civilian and commercial users. Its primary sources of information about solar activity, upstream solar wind conditions, and the geospace environment are NASA’s Advanced Composition Explorer (ACE), NOAA’s GOES and POES satellites, magnetometers, and the USAF’s solar observing networks. Secondary sources include SOHO and STEREO as well as a number of ground-based facilities. Despite a small and unstable budget (roughly $5 million to $6 million U.S. dollars annually) that limits capabilities, the SWPC has experienced a steady growth in customer base, even during the solar minimum years when disturbance activity is lower (Figure 8). The focus of the USAF’s space weather effort is on providing situational knowledge of the real-time space weather environment and assessments of the impacts of space weather on different Department of Defense (DOD) missions. The Air Force uses NOAA data combined with data from its own assets such as the Defense Meteorological Satellites Program (DMSP), the Figure 8. Examples of impact areas and customers for space weather data provided by the Space Weather Prediction Center (SWPC). More than 6500 unique customers subscribe to the SWPC’s product subscription service. Many data files and products are also available on an anonymous FTP server. Selected products are also distributed on the NOAA/National Weather Service dedicated broadcast systems. More than 50 million files are transferred from the SWPC web page each month. More than 500,000 files are created monthly with near-real-time data for 176 different products serving more than 400,000 unique customers every month in more than 120 countries. (Image courtesy of William Murtagh, NOAA Space Weather Prediction Center.)
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Severe Space Weather Events–Understanding Societal and Economic Impacts: A Workshop Report Communications/Navigation Outage Forecasting System, the Solar Electro-Optical Network, the Digital Ionospheric Sounding System, and the GPS network (Figure 9). NASA is the third major element in the nation’s space weather infrastructure. Although NASA’s role is scientific rather than operational, NASA science missions such as ACE provide critical space weather information, and NASA’s Living with a Star program targets research and technologies that are relevant to operations. NASA-developed products that are candidates for eventual transfer from research to operations include physics-based space weather models that can be transitioned into operational tools for forecasting and situational awareness and sensor technology. NOAA, NASA, and the Air Force are all involved in the National Polar Orbiting Environmental Satellite System (NPOESS), the joint civilian-military successor to the DMSP. Among its other objectives, NPOESS was intended to take over the DMSP’s space weather monitoring function. However, in 2006, because of large and increasing cost overruns, the NPOESS program underwent a dramatic restructuring. (Even before these changes, compromises had been made with regard to some of the desired space environmental measurements.) The restructuring eliminated sensors and reduced the size of the on-orbit constellation from three spacecraft to two, resulting in a system that will have less capability to make critical measurements of the space environment than is currently available. The system is planned to last through 2024-2026, with the first NPOESS spacecraft to be launched 2013. Figure 9. Sources and types of space weather data needed to support representative military mission areas. Color coding indicates the Air Force Weather Agency’s current capability level. (Image courtesy of Herbert Keyser, U.S. Air Force.)
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Severe Space Weather Events–Understanding Societal and Economic Impacts: A Workshop Report In addition to NASA, NOAA, and the DOD, several other federal agencies (e.g., the National Science Foundation, the Department of Energy) are involved to varying degrees in the nation’s space weather effort, which is coordinated through the National Space Weather Program under the auspices of the Office of the Federal Coordinator for Meteorology. Other key elements of the nation’s space weather infrastructure are the solar and space physics research community and the emerging commercial space weather businesses. Of particular importance are the efforts of these sectors in the area of model development. Space Weather Forecasting: Capabilities and Limitations One of the important functions of a nation’s space weather infrastructure is to provide reliable long-term forecasts, although the importance of forecasts varies according to industry. With long-term (1- to 3-day) forecasts and minimal false alarms, the various user communities can take actions to mitigate the effects of impending solar disturbances and to minimize their economic impact. Currently, NOAA’s SWPC can make probability forecasts of space weather events with varying degrees of success (Figure 10, top). For example, the SWPC can, with moderate confidence, predict 1 to 3 days in advance the probability of occurrence of a geomagnetic storm or an X-class flare, whereas its capability to provide even short-term (less than 1 day) or long-term forecasts of ionospheric disturbances—information important for GPS users—is poor. The SWPC has identified a number of critical steps needed to improve its forecasting capability, enabling it, for example, to provide high-confidence long-term and short-term forecasts of geomagnetic storms and ionospheric disturbances (Figure 10, bottom). These steps include securing an operational solar wind monitor at L1; transitioning research models (e.g., of coronal mass ejection propagation, the geospace radiation environment, and the coupled magnetosphere-ionosphere-atmosphere system) into operations; and developing precision GPS forecast and correction tools (Box 2). The requirement for a solar wind monitor at L1 is particularly important because ACE, the SWPC’s sole source of real-time solar wind and interplanetary magnetic field data, is well beyond its planned operational life, and provisions to replace it have not been made. Positioned 1.5 million kilometers upstream from Earth, ACE provides a critical ~45 minutes of advanced warning before a CME strikes Earth. Recognizing the importance of an upstream monitor, Congress mandated in the 2008 NASA Authorization Act that the Office of Science and Technology Policy “develop a plan for sustaining space-based measurements of solar wind from the L-1 Lagrangian point in space and for the dissemination of the data for operational purposes.” The plan is to be developed in consultation “with NASA, NOAA, and other Federal agencies, and with industry.” Although the SWPC does not classify SOHO as a primary data source, it relies heavily on SOHO coronographic observations to predict the properties and trajectories of CMEs responsible for large geomagnetic storms. Space Weather Models Successfully forecasting space weather requires the development of a suite of models covering the various domains of the space environment, from the solar corona to Earth’s ionosphere and thermosphere. An area of particular interest is the implementation for operational use of
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Severe Space Weather Events–Understanding Societal and Economic Impacts: A Workshop Report Figure 10. Top: Capability levels of NOAA’s Space Weather Prediction Center in FY 2008. Bottom: Potential capability levels in FY 2014, assuming adequate funding to support the developments listed in Box 2. Green, satisfactory; yellow, less than satisfactory; red, poor. (Image courtesy of Thomas J. Bogdan, Space Weather Prediction Center, NOAA.)
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Severe Space Weather Events–Understanding Societal and Economic Impacts: A Workshop Report Box 2 Future Developments Identified by the Space Weather Prediction Center as Needed to Improve Its Forecasting and Prediction Capability Secure an operational L1 solar wind monitor. Transition a numerical coronal mass ejection/solar wind model into operations. Secure backup capability for GOES-10 XRS (X Ray Spectrometer) data stream. Complete compliance measures necessary for the Space Weather Prediction Center to become a partner in the National Climate Service to help guide future solar observations, research, modeling, and forecast development activities. Transition the whole-atmosphere model into operations. Develop forecast capabilities based on STEREO data streams. Revamp the concept of operations of the Space Weather Forecast Office. Transition a coupled magnetosphere/whole-atmosphere model into operations. Develop precision Global Positioning System forecast and correction tools. Develop operational radiation environment models. physics-based models, which can provide more accurate, longer-lead-time predictions of severe space weather conditions. In addition to physics-based forecast models, there is also a need for improved climatological models of Earth’s radiation environment (Figure 11). As noted earlier (p. 5), radiation belt climatology models are of special importance to the spacecraft industry. Models currently in use at the SWPC include the U.S. Total Electron Content model, which estimates the delays in GPS signals due to the changes in the electron content of the ionospheric path between the GPS satellite and the receiver, and the Wang-Sheeley-Arge model, which predicts solar wind speed and the polarity of the interplanetary magnetic field at Earth. These are two important quantities for determining the severity of geomagnetic disturbances caused by solar wind and CME events. Among the models implemented by AFWA are the Global Assimilation of Ionospheric Measurements (GAIM) model, which assimilates data from a variety of space- and ground-based sources to specify the ionospheric environment, and the Hakamada-Akasofu-Fry (HAF) solar wind model. The Space Weather Modeling System currently under development by the DOD will couple the HAF model with the physics-based ionospheric model within the GAIM model, enabling multiday forecasts of the ionospheric environment and its response to solar wind forcing. To facilitate the transition of physics-based research models to operations, the multiagency Community Coordinated Modeling Center (CCMC) was established in the late 1990s. The CCMC tests and validates advanced space weather models developed by the research community and evaluates their usefulness for operations. The models hosted by the CCMC are available for use by the wider solar and space physics community.