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10 Weather Science and Applications OVERVIEW The dramatic improvement over the last few decades in numerical weather prediction (NWP) for forecasts of a day to a week or more has been a remarkable scientific achievement. Furthermore, weather and short-term climate changes associated with El Niño and La Niña events are now skillfully predicted several months in advance. Those improvements were enabled by assimilation of observations into computer atmospheric models, which were improved through better scientific understanding of the atmosphere and related parts of the Earth system. The general public, decision makers, and industry now depend on multiday forecasts and are pressing for further improvements. Although extreme events (Figure 10.1) and associated impacts on people attract the most attention, both the general public and economic decision makers also rely on the quality of everyday forecasts. For example, the development of renewable energy sources (e.g., wind, solar, and biofuels) will require weather information to locate facilities and to manage the uncertainty associated with variability in natural resources. A large component of the U.S. gross domestic product (about $2 trillion to $3 trillion) is directly or indirectly sensitive to weather and climate (NRC, 2003b). The economic impact (Figure 10.2) is evident in natural-resource management, energy, finance, insurance, real estate, services, retail and wholesale trade, manufacturing, transportation, the nation’s physical infrastructure, and agriculture. The growing demand for weather information has broadened to require not only better understanding of the traditional physical variables of the lower atmosphere but also information about the land and sea surfaces, the chemical properties of the atmosphere, and the state of the near-space environment. To enable major new prediction capabilities, gaps in the observing system, in understanding of atmospheric processes, and in the ability to use observations effectively in models must be filled. The growing global reliance on weather information places responsibility on NASA and the Earth science community to improve Earth science research and operational programs with new space-based and in situ observations that can be used to answer key scientific questions and deliver operational products to provide economic and societal benefits. A balanced mix of proven, proof-of-concept, and new observing technologies is
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FIGURE 10.1 Hurricane season in the United States, 2005. SOURCE: Courtesy of the Cooperative Institute for Meteorological Satellite Studies. needed to enhance decision making in many economic sectors while meeting the growing need for warnings to enable responses to extreme events. Improvements in weather prediction require increased accuracy, reliability, and duration of forecasts with finer spatial and temporal detail for a wider array of weather variables. The ability to deliver new suites of user-tailored forecasts will require higher-quality satellite observations, their effective assimilation into NWP models, and better communication between data producers and user communities. The value of space-based observations will be greatly enhanced if useful new data applications are quickly made available to the government, the public, and the private sector—an improvement that will require an enterprise-wide effort to dramatically shorten the current 20-year delay between the availability of research results and their transition into applications. Rapid infusion of technology into operations and decision support will require improved communication and partnerships among the weather-observation agencies, the university modeling community, and users (NRC, 2000, 2003a,b).
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FIGURE 10.2 Billion-dollar weather disasters, 1980 to 2005. Of the 67 weather-related disasters indicated, 55 occurred during or after 1990. Total costs for the 67 events have been estimated at more than $500 billion based on an inflation/wealth index. The economy’s dependence on the effects of weather demands continuing improvements in forecasting capability. SOURCE: Courtesy of NOAA National Climatic Data Center.
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Achieving those results will require an integrated, vigorous, targeted program of research, technology development, measurements, and monitoring. The roadmap for such a program will include obtaining and using new knowledge to improve existing forecasts, developing new suites of forecasts, and anticipating and mitigating the effects of natural and human-induced hazards through the use of new and more reliable information. The roadmap also envisions fully leveraging multiagency, multisector commitments and expertise to accelerate the transition of research into operations for beneficial uses by decision makers and the public (NRC, 2000, 2003a,b). By 2025, use of a growing weather database will be as common as use of the Global Positioning System (GPS) is today. SATELLITE-SYSTEM STATUS AND STRATEGY FOR 2015–2025 Weather is crucial to all societal and economic activities and has no geographic boundaries. Since the beginning of the space age, the operational and research weather satellites of NOAA, NASA, and DOD have served the diverse weather community well. The United States shares vast amounts of satellite data with international partners daily. Global exchange and exploitation of satellite data is a long-standing hallmark of the international weather community. The efforts of climate, hydrologic, oceanographic, and other research communities benefit from the work of the weather science and applications community (NRC, 2004), which spans traditional weather forecasting (e.g., clouds and rain), chemical weather (e.g., air pollution), and space weather (e.g., solar-induced communication interference). All of those research communities thus share a dependence on satellite weather observations as a primary source of data. The advances in scientific understanding and forecast capability during the four decades since the introduction of satellite meteorology have been remarkable, but further dramatic improvements will require obtaining currently unavailable satellite weather observations during the next two decades (Box 10.1). This section outlines the current status of and weaknesses in the satellite system, priorities for improvements, and an implementation timeline and lists the panel’s recommended tropospheric-, chemical-, and space-weather measurements for enhanced space-based observations needed to ameliorate analysis deficiencies and improve both numerical and human weather prediction. Those measurement missions are discussed in some detail in the section “Priority Weather Observations and Missions” below. The panel’s approach to advance weather science and applications from space draws on a proven foundation of increasingly capable global observing systems, modeling systems, and theoretical and computational advances. As satellite observations have progressed during the last 45 years, so also have data assimilation, numerical weather-modeling capabilities, and theoretical understanding of weather processes. In the last 10 years, the community has been building important new data-assimilation tools to optimize use of global observing data sets. The United States—with leadership from NASA, NOAA, the Naval Research Laboratory, and the weather science research community—is well positioned to continue to exploit the opportunities of the future. However, organizational challenges remain. For example, NASA and NOAA are not well organized to develop new science missions to continue advancing weather science and applications from space. Accordingly, the panel recommends creation of a NASA-NOAA Earth Science Applications Pathfinder (ESAP) program that would allow all special missions or instrument flights to quickly take advantage of new capabilities to realize Earth science societal and economic applications, moving from research into operations.
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BOX 10.1 HURRICANE PREDICTION Weather prediction has advanced greatly during the last few decades. Improvements in global observing systems, advances in data assimilation and numerical modeling,and higher efficiency and capacity of computing resources have all contributed to higher reliability of and increased public confidence in weather forecasts. However, weather analysis and forecasting have not matured to the point where important gains are no longer achievable. Although the 2005 Atlantic hurricane season included some remarkably good forecasts (e.g., Katrina, 3 days before landfall near New Orleans), it also included examples of highly uncertain predictions that resulted in considerable social and economic distress for regions of the southern U.S. coast. For example, the forecast that Hurricane Rita would make landfall near the Galveston-Houston area prompted major evacuations of those communities; the storm actually made landfall to the north of that region with little damage or impact in the two evacuated cities. Hurricane Wilma (Figure 10.1.1) is another striking example of hurricane-forecast uncertainty during the 2005 season. The major numerical models from October 21 agreed on Wilma’s forecast track direction and on a landfall on the south Florida coast, but there were major differences in timing (along-track error). That type of uncertainty is not always solved by consensus or ensemble approaches and leads to low forecaster confidence. The forecasts of Wilma’s eventual impact on south Florida that were provided to the public and emergency managers in charge of evacuation were highly uncertain and led to mass evacuations many days in advance of what was ultimately necessary, with great economic loss. The primary cause of the numerical-model forecast uncertainty was the timing of the interaction of an approaching midlatitude trough with Wilma’s steering flow. The amplitude and speed of the upper-level trough as it left the southwest United States (a radiosonde data-rich region) and entered the Gulf of Mexico (lacking in radiosondes) were uncertain. Special dropsondes released from the NOAA Gulfstream IV aircraft supplied limited observational sampling of the region, but in analysis-sensitive regions like this one continuous assimilation of data is necessary to reduce initial analysis errors substantially and improve the numerical-model forecasts. FIGURE 10.1.1 An example of along-track scatter of the numerical models for the Hurricane Wilma forecast highly relevant to the timing of the landfall in south Florida.
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Current Satellite System and Near-Term Ramp into 2015–2025 The United States enjoys a successful and well-recognized weather-satellite program. NOAA and NASA have implemented both polar and geosynchronous operational satellite programs that serve a broad spectrum of users. NASA’s completed Earth Observing System (EOS) provides new research results and important new capabilities that could be transitioned into NOAA operational programs. NASA’s Earth System Science Pathfinder (ESSP) program will provide important new space observations. DOD also operates weather satellites and shares the data with the larger weather community. Approved continuations and upgrades of the current satellite system are key factors in preparing for the observations for Earth science and applications from space recommended for the decade 2015–2025. In developing its own recommendations, the panel assumed that the NOAA-NASA GOES-R and NOAA-DOD-NASA NPOESS programs would go forward with the current planned instrument complement, including CMIS or a similar instrument on NPOESS, but recognizing the deletion of the Hyperspectral Environmental Suite (HES) for at least the early flights of the GOES-R, -S, -T, and -U series. The deletion of the hyperspectral IR sounder portion of HES is addressed below. The Weather Science and Applications Panel assumed the continued success of NASA’s Aura (launched in July 2004 with 6 years of planned life), CloudSat (with 2 years of planned life), and CALIPSO (launched in April 2006 with 3 years of planned life), as well as the continuation of the Taiwan-U.S. COSMIC mission (launched in April 2006; Cheng et al., 2006). During the next three decades, results from those key missions and the Block 2 NPOESS follow-on will play a central role in key Earth science and applications focus areas, including observations of weather, climate, atmospheric composition, water, human health and security, and oceanography. Analysis and application of the results from recently launched missions and missions due for launch in the period 2007–2014 will provide a strong foundation to guide the implementation of the high-priority missions recommended for the period 2015–2025. In developing its recommendations for future missions, the panel noted that planned follow-on missions are at serious risk. For example, NPOESS was recently restructured to reduce costs, and many capabilities were reduced or eliminated. Space weather measurement capabilities from DMSP F16 and beyond were cut, and climate measurements were eliminated. Despite strong support for the Global Precipitation Measurement (GPM) mission in the decadal survey committee’s interim report (NRC, 2005), which specifically recommended that GPM be launched without delay, NASA has announced another delay in this key weather and climate mission. An international effort to provide more accurate and frequent precipitation measurements, GPM would build on the success of the Tropical Rainfall Measuring Mission (TRMM) to address a critical societal need. With growing demand for water and awareness of the impact of drought on society, the need to better understand the water cycle and means for ensuring the availability of water are of critical concern to all nations The panel thus reiterates in the strongest terms the decadal survey committee’s recommendation that GPM be flown as quickly as possible. GOES-R does not include an operational coronagraph designated as a planned product improvement for possible future GOES missions, and there is no operational follow-on to the critical L1 solar wind measurements being made by ACE. Moreover, the GOES-R HES has been replaced with a GOES sounder to be determined. Measurements from the Atmospheric Infrared Sounder (AIRS) on NASA’s polar-orbiting Aqua satellite showed that better geosynchronous Earth orbit (GEO) vertical soundings than those currently available from GOES are essential for improved weather forecasting (Le Marshall, 2005). Moreover, the sampling from polar-orbiting satellites is too small for observing and adequately predicting the rapidly changing atmospheric conditions that lead to severe weather, including tornados, flash floods, and hurricanes (including intensity and landfall prediction).
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The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS), or instruments of similar capability with newer technology, can provide the needed soundings. Developed under NASA’s New Millennium Program, GIFTS was designed to obtain 80,000 closely spaced horizontal (about 4 km), high-vertical-resolution (about 1–2 km) atmospheric temperature and water vapor profiles every minute from geostationary orbit.1 Because of budgetary considerations, resulting partly from the Navy’s withdrawal of support for a spacecraft and launch vehicle, NASA discontinued funding for GIFTS beyond FY 2005. Therefore, the panel recommends that NASA complete the space qualification of a hyperspectral sounder and ensure its flight early in the 2010s and that NOAA ensure that the ground-based processing system is ready for demonstration. The panel further recommends the transition from demonstration to operational capability by 2018. The demonstration and transition to operational GEO hyperspectral soundings could be made within the NASA-NOAA ESAP program recommended above. In the section “Priority Weather Observations and Missions” below, the panel recommends flights of an all-weather GEO sounder and a GEO chemistry mission. Together, these three flights would form a robust and synergistic GEO “carousel”—similar to the low-Earth-orbit (LEO) A-Train—bounded by the GOES-East and GOES-West satellites. The challenge is to combine the NPOESS and GOES missions with the NASA research missions and the international satellite missions to deliver the observations and products required by society. NPOESS requires about 30 to 40 percent (and GOES another 5 to 10 percent) of the annual U.S. expenditures of about $2.5 billion for Earth science and applications missions. The NPOESS program will be a working example of interagency and community interaction leading to the transition of research to operational applications for societal and economic benefit. A vision of the weather and related sciences without a central role for NPOESS and GOES would be incomplete. NPOESS and GOES-R should maintain their requirements and objectives and carry their full complement of advanced technology instruments even if some are delayed. Otherwise, the weather data sets and recommended vital missions for Earth science and applications for 2015–2025 will be crippled. Baseline R&D and Observation Strategy for 2015–2025 In developing a baseline R&D and observational strategy for 2015–2025, the panel drew on many sources of information. In response to the decadal survey committee’s RFI, the community provided more than 75 thoughtful weather-related responses (see Appendixes D and E). Further expert knowledge of the new challenges for weather science and applications was provided through agency roadmaps and through published National Research Council studies on research and technology planning. Agency scientists and leaders provided the panel with considerable information in discussions and presentations. The panel is also aware of needs in and plans of the private sector. New challenges are central to the development of a research and observational strategy for weather science for the decades ahead. Key physical, dynamical, and chemical processes associated with severe weather (e.g., hurricanes and tornados) are neither fully understood nor characterized, and so high priority is placed on measurements that will contribute to successful forecasting of such events. Key processes in which further observations are needed to advance understanding include the genesis and evolution of strong midlatitude and tropical storms, major summertime precipitation systems, air-pollution events, and global chemical-weather characteristics. Research and operational forecast systems do not currently include all the processes or observations necessary to understand and predict the full range of weather systems. For example, the interactions between the chemical and physical properties of condensation 1 See http://cimss.ssec.wisc.edu/itwg/itsc/itsc13/proceedings/session7/7_1_lemarshall.pdf.
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nuclei aerosols and cloud water and ice, with the ensuing formation of a variety of precipitation patterns, are not adequately understood, modeled, or predicted. Improving air-quality forecasts on regional to global scales will require furthering the understanding of the complex interactions among sources, sinks, transport, and chemistry of tropospheric gases and aerosols. Furthering that understanding will require advances in space-based observations. In the realm of space weather, many magnetoelectrodynamic processes are not well understood. Initiation of solar flares and coronal mass ejections, geomagnetic storm physics, and basic mechanisms of ionospheric irregularity formation and propagation require substantial measurement and research before forecasting requirements can be met. Shortfalls in knowledge about key weather events and processes place the United States in a position where it cannot meet the increasing requirements for improved predictions of major weather storms, events, and processes. Moreover, the growing complexities of society and long-term population growth and movements have increased vulnerability to damaging weather events. A considerable body of research provides clear directions for adapting to and mitigating high-impact events through improvements in forecasts. PRIORITY WEATHER OBSERVATIONS AND MISSIONS To determine priorities for weather observations and missions, the panel considered the RFI responses and presentations by leaders in the community. Evaluations were based on potential to transform science, promote societal applications, and advance forecasting and on risk, readiness, and cost. The panel also considered the ability of proposed measurements to address international or national plans and to address the goals of the Global Earth Observing System of Systems (GEOSS).2 The process led to identification of the key applications and societal benefits, key science themes, and key satellite observations listed in Box 10.2 and to the conceptual missions proposed in the discussions below on tropospheric-weather measurements, chemical-weather measurements, and space-weather measurements. The conceptual missions include tropospheric wind measurements; all-weather measurement of temperature and humidity profiles, including surface precipitation and sea-surface temperature; an operational radio occultation system for high-vertical-resolution, all-weather temperature and water vapor profiles; aerosol and cloud property observations; an air-pollution monitoring system with high temporal resolution; comprehensive tropospheric aerosol characterization; comprehensive tropospheric ozone measurements; and a suite of space-weather instruments consisting of a solar monitor, an ionospheric mapper, and a system of “space-weather buoys” implemented through a constellation of magnetosphere microsatellites. The GPS radio occultation measurements recommended for characterizing tropospheric weather are also useful for characterizing space weather and climate and are mentioned in that subsection. Tropospheric-Weather Measurements The panel’s four recommended measurement missions for characterizing tropospheric weather are outlined in Table 10.1 and discussed below. 2 Sixty-one countries agreed on February 16, 2005, to work together over 10 years to develop an implementation plan for a coordinated, international, global system to observe Earth on a continuing basis. The global system, called GEOSS, will provide in situ and remotely sensed data and their integration to address diverse societal needs for Earth observations.
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BOX 10.2 BENEFITS, KEY SCIENCE THEMES, AND REQUIRED SATELLITE OBSERVATIONS FOR WEATHER Societal Benefit Enhanced forecasts for hurricane and cyclone tracks, severe winter weather, floods Public-health risk alerts associated with pollutant outbreaks and heat waves Improved evacuation guidance for extreme-weather-related hazards Development of renewable energy sources, sites Decision-support tools for management of natural resources, civil infrastructure (water, wildfire abatement, communication systems) New warnings of coastal environmental contamination, and hazard conditions (influx of Portuguese man-of-war) Science Themes Amelioration of deficiencies in numerical model forecasts during severe weather events Improved understanding of causes of the high intensity and the track evolution of hurricanes Development of new suites of targeted-use forecasts in air quality and space weather Quantification of pollution emissions and determination of aerosol characteristics that affect human health Required Satellite Observations Direct three-dimensional winds over the oceans, the tropics, and the Southern Hemisphere, where radiosonde observations are scarce Integrated sea-surface temperature and high-resolution profiles of temperature, humidity, precipitation along coast and in all-weather conditions Low-cost, operational profiles of temperature and moisture in the lower stratosphere and mesosphere Pollution variables across large continental regions (aerosols, tropospheric gases) coordinated with cloud and precipitation measurements Tropospheric Winds Mission Summary—Tropospheric Winds Variables: Vertical profile of horizontal winds Sensors: Wind lidar (preferred), scatterometer, Molniya imager Orbit/coverage: LEO/global Panel synergies: Climate, Health, Water The panel began by identifying, from the viewpoint of the weather science and applications community, the current capabilities and projected requirements for observations of the vertical profile of horizontal winds. The correct specification and analysis of tropospheric winds is an important prerequisite for accurate NWP. Despite recent advances in assimilation of radiances, improved accuracy and resolution of wind-profile data remain essential requirements for improved NWP because of its unique role in specifying the initial potential vorticity, which is a key dynamic property that is a major determinant of atmospheric evolution. The value of accurate wind measurements in day-to-day weather forecasting is well established.
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TABLE 10.1 Weather Panel Summary of Priority Tropospheric-Weather Measurement Missions Summary of Mission Focus Variables Type of Sensor(s) Coverage Spatial Resolutiona Frequencya Synergies with Other Panels Related Planned or Integrated Missions Tropospheric winds (three options) Vertical profile of horizontal winds Wind lidar (preferred option) Global 350 km horizontal, 1 km vertical TBD Climate Health Water 3-D Winds Ocean-surface vector winds Scatterometer Global 20 km 6–12 hr NPOESS Water vapor tracked winds Molniya imager Northern Hemisphere 2 km IR/WV imagery, 1 km visible imagery, ~25 km vector spacing 15 min during 8-hr apogee dwell All-weather temperature and humidity profiles Temperature, humidity profiles in clear and cloudy conditions; surface precipitation rate; sea-surface temperature Microwave array spectrometer; precipitation radar Regional or global 25 km (humidity and precipitaton rate), 50 km (temperature) horizontal, 2 km (humidity and temperature) vertical 15–30 min Climate Health Water PATH GPM Radio occultation Temperature, water vapor profiles GPS Global ~200 m vertical ~2,500/day Climate Health Water GPSRO Aerosol-cloud discovery Physical, chemical properties of aerosols; influence of aerosols on cloud formation, growth, reflectance; ice, water transitions in clouds Multiwavelength aerosol lidar, Doppler radar, spectral polarimeter, A-band radiometer, Submillimeter instrument, IR array Global 200 m vertical TBD Climate Health ACE aColumn entries are targets based on a current assessment of expected future mission performance capability. Further, more detailed studies may be warranted.
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For example, the path and intensity of tropical cyclones are modulated by environmental wind fields (see Box 10.1). Reliable global observations of winds are also needed to improve scientific understanding of atmospheric dynamics, the transport of air pollution, and climate processes. Both scientific and forecasting applications are severely limited by the lack of data on the vertical profile of the horizontal winds over the oceans, the tropics, and in the Southern Hemisphere, where radiosonde observations are scarce. Surface wind observations (from anemometers and scatterometers) and single-level upper-air wind observations (from aircraft and cloud-drift winds) can provide only partial wind information over data-sparse regions. Satellite sounders provide good global coverage of microwave and infrared radiances, which can be assimilated directly for an accurate definition of temperature and humidity profiles. When that information is coupled with surface pressure information, the midlatitude wind field can be estimated with approximations of geostrophic and hydrostatic balance. In the tropics, however, geostrophic approximation is less valid, and direct measurements of the wind are required to produce accurate analyses of atmospheric flow. In the extra-tropics, wind data are important for identifying intense small-scale features, such as jet streaks, which involve strong departures from geostrophic balance. Because wind is ultimately related to the transport of all atmospheric constituents, its measurement is also crucial for improving understanding of the sources and sinks of constituents, such as atmospheric water, carbon, trace gases, and aerosols. In summary, despite the recent advances and sophistication of modern data-assimilation methods, large analysis uncertainties remain over wide areas of the globe, especially for the three-dimensional tropospheric wind field. More accurate and reliable and longer-lead-time weather forecasts, driven by fundamentally improved tropospheric wind observations from space, would have directly measurable societal and economic impacts. To identify and achieve an improved tropospheric wind-observing system by 2025, the weather panel recommends a phased approach that builds on the existing observing system, addresses major gaps, and sets priorities among activities on the basis of technical readiness and potential impact. Phased Implementation of a Doppler Wind Lidar System (2015–2025) A hybrid Doppler wind lidar (HDWL) in low Earth orbit (LEO) could dramatically improve weather forecasts (Baker et al., 1995; Atlas, 2005) by making global measurements of the wind profile through the entire troposphere and into the lower stratosphere under a wide variety of aerosol loading conditions (Box 10.3). In recognition of the importance of wind-profile data, the Panel on Water Resources fully concurs with the weather panel’s recommendation that a lidar horizontal wind profiling mission should have top priority. Owing to the complexity of the technology associated with an HDWL, the panel strongly recommends an aggressive program to design, build, aircraft-test, and ultimately conduct space-based flight tests of a prototype HDWL. The panel recommends a two-stage space-implementation approach. The two stages, discussed below, depend heavily on an aggressive and continuing technology-development program that supports both the coherent and the noncoherent Doppler wind lidar (DWL) techniques and all other technologies necessary for implementation of the HDWL operational demonstration mission. Stage L Because the European Space Agency (ESA) demonstration of a one-component wind lidar measurement with the noncoherent DWL technique does not address all the relevant techniques and technologies needed for the HDWL mission, the panel recommends that NASA support the development and space demonstration of a prototype HDWL system capable of global wind measurements to meet demonstration requirements that are somewhat reduced from operational threshold requirements, as described in a 2001 NOAA-NASA workshop. An HDWL demonstration mission in around 2016 should include the demonstration of a technique for the coherent and noncoherent DWLs that would enable
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Comprehensive Tropospheric Ozone Measurements Mission Summary—Tropospheric Ozone Measurements Variables: Tropospheric ozone; ozone precursors; pollutant and trace gases (CO, NO2, CH2O, SO2); aerosols; CO with day-night, vertical sensitivity; tropospheric ozone, aerosol profiles with lidar in second phase Sensors: UV spectrometer, SWIR-IR spectrometer, microwave limb sounder; future, ozone-aerosol lidar Orbit/coverage: LEO/global Panel synergies: Climate, Health Understanding and modeling tropospheric chemistry on regional to global scales requires a combination of measurements of O3, O3 precursors, and pollutant gases and aerosols with sufficient vertical resolution to detect the presence, transport, and chemical transformation of atmospheric layers from the surface to the lower stratosphere. Adequate vertical resolution is critical because of the strong vertical dependence in photochemistry and atmospheric dynamics that contribute to determining the budget of O3 and other pollutants across the troposphere and lower stratosphere. The weather panel identified comprehensive tropospheric ozone measurements as a high-priority mission to provide the needed global vertical distribution of O3, O3 precursors, and other pollutants across the troposphere and into the lower stratosphere. It also strongly complements the Panel on Human Health and Security recommendations to address air pollution and exposure to UV radiation. The goal of the comprehensive tropospheric ozone measurement mission is to improve the understanding of chemical-weather processes on regional to global scales. To achieve that goal, the mission requires the measurement of the global distribution of tropospheric O3 with sufficient vertical resolution to understand tropospheric chemistry and dynamic processes in tropical, midlatitude, and high-latitude regions and the measurement of key trace gases (CO, NO2, CH2O, and SO2) and aerosols that either are related to photochemical production of O3 or can be used as tracers of tropospheric pollution and dynamics. The mission would use a combination of active and passive instruments to achieve the needed global measurements of tropospheric O3, CO, and aerosol profiles and column measurements of O3, NO2, SO2, CH2O, and aerosols. The unique combination of measurements will provide data to validate numerical models under a wide array of atmospheric and pollution conditions from the tropics to the polar regions. The global measurements will directly complement the regionally focused measurements from GEO and provide more detailed vertical information than can now be provided with nadir-sounding passive instruments. The vertical resolution of O3 measurements should be less than 2 km, with concurrent measurements of aerosols to less than 150 m. That can be accomplished with a differential absorption lidar (DIAL) system operating in the ultraviolet for O3 and in the visible-infrared for aerosols. Measurements of CO, with continuous coverage at the equator, are needed at three or four vertical levels in daytime and two or three levels at night, with a horizontal spatial resolution no larger than 5 km, including a surface-reflectance measurement for PBL sensitivity. That capability exceeds what is available with current satellite instruments. Simultaneous column measurements of O3, NO2, SO2, CH2O, and aerosols are needed with a capability for increased sensitivity to O3 near the surface. Except for the near-surface O3 measurement, this capability could be implemented in a manner similar to that of current satellite instruments. The DIAL O3 and aerosol profile measurements need to be made from LEO, but the passive measurements of CO, O3, NO2, SO2, CH2O, and aerosols can be made globally from either LEO or MEO, or possibly even L-1 with some compromise in performance. It is expected that in the next decade, it will not matter that the active and passive instruments will be on different platforms, because the data-assimilation techniques will enable the seamless combination of data into an integrated numerical model.
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Because the space-based O3 DIAL requires technological development, the weather panel recommends a phased approach for the implementation of this mission. It is highly desirable to complement the chemical-weather GEO mission with a global tropospheric composition mission in the same time frame, and so the weather panel recommends that the passive portion of the mission be launched into a LEO in the middle of the coming decade (about 2017) while all the components of the more complex O3 DIAL mission are developed and tested by NASA for launch early in the following decade (after 2020). In support of the DIAL O3 development, NASA has begun initial funding of several key components as part of the IIP. Because the active portion of the mission has high potential payoff for chemical weather, the associated technology development needs to be aggressively supported during the next decade. The combined active and passive portions of the mission will provide new information on the chemistry and dynamics of the troposphere and lower stratosphere to guide the development and application of regional- and global-scale CTMs. That will result in improved knowledge of chemical weather processes and better chemical weather forecasts. This mission is a natural follow-on to the current group of Aura and Envisat satellites that are contributing to chemistry and air-pollution investigations of the lower atmosphere. The addition of the new active and passive measurements of O3, O3 precursors, and pollutant gases and aerosols will greatly improve the understanding of tropospheric chemistry and dynamics, including the role of stratosphere-troposphere exchange in influencing the composition of the troposphere. Space-Weather Measurements Space-weather information is needed most for the protection of technological systems that are vulnerable to space-weather effects and to ensure human health and safety. Radiation from solar-flare particles and galactic cosmic rays presents a hazard not only to space-based systems and human spaceflight but also possibly to crews and passengers of commercial and military aircraft. Airline pilots and crew members are among the most highly exposed radiation workers in the nation, and they depend on reliable space-weather information to protect themselves and their passengers, as was done for the first time during the space storm of October and November 2003 (Box 10.6). As the nation plans for crewed missions to the Moon and Mars, the capacity for long-term prediction and warning of radiation hazards will be critical. Some estimates place the direct global economic impact of space weather at about $400 million per year. Changes in flying routes due to high radiation and polar communication blackouts can cost airlines around $100,000 for each incident. A March 1989 geomagnetic storm caused $13 million in damage to Quebec’s commercial power grid. Total economic losses have been estimated in the billions. The economic impact of similar incidents in the northeastern United States is potentially in the billions of dollars. Space-weather events can also damage or destroy multi-million-dollar satellite systems. During the October-November 2003 storm, one satellite was permanently disabled, and the operations of 30 others were disrupted. National security interests can also be affected by space weather. The losses of satellite capabilities, relied on for everything from reliable communication to precision navigation, can affect the ability to perform military, disaster-recovery, and humanitarian operations. Even loss of non-space-based communication systems (e.g., shortwave radio) due to space-weather events has an impact on U.S. national capabilities. Given U.S. reliance on space or radio signals that pass though space, the idea of space-situational awareness is increasingly important. Knowing when and where systems may not perform will be crucial to the future effectiveness of the nation’s operations. The basic goal of space-weather monitoring missions is to forecast space weather conditions days in advance and to specify current conditions. The three missions highlighted in this section—a solar monitor, an ionospheric mapper, and a network of magnetosphere microsatellites—address this need and are
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balanced in such as way as to provide comprehensive, multiregional measurements that will not only improve forecast ability but also help to answer many fundamental science questions related to space weather. To accomplish those goals, it is assumed that NOAA will continue to provide the essential data for operations and research from all current GOES space-weather sensors, including solar x-ray imaging, solar x-ray and extreme ultraviolet (EUV) integrated whole-disk measurements, and in situ energetic particle and magnetic-field measurements. It is also assumed that all planned DMSP satellites will launch, providing in situ and remote-sensed ionospheric data well into the next decade. Without the addition of planned product improvements, NPOESS will provide no remotely sensed space-weather data, and this would mark a huge reduction in capability over the next decade. The panel expects the GOES-R program to add to space-weather data and suggests that it could provide more than now planned. Other missions in planning are also expected to contribute proof-of-concept missions to operational space-weather follow-on satellites; these include STEREO, Solar-B, the Solar Dynamics Observatory, COSMIC, radiation-belt storm probes, and C/NOFS. The weather panel included space weather in its scope of examination as charged, but because much of its activity falls in the category of Sun-Earth science (at NASA) and the decadal survey committee chose to focus its mission recommendations on the Earth Science Division in NASA, the panel’s recommended space-weather missions are not included in the final synthesis mission list. The weather panel strongly believes that the space-weather missions should be funded and urges NASA to consider the panel’s recommendations in context with recommendations made in the decadal strategy for solar and space physics (NRC, 2003c). Solar Monitor The ability to specify and forecast changes in the solar atmosphere has important societal and economic benefits. Astronauts’ health is protected when they take shelter or postpone a space walk to reduce their radiation exposure from a solar energetic-particle event. The billion-dollar International Space Station arm is saved from harm when it is kept stowed during the same conditions. Because of their influence on radio communication at high latitudes, strong or severe radiation storms require airlines to divert flights from the polar regions. Large bursts of x-rays, which are often associated with radiation storms, affect radio communications on the dayside of Earth and degrade navigational capabilities. Ejections of large volumes of high-velocity coronal material result in the largest geomagnetic storms on Earth, requiring power companies to initiate changes in their operations to protect their equipment and customers. All those effects would be lessened if it were possible to better understand and predict changes in the solar atmosphere at the Sun and how they evolve as they expand outward into the solar system. Predictive capability depends on answering many scientific questions. For example, when and where on the Sun will active regions appear, and when will they explosively erupt? What is happening on the Sun’s farside, and what will conditions be when farside features rotate into Earth view? Can the solar wind conditions—especially velocity, density, and magnetic field—that will reach Earth several days after leaving the Sun be predicted from solar observations? With the Solar Monitor mission, progress can be made toward answering those and other key solar scientific questions, and that will improve the ability to serve society and those affected by space weather. The Solar Monitor mission would consist of a full suite of sensors to characterize the solar surface, atmosphere, and heliosphere. An evolutionary approach would ensure that as technology evolves, more detailed and comprehensive measurements could be made. Elements making up the Solar Monitor are the following.
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BOX 10.6 SPACE WEATHER During late October and early November 2003, the Sun unleashed a massive assault on Earth. The assault took the form of electromagnetic energy, giant clouds of ionized gas called coronal mass ejections (CMEs), and deadly high-intensity radiation (Figure 10.6.1).The sequence of events, now termed the “Halloween Storm,” included damage to or destruction of a vast array of technological systems. Three sunspot groups were active on the Sun by October 27, 2003. Together, they produced a series of violent solar flares on the Sun’s surface. From October 22 to November 4, the regions produced 80 M-level (the second-highest category) solar flares and 24 X-level (the highest category) solar flares, including three of the 10 most intense flares ever recorded, and an X28 solar flare on November 4 that was the most intense ever. The energy from those flares disrupted worldwide radio communication systems and over-the-horizon radar operations. The clouds of gas, CMEs, ejected in association with the flares traveled at over a million miles per hour, arrived at Earth typically 2–5 days after each flare, and caused intense geomagnetic storms. In one case, traveling at an astonishing 5 million miles per hour, a CME reached Earth in only 19 hours. These severe storms produced further loss of communication systems, including military satellite communication; degraded GPS navigation;and induced commercial-power problems in the United States and Northern Europe, in the most extreme instance causing a power outage in Sweden that affected 20,000 homes. Perhaps the most devastating effect of the flares was the result of high-energy protons, which can arrive in only tens of minutes after a flare onset. The largest proton event, the fourth-largest ever recorded, began on October 28 and lasted for 3 days. Hurtling toward Earth at nearly the speed of light, these subatomic bullets caused great havoc with the world’s satellite systems. Many satellite operators took protective measures to prevent problems, but 30 satellites experienced serious problems, including the permanent loss of a $650 million Japanese satellite during one of the events. The radiation from the particles also posed a substantial danger to aircraft operations, causing airlines to reroute flights to avoid the polar regions. The Federal Aviation Administration issued its first radiation alert ever for airline passengers above 25,000 ft, and the astronauts on the International Space Station were moved into a radiation-protected area to prevent exposure. In the end, the period went down in history as one of the most significant space-weather events ever. The Halloween Storm is a reminder that, with little warning, severe space weather can disrupt systems all over Earth.
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FIGURE 10.6.1 A montage of Solar and Heliospheric Observatory (SOHO) imagery of the October 28, 2003, flare and CME activity. (Top left) Sunspots with the Michelson Doppler Imager (MDI) instrument. (Top right) X-17 flare with the Extreme-ultraviolet Imaging Telescope (EIT) instrument. (Bottom right) CME with the Large Angle and Spectrometric Coronagraph (LASCO) C3 instrument. (Bottom left) CME closeup with the LASCO C2 instrument. SOURCE: Courtesy of NASA and the European Space Agency.
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Multispectral Solar Imagery A broad spectral range of high-resolution solar imagery is necessary to characterize solar activity and features. White-light imagery allows the characterization of sunspots, a long-time measure of solar activity. That is necessary not only to support operational concerns for flare forecasting but also for continuity and enhancement of a data record that dates back several centuries. Hydrogen-alpha imagery provides active region identification and analysis and solar-flare monitoring. Ultraviolet and x-ray imagery allows analysis of the Sun’s chromosphere and corona for active-region development, magnetic-field assessment, and coronal-hole monitoring. Infrared imaging will allow direct measurement of coronal magnetic fields. A vector magnetograph will allow high-resolution determination of solar surface magnetic fields—a critical boundary condition for solar wind modeling and forecasting. Initial missions should be a combination of Earth-orbiting and L1, but over the next 10–20 years the missions should migrate closer to the Sun both to enable higher-resolution imagery of detailed solar processes and to increase the warning time for solar wind disturbances. Multispectral imagers should eventually be placed in solar orbit (both equatorial and polar) at less than 50 solar radii, and plans should include highly elliptical coronal sampler probes. A current gap in solar modeling and forecasting ability is the lack of knowledge about conditions on the Sun’s farside. Future missions should be placed to enable farside observations. Coronal Mass Ejection Imaging One of the most dramatic improvements in space-weather forecasting would be the ability to three-dimensionally image and track Earth-directed CMEs. Operational STEREO-type platforms must be continued; three-dimensional CME imaging will be essential to the ability to reliably predict geomagnetic disturbances. In Situ Solar Wind Measurements of the solar wind at L1 have greatly improved the ability to anticipate (in the short term) geomagnetic disturbances. L1 measurements are also vital for validating how well models based on solar observations predict conditions on Earth. Solar-wind measurements along the Sun-Earth line should continue and eventually be improved by a capability for making measurements closer to the Sun (increasing forecast lead time) and by making multipoint measurements (to analyze CME structures). Eventual crewed missions to Mars will require a solar-wind monitor at the Mars L1 point. Ionospheric Mapper As U.S. dependence on GPS technology continues to grow, so also does the need to specify and forecast conditions in the ionosphere that contribute to GPS errors and outages. Surveying companies, deep-sea drilling operations, land-drilling mining, and military operations all struggle with the economic and societal results of ionospheric effects on GPS. Military and commercial airline communication is affected by ionospheric conditions, especially in the polar regions but also in its dependence on GPS at other locations. To alleviate those impediments to the use of modern technology, better space-weather specification and prediction of conditions in the global ionosphere are needed. Yet, many scientific questions still need to be solved. The space weather research community does not yet fully understand how the ionosphere varies in response to changing solar EUV or how it responds to geomagnetic storms. The community does not yet understand the source of midlatitude ionospheric irregularities or the physics of high- or low-latitude scintillation regions. Those are only a few examples of scientific questions and space-weather issues that can be addressed through improved satellite observations, such as ones that can be made by the Ionospheric Mapper mission.
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The Ionospheric Mapper mission is designed to improve the nation’s ability to specify and forecast the ionosphere and its effects on high-frequency (3–30 MHz) through super-high-frequency (3–30 GHz) signal propagation. The primary measurements necessary are related to ionospheric plasma density and to variations in ionospheric signal amplitude or phase induced by small-scale variations in ionospheric properties known as scintillation. Geostationary UV Imager A constellation of ionospheric UV imagers could greatly improve the ability to quantify ionospheric scintillation, a primary hazard for communication, radar, and navigation systems. As a phenomenon that is confined primarily to the equatorial and auroral regions, ionospheric scintillation is not ideally suited to measurements from low Earth orbit. Imaging the ionosphere from geostationary orbit has the potential to revolutionize how ionospheric scintillation is characterized and predicted. Eventually, a pole-sitter type of orbit should be used to provide continuous coverage of polar ionospheric conditions. UV imagers at the L1 and L2 points would provide unique local-time-stationary vantage points for ionospheric observing. Low-Earth-Orbit Ionospheric Sensing A low-Earth-orbiting component is necessary to obtain in situ ionospheric plasma, electromagnetic field, and neutral atmosphere parameters. Remotely sensed data (e.g., UV imagery) can also be obtained at higher resolution to complement geostationary data. Data from low-Earth polar orbiters offer the only way to characterize the high-latitude ionosphere and scintillation environment. Radio occultation instruments in this orbit would also provide a valuable data set for ionospheric modeling. High-Density Magnetospheric Network of Microsatellites With hundreds of communication, navigation, military, and scientific satellites in low Earth orbit through geosynchronous regions, there is a need to specify and forecast the space-weather conditions in which these assets operate. Knowledge of space-weather conditions is vital for the safe and successful operation of spacecraft and to protect the enormous economic investment in the spacecraft and their instruments. Perhaps even more important, it is necessary to protect the societal services provided by the satellites. Satellite operators take actions to protect their systems on the basis of forecasts of magnetospheric conditions, as they did during the Halloween Storm (see Box 10.6), but there are still many outstanding scientific questions that need to be answered to provide more timely and accurate forecasts of space-weather conditions. The formation and depletion of particles in energy ranges from a few electron volts to millions of electron volts must be understood to protect national assets effectively. Energetic particles, such as the so-called MeV electrons, are known to induce charging and damage in spacecraft components, but the physical processes that energize these particles and the processes that cause their loss are not understood. Much work is needed to understand the radiation-belt environment surrounding Earth. There should be a better understanding of magnetospheric current systems (e.g., the ring current and field-aligned currents) that are so critical to geomagnetic-storm evolution and intensity. A high-density magnetospheric network would provide many of the observations needed to improve understanding and to protect resources and services. The magnetosphere is a region for which data are exceedingly sparse. A few point measurements are available operationally, but there is nowhere near the coverage needed to understand, detect, characterize, and predict the many multiscale processes that occur throughout this tremendous volume of space. Yet, it is the medium within which nearly all satellites operate, and disturbances and changes in that medium can potentially have devastating effects on satellite systems.
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Satellite as a Sensor Every satellite launched into Earth orbit can, and should, include a small on-board sensor to measure the in situ particle environment and include that information in any real-time data streams. Such sensors already exist, are quite small, and use very little power. Microsatellite-Nanosatellite Networks Even if every U.S. satellite contained an on-board sensor, coverage would still be insufficient to adequately characterize the magnetosphere. A huge step toward that goal would be a dense network of extremely small, low-cost microsatellites designed to sample the particle and electromagnetic field environment and to transmit results in real time. Such a system, initially deployed throughout the inner magnetosphere, would allow for the possibility of advanced data assimilation and modeling systems for the magnetosphere, analogous to the current observational state for terrestrial weather. As technology improves, nanotechnology could be exploited to produce smaller and smaller sensors that could be deployed in even greater numbers, eventually expanding into the outer magnetosphere and inner heliosphere. Additional Measurement Capabilities Radio Occultation Mission An increase in the accuracy of space-weather services allowing for a 1 percent gain in continuity and availability of GPS would be worth $180 million per year. To achieve such economic gains, it is necessary to improve data-assimilative ionospheric models, which will soon begin to use data from radio occultation missions, such as COSMIC. Of the space-based platforms potentially planned, an operational COSMIC follow-on (such as COSMIC II) holds the most promise to work in synergy with the missions proposed here. Radio occultation measurements (vertical profiles of electron density and line-of-sight total electron content) hold tremendous promise as an observational constraint on ionospheric modeling. Combined with ground-based measurements, they allow for accurate reconstruction of the entire three-dimensional ionosphere. The radio occultation instrument on MetOp could also contribute in this regard, although it is not currently planned to produce ionospheric measurements. Ground-based Systems Several ground-based systems are also necessary to provide complementary measurements of the space environment. A global network of ionosonde measurements is necessary to provide bottom-side profiles of the ionosphere—the only means by which such information is available. Ground-based total electron content measurements (using GPS receivers) provide a network of integrated line-of-sight measurements that are best used in combination with both ionosondes and space-based measurements. GPS and SATCOM receiver-based scintillation measurements provide the only direct measures necessary for global and regional scintillation specification and modeling. Incoherent scatter radars, currently used only for research purposes, could be exploited for operational use by providing plasma characteristics, electric fields, and ionospheric convection patterns (critical for accurate modeling). Ground-based magnetometers are necessary, primarily for geomagnetic-disturbance specification and model initialization but also for continuity of long-term geomagnetic observations. Ground-based solar telescopes complement space-based platforms by providing solar observations at lower cost and with greater flexibility, although the resolution and spectral coverage are insufficient to meet all requirements. Radio telescopes in particular are too large to place on space-based platforms and are thus most cost-effectively deployed on Earth’s surface.
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SPECIAL ISSUES, REQUIREMENTS, AND COMPLEMENTARY ACTIONS The panel believes strongly that a successful U.S. program of weather science and applications from space requires much more than new technology on satellites. International Collaboration More than 100 environmental satellites are launched each decade. Fewer than 20 percent are solely U.S. missions. Thus, it is important that some of our Earth science for weather continue to be planned in coordination with international partners. New and ever better ways should be used to ensure free and open exchange of data and leveraging of complementary missions. Existing, substantial international collaborations on the TRMM, CloudSat, CALIPSO, GPM, COSMIC, and other missions demonstrate that U.S. Earth science has much to gain from more such activities, including the emerging GEOSS as a new focal point for international activities, joining ICSU, COSPAR, and other proven mechanisms. Complementary Nonsatellite Observing Systems Great value is added to weather-related Earth science by suborbital UAVs, ground- and ocean-based observing networks, and in situ observations. In particular, the community recognizes the potential value of UAVs to complement satellite profiles of tropospheric- and chemical-weather variables. UAVs are particularly well suited for conducting tropospheric weather investigations in hazardous environments and when missions require long endurance, such as in investigating and monitoring hurricanes. The ability to provide unique remote and in situ measurements that complement satellite observations can improve forecasts of severe storms in data-sparse regions (e.g., over the oceans). Likewise, the study of chemical and dynamical interrelationships in the troposphere and lower stratosphere requires measurement capabilities over remote regions of the world or at very high altitudes, where the unique capabilities of UAVs are particularly useful. It is only through detailed studies of complex Earth science processes using remote and in situ measurements from ground- and ocean-based and suborbital platforms that the satellite measurements can be properly interpreted. The synergism among different scales of measurements is essential for a complete and robust program. The Essential Ground Segment: Models, Data Assimilation, and High-Performance Computers The panel recommends supporting the development of cutting-edge models, data-assimilation tools, and high-performance computers, which are critical for the success of the priority missions. A good portion of U.S. Earth science resources must be placed in a robust ground segment of NOAA, NASA, and partner agencies, with special access provided to the weather science research community. The priority observations and missions recommended by the panel must be designed to optimize their incorporation into modeling systems. Full exploitation of the missions identified by the Earth science and applications decadal survey requires not only timely and substantive initial analyses but also reanalyses as models and data-assimilation systems advance. The productive use that the weather science community continues to make of reanalyses that are now somewhat obsolete is a testimony to their essential value. NOAA’s relatively new Science Data Stewardship Program for satellite data records should be strengthened for use over the decades. The satellite records are a national asset and must be addressed accordingly. Advances in information technology and new methods for data assimilation will make reanalyses efficient, more accurate, and even more useful in
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extracting information from the observing systems if the community plans appropriately for archiving of the required satellite data (NRC, 2005). Transition of Science Results to Operations and to Users: Agency Collaborations Without the required flow of new weather science research results to users, the vision of the weather panel will not be realized. Societal and economic applications will be inefficient without the design of end-to-end, research-to-operations, and operations-to-users systems for the coming decades (see NRC, 2000, 2003a,b, 2004). The end-to-end data and product-distribution systems are vital to a successful Earth science program. Academe, the public, the private sector, and user groups must all be parts of the overall program of each new mission. Agencies leading Earth science and applications from space need flexible mechanisms to work together and with external constituencies to fully exploit opportunities in the coming decades. REFERENCES Anthes, R.A., C.Rocken, and Y.-H.Kuo. 2000. Applications of COSMIC to meteorology and climate. Terr. Atmos. Ocean. Sci. 11:115–156. Atlas, R. 2005. Results of recent OSSEs to evaluate the potential impact of lidar winds. Proc. of SPIE 58870K:1–8. Baker, W., G.D.Emmitt, F.Robertson, RM.Atlas, J.E.Molinari, D.A.Bowdle, J.Paegle, R.M.Hardesty, RT.Menzies, T.N. Krishnamurti, R.A.Brown, M.J.Post, J.R.Anderson, A.C.Lorenc, and J.McElroy. 1995. Lidar measured winds from space: A key component for future weather and climate prediction. Bull. Am. Meteorol. Soc. 76:869–888. Bauer, P., and A.Mugnai. 2003. Precipitation profile retrievals using temperature sounding microwave observations. J. Geophys. Res. 108(D23):4730. Bauer, P., P.Amayenc, C.Kummerow, and E.Smith. 2001. Over-ocean rainfall retrieval from multisensor data of the tropical rainfall measuring mission. Part II: Algorithm implementation. J. Atmos. Oceanic Tech. 18:1838–1855. Bengtsson, L., G.Robinson, R.Anthes, K.Aonashi, A.Dodson, G.Elgered, G.Gendt, R.Gurney, M.Jietai, C.Mitchell, M.Mlaki, A.Rhodin, P.Silvestrin, R.Ware, R.Watson, and W.Wergen. 2003. The use of GPS measurements for water vapor determination. Bull. Am. Meteorol. Soc. 84:1249–1258. Böckmann, C., I.Mironova, D.Müller, L.Schneidenbach, and R.Nessler. 2005. Microphysical aerosol parameters from multiwave-length lidar. J. Opt. Soc. Am. A 22:518–528. Cheng, C.-Z., Y.-H.Kuo, R.A.Anthes, and L.Wu. 2006. Satellite constellation monitors global and space weather. EOS 87(17):166. Edwards, D., P.DeCola, J.Fishman, D.Jacob, P.Bhartia, D.Diner, J.Burrows, and M.Goldberg. 2006. Community input to the NRC decadal survey from the NCAR Workshop on Air Quality Remote Sensing From Space: Defining an Optimum Observing Strategy. Community Workshop on Air Quality Remote Sensing from Space: Defining an Optimum Observing Strategy, February 21–23, 2006, National Center for Atmospheric Research, Boulder, Colo. Available at http://www.acd.ucar.edu/Events/Meetings/Air_Quality_Remote_Sensing/Reports/AQRSinputDS.pdf. Ferraro, R.R. 1997. Special sensor microwave imager derived global rainfall estimates for climatological applications. J. Geophys. Res. 102(D14):16715–16735. Gasiewski, A.J., and D.H.Staelin. 1990. Numerical modeling of passive microwave O2 observations over precipitation. Radio Sci. 25(3):217–235. Grund, C.J., and E.W.Eloranta. 1991. The University of Wisconsin high spectral resolution lidar. Opt Engineering 30:6–12. Hajj, G., L.C.Lee, X.Pi, L.J.Romans, W.S.Schreiner, P.R.Straus, and C.Wang. 2000. COSMIC GPS ionospheric sensing and space weather. Terr. Atmos. Ocean. Sci. 11:235–272. IGACO Theme Team. 2004. The Changing Atmosphere, An Integrated Global Atmospheric Chemistry Observation Theme for the IGOS Partnership. ESA SP-1282, GAW Report No. 159 (WMO TD No. 1235). European Space Agency, Noordwijk, The Netherlands. Kummerow, C.D., Y.Hong, W.S.Olson, S.Yang, R.F.Adler, J.McCollum, R.Ferraro, G.Petty, D.B.Shin, and T.T.Wilheit. 2001. The evolution of the Goddard Profiling Algorithm (GPROF) for rainfall estimation from passive microwave sensors. J. Appl. Meteorol. 40:1801–1817. Kursinski, E.R., G.A.Hajj, S.S.Leroy, and B.Herman. 2000. The GPS radio occultation technique. Terr. Atmos. Ocean. Sci. 11:53–114. Le Marshall, J., J.Jung, J.Derber, R.Treadon, S.J.Lord, M.Goldberg, W.Wolf, H.C.Liu, J.Joiner, J.Woollen, R.Todling, and R. Gelaro. 2005. Impact of atmospheric infrared sounder observations on weather forecasts. EOS 86(11):109, 115–116.
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Representative terms from entire chapter: