News! 071109 AN ERA OF EARTH OBSERVATIONS: LOOKING BACK AT 50 YEARS
AN ERA OF EARTH OBSERVATIONS: LOOKING BACK AT 50 YEARS
Source: http://earthobservatory.nasa.gov/Newsroom/MediaAlerts/2007/2007110925922.html
Since the launch of Sputnik I in 1957, thousands of satellites have been sent into space on missions to collect data about the Earth. Today, the ability to forecast weather, climate, and natural hazards depends critically on these satellite-based observations. Satellites have revolutionized how humans view and understand the home planet, helped address fundamental scientific questions, and enabled a plethora of applications with important societal benefits. Continued Earth observations from space will be required to address scientific and societal challenges of the future.Where will a developing hurricane make landfall? What is the status of the ozone layer? How much will sea level rise? No other single measurement platform has revolutionized the ability to address these and other fundamental Earth science questions as much as satellites orbiting the Earth. From weather forecasting to high-tech navigation systems to answering fundamental questions about the Earth’s climate, satellites have become a crucial part of a wide variety of scientific endeavors and practical applications over the past 50 years.The National Research Council convened a committee to examine the scientific accomplishments that have resulted from space-based satellite This report concludes that the advent of satellite observations has revolutionized the Earth research endeavor, and highlights examples of how such observations have led to new discoveries, opened new avenues of research, and provided important societal benefits by improving the predictability of Earth system processes. These scientific achievements underscore the importance of satellite observations and the need for a renewed commitment to Earth observations from space.The Unique Value of Satellite ObservationsObservations from space over the past 50 years have fundamentally transformed the way people view the Earth. The image of the “blue marble” (Figure 1) is taken for granted now, but it was revolutionary when it was taken in 1972 by the crew on Apollo 17. Since then, the capability to look at Earth from space has grown increasingly sophisticated as space observations evolved from simple photographs to quantitative measurements of properties such as temperature, concentrations of atmospheric gases, and the exact elevation of land and ocean.The global view from satellite observations is unmatched in its ability to resolve the dynamics and variability of Earth processes. Ship-based observations, for example, cannot provide spatial coverage frequently enough to detect the dynamic nature of the ocean. Similarly, aircraft and weather balloon measurements alone cannot resolve the details required to understand the complex dynamics of ozone depletion.Satellite observations have not only transformed the Earth sciences—vastly more accurate global observations and consequently improved predictability of Earth processes also provide profound social benefits. From revolutionizing the ability to predict weather to enabling the development of the Global Positioning System, satellites have become essential to everyday applications that improve human safety and the quality of life.Scientific Accomplishments Resulting from Satellite ObservationsThe report provides examples of how satellite observations have enabled Earth scientists to address fundamental questions ranging from atmospheric circulations and composition to the role of aerosols in climate, year-to-year variability in sea ice, the role of the ocean in climate change, and the convection of the Earth’s crust. Many of these scientific advances have direct societal applications; a selection of these is described below.Weather Imagery and ForecastingSome of the most broadly used products from satellites are weather observations that enable forecasts. Since satellite images have become readily available, no hurricane or typhoon has gone undetected, providing affected coastal areas with advance warning and crucial time to prepare.Decades of satellite observations have enabled scientists to address fundamental questions about weather and climate. Satellite observations yield continually updated knowledge of the state of the atmosphere, helping meteorologists to devise models that project the weather into the future with much improved accuracy compared to pre-satellite forecasts. Consequently, 7-day forecasts have more than doubled in accuracy over the past three decades, particularly in the southern hemisphere. These improvements are saving countless human lives and have an enormous economic value.Tracking Pollution and Monitoring Ozone DepletionAs a result of satellite-based observations, pollution is now viewed as a global, not a local, phenomenon. Information from satellites provides crucial data to inform models of pollution dynamics and helps scientists predict changes in the atmospheric composition with greater confidence.For example, satellites have been used to monitor the atmosphere’s ozone layer, which blocks damaging ultraviolet light from reaching the Earth’s surface. Satellite observations from the Nimbus series in the 1980s provided the first global maps of ozone depletion caused by the release of manmade chlorineand bromine-containing compounds. These observations became critical to the development of the Montreal Protocol, an international agreement designed to phase out ozone-destroying compounds.Satellite observations continue to track the size and depth of the Antarctic ozone hole and the more subtle, but dangerous, losses of ozone over heavily populated regions. Recent satellite observations show a decrease in chlorine-containing gases and the apparent beginning of an ozone recovery in some areas, yielding increased confidence that the Montreal Protocol is indeed achieving its goal.The Global Positioning SystemThe development of the Global Positioning System (GPS), which provides location information accurate to the centimeter or better even in remote areas, is another transformative advance enabled by satellite observations. Inexpensive GPS receivers are now taken for granted by consumers who are rapidly becoming accustomed to GPS-based navigation on the road, on the water, or in the air. These technologies rely on an enormous body of fundamental science developed over the past decades, including accurate position information of satellites, very stable clocks, and well-calibrated atmospheric corrections.Climate ScienceMany scientific advances presented in the report directly contribute to the improved understanding of the Earth’s climate system. For example, current understanding of climate change has been improved by basic satellite-based research on sea surface temperature, ice sheet flows, the El Niño-Southern Oscillation, and Earth’s carbon cycle and energy fluctuations.Research on ice sheet flows provides an example of how satellites have enabled major advances in the study of climate. Before satellites, it was assumed that the mass of the ice sheets in Antarctica and Greenland was controlled by the difference between ice meltingand accumulation rates and that the rate of ice discharge into the ocean was constant. Satellite radar images from RADARSAT, however, transformed this view, revealing dynamic variability in ice sheets and showing how ice is discharged into the ocean through complex networks of ice streams. Furthermore, data from satellites revealed that the rate of ice stream flow toward the sea increases measurably in response to climate change, which could result in a significant rise in sea level. The collapse of Antarctica’s Larsen B Ice Shelf in 2002—captured by frequent satellite observations—dramatically illustrated this dynamic on astonishingly short time scales.Another important contribution to climate science was made by the Advanced Very High Resolution Radiometer, which has provided long-term records of many parameters important to the climate system. For example, the sea surface temperature record elucidated the role of the ocean in climate variability such as El Niño; and the observed rise in sea surface temperature has provided critical evidence for global warming. These and other satellite observations have advanced understanding of the climate system and dramatically improved climate models.Monitoring Agricultural LandsSatellite observations are also used to detect changes in land-cover, which can have major societal benefits. Scientists first applied satellite information to monitor and forecast the productivity of large-area crops in the 1970s. Since then, federal agencies have routinely used satellite imagery offered by the Landsat series and other missions in crop commodity forecasting. A particularly noteworthy application of satellite data is the Famine Early Warning System Network, which was initially set up in Sub-Saharan Africa and now operates in other arid environments of the developing world. This system uses satellite images in conjunction with ground-based information to predict and mitigate famines.Realizing the Potential of Earth Observations from SpaceOver the past 50 years, Earth observations from space have accelerated the cross-disciplinary integration of analysis, interpretation, and ultimately, understanding of dynamic processes that govern the planet. The next decades will likely build on this momentum to bring more remarkable discoveries and an increased capability to predict Earth processes to better protect human lives and property.
Although many past scientific accomplishments from satellite observations have led to important societal benefits, it is important to recognize the basic, fundamental observations and research behind the work that enabled the development of practical applications. Realizing the potential of Earth observations from space will require a renewed national and international commitment to Earth satellite missions and continued support for the fundamental research challenges in this fertile area of science.The critical infrastructure to make the best use of satellite data has taken decades to build and is now in place; the scientific community is poised to make great progress toward understanding and predicting the complexity of the Earth system. However, the current capability to observe Earth from space is in jeopardy. Resources will be required to maintain the current momentum and ensure the workforce and infrastructure built over the past decades remains in place.Training and Maintaining the Required WorkforceA trained workforce is needed to develop tools to analyze and interpret satellite observations. Training and maintaining this workforce is possible only if the data are continuously accessible to the broad scientific community; for this reason, open access to satellite data is crucial. As NASA’s data policy has demonstrated, providing open and free access to global data to an international audience creates a more interdisciplinary and integrated Earth science community. International data sharing and collaborations on satellite missions also lessens the burden on individual nations to maintain Earth observational capacities.Maximizing the Utility of Instruments and InfrastructureThe value of satellite observations from space and their potential to benefit society can increase dramatically as instruments become more accurate. In addition, essential infrastructure, such as models, computing facilities, and ground networks, are required to validate and maximize the utility of satellite data. For this reason, multiple, synergistic observations, including orbital, suborbital, and in situ measurements, linked with the best models available, should be employed and supported.Furthermore, the length and continuity of a given data record often yields additional scientific benefits beyond the initial research results of the mission and beyond the monitoring implications for operational agencies. Follow-on missions are especially valuable, as the value of the data increases significantly with seamless and inter-calibrated time series. Longer data sets also often increase the value of historical pre-satellite data sets and are required to quantitatively assess global change.
Source: http://earthobservatory.nasa.gov/Newsroom/MediaAlerts/2007/2007110925922.html
Since the launch of Sputnik I in 1957, thousands of satellites have been sent into space on missions to collect data about the Earth. Today, the ability to forecast weather, climate, and natural hazards depends critically on these satellite-based observations. Satellites have revolutionized how humans view and understand the home planet, helped address fundamental scientific questions, and enabled a plethora of applications with important societal benefits. Continued Earth observations from space will be required to address scientific and societal challenges of the future.Where will a developing hurricane make landfall? What is the status of the ozone layer? How much will sea level rise? No other single measurement platform has revolutionized the ability to address these and other fundamental Earth science questions as much as satellites orbiting the Earth. From weather forecasting to high-tech navigation systems to answering fundamental questions about the Earth’s climate, satellites have become a crucial part of a wide variety of scientific endeavors and practical applications over the past 50 years.The National Research Council convened a committee to examine the scientific accomplishments that have resulted from space-based satellite This report concludes that the advent of satellite observations has revolutionized the Earth research endeavor, and highlights examples of how such observations have led to new discoveries, opened new avenues of research, and provided important societal benefits by improving the predictability of Earth system processes. These scientific achievements underscore the importance of satellite observations and the need for a renewed commitment to Earth observations from space.The Unique Value of Satellite ObservationsObservations from space over the past 50 years have fundamentally transformed the way people view the Earth. The image of the “blue marble” (Figure 1) is taken for granted now, but it was revolutionary when it was taken in 1972 by the crew on Apollo 17. Since then, the capability to look at Earth from space has grown increasingly sophisticated as space observations evolved from simple photographs to quantitative measurements of properties such as temperature, concentrations of atmospheric gases, and the exact elevation of land and ocean.The global view from satellite observations is unmatched in its ability to resolve the dynamics and variability of Earth processes. Ship-based observations, for example, cannot provide spatial coverage frequently enough to detect the dynamic nature of the ocean. Similarly, aircraft and weather balloon measurements alone cannot resolve the details required to understand the complex dynamics of ozone depletion.Satellite observations have not only transformed the Earth sciences—vastly more accurate global observations and consequently improved predictability of Earth processes also provide profound social benefits. From revolutionizing the ability to predict weather to enabling the development of the Global Positioning System, satellites have become essential to everyday applications that improve human safety and the quality of life.Scientific Accomplishments Resulting from Satellite ObservationsThe report provides examples of how satellite observations have enabled Earth scientists to address fundamental questions ranging from atmospheric circulations and composition to the role of aerosols in climate, year-to-year variability in sea ice, the role of the ocean in climate change, and the convection of the Earth’s crust. Many of these scientific advances have direct societal applications; a selection of these is described below.Weather Imagery and ForecastingSome of the most broadly used products from satellites are weather observations that enable forecasts. Since satellite images have become readily available, no hurricane or typhoon has gone undetected, providing affected coastal areas with advance warning and crucial time to prepare.Decades of satellite observations have enabled scientists to address fundamental questions about weather and climate. Satellite observations yield continually updated knowledge of the state of the atmosphere, helping meteorologists to devise models that project the weather into the future with much improved accuracy compared to pre-satellite forecasts. Consequently, 7-day forecasts have more than doubled in accuracy over the past three decades, particularly in the southern hemisphere. These improvements are saving countless human lives and have an enormous economic value.Tracking Pollution and Monitoring Ozone DepletionAs a result of satellite-based observations, pollution is now viewed as a global, not a local, phenomenon. Information from satellites provides crucial data to inform models of pollution dynamics and helps scientists predict changes in the atmospheric composition with greater confidence.For example, satellites have been used to monitor the atmosphere’s ozone layer, which blocks damaging ultraviolet light from reaching the Earth’s surface. Satellite observations from the Nimbus series in the 1980s provided the first global maps of ozone depletion caused by the release of manmade chlorineand bromine-containing compounds. These observations became critical to the development of the Montreal Protocol, an international agreement designed to phase out ozone-destroying compounds.Satellite observations continue to track the size and depth of the Antarctic ozone hole and the more subtle, but dangerous, losses of ozone over heavily populated regions. Recent satellite observations show a decrease in chlorine-containing gases and the apparent beginning of an ozone recovery in some areas, yielding increased confidence that the Montreal Protocol is indeed achieving its goal.The Global Positioning SystemThe development of the Global Positioning System (GPS), which provides location information accurate to the centimeter or better even in remote areas, is another transformative advance enabled by satellite observations. Inexpensive GPS receivers are now taken for granted by consumers who are rapidly becoming accustomed to GPS-based navigation on the road, on the water, or in the air. These technologies rely on an enormous body of fundamental science developed over the past decades, including accurate position information of satellites, very stable clocks, and well-calibrated atmospheric corrections.Climate ScienceMany scientific advances presented in the report directly contribute to the improved understanding of the Earth’s climate system. For example, current understanding of climate change has been improved by basic satellite-based research on sea surface temperature, ice sheet flows, the El Niño-Southern Oscillation, and Earth’s carbon cycle and energy fluctuations.Research on ice sheet flows provides an example of how satellites have enabled major advances in the study of climate. Before satellites, it was assumed that the mass of the ice sheets in Antarctica and Greenland was controlled by the difference between ice meltingand accumulation rates and that the rate of ice discharge into the ocean was constant. Satellite radar images from RADARSAT, however, transformed this view, revealing dynamic variability in ice sheets and showing how ice is discharged into the ocean through complex networks of ice streams. Furthermore, data from satellites revealed that the rate of ice stream flow toward the sea increases measurably in response to climate change, which could result in a significant rise in sea level. The collapse of Antarctica’s Larsen B Ice Shelf in 2002—captured by frequent satellite observations—dramatically illustrated this dynamic on astonishingly short time scales.Another important contribution to climate science was made by the Advanced Very High Resolution Radiometer, which has provided long-term records of many parameters important to the climate system. For example, the sea surface temperature record elucidated the role of the ocean in climate variability such as El Niño; and the observed rise in sea surface temperature has provided critical evidence for global warming. These and other satellite observations have advanced understanding of the climate system and dramatically improved climate models.Monitoring Agricultural LandsSatellite observations are also used to detect changes in land-cover, which can have major societal benefits. Scientists first applied satellite information to monitor and forecast the productivity of large-area crops in the 1970s. Since then, federal agencies have routinely used satellite imagery offered by the Landsat series and other missions in crop commodity forecasting. A particularly noteworthy application of satellite data is the Famine Early Warning System Network, which was initially set up in Sub-Saharan Africa and now operates in other arid environments of the developing world. This system uses satellite images in conjunction with ground-based information to predict and mitigate famines.Realizing the Potential of Earth Observations from SpaceOver the past 50 years, Earth observations from space have accelerated the cross-disciplinary integration of analysis, interpretation, and ultimately, understanding of dynamic processes that govern the planet. The next decades will likely build on this momentum to bring more remarkable discoveries and an increased capability to predict Earth processes to better protect human lives and property.
Although many past scientific accomplishments from satellite observations have led to important societal benefits, it is important to recognize the basic, fundamental observations and research behind the work that enabled the development of practical applications. Realizing the potential of Earth observations from space will require a renewed national and international commitment to Earth satellite missions and continued support for the fundamental research challenges in this fertile area of science.The critical infrastructure to make the best use of satellite data has taken decades to build and is now in place; the scientific community is poised to make great progress toward understanding and predicting the complexity of the Earth system. However, the current capability to observe Earth from space is in jeopardy. Resources will be required to maintain the current momentum and ensure the workforce and infrastructure built over the past decades remains in place.Training and Maintaining the Required WorkforceA trained workforce is needed to develop tools to analyze and interpret satellite observations. Training and maintaining this workforce is possible only if the data are continuously accessible to the broad scientific community; for this reason, open access to satellite data is crucial. As NASA’s data policy has demonstrated, providing open and free access to global data to an international audience creates a more interdisciplinary and integrated Earth science community. International data sharing and collaborations on satellite missions also lessens the burden on individual nations to maintain Earth observational capacities.Maximizing the Utility of Instruments and InfrastructureThe value of satellite observations from space and their potential to benefit society can increase dramatically as instruments become more accurate. In addition, essential infrastructure, such as models, computing facilities, and ground networks, are required to validate and maximize the utility of satellite data. For this reason, multiple, synergistic observations, including orbital, suborbital, and in situ measurements, linked with the best models available, should be employed and supported.Furthermore, the length and continuity of a given data record often yields additional scientific benefits beyond the initial research results of the mission and beyond the monitoring implications for operational agencies. Follow-on missions are especially valuable, as the value of the data increases significantly with seamless and inter-calibrated time series. Longer data sets also often increase the value of historical pre-satellite data sets and are required to quantitatively assess global change.
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