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- Fifty Years of Earth-observation Satellites | American Scientist
- It's 50 years since climate change was first seen. Now time is running out
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You are going to email the following Climate warning, 50 years later. Message Subject Your Name has forwarded a page to you from Science. Message Body Your Name thought you would like to see this page from the Science web site. Save to my folders. Remote sensing of the cryosphere is, however, sometimes restricted by the polar environment.
The orbital inclination of many satellites means that their sensors do not cover regions with latitudes greater than 80 degrees. Moreover, at any time, at least 50 percent of the polar regions are covered by cloud, and during their respective winters each endures extended periods of darkness, making the consistent use of visible and infrared sensors problematic. These issues have led to the extensive use of microwave instruments.
The continuous availability of radar data over the past decade has provided significant advances in understanding the cryosphere. Sea-ice extent and movement are key indicators of climate change, and are also important for ship routing and weather forecasting. A succession of passive microwave radiometers has led to continuous records since , with spatial resolution improving with each new radiometer. At the same time, SAR data have enabled discrimination between seasonal and persistent ice types, and monitoring of sea-ice reductions consistent with global warming.
Significant disintegrations of Antarctic Peninsula ice shelves, also coincident with climate warming, were observed using optical and SAR imagery, as was accelerated ice discharge on Greenland. Ice thickness also represents an important climate-change indicator. Although its measurement is problematic, data from satellite radar altimeters and infrared radiometers have shown promise as model inputs, especially when on-site numbers are available for calibration. Satellite altimeter data have even been used to map a vast freshwater lake beneath Antarctica.
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Topography remains perhaps the most fundamental observation for an ice sheet, with regular, accurate measurements providing information on direction and magnitude of flows, which are vital parameters for glacial mass-balance estimates. Radar and laser altimeters, as well as SAR interferometry, have all proved capable of producing accurate measurements of ice-sheet topography and dynamics.
Recent years have seen the application of data from Earth-observation satellites extend into new research fields. Urban and regional planners require nearly continuous acquisition of data to formulate policies and programs, and new satellites with increased spatial and spectral resolution provide data to meet these requirements. From flood-risk modeling, subsidence detection and traffic management, to archaeological surveying, landmine detection and even crime-risk mapping from nighttime imagery, satellite imagery is now widely used for societal applications.
The year archive of Landsat imagery provides data for land-use and urban-growth modeling, whereas nighttime imagery of electrified urban areas is facilitating the construction of global human-population spatial databases, which are finding applications in disease-burden estimation and epidemic modeling. Globally consistent satellite data on a range of climatic variables now exist, including temperature, rainfall and vegetation area.
These data are beginning to find significant applications across the low-income regions of the world in exploring food security, resource accessibility and the construction of early-warning systems in planning for the effects of crop failure and disease outbreaks.
Fifty Years of Earth-observation Satellites | American Scientist
The resultant maps are improving decision making and efficient resource allocation. Moreover, with the climatic and environmental preferences and tolerances of numerous species quantified, the same global imagery is helping to infer present and future distributions for improved conservation planning. From the availability of habitats for giant pandas, to the distributions of malarial mosquitoes, satellite imagery has become an important asset for ecologists and epidemiologists alike.
The last half-century has seen satellite remote sensing come of age as a multidisciplinary research field, with a balance of theory, practice and operational application. It still faces barriers to becoming a fully global and cross-disciplinary data source, particularly in low-income countries, but in many cases these limitations are being reduced. The continued increase in computing power and decrease in costs are making satellite imagery more manageable and affordable.
However, the building of image archives spanning different time periods still requires significant resources. A composite view of Hurricane Katrina on August 28, , shows data from several instruments aboard two satellites. Blue indicates at least a quarter inch of rain an hour, whereas green represents half an inch, yellow an inch and red two inches. The increasing number of Earth-observation satellites and the availability of imagery are driving down data costs.
Free online databases and open distribution of processed imagery are making many types of data available to all. Although this is a welcome trend, it remains exceptional, with even unprocessed data from numerous satellites not readily available and many operators still charging high fees for imagery. Software for handling and processing satellite imagery was previously rare, as well as complex and expensive, but is becoming widespread and more user-friendly.
Basic software is now, in many cases, cheap or even free, but the most powerful and advanced programs still require costly licenses. Training in the use of satellite imagery has also grown as such data become central to numerous disciplines, but cutting-edge computing, imagery and software often mean that course costs remain prohibitively high for institutions in low-income countries.
It's 50 years since climate change was first seen. Now time is running out
Increasingly, limitations in satellite-data applications have shifted from the technology of acquiring the data to the techniques on the ground required to optimally exploit the information within the remotely sensed data. The conventional trade-offs in spectral, spatial and temporal characteristics, which must now be solved by choosing imagery from different satellite sensors, are gradually being made unnecessary by new technology.
Forthcoming launches and plans should herald the first images with a spatial resolution under half a meter, high spatial resolution SAR imagery, laser imaging and detailed nighttime data. Improvements in data processing and fusion could help eliminate cloud-obscured and nighttime data loss, and provide multi-image virtual databases for modeling of environmental and social processes. Finally, the declassification of military space technology may well provide valuable new data in the future, just as it has in the past.
There can be no doubt that satellite remote sensing is likely to continue to grow as an operational tool for mapping, monitoring and managing the Earth, as a profit-making entity and as a primary data source for Earth-system science.
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Existing trends in satellite design are likely to continue, and new ones will emerge, driven by both operational need and profits. Although global issues such as climate change and its effects will continue to provide justification for large multisensor satellites, the design directions in which smaller commercial satellites will head is less clear. The potential for real-time imagery has just begun to be realized, and personalized imagery beamed to handheld devices will soon show users their positions in traffic or current weather at their destinations.
To speculate further, the online availability of such imagery could facilitate a real-time or "live" Google Earth. Such a resource potentially enables revolutionary studies involving the global tracking of terrestrial and oceanic life, which could help create, for instance, real-time disease epidemic models, dynamic traffic control and reactive conservation—but it also raises significant security and privacy concerns.
Despite significant proven potential, the future supply of high-quality Earth-observation data for research and other applications remains unclear. For instance, funding cuts in U. At a time when unprecedented changes are taking place in the Earth's atmosphere, oceans and land surface, it is difficult to rationalize any scaling back of demonstrably successful and valuable satellite remote-sensing programs. Such examples emphasize the need for multinational cooperation in Earth observation to maintain a consistent supply of global data and ensure another 50 years of continuous measurements, stunning images and a deeper understanding of the Earth.
View the discussion thread. Skip to main content. Tatem , Scott J. Goetz , Simon I. Image courtesy of ESA. Climate-driven trends in contemporary ocean productivity. Crisis in Earth observation. Satellite radar interferometry for monitoring ice sheet motion: Application to an Antarctic ice stream. A satellite view of aerosols in the climate system.
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In response to this question, the Paris Agreement has been created, numerous countries have pledged a commitment to being carbon neutral before , and the car industry has been turning to electric vehicles. In Brief New data by a former NASA climate science demonstrates exactly how the planet's temperatures have risen in the last few decades. Temperature extremes are just one of the many effects of climate change, but thankfully, many nations and organizations are putting forth initiatives to help solve the problem.