We've also seen areas of vegetation decline in water-limited semi-arid environments. Since and Landsat-4, the system has been able to resolve features on the ground as small as 30m across. And while there are now plenty of other imaging spacecraft up there that can boast a much sharper view in the tens of centimetres , none comes close to Landsat for longevity.
This is the power that enables scientists to pull out the real trends in time. Just as important - the data is free and open. Anyone anywhere can access and use Landsat pictures at no cost. Landsat-9 still has a job of work to do before it can be declared operational. The spacecraft's Atlas rocket dropped it off at just under km in altitude. Close close Search search. Earth observation. A new look at your world For a weather-independent data source, high-frequency revisits, very-high-resolution imagery or even all of the above in a single system — we can provide the right Earth observation satellite for every customer.
Read more. Earth observation satellites portfolio Deliverable in absolute record time, our leading-edge systems are designed as off-the-shelf products that can be individually customised to comply with specific customer requirements. Figure Storms in the Sahara desert often blow copious amounts of sand and dust out to sea.
As archives of Landsat imagery have built up over the years, so have more-detailed insights into land-cover changes, exemplified by large-scale mapping of deforestation, useful not only for land-use planning but also for screening for such activities as illegal logging.
The advantages of satellite remote sensing for mapping had similar impacts on soil, agricultural and forestry sciences. Some examples include continental-scale mapping of fires and the advent of precision agriculture and forest management, where growth, water stress, disease and pests can be monitored.
Oceanographic research has also been revolutionized by satellite-based measurements. Researchers can now rapidly acquire and analyze global data sets on sea-surface temperature, surface wind speed and direction, height of surface swells, concentrations of phytoplankton and suspended sediments, wave distributions, and changes in sea-surface height associated with tides and currents. Prior to the s such properties could only be determined through expensive and extensive marine expeditions, but the regular availability of such measurements from spaceborne sensors has now led to long-term studies of sea-level rise and surface-temperature variations, such as the ENSO.
Some of the earliest significant advances came from Nimbus-7's Coastal Zone Color Scanner and its pioneering large-scale data collection of oceanic biological processes. Oceanic phytoplankton contributes around half of the biosphere's net primary production of biomass and therefore represents a significant component of the global carbon cycle.
Measurements of chlorophyll distribution from satellites provided the basis for the first large-scale estimates of oceanic net primary production and the discovery of its close coupling to climate. The development of satellite altimeters also enabled global mapping and a new understanding of a range of features through the detection of changes in water height that indicate gravitational concentrations.
These include sea-floor topography, tidal-energy dissipation and sea-level rise, as well as detailed characterization of the December Sumatra tsunami.
Half have been designed to support weather forecasting, whereas the others have been more research focused. Short-term weather-prediction science has advanced significantly through the use of active microwave instruments, as these operate through cloud cover and without daylight.
Microwave and infrared sensors can now be used to map atmospheric temperature profiles, water vapor distribution, surface pressure and precipitation.
TRMM data have contributed to an increased understanding of tropical rainfall processes, including quantification of the inhibiting effects of air pollution on rainfall. As with many satellites initially launched for research purposes, the success of TRMM has meant that its mission has been extended annually well past its expected life. Before-and-after images provide an essential resource for understanding the extent of disasters.
Images such as this one of New Orleans before Hurricane Katrina left make it clear just how extensively the city was flooded in a second image 17 days after the storm right.
The interactions of electromagnetic waves with the Earth's atmosphere are determined by both their wavelength and by the atmosphere's pressure and temperature and the particulates suspended within it. The scattering, emission, refraction and absorption of electromagnetic waves interacting with the atmosphere is a complex science, but Earth-observation satellite data have formed the basis of some significant advances in this realm, including the first global measurements and maps of the Arctic and Antarctic ozone "holes," through use of the Nimbus-7 Total Ozone Mapping Spectrometer to measure backscattered solar ultraviolet radiation.
The same sensor was used to quantify global tropospheric ozone levels related to air pollution, whereas improved sensors provided unprecedented maps of global smoke, dust and nitrogen oxide levels. The study of the mechanisms controlling the global climate system and its changes has become heavily dependent on the use of satellite observations.
The data are routinely used to populate models of climate, but they also both confirm model results and provide new data that either contradict predictions or indicate where models fall short. Satellite remote sensing has proved invaluable in studying the Arctic and Antarctic without the need for humans to disturb or endure these fragile, extreme environments.
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. 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. 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.
Swarm -- The three-satellite Swarm mission, due for launch in mid, will provide the best-ever survey of Earth's geomagnetic field, boosting scientists' understanding of the Earth's interior and climate. The spacecraft will operate in polar orbits between and km altitude. ESA is working on multi-mission facilities and ground segment operations, as well as the space component based on a series of satellites missions the Sentinels.
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