Overview
Current areas of strength of the Earth observation satellites providing data today include:
— Atmospheric chemistry measurements, including ozone, provided by instruments on NOAA satellites, NASA’s Aura and Terra missions, the NASA/NOAA/DoD Suomi NPP, CSA’s SCISAT-1, ESA's Envisat (which ended operations in April 2012), JAXA’s GOSAT, and IASI and GOME-2 on MetOp;
— Aerosol properties, provided by dedicated instruments like CALIOP on Calipso and MISR on Terra, but also by instruments on EUMETSAT’s MetOp, the multidisciplinary VIIRS sensor on Suomi NPP, and by traditional imagers like MERIS and AVHRR in LEO and SEVIRI in GEO;
— Atmospheric humidity and temperature profiles routinely provided for operational meteorology by the NOAA, DMSP, MetOp, FY-1 and FY-3 series polar-orbiting satellites and by a number of meteorological geostationary satellites;
— Atmospheric winds (through cloud tracking), cloud amount and tropical precipitation estimates provided for most of the globe by the traditional imagers mounted on geostationary meteorological satellite series like MSG (EUMETSAT), GOES (NOAA), Himawari/MTSAT (JMA), FY-2 (CMA), COMS (KMA/KORDI), Elektro-L (Roshydromet/Roscosmos) and INSAT (IMD);
— Multi-purpose imagery for both land and sea collected by medium- and high-resolution optical and synthetic aperture radar instruments for use in environmental, public, and commercial applications. Optical sensors include AVHRR on the NOAA and EUMETSAT polar-orbiters and those on Terra and the SPOT, Landsat, Resourcesat, Cartosat, and Resurs series. SAR sensors include those on the RADARSAT, Meteor-M, TerraSAR and Cosmo-SkyMed series and on RISAT. Missions such as ALOS-2 and Sentinel-1, with their increased spatial resolution, ensure improved data collection and application opportunities into the future;
— Sea-surface temperature (SST) information generated by data from existing operational meteorological satellites, such as AVHRR or VIIRS on low-Earth orbit platforms, and by sensors in geostationary orbit, like VHRR on INSAT-3A and SEVIRI on MSG. Besides operational meteorological instruments, SST is the target of dedicated instruments like MODIS on the Aqua/Terra platforms and AATSR on Envisat (ended 2012). Satellites such as Jason-2/OSTM, Oceansat-2 and SMOS are now also making consistent and continuous measurements of other important oceanographic parameters, such as ocean topography and surface currents, sea-surface winds, ocean colour and sea-surface salinity; ocean colour observations are also available now from geostationary orbit, with the GOCI instrument on COMS;
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— Sea ice and ice-sheet extent, currently measured by a range of missions (including DMSP, ICESat-II, MetOp, TerraSAR-X), with continuity provided by missions such as CryoSat-2, RADARSAT-2 and ALOS-2.
Future missions will feature a new generation of technology and techniques to enable Earth observation satellites to extend their contribution, including:
— A significant increase in information about the chemistry and dynamics of the atmosphere. This includes long-term global measurements of concentrations of ozone and many other trace and greenhouse gases, including carbon dioxide and methane; better information on the role of clouds in climate change; the ability to map cloud cover and precipitation better (including over the oceans); measurements of 3D atmospheric winds without the need for cloud tracking, either from active (lidar) sensors or passive hyperspectral infrared sounders in geostationary orbit; global aerosol distributions; and extended coverage of atmospheric measurements into the troposphere to allow improved pollution monitoring. Just as significantly, existing measurement capabilities for many key parameters, such as atmospheric humidity and temperature, will have greatly improved accuracy and spatial resolution. For future missions, several novel, active instruments, such as cloud and rain radars, and lidar instruments, have been proposed. In addition to these developments, progress in developing passive hyperspectral infrared sounders has been such that the urgently needed deployment of these instruments in geostationary orbit is realistic;
— Improved repeat coverage, resolution and accuracy of many oceanographic measurements, including sea level, ocean surface vector winds, sea-surface salinity, coastal ocean properties and ocean colour and biology;
— New information on global land surface processes, through use of an increased number of spectral bands (hyperspectral imagers), as well as multi-directional and polarisational capabilities of future imaging sensors;
— Estimates from innovative new lidar systems of global biomass and carbon stocks, as well as the mass balance of the polar ice sheets and their contributions to global sea-level rise.
We can expect the exact plans to change as space agency programmes evolve to keep pace with accepted scientific and political priorities regarding information about the Earth System and its climate – including the influence of the processes initiated by the Intergovernmental Panel on Climate Change, the UN Framework Convention on Climate Change and the Group on Earth Observations. |
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