Current areas of strength of the Earth observation satellites providing data today include:

— atmospheric chemistry measurements, including ozone, provided by instruments on NASA’s Aura and Terra missions, ESA’s Envisat, and GOME-2 on MetOp;

— aerosol properties, provided by dedicated instruments like CALIPSO and MISR, but also by instruments on ESA’s Envisat and EUMETSAT’s MetOp, 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 and MetOp 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), MTSAT (JMA), FY-2 (CMA), and INSAT/Kalpana (IMD);

— multi-purpose imagery for both land and sea collected by high resolution optical and synthetic aperture radar (SAR) instruments for use in environmental, public, and commercial applications. Optical sensors include AVHRR on the NOAA and EUMETSAT polar orbiters and those on ALOS, Terra, and the SPOT, Landsat and IRS series. SAR sensors include those on the ERS/Envisat and RADARSAT series and on ALOS. Future missions and increasing spatial resolution will ensure improved data collection and application opportunities;

— sea surface temperature (SST) information generated by data from existing operational meteorological satellites, such as AVHRR on low Earth orbit platforms, and by sensors in geostationary orbit, like INSAT and SEVIRI. Besides operational meteorological instruments, SST is the target of dedicated instruments like AATSR and instruments on the Aqua/Terra and ERS/Envisat series. Future plans should provide continuity. Satellites such as QuikSCAT, Jason-1, and Envisat are now also making consistent and continuous measurements of other important oceanographic parameters, such as ocean topography, ocean currents and sea surface winds;

— sea ice and ice sheet extent, currently measured by a range of missions (including ALOS, DMSP, ICESat, MetOp, TerraSAR-X and RADARSAT), with future continuity provided by missions such as CryoSat-2 and RADARSAT-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; information on the role of clouds in climate change; the ability to better map cloud cover and precipitation (including over the oceans); measurements of 3D atmospheric winds without the need for cloud tracking, either from active 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 ocean surface winds, ocean colour and biology;

— new capabilities for determination of the Essential Climate Variables soil moisture and ocean salinity, starting with ESA’s SMOS mission;

— new information on global land surface processes, through use of an increased number of spectral bands, 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 change;

— improved measurements of global ocean currents, based on data from altimeters and gravity field instruments, such as GRACE and GOCE.

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 Group on Earth Observations (GEO), the UN Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC).