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 ESA’s
Envisat and 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/Kalpana
(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
Envisat, 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. Future missions, such as
ALOS-2 and Sentinel-1, 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 or
VIIRS on low-Earth orbit platforms, and by
sensors in geostationary orbit, like VHRR on
INSAT-3A and Kalpana-1 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,
SMOS and Aquarius 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, MetOp, TerraSAR-X), with
continuity provided by missions such as
CryoSat-2, RADARSAT-2 and ALOS-2 (from
2014).
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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