Earth
observation plans: by measurement
Introduction
In
2002, there are over 60 satellites operating (annex A) and providing
important data about the Earth and its environment, helping us to
develop our understanding of the basic Earth system and of human
influences on it. These data cover measurements of a very wide range
of geophysical parameters, spanning the whole spectrum of the environment
including atmosphere, land, oceans, and ice and snow. This section
considers some of the key observations contributed by EO satellites,
as indicated in the table.
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This
list is not comprehensive, but does include many key measurements
of interests to the main user groups of Earth observation satellite
data, and describes a significant part of the capability of current
and planned instruments.
The
CEOS Database contains considerably more detail on the expected
performance of the various CEOS agency missions and on the specifications
of the requirements for certain applications and users. For example,
the CEOS Database provides information on more than 120 different
geophysical measurements. See below for contact details for access
to the CEOS Database.
This
section identifies the satellite instruments which primarily contribute
data for any particular measurement from the list above and indicates
the plans for future provision of that measurement over the next
15 years. Measurement continuity is a key requirement in many areas,
for example in providing confidence to sustain public and commercial
investment in operational applications of Earth observation data.
It is also of paramount importance for the generation of long term
datasets required for global environmental programmes and for climate
change studies. This section also identifies the prospects for achieving
that continuity given the programmes and plans that exist in 2002
whether it may be provided by a single series of satellites
dedicated to a particular measurement, or whether users of that
measurement must look to various satellite missions planned by different
agencies world-wide to satisfy their information requirements.
The
need for this continuity, and to ensure that the measurements by
different agencies from different countries can be inter-compared
and calibrated requires a significant degree of coordination in
mission planning and data provision. Harmonisation and maximum cost-effectiveness
for the total set of space-based observation programmes is the objective
of CEOS. Harmonisation of the space-based and in-situ observational
resources is the aim of IGOS (see annex B). The IGOS Partnership
provides a forum for establishing the performance and timing necessary
from CEOS agency missions in order to satisfy the information requirements
of the IGOS Themes, and of international programmes such as the
Global Climate Observing System (GCOS), Global Ocean Observing System
(GOOS), the Global Terrestrial Observing System (GTOS), the World
Climate Research Programme (WCRP), and the International Geosphere-Biosphere
Programme (IGBP).
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Overview
Current
areas of strength of the Earth observation satellites providing
data today include:
- Atmospheric
chemistry measurements, including of ozone, are being provided
by the NASA TOMS instrument on the TOMS Earth Probe, by CSA's
MOPITT instrument on Terra, and by OSIRIS on Odin. Significant
new capabilities became available in March 2002 when ESAs
Envisat mission was launched with several advanced instruments;
- Atmospheric
humidity and temperature profiles are routinely provided for operational
meteorology by the NOAA and DMSP series polar orbiting satellites
and by
a number of meteorological geostationary satellites;
- Atmospheric
winds (through cloud tracking), cloud amount and tropical precipitation
estimates are provided for most of the globe by the geostationary
meteorological satellite series Meteosat, GOES, GMS, and INSAT;
- Multi-purpose
imagery for both land and sea is being collected by both high
resolution optical and synthetic aperture radar (SAR) instruments
for use in environmental, public, and commercial applications.
Optical sensors include AVHRR on the NOAA polar orbiters and those
on Terra, SPOT, Landsat, and IRS series. SAR sensors include those
on the ERS/Envisat and RADARSAT series. Future missions and increasing
spatial resolution will ensure improved data collection and application
opportunities;
- Sea
surface temperature information is being generated by data from
existing meteorological satellites and from instruments on the
Terra and the ERS/Envisat series. Future plans should provide
continuity. Satellites are now also making consistent and continuous
measurements of other important oceanographic parameters such
as ocean topography, ocean currents, and sea surface winds
such as from QuikSCAT,
Jason-1, and Envisat;
- Sea
ice and ice sheet extent are being measured by a range of missions
and continuity is planned.
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, including: 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 3-D atmospheric winds without the
need for cloud tracking; 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. A variety of novel instruments will be
used such as cloud and rain radars, and lidar instruments
proposed for future missions;
- Improved
repeat coverage, resolution, and accuracy of many oceanographic
measurements, including ocean surface winds, and ocean colour
and biology;
- New
capabilities for determination of soil moisture and ocean salinity
starting with ESAs SMOS mission;
- New
information on global land surface processes, through use of increased
number of spectral bands, and multi-directional and polarisational
capabilities of future imaging sensors;
- Insights
into vegetation canopy structure, estimates of global biomass
and carbon stocks, and estimates of mass balance of the polar
ice sheets and their contributions to global sea level change
from innovative new lidar systems, including those on future
ESA and NASA missions;
- 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
for information on the Earth system.
Measurement
timelines
For
each measurement category listed in the table at the top of this
page, a brief discussion is given below of the significance of that
measurement, together with an indication of the present and future
measurement capabilities of satellite observations. This description
is supported by two timeline diagrams spanning the period 2002-2018,
indicating the instruments contributing to that measurement and
the missions on which they are expected to fly.
The
first timeline shows missions that are either:
- Current:
where at least the prototype has been launched, and financing
is approved for the whole series; or
- Approved:
where financing is available for the whole series, the prototype
is fully defined, the development is in phase C/D.
The
second shows missions which are not yet approved rather they
are:
- Planned:
financing is available up to the end of phase B, financing of
the full series is being considered; or
- Considered:
conceptual studies and phase A have been completed, financing
of phase B is in preparation.
Of
course, all missions have a degree of uncertainty. This description
of mission status reflects information available from the relevant
agencies at the time of compilation. If the month of the launch
of a planned mission has not been specified the timeline is shown
to commence at the beginning of the planned year of launch. Note
also that missions currently operating beyond their planned life
are shown as operational until the end of 2002 unless an alternative
date has been proposed.
The
timelines in this section represent a qualitative analysis of the
provision of data from Earth observation satellites in terms of
a number of key geophysical measurements and the requirement for
those measurements in different disciplines.
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