Executive
Summary of the
CEOS Analysis Group
1
Analysis Group (AG) work process
Since its formation in November 1996,
the AG has focused on the 6 prototype projects initiated by the Strategic
Implementation Team (SIT). The task of the AG is to supply CEOS Participants
and the SIT with an analysis of the extent to which existing and planned
missions are meeting the current set of defined user requirements. The
AG's work has been integrated with Affiliates' plans for similar analyses.
The AG has also provided a useful forum for the projects to take forward
their discussions.
The AG has adopted an analysis technique
that is based upon the content and structure of the CEOS database. In
order to "interrogate" the database in an objective manner, the AG has
further developed an existing software tool, already adopted by a number
of CEOS Affiliates. The tool, which is intended to highlight critical
areas for more detailed analysis, takes users' requirements and statements
of provision from the database and carries out a comparative, quantitative
analysis of the degree to which users' needs for space-based information
are met.
The AG's report is intended to assist
the SIT in developing further and implementing the space component of
an overall IGOS - as well as investigating, with relevant partners,
the practical, political, and programmatic mechanisms to act upon recommendations
regarding correction of gaps/overlaps in observing programmes.
2
Results of analyses
2.1
Project recommendations
The AG's activities to date have shown
that a truly integrated strategy in any area of Earth Observation is
much more than simply identifying gaps and overlaps. First the participants
must agree on the "state of the observations/science" in the focused
area. This leads to the identification of many more gaps than overlaps.
It appears that each of the 6 prototype projects is currently at this
stage of development, and as such, will require additional time and
effort to contribute to the development of an integrated global observing
strategy and to demonstrate its value.
Long-term
continuity of ozone measurements
The long-term outlook for space-based
total ozone measurements (NPOESS, METOP) is very encouraging, but there
are concerns about the early part of the next century. In spite of the
relatively large number of current and planned space-based instruments
for measurement of the vertical profiles of ozone and associated species,
it is clear that a more integrated and better defined strategy (involving
ground- and balloon-based measurements as well as space-based ones)
is necessary.
Observations of ozone alone are not adequate
to interpret ozone changes. Much more serious consideration must
be given to validation and calibration of space-based chemistry measurements,
as these are essential to ensure the establishment and long-term maintenance
of data quality across multiple platforms and instruments.
Upper
Air Measurements
The loss of radiosonde observations (raobs)
will have a negative impact on global numerical weather prediction forecasts
which could be considerably mitigated if appropriate and immediate action
is taken to use satellite sounding and wind data over land where the
raobs are being removed.
Full capability of current satellite
remote sensing measurements is not being realised. More resources must
be focused towards better usage of the data.
The present suite of satellite observations
does not meet median or optimum NWP requirements, with wind profiles
needing the most improvement. Additionally, a global geostationary sounding
capability is required.
System simulation experiments are required
in order to study the impact of future observing systems as well as
to synthesise the best composite observing system (satellite, ground,
and other) and strategies such as adaptive observations.
Space agencies must work with NWP
centres to enhance use of satellite observations over land in the near-term
to help mitigate the decrease in radiosonde observations.
GODAE
Overall, in terms of spatial resolution,
frequency and timeliness most of the data will be close to optimum for
all the periods and requirements.
In terms of accuracy (RMS), the requirements
are fulfilled at better than the threshold level with the exception
of salinity and wind vectors. However, wind speed data are available
at better than threshold requirement and would cover a gap in vector
data, particularly if other data can provide direction. It is recommended
that the proponents of GODAE should, in collaboration with the suppliers,
revisit the accuracy definition for speed and direction of the instruments
providing wind vector data.
In the case of both winds and ocean topography
there appears to be a problem of long term continuity. Concerning
wind vectors, beyond 2004 there will only be the one double sided scatterometer
flying on METOP/EPS (programme still in the approval process in Europe).
An early confirmation of SeaWinds 2 as a payload on ADEOS III is needed.
In addition, once ENVISAT is launched, the scatterometer on ERS1/2 is
planned to be closed down. It is recommended that SIT address these
problems.
For ocean topography there are no firm
plans for data beyond 2004. It is also recommended that the relevant
agencies consider how continuity of Jason and RA-2 can be ensured.
Of the variables required, only salinity
is unobservable during the GODAE period and it is recommended that the
space agencies consider how they can respond to this technical challenge.
For sea surface temperature and sea ice
cover, there should be no problem with long term availability of adequate
data. Any improvement should focus on the accuracy of SST measurements.
However, this is seen as a low priority compared to those set out above.
Long-term
ocean biology measurements
Initial analyses have shown that existing
sensors and those under development will provide data of useful precision.
Noting that the objectives of this project are presently being carried
out very effectively by the International Ocean Colour Coordinating
Group (IOCCG), it is the appropriate body to develop future recommendations
concerning IGOS to the SIT.
Global
Observations of Forest Cover (GOFC)
Present and future missions of CEOS agencies
should provide ample coarse and fine resolution optical data and C-band
SAR data for GOFC.
SIT should be aware of a serious gap
in L-band data which is likely to occur between the end of the JERS-1
mission (likely 1998-2000) and the beginning of the ALOS mission (planned
for 2003).
A well designed acquisition strategy
is important to ensure sufficient usable fine resolution optical data.
Adequate land cover change information
requires long time series of data and blended high and low resolution
products. The SIT should consider ways of improving the accuracy
of these data by having high and low resolution sensors on the same
platform or flying in tandem.
Disaster Management Support
Strong support and enthusiasm for this
project have been demonstrated by a number of CEOS agencies and organisations
involved with various aspects of disaster management, including civil
preparedness. Noting this promising start, the SIT should continue
to support the project through active participation of agency representatives
in:
- development of information servers
including links to agency systems and, where possible, to relevant data
and information;
- hazard task teams which will address
requirements for specific hazards (eg flooding, fires);
- project planning and oversight.
The SIT should encourage the participation
of space agencies not yet directly involved.
The SIT should assist the project
in developing outreach initiatives, especially for developing countries.
2.2
Database and analysis process recommendations
The main lesson is that the analysis
of satellite requirements and performances is a very complex matter
that cannot be accomplished without significant effort and time. Furthermore,
unless sufficient resources are devoted to the problem then the results
of the analysis will be misleading and dangerously counter-productive.
In this context the AG reviewed the scope
of the analysis process, the suitability of the available databases
and the analysis methodology. As regards scope, the AG recognised that
user groups were already studying the theoretical capabilities of satellite
systems, so that the AG could concentrate on the current and probable
product plans of the space agencies.
A comparison of the two sets of results
could then in due course serve to identify short-term improvements to
the existing systems. The AG should not concern itself with matters
such as data policy and data costs, although this would be of concern
of the projects.
Concerning the databases, the AG recognised
that considerable efforts had been made, notably in June 97, to populate
them, but that there were still very significant errors and omissions.
As a consequence of this experience the AG makes a number of recommendations:
- that the quality control of the
databases must be drastically improved;
- that a single entity should become
the focal point for all queries and suggestions regarding the structure
and content of the database, with CEOS Members and Affiliates still
"owning" the data;
- that further efforts must be made
to populate and correct the database.
Significant effort is required from CEOS
participants to realise the potential of the database. Without a reliable
database, the work of the AG is undermined and no robust decision regarding
the implementation of an IGOS can be made. The AG recommends, with
the highest priority, that CEOS participants provide sufficient resources
to correct factual errors in the database immediately.
As regards the analysis tool, the AG
noted that this had been created initially to deal with upper air data
for NWP. It had been optimised for that purpose and its use for other
applications revealed some problems which were corrected after the Tokyo
workshop. However, the tool itself revealed that there was a number
of underlying problems with some of the definitions, including those
of resolution and accuracy, which need to be addressed in further developments
of the database.
Example summary charts (for the Upper
Air project) are attached to this Executive Summary, while the corresponding
parameter data sheets are attached to the main report. These example
summary charts were constructed after making local corrections to the
information extracted from the database.
2.3
Cross cutting issues
Each project should report to the SIT,
including its progress in defining a long-term strategy, a schedule
of milestones, and specific recommendations or requests, where appropriate,
for CEOS agency action.
Once the initial deficiencies of the
CEOS database are addressed and an effective oversight process put into
place, in the longer-term the CEOS database should be expanded to address
wider project needs such as integrated data products. IGOS should have
access to other sources of data such as in-situ sources of observations.
The SIT should address data policy
issues to encourage, rather than inhibit, the use of CEOS agencies'
data for the IGOS pilot projects.
Timely availability of baseline datasets,
such as gravity and digital terrain models, must be included in the
overall IGOS consideration, even if not specifically associated with
a pilot project.
3
Recommendations for the way ahead
The AG concluded that considerable progress
had been made with the analysis process and with the understanding of
the factors which are important for further development of the database.
It believes that the six SIT projects have made considerable progress
in their planning in conjunction with the AG process.
This was a very intensive activity, with
three large meetings within the space of six months. Such a high level
of activity is not justified for the future and the AG believes its
work can be continued more efficiently through much smaller groups.
The continued evolution of the database
and analysis tools should be monitored through a small (2 -3 persons)
"Common Dataset Validation Team" that has been set up by the CEOS Secretariat.
This team should encourage all participants to check and correct their
entries in the database as soon as possible. Only when the database
problems have been addressed can future meaningful analyses be conducted.
It is clear that some group which sits
outside each of the projects, but which has direct access to the results
of their work, is needed. It is therefore proposed that a recommendation
to CEOS Plenary is made that these activities take place within the
framework of the SIT, possibly by establishing an SIT subgroup. The
roles should be to:
i) synthesise the recommendations of
the six existing projects and any new projects that may be defined;
ii) draw general inferences from the
output of the projects and any new future projects;
iii) remain informed on the scientific
integrity of the common dataset as implemented by the Validation Team;
iv) assist in the development of analysis
tools in response to projects' needs;
v) maintain oversight of those requirements
of Affiliates which are not addressed within the six projects and ensure
that these are taken into account in the future development of an IGOS.
The AG considers that its initial task
has been achieved. Given the establishment of the group referred to
above, a recommendation to dissolve the AG should be made to the 1997
CEOS Plenary.
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