Memorandum 49
Submission from the National Physical
Laboratory
0. SUMMARY
0.1 The UK has the key elements of infrastructure
and expertise necessary to take full advantage of the emerging
opportunities from Earth Observation. However, the lack of data
quality and inflexibility of funding mechanisms within the UK
are a major barrier to the development of a flourishing EO-based
industrial sector, and to the provision of reliable data to inform
and monitor policy decisions.
0.2 Opportunities exist and are emerging
for the UK to take a lead role in a number of key aspects effecting
data quality. These opportunities need to be nurtured and targeted
as priority issues for the UK in order to maximise the benefit
of Earth Observation to the UK and for it to remain at the forefront
of public imagination inspiring the next generation of scientists.
1. INTRODUCTION
1.1 This submission is made on behalf of
the National Physical Laboratory, the UK's national standards
laboratory, which underpins the National Measurement System (NMS),
ensuring consistency through traceable calibration of all measurements
throughout the UK, and that UK measurements are similarly compatible
with our international trading partners.
1.2 Our role is to deliver world-class measurement
science, to provide measurement infrastructure for the UK and
to maximise the impact that this science and infrastructure has
on the UK economy and quality of life—including key issues
such as climate change and the maintenance and development of
a sustainable environment.
1.3 This submission draws on our expertise
in measurement science and our knowledge of the international
space sector derived in part from our leadership role in a variety
of Earth Observation calibration and validation activities.
1.4 In addition to the development and provision
of measurement and instrumentation services to the space and in
particular Earth Observation community, NPL represents the UK,
and in some cases the international metrology community as a whole,
on a number of key committees. These include Committee on Earth
Observation Satellites Working group on Calibration and Validation
(CEOS WGCV), Network for Detection of Stratospheric Change (NDSC)
and World Meteorological Organisation (WMO). It also supports
UK government funded research within the research councils and
government policy (in this context) through Defra, DTI and associated
agencies. NPL is recognised as the European lead national metrology
institute (NMI) in this sector and is providing strategic support
to the European Space Agency (ESA).
1.5 NPL and metrology play a major role
in many other space activities, eg:
— Time standards necessary for satellite-based
global positioning systems.
— Communications between satellites
and to ground.
However, this submission focuses on an area
in which metrology is most critical—Earth Observation (EO)
data, ie data collection at satellite sensor through to highly
processed data (data product) as received by the "end user"
or customer. At present, the end users are predominantly public
funded bodies, where EO data is increasingly providing the critical
evidence for the development and monitoring of the impact of government
policy.
2. THE IMPORTANCE
OF DATA
QUALITY FOR
EVIDENCE-BASED
POLICY DEVELOPMENT
AND MONITORING
2.1 It has long been recognised that measurements
used for trade and regulation must be based upon an agreed international
system of units. Such a system was formalised through the Convention
of the Metre in 1875, which set up the System International for
measurement units, which is used around the World today.
2.2 However, the Convention only defines
the base units, and in the intervening 130 years formalised arrangements
have been established, eg quality procedure covered by ISO 17025,
to ensure the validity of measurements made against the SI units.
These have ensured that items for trade can be reliably specified
across national borders, for example precision pieces of an automobile
engine can be manufactured in more than one European State and
assembled in another. They also ensure that regulators and policy
makers can carry out their work with confidence, for example emission
levels from vehicle engines can be evaluated by the manufacturer
and then the vehicles traded around the World subject to national
emission control regulation.
These examples demonstrate one of the
essential requirements for a market, confidence in the commonality
and reliability of measurement data on the products or services
traded.
2.3 Clearly this requirement has not gone
unnoticed by those designing and operating Earth Observation data
collecting instrumentation. They all make their measurements using
the same SI units. However, there is no formalised arrangement
in Europe to ensure the general validity of such data. Indeed,
there is strong evidence that data collected by different EO instruments
often have significant discrepancies. For example this is a factor
in the international controversy over the issue of climate change.
The discrepancies and biases do not arise from any lack of care
in the design and calibration of EO instrumentation, but from
the extremely challenging requirements for accuracy that are made
on such instruments, if the data they collect are to meet the
requirements of policy makers and regulators, and of the challenges
of operating in the hostile space environment.
2.4 Until recently most EO satellite missions,
with the exception of meteorological satellites, have been initiated
and operated to meet clear science driven objectives. However,
as their success is promoted to a wider user community, new applications
become apparent. These applications, like the weather services,
often require data products to be produced in a more operational
mode—focusing more on reliability and consistency than the
flexibility often seen as a necessity accompanying a science mission.
To meet these emerging demands, many science missions have been
modified to produce some products in an operational manner. It
has also triggered initiatives such as GMES (Global Monitoring
for Environment and Security), which seeks to build the necessary
infrastructure to enable true operational services to be developed
and exploited to the benefit of European industry and its citizens.
Such services draw on data derived from all components of the
EO sector: space, in-situ, airborne and in most cases the
synergistic combination of them.
EO operational services are unlikely to
successfully develop for monitoring the environment and security
without establishing formalised arrangements for validating the
data collected by EO instruments, both terrestrial and space borne.
2.5 The establishment of the joint EU, ESA
GMES initiative is a measure of the importance governments and
the Commission have given to issues that EO data can help to address.
This has been further reinforced through the establishment of
the global initiative, GEOSS (Global Earth Observation System
of Systems), which seeks to establish coordinated efforts between
largely existing activities to address a set of key societal themes.
2.6 Examples of applications for EO data
include:
— Understanding the drivers for climate
change:
— To inform European policy on
necessary steps to protect the living conditions of citizens,
whilst not putting at risk European competitiveness with ineffective
or unnecessary emission controls.
— To remove any equivocation over
the affects of human activity on the Earth's climate, to strengthen
the European negotiation position with countries which are not
yet convinced of the urgency to reduce industrial and transport
emissions.
— Monitoring the effects of climate
change:
— Monitoring European costal zone
to manage the effects of sea level rise.
— Monitoring biodiversity.
— Monitoring of food production, pests
and disease across Europe.
— For the security of food production.
— To measure the impact and police
subsidies provided by the EU to food producers.
— To measure the impact of the
release of GMO on biodiversity.
— Monitoring air and water quality
for the health of citizens.
— Monitoring and policing pollution
so that those responsible for major pollution events can be challenged
for compensation.
— Management of major calamities, eg
cyclones, floods and storms.
These issues affect decisions on investments
and regulations that will have significant economic impact in
Europe and require data that is unequivocal, from which international
protocols that tackle issues at a global level can be agreed,
and ultimately will require data that is robust enough to be challenged
in court.
3. UK STRENGTHS,
WEAKNESSES AND
OPPORTUNITIES
Strengths
3.1 The UK is internationally recognised
as being strong in many aspects of Earth Observation. It has a
well-coordinated academic research community funded through the
research councils. This community is involved in all aspects of
Earth Observation including: instrument design, build, calibration,
validation and operation. It exploits and develops expertise in
modelling and data manipulation as well as the more engineering-based
activities.
3.2 The UK also has an efficient and expanding
"added value" commercial sector, which develop application
specific data products. The strength of this sector stems from
government policies of the 1980s, which emphasised that funding
for Earth Observation should be focused on applications with commercial
or Government policy objectives. The industrial sector is also
engaged in some hardware manufacturing, which includes instrumentation
and platforms etc. It is worth noting that it has become particularly
strong in the small satellite business, with Surrey Satellite
Technology Ltd being a particularly good example.
3.3 Finally the UK has a potentially large,
relatively astute and innovative user community. Public funded
bodies already use remote sensing for a wide range of operational
activities including land/forest management, pollution and air
quality monitoring, mapping etc. Climate change studies, monitoring
and adaptation to its impact are arguably the most demanding (in
terms of accuracy) of current applications. However, whilst there
is some coordination between government agencies and departments
this is very weak and leads to inefficiency and fragmentation.
It leads to duplication of effort in studies and expertise, but
more seriously it prevents the development of critical mass to
allow coordinated funding for larger scale projects, which would
allow the UK to take on greater international leadership roles.
Sufficient critical mass might stimulate and justify UK led missions
with more operational objectives, controlled by user needs.
The UK has a strong infrastructure in
all aspects of Earth Observation and is well placed to play a
major role in exploitation.
Weaknesses
3.4 Although the UK EO sector has many strengths,
it regularly fails to achieve its "juste retour" from
its ESA contribution. This failing is because the necessary full
complement of key skills and prototype technologies are not available
to make credible bids. The success of nations such as Germany
and France can often be attributed to the underpinning support
of strong national programmes, which allow critical mass and expertise
to be developed and maintained in the interim periods between
the larger ESA missions. It also allows strong links to be established
between academia and the commercial sector with the ready supply
of data to further research aims. National programmes also encourage
the establishment of clear national objectives for both science
and policy and make possible the development of low cost missions
to meet defined priorities. These in turn help to steer the direction
of the multi-national bodies such as ESA and EUMETSAT and act
as catalysts for wider international collaborations with agencies
from Japan, USA etc.
3.5 The British National Space Centre (BNSC)
whilst being the de facto focus for space activities in
the UK, has few mechanisms or resources to influence or steer
UK and international efforts. Despite this the UK still manages
to play a significant role in international affairs, through the
efforts of individuals and targeted funding from BNSC. BNSCs influence
was weakened when most of the UK space budget was transferred
to the research councils. The government aim was to simplify funding
by bringing together all discretionary research funding. Whilst
this has advantages, it limits flexibility and innovation particularly
for more application-focused research objectives because of eligibility
criteria attached to the funding mechanisms of the research councils.
In particular, Public Sector Research Establishments (PSREs) such
as NPL cannot be directly funded by research councils for EO research.
Not only is this a barrier to innovation, in some cases it can
lead to inefficiency and duplication of capabilities. There are
many examples of university departments obtaining research grants
to establish capabilities for "one-off" experiments
or calibrations when facilities already exist in a developed or
semi-developed form within a PSRE. Similarly, it is difficult
for PSREs to take part in "Announcement of Opportunity"
(AO) calls from ESA, since they often require as a prerequisite,
national funding. This is particularly true for calibration and
validation activities within ESA, which are nearly always by AO
calls, and as a consequence are limited in participation to academic
institutions.
3.6 This inflexibility and restriction on
participation is particularly damaging for the future of the EO
sector. The evolution of EO from largely science driven objectives
into user driven services requires robust, operationally delivered
data products targeted at user needs. The operational production
and delivery of these services will be through commercial organisations.
Such services, both as delivered and during development, will
require a more rigorous, transparent level of Quality Assurance
(QA) and hence calibration and validation than is currently provided.
Although still largely science based, this same level of QA is
increasingly demanded of climate change studies in order to allow
governments to take informed evidence based policy decisions.
It is hard to see how the QA necessary to meet these demands can
be achieved without significant change to calibration and validation
practices.
Opportunities
3.7 As the market for quality assured EO
data develops it presents a significant opportunity for the UK
to provide the necessary infrastructure to underpin this "certification"
activity. The British Government is well versed at championing
and implementing appropriate regulatory frameworks to satisfy
all stakeholder interests. Politically it continues to provide
international leadership for environmental issues, a position
and activity acclaimed by all political parties. The already strong
added value space sector is well placed to exploit new "certified"
data products.
However, this opportunity may be missed
by the UK because of the fragmented nature of funding from government
departments and the limited access to the only major UK source
of space research funding through the research councils.
CASE STUDY
The following example illustrates an innovative
opportunity for the UK to establish a unique position as the international
benchmark reference for all optical-based Earth Observation measurements
made from space. In addition, it provides the necessary accuracy
to reduce uncertainty in measurements underpinning climate change,
and consequently removing the opportunity for sceptics to debate
its cause and consequences.
The Earths biosphere and climate is driven by
the input energy from the Sun. This energy is largely concentrated
in the optical region of the spectrum from the UV to NIR (200
to 2,500 nm). All surfaces, vegetation, soils etc exhibit unique
spectral signatures in their reflectance characteristics, in the
case of vegetation this varies not only with species but also
life cycle. Similarly pollutants, on land and water, aerosols
in the atmosphere can all be characterised, qualitatively and
quantitatively by their spectral signature. For some simple diagnostics,
spatial maps, land cover etc, absolute accuracy is of limited
importance. However, as soon as temporal information is required,
such as is necessary for climate change, or that the data needs
to be combined with another sensor, then accuracy becomes critical.
The calibration of every optical sensor launched
into orbit has changed from ground to orbit, and continues to
degrade with time. The size of this change varies between sensor
type and even between nominally identical sensors. This make it
difficult to establish a baseline from which to reference climate
change and also to compare and combine data products from different
missions, since each sensor will be seen to have an unknown bias
with respect to the truth.
The solution to this problem, bias and drift,
in principle is simple and only needs to reflect the processes
employed in the terrestrial environment ie regular recalibration
against SI standards traceable to a national standards laboratory.
However, the inability to retrieve space sensors makes this difficult
to achieve in practise. As an alternative, in-flight calibration
systems have been devised, but all fail in varying degrees with
respect to the necessary accuracy and demonstration of traceability,
as the transfer artefacts used, also drift with time.
Recognising the issue the international community
is starting to consider the establishment of a dedicated space-based
reference satellite, which could serve to provide a set of "benchmark
calibrations" of the Sun, Moon, Earth deserts, which all
other in-flight sensors could view allowing the removal of bias
through normalisation. If the reference satellite were sufficiently
accurate this would also improve the accuracy of the other sensors
in addition to simply removing bias.
Although the call for such a mission concept
is only now being discussed internationally, the UK already has
a designed solution. In 2003, NPL led an international team in
a proposal for a mission called TRUTHS (Traceable Radiometry Underpinning
Terrestrial- and Helio- Studies). The proposal was in response
to an ESA call for Earth Explorer missions and although at the
time was unsuccessful stimulated significant interest for its
innovative concept.
TRUTHS proposed the flight of a small satellite
with a suite of instruments to measure incoming solar radiation
and spectrally resolved reflected radiation from the Earth or
Moon. The instrumentation was designed to have accuracies 10x
better than any previous mission. This accuracy was guaranteed
by the use of a novel calibration system, which incorporated a
"primary standard" and the establishment in space of
calibration chain analogous to that carried out on the ground.
In essence, the satellite could be considered as a "standards
laboratory" in space and is widely acknowledged as the only
technically viable solution to achieve the accuracies necessary
for such a benchmark mission.
The TRUTHS satellite would provide traceability
to all other optical sensors by transferring its high accuracy
to commonly viewable reference targets such as the Sun, Moon and
Earth deserts.
Whilst acknowledged as a breakthrough concept,
it is surprisingly difficult to develop and exploit the idea further,
even to the stage of a full study. Although all technologies required
for implementation are available within the UK there is no funding
mechanism for its development, as the idea originated within a
PSRE. A further barrier to funding is the wide range of applications
it would address, underpinning, measurements of the Oceans, Land
and atmosphere for Earth Observation and measurements of the Sun.
Each of these applications is considered separately when evaluating
a project for funding. All four academic communities are supportive
of the aims of the project but find it difficult to pool resources
for a shared mission, which they perceive has a large "operational"
component, and insufficient focus on each of their own individual
objectives.
EO does not as yet have sufficient priority
within any one government department for data quality to be seen
as a driver, or for which the additional international kudos that
would be generated, to be considered important.
However, with the international community starting
to request a mission for which TRUTHS is the only currently proposed
response, it will not be long before the ideas are exploited elsewhere.
This will result in a lost opportunity for the UK to lead a project
that provides the foundation of data quality for Earth Observation
measurements in the future, which will underpin policy decisions
that affect the future of the whole planet.
October 2006
| 
