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THE POLAR CONTEXT
An Introduction to Earth Observation
Satellite-borne Earth Observation (EO) systems have been providing imagery for more than two decades, and in recent years have seen a dramatic increase in data availability, quality, and access by end-users. EO is particularly useful for the monitoring of extensive, remote and isolated geographic regions that do not lend themselves easily to conventional, field-based data collection.
The discipline of remote sensing is concerned with the gathering of information about targets of interest from a distance. This is achieved by measuring the amount of electromagnetic energy emanating from those targets. EO systems are broadly classified into passive and active sensors. Passive sensors register the amount of solar radiation reflected or thermal radiation emitted by the earths surface and therefore rely on an external source of illumination. Conversely, active sensors provide their own illumination by generating and emitting electromagnetic energy and measuring the proportion of that energy reflected by the targets of interest.
The principal active remote sensing systems employ synthetic aperture radar (SAR) sensors. SAR systems do not rely on the sun to provide illumination and can therefore acquire imagery day or night. Moreover, the radiation used in SAR sensing can penetrate haze or cloud cover. These systems are therefore particularly desirable in areas, such as the North, that are characterized by significant levels of cloud cover or darkness throughout the year.
The utility of a remote sensing system for a particular application is determined by its spatial resolution, revisit frequency and spectral configuration. Spatial resolution determines the amount of detail that can be captured by the sensor. It is expressed as the size of a picture element (pixel) in ground distance units (e.g. meters). Todays operational EO systems deliver data at resolutions ranging from <1 m to 1 km. A related parameter is the swath coverage the area on the ground covered by a single image which is inversely proportional to the resolution. The revisit frequency of the sensor is defined as the time interval between the successive imaging of the same geographic area. Revisit rates of current systems typically range from less than 1 day to 30 days. The spectral configuration of a sensor includes the number of spectral bands as well as their positioning in the electromagnetic spectrum and their sensitivity.
Polar regions are distinctly different from other geographic areas and share a common set of characteristics, including large, remote areas of limited accessibility; low population densities; sensitive ecosystems of global importance; rich non-renewable (hydrocarbons, minerals) and renewable (fisheries, forestry) resources; and increasing industrial activity.
In recent years, the uniqueness of these
polar regions and their importance to the world has been recognized,
and efforts have been made to develop policies in a cooperative manner
across regions and nations. These policies are aimed at resolving the
specific environmental and development challenges faced by polar regions.
But, how can millions of square kilometers of one of the most remote and difficult regions in the world be monitored? Fortunately, there is a way - the poles are currently covered by wide range of advanced sensors that can continuously monitor many parameters of interest to scientists, residents, and other polar stakeholders. These sensors sit on earth observation satellites.
Earth Observation (EO) is a powerful tool
in the polar context. Because of the extent, remoteness, and isolation
of these regions, remote sensing is often the only cost effective and
technically feasible means of obtaining information. Also, modern sensors
can provide types of information that are not available from any other
source. This information can support monitoring and analysis of issues
relating to the environment, safety, and sustainable development.
Global Monitoring for the Environment and Security (GMES) is a joint initiative of the European Commission and the European Space Agency, designed to establish a European capacity for the provision and use of operational information for Global Monitoring of Environment and Security.
The GMES overall aim is to support Europe's goals regarding sustainable development and global governance, in support of environmental and security policies, by facilitating and fostering the timely provision of quality data, information, and knowledge.
Two main objectives are addressed:
GMES was created in the response to the need by Europe for geo-spatial information services. It provides autonomous and independent access to information for policy-makers, particularly in relation to environment and security.
GMES also represents the European contribution to the international Global Earth Observation System of Systems, GEOSS, which was established at the third Earth Observation Summit in Brussels, in February 2005.
The European Space Agency (ESA) develops the European space programme and ensures that it is carried through. ESA's mission is to shape the development of Europe's space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe.
The Agency's projects are designed to find out more about the Earth, its immediate space environment, the solar system and the Universe, as well as to develop satellite-based technologies and services, and to promote European industries. ESA also works closely with space organisations outside Europe to share the benefits of space.
ESA has 17 Member States, including: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. In addition, Canada, Hungary and the Czech Republic participate in some projects under cooperation agreements.
In November 2001 the ESA Ministerial Council approved a new programme dedicated to GMES, called the Earthwatch GMES Service Element (GSE). In a competitive process, ESA funded 10, and subsequently two additional activities for a "Consolidation Phase". From this, a procurement plan was developed for seven follow-on programs, of which Polar View is one:
Three European-Scale Portfolios (Large)
Four Regional-Scale Portfolios (Medium)
The GSE services will seek to provide valuable information, primarily derived from Earth Observation (EO) data that will help policy makers, public bodies, and nongovernmental organizations (end-user organizations) to formulate, implement, evaluate and adhere to public policies relating to the environment and security at local, national, regional, international and global levels.