The Envisat satellite has an ambitious and innovative payload designed to ensure the continuity of the data measurements from ESA’s ERS satellites. Envisat data supports Earth science research and allows monitoring of the evolution of environmental and climate changes. Furthermore, the data will facilitate the development of operational and commercial applications.
The main objective of the Envisat programme is to provide Europe with an enhanced capability for remote sensing observation of Earth from Space, with the aim of furthering the ability of participating states to take part in the studying and monitoring of the Earth and its environment.
Its primary objectives are:
- to provide for continuity of the observations begun with the ERS satellites, including those obtained from radar-based observations;
- to enhance the ERS mission, notably the ocean and ice missions;
- to extend the range of parameters observed to enable us to learn more about the factors determining the environment;
- to make a significant contribution to environmental studies, notably in the area of atmospheric chemistry and ocean studies (including marine biology).
These are coupled with two related, secondary objectives:
- to allow the Earth’s resources to be more effectively monitored and managed;
- to improve our understanding of solid Earth processes.
The mission is an essential element in providing long-term continuous data sets that are crucial for addressing environmental and climatological issues. It will at the same time further promote the gradual transfer of applications of remote sensing data from experimental to pre-operational and operational exploitation.
Envisat, as an undertaking of ESA member states plus Canada, constitutes a major contribution to the effort of Space agencies worldwide to provide the data and information required to further the understanding, modelling, and prediction of environmental and climate changes.
This mission includes both global and regional mission objectives (see below) with the corresponding need to provide data to scientific and applications users (see below) within various time scales.
Continuous and coherent global data sets are needed by the scientific and application community in order to understand more about climate processes and to improve climate models.
Some global applications require near-real-time data delivery (within a few hours to one day of acquisition). Specific examples include:
- ” forecasting the sea state conditions at various scales;
- monitoring sea surface temperature;
- monitoring some atmospheric species (e.g., ozone for warning purposes);
- monitoring some atmospheric variables (e.g., temperature, pressure, water vapour, cloud top height, earth radiation budget, etc.);
- monitoring ocean colour for supporting fisheries and pollution monitoring (complementing the regional missions).
Some of the global objectives require products available in off-line mode (days to weeks of acquisition). Specific examples include quantitative monitoring of:
- radiative processes;
- ocean-atmosphere heat and momentum exchange;
- interaction between the atmosphere and land or ice surfaces;
- composition of the atmosphere and associated chemical processes;
- ocean dynamics and variability;
- ice sheet characteristics and sea ice distribution and dynamics;
- large-scale vegetation processes in correlation with surface energy and water distribution;
- ocean primary productivity;
- natural and man-made pollution over the oceans;
- support for major international programmes (GCOS, IGBP, etc.).
Continuous and coherent regional data sets are needed by the scientific and application user community for a variety of objectives such as:
- ” sea ice off-shore applications;
- detecting and mapping snow and ice;
- monitoring coastal processes and pollution;
- monitoring ship traffic;
- monitoring agriculture and forests;
- monitoring soil moisture and large-scale vegetation processes;
- geological features and mineral resources;
- applications linked to SAR interferometry (DEM generation, hazard monitoring, etc.);
- hydrological research and applications;
- support for fisheries in coastal waters.
Some of the regional objectives (e.g., sea ice applications, marine pollution, maritime traffic, hazard monitoring, etc.) require near-real-time data products (within a few hours of acquisition) generated according to user requests. Others (e.g., agriculture, soil moisture, etc.) require fast turnaround data services (a few days). The remainder are generally satisfied with off-line (few weeks) data delivery.