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GCOS Ocean Surface ECV Definition: Ocean color is an ECV needed to support the carbon cycle monitoring requirements of the UNFCCC (United Nations Framework Convention on Climate Change). It is also a climate variable that cannot be globally monitored without using satellite observations. In order to cover the long time span necessary for climate monitoring purposes, the required ocean color data set can only be built by merging together observations made with different satellite systems. Data-merging is also necessary to achieve global daily coverage, as no single sensor is capable of observing every part of the globe every day. To ensure that different periods of the ocean color time series can be compared, merging together data from differently engineered satellite systems requires a very thorough calibration and validation covering the entire spatial and temporal extent of the data set. This last aspect is essential if the data set is to achieve the required quality to become an accepted Climate Data Record, defined as a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and change. More... (from the GlobColour web site) Introduction: Knowledge of ocean ecosystem change is not adequate. Satellites provide global coverage of surface ocean colour, but the linkage between surface ocean colour and ecosystem variables, including chlorophyll-a and its distribution with depth, remains limited. In addition, enhanced in situ sampling of ocean colour and ecosystem variables is technically feasible.
The most important OCR data products currently in use are chlorophyll-a concentration (a proxy for phytoplankton biomass), coloured organic matter, particulate organic carbon, and suspended sediments. Other products are in development. OCR data products are the only measurements related to biological and biogeochemical processes in the ocean that can be routinely obtained at ocean basin and global ocean scales. These products are used to assess ocean ecosystem health and productivity and the role of the oceans in the global carbon cycle, to manage living marine resources, and to quantify the impacts of climate variability and change.
To address the issues raised above, GCOS and GOOS are supporting the plans being developed through participating CEOS space agencies to implement an Ocean Colour Radiometry Virtual Constellation. The International Ocean Colour Coordinating Group (IOCCG), acting for GOOS and GCOS, will give oversight to ensure the measurements are implemented in accordance with GCMPs and the requirements outlined in the Satellite Supplement to the IP-04, as well as to promote associated research. Satellite Observations: Remote sensing measurements of ocean colour (i.e. the detection of phytoplankton pigments) provide the only global-scale focus on the biology and productivity of the ocean’s surface layer. Phytoplankton are microscopic plants that live in the ocean, and like terrestrial plants, they contain the pigment chlorophyll, which gives them their greenish colour. Different shades of ocean colour reveal the presence of differing concentrations of sediments, organic materials and phytoplankton. The ocean over regions with high concentrations of phytoplankton is shaded from blue-green to green, depending on the type and density of the phytoplankton population. From space, satellite sensors can distinguish even slight variations in colour which cannot be detected by the human eye. Ocean biology is important not only for understanding ocean productivity and biogeochemical cycling, but also because of its impact on oceanic CO2 and the flux of carbon from the surface to the deep ocean. Over time, organic carbon settles in the deep ocean, a process referred to as the ‘biological pump’. CO2 system measurements, integrated with routine ocean colour and ecological/biogeochemical observations, are critical for understanding the interactions between oceanic physics, biology, chemistry and climate. CO2 measurements are also important for making climate forecasts and for satisfying the needs of climate conventions. At a local scale, satellite observations of ocean colour, usually in conjunction with sea surface temperature measurements, may be used as an indication of the presence of fish stocks. Measurements may also be used to monitor water quality and to give an indication of the presence of pollution by identifying algal blooms. Measurements of ocean colour are particularly important in coastal regions where they can be used to identify features indicative of coastal erosion and sediment transfer. An Ocean Theme was set up within the former IGOS framework in 1999 to develop a strategy for an observing system serving research and operational oceanographic communities and other users. Building on the CEOS Ocean Biology and GODAE Projects, the Ocean Theme Team published its final report in January 2001. This brought together information on: the variety of needs for global ocean observations; the existing and planned observing systems; the planning commitments required to ensure long term continuity of the observations. In recent years there has been a steady flow of ocean colour data at various scales from instruments such as OCTS (on ADEOS), SeaWiFs, OCM (on IRS), MODIS (on Terra and Aqua), and MERIS (on Envisat), as well as POLDER and PARASOL. As the timeline shows, a number of current missions will end in the near future. Information available on agency plans indicates that future continuity will be provided by OCM-2 on Oceansat-2 (India), the HY-2 series (China), Sentinel-3 (Europe) and others. Beyond these research or pre-operational missions, NOAA is developing VIIRS for its NPOESS missions – with an operational capability for ocean colour. Four actions were identified in the CEOS response to GCOS requirements: ISRO will lead planning of Oceansat-2, ESA and the EC of Sentinel-3, and JAXA of GCOM-C, which are all new missions planned to carry an ocean colour sensor; relevant CEOS agencies will examine their respective plans to maintain continuity of the 25-km-resolution ocean colour global product; CEOS agencies will cooperate to support the combination of all existing ocean colour data sets into a global FCDR; in consultation with GCOS and the relevant user communities, CEOS agencies will explore the means to secure, by 2011, continuity of the 1-km-resolution global ocean colour product needed to fulfil the target GCOS requirements (satellite Missions) (from the CEOS web site) Satellite Observation: Ocean colour measurements from space are the focus of the International Ocean Colour Coordinating Group (www.ioccg.org/). Additional Information:
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Data, Product, Metadata and Information Access [ECV Matrix Main Page] [About the ECV Matrix] [Reference Documents] [Contact] [Updated February 25, 2011]
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