Fraction of Absorbed Photosynthetically Active Radiation (FAPAR)
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Solar radiation in the spectral range 400–700 nm, known as photosynthetically active radiation (PAR), provides the energy required by terrestrial vegetation to produce organic materials from mineral components. The part of this PAR that is effectively absorbed by plants is called FAPAR. FAPAR is related to, but different from, Leaf Area Index, which describes the amount of leaf material in the canopy. FAPAR plays a critical role in assessing the primary productivity of canopies, the associated fixation of atmospheric CO2 and the energy balance of the surface. Monitoring FAPAR provides information on the amount and health cycle of vegetation. |
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| Domain: | Terrestrial | |
| Subdomain: | Biology | |
| Scientific Area: | Biosphere | |
| ECV Steward: | Nadine Gobron | |
| Products: | Fraction of Absorbed Photosynthetically Active Radiation | |
FAPAR Satellite Image
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Figure : FAPAR on 12 September 2017 and 22 October 2017 of the same region. Data from Sentinel S2B MSI.
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ECV Products and Requirements
These products and requirements reflect the Implementation Plan 2022 (GCOS-244).
The requirements are found in the complete 2022 ECVs Requirements document as well: ECV FAPAR.
| Products | Fraction of Absorbed Photosynthetically Active Radiation | ||
| (*) | Unit | Values | |
| Horizontal Resolution | G | m | 10 |
| B | |||
| T | 250 | ||
| Vertical Resolution | G | - | |
| B | - | ||
| T | - | ||
| Temporal Resolution | G | d | 1 |
| B | |||
| T | 10 | ||
| Timeliness | G | d | 1 |
| B | 5 | ||
| T | 10 | ||
| Required Measurement Uncertainty (2-sigma) | G | % | 5% for values ≥0.05; 0.0025 (absolute value) for smaller values |
| B | |||
| T | 10% for values >0.05; 0.005 (absolute value) for smaller values |
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| Stability | G | % | <1.5 |
| B | |||
| T | <3 | ||
(*) Goal (G): an ideal requirement above which further improvements are not necessary. Breakthrough (B): an intermediate level between threshold and goal which, if achieved, would result in a significant improvement for the targeted application. The breakthrough value may also indicate the level at which specified uses within climate monitoring become possible. It may be appropriate to have different breakthrough values for different uses. Threshold (T): the minimum requirement to be met to ensure that data are useful.
Data Sources
This list provides sources for openly accessible data sets with worldwide coverage for which metadata is available. It is curated by the respective GCOS ECV Steward(s). The list does not claim to be complete. Anyone with a suitable dataset who wishes it to be added to this list should contact the GCOS Secretariat.
- Copernicus Climate Change Service (C3S) data store
- Satellite ECV Inventory by the CEOS/CGMS Working Group on Climate (WGClimate)
