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Terrestrial Observation Panel for Climate (TOPC)
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Chairman: Prof. Han Dolman.

Anomalies in the fraction of absorbed photosynthetically active radiation (FAPAR) over Europe for August 2003, compared with mean levels for the previous five years. Data are available at http://fapar.jrc.it/.


The Terrestrial Observing Panel for Climate (TOPC) is part of the Global Terrestrial Observing System (GTOS) and the Global Climate Observing System (GCOS). TOPC liaises with relevant research and operational communities to identify measurable terrestrial properties and attributes that control the physical, biological and chemical processes affecting climate, which are themselves affected by climate change, or serve as indicators of climate change.

A major milestone in meeting the TOPC objectives was the completion of the second report on the adequacy of the current climate observing system, prepared for the Conference of the Parties to the UN Framework Convention on Climate Change. This document identified the needs – and, unfortunately, the gaps – in our current climate observing system.

The response from the Parties was to ask for a tenyear Implementation Plan that would eliminate gaps and provide the climate observations needed to support the goals of the Convention. During 2004–2005, TOPC provided the terrestrial components of this plan.

Implementation progress

The Global Runoff Data Centre (GRDC) has identified a network of 380 key rivers worldwide where river discharge monitoring is essential: the Global Terrestrial Network for Rivers (GTN-R). The 80 hydrological services responsible for these rivers have been contacted and GRDC is beginning to receive updates of historical data for some rivers.

Two offers to host a global lakes database – documenting area, levels, temperatures freeze and thaw dates and other lake measurements (Russia and Canada) – have been received by TOPC. Without such central repositories, it will be impossible to build a long-term view of changes in a crucial part of our planet’s freshwater resource. Space agencies, through their Committee for Earth Observation Satellites (CEOS), have agreed to provide multi-decadal climate products covering the terrestrial, oceanic and atmospheric domains wherever possible. Although discussions continue, advanced product generation has begun in critical terrestrial areas, including burn scars, land cover, fraction of absorbed photosynthetically active radiation (FAPAR) and land-surface albedo.

However, internationally agreed validation protocols and benchmarks are not always available for terrestrial climate variables. TOPC and other GTOS science panels, especially GOFC-GOLD, are collaborating with the CEOS’ Working Group on Calibration and Validation to establish such protocols and benchmarks. Formal intercomparison exercises have begun among FAPAR measurements from a range of sensors, and for directional hemispherical reflectance factor (or black sky albedo) products generated from polar orbiting and geostationary satellites. A report describing validation protocols for land cover products has been completed, and selected space agencies have made commitments to the generation of new global land cover datasets at resolutions of 250–300 metres, a significant improvement on currently available global land cover maps.

Future orientations

TOPC will continue to work with space agencies to help ensure that optimum use is made of earth observing satellite data for monitoring the terrestrial component of our climate system. Work will continue with in situ monitoring services to ensure, for example, that gaps identified in the global glacier and permafrost monitoring networks are filled, and TOPC will continue to work with GTOS and GCOS’ sponsors – especially FAO and WMO – on the establishment of a formal process for issuing technical guidelines for terrestrial observations.

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© FAO   ::   Global Terrestrial Observing System - GTOS   ::   20 April 2007