10.1 Land Cover Change
Dr Cihlar introduced the subject by reviewing the status of land cover mapping. Land cover and cover change are important environmental variables identified by TOPC (Global Climate Observing System, 1997). In addition tot he general importance of land cover products, they are a critical input to the two pilot projects, NPP/NEP and GOFC.
In recent years, significant progress has been made in the development of global land cover products at the resolution of ~1000 m, and two global products have been completed from AVHRR composites (accessible through GOSIC). In addition, rapid progress may be expected over the next two years with the imminent launch of EOS Terra and research groups poised to use the ensuing data for land cover mapping.
Significant methodological development is required for the high resolution data (~25 m). Because of the mosaic-type coverage of large areas constituted by individual scenes, the data processing and classification procedures are not yet uniform and sufficiently automated to produce consistent regional or global products. Nevertheless, there are a variety of approaches and some convergence is developing towards a consensus strategy in this area. Several countries or research institutions have mapping programmes under way that cover fairly large areas and whose experience is highly relevant to the development of a globally applicable methodology.
TOPC discussed the above issues, with a view to defining a strategy for the production of quality land cover data sets for climate-related applications. It was agreed that, for the medium-resolution data (250-1000 m), TOPC and the two pilot projects should establish closer linkages with research teams involved in this area. For fine resolution data, there is a need to review the experience with various approaches with a view to defining a consensus approach(es), possibly regionally dependent. Given the special interest of GOFC in these products; and the planning and contacts already established, GOFC provides a suitable mechanism for attempting to obtain this consensus. It was also recalled that at the first GOFC workshop in Ottawa, a number of participants expressed interest in a community activity regarding land cover classification methodologies from high resolution data
Regarding land cover data sets, TOPC made the following recommendations:
Recommendation 10.1: TOPC recommends that close links be established with groups involved in the preparation of global or significant regional data sets, to facilitate early access to such data sets and to highlight their availability for G3OS purposes.
Recommendation 10.2: TOPC recommends that GOFC take the lead in organising a workshop on land cover classification and mapping methodologies involving high resolution data sets over large areas.
