Long-term observations of land surface characteristics

There is a new awareness of the potential importance of land surface observations in climate studies. This paper suggests a three-pronged, (in situ, satellite, and numerical model-based) observation strategy for land surface observations in the Global Climate Observing System (GCOS). This strategy is based on the premise that the land surface's importance lies in its links to the atmosphere and, in particular, in its role in determining and modulating the fluxes of momentum, sensible and latent heat and in the surface radiation budget. Specific suggestions include: (a) harnessing the potential of the WMO's World Weather Watch to provide regular observations of key land surface properties i.e., soil moisture and soil temperature; (b) utilization of satellites to provide land surface 'reference' data sets and encourage development of stable satellite data sets for land surface monitoring; and (c) use of numerical-model-based data assimilation systems (DAS) to augment in situ and satellite observations.