Land surface remote sensing in continental hydrology

The transfer of energy and water, as well as gaseous components, in the soil–plant–atmosphere system plays a crucial role in many processes involved in climate change. The surface energy balance drives both evapotranspiration (closely linked to the CO2 flux) and sensible heat flux. By providing direct information on heat dissipation efficiency, surface temperature appears to be a key variable. In particular, a lot of work has been conducted on estimating evapotranspiration from thermal infrared (TIR) remote sensing measurements, in order to derive information relevant to agriculture (monitoring plant growth, detection of water stress, crop yield forecasting, etc.) or hydrology (water cycle monitoring, catchment water budget, etc.). This chapter first very succinctly presents the relationship between surface temperature and the surface energy balance, providing the reader with reference publications for further reading. This is followed by a review of the data available in the thermal infrared (TIR) domain and an analysis of various sources of uncertainty affecting surface temperature measurements and their impact on the final accuracy. The different methods for estimating and spatializing actual evapotranspiration (AET) are then discussed. Finally, practical applications of TIR information other than AET are briefly mentioned

Exploiting satellite altimetry in coastal ocean through the ALTICORE project

International audienceAltimeter-derived information on sea level and sea state could be extremely important for resolving the complex dynamics of the coastal ocean. Satellite altimetry was not originally conceived with coastal ocean in mind, but future missions (AltiKa and CryoSat-2) promise much improved nearshore capabilities. A current priority is to analyze the existing, under-exploited, 15-year global archive of coastal altimeter data to draw recommendations for these missions. There are intrinsic difficulties in processing and interpretation of the data, e.g.: the proximity of land, control by the seabed, and rapid variations due to tides and atmospheric effects. But there are also unexploited possibilities, including higher along track data rates and multi-altimetry scenarios that need to be explored. There are also difficulties of accessing and manipulating data from multiple sources, many of which undergo regular revision and enhancement. In response to these needs, the ALTICORE (ALTImetry for COastal REgions - www.alticore.eu) project started in December 2006, funded for two-years by the European INTAS scheme (www.intas.be). The overall aim of ALTICORE is to build up capacity for provision of altimeter-based information in support of coastal ocean studies in some European Seas (Mediterranean, Black, Caspian, White and Barents). ALTICORE will also contribute to improved cooperation between Europe and Eastern countries and enhance networking of capacity in the area of satellite altimetry. This paper discusses the approach, summarizes the planned work and shows how the coastal community should eventually benefit from better access to improved altimeter-derived information