Context and objectives
In the water cycle, land evapotranspiration is the water vapour exchange from the surface to the atmosphere, through ground or water bodies evaporation and vegetation transpiration processes. In meteorology, climatology and water studies, it is an essential variable to determine. Estimation at large scale is still very difficult, but recent advances in remote sensing pave the way to a better monitoring at continental scale.
Remote sensing is gaining more and more interest for the land surface modelling applications and to new method to monitor evapotranspiration. In this context, an operational model, LSA-SAF ET, has been developed based on MSG/SEVIRI derived data, to provide land evapotranspiration estimates over Europe, Africa and South America at 3 to 5 km resolution (http://landsaf.meteo.pt).
The objective of this study is to assess the benefits and possible improvement of using biophysical parameters derived from moderate to high resolution remote sensing (e.g. PROBA-V) for the monitoring of the evapotranspiration at the kilometer scale over large areas (continental scale). More specifically, this project aims at
- the improvement of the LSA-SAF land evapotranspiration product over large continental areas, and also
- studying the interest of biophysical variables derived from the upcoming satellite for other land surface modelling applications.
Expected scientific results
We will develop a methodology for an optimised use of PROBA-V like vegetation data for ET monitoring over large areas, i.e. continents, at a few kilometers scale, and especially for the LSA-SAF ET model. Improved results should occur for regions where the landscape is very patchy, and where vegetation changes fast. We expect a full evaluation of the remote sensing possibilities regarding biophysical parameters, by comparing against a wide range of observations and models. We plan to deliver recommendations on the use of PROBA-V like derived biophysical parameters in different applications of land surface models, and especially the LSA-SAF land evapotranspiration.
We expect to contribute to the efforts in monitoring land evapotranspiration at the sub-kilometer scale over large areas, by studying new synergies between remote sensing data across different spatial scales.