Modeling radiation, heat and mass (water vapour and carbon) exchanges at the land-atmosphere interface using multi-angular optical and thermal measurements

Background

Global change projections on decadal and century time scales are built on foundations of conceptual understanding for homogeneous areas and therefore have significant uncertainty associated with the difficulty in the representation of land-surface processes over real heterogeneous land surfaces. With the advent of a new generation of global imaging spectroradiometers capable of acquiring simultaneous multi-angular observations, both qualitatively new approaches and quantitative improvements in accuracy are achievable by exploiting the multi-angle signals. However, a consistent modelling of the complete spectra from 0.3 to 14 µm and its coupling with detailed processes of turbulent heat, water vapour and carbon exchanges in understanding the 3D nature of these processes remains a major challenge. This project builds upon existing concepts such as the theory underlying the model families SAIL and CUPID, but extending both theory and modelling approach to deal with truly 3D canopies and the related 3D nature of convective transfer of energy, heat and mass (water and carbon) in the canopy space. This will contribute significantly towards a better understanding of land – atmosphere exchange processes of radiation, heat and mass at heterogeneous land surfaces based on multi-angular synergistic optical and thermal measurements obtained with space- and airborne sensors. Data obtained with existing multi-angular observation systems will be used to assess the added value of the multi-angular synergistic hyper-spectral and thermal infrared capabilities of new satellite missions.

Objectives

There are four work packages in this project as:

-	Description the 3D nature of vegetation – soil mixtures in coupled radiative and turbulent heat, water vapour and carbon transfer processes for different canopy types (SAIL model family, CUPID).

-	Investigation of the exact coupling of the different radiation and heat fluxes in a realistic 3D canopy.

-	Developing detailed 3D model components incorporating 3D description of the canopy, spectral and directional variability of emissivity, and the directional behaviour of reflection and emission.

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Development of a theoretical description and its realization in a modeling system of the coupled radiation, heat, water vapour and carbon fluxes at the land-atmosphere interface (EcoRTM) for the exploitation of multi-directional and synergistic hyperspectral-radiometric observations to be provided by future Earth Observation satellite sensors.

The major deliverables and milestones will be:

-	Report of the requirements for 3D description of different canopy structures, improved new model code of the different components. Progress meeting and progress report.

-	Conduction of new field experiments, a comprehensive set of field experiment data and satellite data for further analysis and improved process description. Progress meeting and progress report.

-	Synthesis of experimental results, improvement of all model components on the basis of experimental findings. Progress meeting and progress report.

-	Availability of EcoRTM system and image simulation results compared to actual satellite data. Progress meeting and progress report.

A dedicated field experiment site near Enschede, in collaboration with the waterboard Regge and Dinkel and the foundation Nutuurmonumenten, is being established as part of ITC Earth Observation Sites for Research and Education.