Retrievals of Parameters Characterising Land Surface Interactions from the satellite-derived Ts/VI Feature Space

Earth Observation (EO) when used synergistically with simulation process models provides a promising direction towards estimating key parameters characterising land surface interactions (LSIs). Some of the most commonly used techniques for this purpose are based on the physical relationships encapsulated in the feature space established when a satellite-derived land surface temperature (Ts) is plotted against a spectral vegetation index (VI).

The objective of this study has been two-fold: first to explore the effectiveness of one such Ts/VI technique, commonly called the “triangle” method, to retrieve soil moisture and evapotranspiration rates, when integrated with ESA’s Sentinel-3 satellite data. Secondly, to appreciate the ability of this technique to retrieve new biophysical parameters characterising LSIs, namely the Evaporative (EF) and Non-Evaporative (NEF) fractions, CO₂ & O₃ fluxes and Water Use Efficiency (WUE).

Predicted parameters were compared against co-orbital ground measurements acquired from several European sites belonging to the CarboEurope ground observational network. The main preliminary findings of the study are presented and the main challenges that still impede their accurate spatio-temporal estimation by the TS/VI domain are also highlighted.

To our knowledge, this study represents the first comprehensive exploration of the performance of this particular methodological implementation using Sentinel-3 EO and is the first investigation into the effect of extending this particular method to retrieve spatiotemporal estimates of other key LSI parameters from the TS/VI domain. As such, this study is of considerable value in regards to the future use of this inversion modelling scheme, opening up potentially new opportunities in future implementations of it in many practical applications and research investigation alike.

In the present work Dr Petropoulos participation has received funding from the European Union’s Horizon 2020 research and innovation programme ENViSIoN under the Marie Skłodowska-Curie grant agreement No 752094.

KEYWORDS: land surface interactions, Sentinel 3, Ts/VI domain, triangle, CarboEurope