A conceptual remote sensing based interception-infiltration model for regional and global applications

Abstract. We present a remote sensing driven modelling approach to simulate the one dimensional water transport in the vadose zone of unsaturated soils on a daily basis, which can be used for regional to global applications. Our model needs van Genuchten parameters to calculate the hydraulic conductivity, which we estimated using the ISRIC-WISE Harmonized Global Soil Profile Dataset Ver. 3.1 and the Rosetta programme. We calculated all needed parameters for 26 global main soil types and 102 soils of second order, which are based on the original, global FAO 1974 soil classification. Soil depth and the layering of one to six layers were defined for each soil. The parameters for the main soils are presented in this paper. Interception by vegetation is also considered using remote sensing calculated Leaf Area Index (LAI) time series from SPOT-VEGETATION. Precipitation is based on daily time series from the European Centre for Medium-Range Weather Forecasts (ECMWF). For Germany we compared our model output with soil moisture data from the ECMWF, which is based on the same precipitation dataset. We found a good agreement for the general characteristics of our modelled plant available soil water with this dataset, especially for soils which are close to the standard characteristics of the ECMWF. Disagreements were found for soils under stagnant moisture and for shallow soils, which are not considered in the ECMWF model scheme, but can be distinguished with our approach. The proposed approach for combining established model formulations for interception and one-dimensional vertical water transport with time-series of remote sensing data intends to contribute to the realistic parameterization of the soil water budged. This is especially needed for the global and regional assessment of e.g. net primary productivity which can be calculated with vegetation models.