In order to evaluate the reliability of the soil moisture estimates obtained from the LISFLOOD hydrological model ([1]) in the context of the European Flood Alert System, we compare them to soil moisture estimates derived from ERS scatterometer data ([2]). We assess the spatial features of the two products by means of variogram analysis and scaling behaviour. The two datasets show good agreement over large regions, with 90 % of the area having a positive correlation coefficient and 66 % having a root mean square error less than 0.5. Major inconsistencies are located in mountainous regions such as the Alps or Scandinavia where both the methodologies suffer from insufficiently resolved land surface processes at the given spatial resolution, as well as from limited availability of satellite data on the one hand and the uncertainties in meteorological data retrieval on the other hand. The analysis of the variograms shows that both datasets have a similar behaviour at the larger distances. The ERS scatterometer variogram shows a quite linear behaviour, giving the impression that the sill has not been reached yet; the LISFLOOD variogram has a rapid increase at small distances, then a rather asymptotic behaviour. At short lags the higher variability of the LISFLOOD soil moisture estimates due to their higher resolution can be detected. Analyzing the scaling behaviour, we observe a power law decay of the variance with respect to the averaging area. The exponents for the two datasets, despite being quite different, show some consistency in their temporal variability in not perturbed periods.

LAGUARDIA Giovanni;  NIEMEYER Stefan; 

2009-04-15

ESA Conference Bureau

JRC41823

https://publications.jrc.ec.europa.eu/repository/handle/JRC41823,