Perturbing hydrology parameters in seasonal forecasts

Methods to explicitly represent uncertainties in weather and climate models have reduced model biases and improved forecast skill when implemented for the atmosphere. However, these methods have not yet been applied to the land surface.

At certain times and in certain places the land surface is strongly coupled to the atmosphere, such as during the 2003 heatwave over Europe when dry soil led to extreme summertime temperatures.

Improvements in the representation of uncertainty in the land surface may then lead to improvements in forecast for the atmosphere in cases like this.

We analyze seasonal experiments performed with the ECMWF weather and seasonal climate forecasting model, the Integrated Forecasting System (IFS), with different kinds of perturbation made to the land surface, in order to investigate the effect of explicitly incorporating uncertainty in this domain.