A Weighted Catchment View Approach for Evaluation of Euro Cordex Regional Climate Models

Climate change is increasingly affecting every aspect of human life on Earth. Many regional climate models (RCMs) have so far been developed to carefully assess this important phenomenon on specific regions. Hence, the functional evaluation of RCMs for simulating catchment climatic characteristics has been the target of many studies in the literature. To accomplish this task, many studies apply interpolation techniques (re-gridding, remapping and rescaling) for matching the resolutions of observations with the ones related to RCMs or vice versa. Moreover, they calculate arithmetic mean value of climatic data over a catchment for representing hydro-climatic variables (precipitation and temperature) of a catchment. This study proposes a novel approach that does not require any interpolation techniques for matching the resolutions, resulting in the improvement of RCM evaluations. In addition, the weighted average of data over a catchment is a comparison variable for the evaluation of RCMs, considering the different distribution of data´s geographical locations within a catchment. The weights for every data point are calculated based on the Thiessen polygon area of the corresponding point divided into the total area of catchment. To see the application of the method,10 RCMs captured from the European Coordinated Downscaling Experiment (EURO CORDEX) platform are evaluated by the proposed method on the river Chiese catchment located in the northeast of Italy, identifying the models with the appropriate performance for precipitation and temperature simulation of the catchment.