Tasks of the StaRMIP project

This project is composed of two successive phases for CTRL and future climate.

Phase 1 consists in implementing the statistical downscaling models (SDMs), developing the indicators of quality and simulating the HR fields of precipitation (PR) and temperature (T) in context of CTRL climate. The simulated fields will be assessed (uncertainties, indicators, comparison with RCM, etc.) by comparisons to high-resolution (HR) gridded data from the “European Climate Data & Assessment” (ECA&D) project. The simulated fields will then be used as inputs into two daily hydrological models (GR4J and HydroStrahler), to compare observed and simulated water flows over the CTRL period for three Mediterranean catchments. The hydrological models will be preliminary calibrated and validated over long time periods based on the gridded PR and T data from the ECA&D project. A new statistical downscaling model will be developed to fill the main gaps of the state-of-the-art approaches.

Phase 2 of this project relies on phase 1 to select the most efficient GCMs and statistical downscaling models on CTRL climate. Based on these choices, HR fields of future PR and T will be generated, evaluated in turn, and used as inputs in the selected hydrological models to analyze the hydrological impacts of future climate change.
Project management and coordination (PMC) will include an international scientific committee to supervise the good advancement of the work in a consistent way with the related international projects, to serve as a bridge towards and from these projects. Researchers involved in various projects have already accepted to form this committee. PMC will promote the results of the project (e.g., articles, conferences) and manage the specific StaRMIP web site to provide the statistical simulations and the different SDM algorithms and indicators developed. PMC will also be in charge of the international workshop on regionalization.

To perform the two phases, StaRMIP is structured in three tasks.

Task 1 (resp.: J. Carreau) will be in charge of the SDMs. First, those models will be theoretically studied and practically implemented. The set of common low-resolution variables (i.e., predictors) to drive the different statistical downscaling models and compare them in a fair manner will be selected in this task (this will be done as independently as possible of the SDMs themselves, although some adaptations may be expected). A new statistical downscaling model will be developed to extend state-of-the-art approaches and fill their main gaps. Then, HR fields of PR and Twill be statistically simulated for CTRL and future climates.

Task 2 (resp.: S. Bastin) is devoted to the evaluation of the HR simulations. First, indicators of the quality of the HR simulations will be developed. Those indicators will be useful for both dynamical and statistical models, as well as discharge runoff. Next, this task will deal with the evaluation of the regional uncertainties in CTRL climate (phase 1) through model-merging techniques, and will also contain statistical-dynamical comparisons. Finally, task 2 will provide statistical modeling of uncertainty of SDM projections in future climate (phase2), and will study the evolutions of the indicators compared to CTRL climate.

Task 3 (resp.: D. Ruelland) will use the HR statistical simulations of PR and T to study the associated hydrological uncertainties and impacts. First, the hydrological models will be calibrated on three Mediterranean catchments (Moulouya, Ebro, Hérault) based on an automatic procedure. Then, a sensitivity analysis of the modeled water flows to the uncertainties of the simulated HR climate fields in CTRL climate will be performed. Next, a prospective evaluation of the impacts of climate change on the future flows of those three catchments will be realized. The goal will be to simulate future trends in hydrological regimes of the catchments under climate change (changes in seasonal regime of river flows and inter-annual variations in flows).

Moreover, a "task 0" (resp.: M. Vrac) for project management has been created for financial and organisational management and scientific logistic (datasets, etc.). This task and an international scientific committee (i) will supervise the work progresses and communication between tasks, (ii) will serve to the diffusion of the results of the project, the statistical simulations and the different downscaling algorithms and indicators developed and (iii) the good advancement of the project in a consistent way with the related international projects. It will then serve as a bridge toward and from these projects. Researchers involved in various projects have already accepted to form this committeeThis “steering” committee will meet once a year to express opinions on the achieved results and to provide prospective advices.