High-resolution hydro-meteorological modeling of extreme weather events over complex orography areas: applications of WRF and WRF-Hydro model configurations

Francesca Viterbo

CIMA Foundation, Savona, Italy; Institute of Atmospheric Sciences and Climate, National Research Council, Turin, Italy; University of Genova, Genova, Italy

Wednesday, Nov 02, 2016, 11:00 am
DSRC Room 2A305

Abstract

High-resolution and reliable precipitation data are crucial needs to improve the predictive ability of extreme meteorological events, especially over complex topography. Historically, the atmosphere and the terrestrial hydrologic cycles have not been well integrated in terms of coupled modeling systems: usually precipitation and runoff have been considered separately, with a sort of one-way cause-effect relationship.

Recently the need for improving hydro-meteorological predictions for flood, droughts and water resources has become more critical and has deserved a growing attention to fully two-way coupled atmospheric-hydrologic approaches. Fully coupled high-resolution models, such as the coupled WRF/WRF-Hydro system, are new generation tools designed to link the multi-scale processes of the atmosphere and the terrestrial hydrology and to perform coupled and uncoupled multi-physics simulation over a wide range of spatial and temporal scales, ranging from the event-scale to the seasonal one.

The improved representation of lateral redistribution and infiltration runoff and exfiltration processes provide a more complete depiction of terrestrial hydrologic states and fluxes which influence land-atmosphere energy exchanges.

In this study the two model approaches (stand-alone WRF vs. fully coupled WRF/WRF-Hydro) are explored for different time scales (from single event to seasonal scales) and different spatial resolutions, in order to investigate: 1) the capability of each model suite to describe the physical processes leading to severe rainfall in complex topography 2) the sensitivity of each model configuration to the choice of different parameterizations and the importance of a correct model calibration for both atmospheric and hydrological needs 3) the possible improvement in predictability if we compare WRF stand alone and WRF-Hydro model application 4) whether it is more relevant a better description of the dynamics (higher resolutions, correct choice of parameterizations etc.) or a better representation of the physical processes (meteorological only approach Vs. fully coupled hydro-meteorological WRF-Hydro simulations) in the representation of some kind of extreme hydrometeorological events.

The results of two experiments will be shown: in the first case study, the WRF stand alone approach has been applied at event scale over the complex topography of Himalaya-Karakorum-Hindukush range for Pakistan 2010 flood; in the second, the WRF-Hydro fully two-way coupled configuration has been run at a seasonal scale over the Appennines mountains in central Italy.