Development and Implementation of Parameterization of the Tidal Effect in Weather Research Forecasting (WRF) Model

We have developed a parameterization of tidal effect for use in NOAH LSM and validated the model using observations taken over the tidal flat of the western coast of South Korea. The parameterization is based on the energy budget of water layer with changing thickness above the soil. During flow tide, heat transfer by the moving water has been considered in addition to surface energy budget. Some penetration of solar radiation through water layer is also considered in the surface energy budget. The water thickness varying with time is used as the additional input. Seven days with the clear sky and westerly winds during the daytime are selected for the validation of the model. Two simulations are performed in an offline mode; the control simulation without the tidal effect (CONTROL) and simulation with the tidal effect (TIDE). Comparisons of the model results have been made with eddy-covariance measurements and soil temperature data at the tidal flat. Observations show that inundation significantly reduces both sensible and latent heat fluxes during daytime, which is well simulated in TIDE. The diurnal variation and magnitude of soil temperature is better simulated in TIDE than in CONTROL. The tidal parameterization is implemented in weather research and forecasting (WRF) model. Newly added inputs are tide information, time varying water depth and SST. Gridded tide information and water depth data has been produced using output from tide model (MOH1D). Tide effect is considered only in domain with 1 km horizontal resolution where tidal flat is resolved. The impact of tidal parameterization on the simulation of precipitation in downwind area of tidal flat has been investigated through WRF simulation for the Sep 21 of 2010 with concentrated rainfall in Seoul.