P46 Effect of the land surface hydrologic processes on land-air interactions in Taiwan using WRF-Noah and WRF-NoahMP.
Tzu-Ying, Chen, and Fang-Yi Cheng, Graduate institute of Atmospheric Physics, National Central University, Taiwan
The land surface
hydrologic processes such as surface/subsurface runoff and soil-groundwater
interaction strongly affect soil moisture. In order to understand how the land
surface hydrologic processes affect the land-air interactions in Taiwan, the
WRF model coupled with two land surface models (Noah and Noah-MP) were applied.
The major difference between the two LSMs is that a free drainage is specified
as the lower boundary condition in Noah LSM while the Noah-MP considers the
dynamic interactions between the soil and the aquifer. Moreover, Noah-MP LSM
adopts semi-tile approach to calculate energy fluxes from vegetated and bare
land separately, while Noah LSM combines surface layer of vegetation and soil
surface, over which surface energy fluxes are computed.
The study period is from 1 August to 10 August 2015 during which a moderate
intensity typhoon made a landfall in Taiwan. Before the influence of the
typhoon, the atmospheric conditions were relatively dry and calm and soils were
also dry. Unlike Noah LSM, Noah-MP LSM considers the groundwater exchanging
processes between the aquifer and the soils. With the upward water flux from
the aquifer, the Noah-MP LSM simulates higher soil moisture and higher latent
heat flux. The increased moisture in the atmosphere before typhoon landing,
which further affects the rainfall simulation.