Influence of Soil Moisture Data Assimilation on Numerical Simulations of the Inland Evolution of Hurricane Harvey

After a hurricane makes landfall, its strong interaction with land surface become essential for the evolution of storm-related inland wind and precipitation. Soil moisture has significant influence on the mass and energy exchanges between the land surface and the near-surface atmosphere. In this study, the effect of soil moisture on the inland evolution of Hurricane Harvey (2017) is examined. With the Noah land surface model and mesoscale community Weather Research and Forecasting (WRF) model, the influences of assimilation of soil moisture data on numerical simulations of Hurricane Harvey is investigated. Soil moisture data is assimilated by the NASA Land Information System (LIS) framework with the Noah land surface model, which includes an assimilation of retrieved soil moisture estimates from the NASA Soil Moisture Active Passive (SMAP) radiometer. A cumulative distribution function (CDF) matching bias correction is applied to the SMAP soil moisture data.

Two sets of experiments with LIS are conducted during 26-31 August 2017 after a spin-up period. The Open-loop LIS (OL-LIS) run uses Noah-3.6 LSM with NLDAS-2 meteorology forcing, and the data assimilation run assimilates SMAP soil moisture retrievals (SMAP-DA). For both experiments, the soil layer thicknesses of 10, 30, 60 and 100 cm depth are used. Land masks are taken from the MODIS 44W land-water mask classification. The soil texture is formulated from the blended State Soil Geographic (STATSGO)v1 and Food and Agriculture Organization (FAO) soil texture map. SMAP L3 Radiometer Global Daily 36 Km EASE-Grid Soil Moisture (version5 retrievals SPL3SMP), obtained from the National Snow and Ice Data Center (NSIDC) are assimilated.

With the different soil states (with and without soil moisture data assimilation) in the Noah land surface model, the numerical simulations are performed using coupled Noah land surface model and WRF model to evaluate the influence of soil moisture on the evolution of Hurricane Harvey. Specific attention will be given to the impacts on the forecast of Hurricane Harvey’s rainbands and associated convective cells over the Houston metropolitan area and Southeast Texas.