We have been undertaking a major collaborative research effort to develop the unified Noah land surface model (LSM) for numerical weather prediction models. In this paper, we will present the verification results of the unified Noah LSM coupled with the Weather Research and Forecast Model (WRF) for some selected summer cases. Surface observations from the International H2O Project 2002 (IHOP) field experiment were used for these verifications. IHOP took place in the summer of 2002 (from 13 May to 25 June) over the southern great plains of the United States. A few clear sky days from this period were identified as good candidates for verifying the coupled WRF/Noah LSM system.

A number of short-term numerical experiments were conducted using initial data from different land-data assimilation systems that include AGRicultural METeorology Modeling System (AGRMET) from AFWA and Eta model data assimilation system (EDAS). The model was integrated for 24 hours in each of these selected cases. A 10 km horizontal resolution was used for these experiments. The model shows encouraging results when compared with observations. We verfied simulated surface radiation forcing, surface sensible and latent heat fluxes, near-surface meteorological variables, soil moisture and temperature, and aircraft measured fluxes.One key issue we will address is to which degree the differences in initial soil moisture and temperature obtained from various land data assimilation system will impact the coupled WRF forecasts.