1. MODEL WIND FIELD COMPARE WITH HRD WIND FIELD
In the second and fourth slide, the model wind field shown here are HRD wind interpolated onto the model domain with 1/12 degree resolution. The resolution for HRD wind is about 6km, which is about 1/20 degree. As you suspected, the model wind field is not exactly equal to HRD wind, the difference are within 2m/s except somewhere on land (lower right corner) and at the center (slide 3, 5). I think what happened is that when I interpolated the HRD wind onto the larger resolution model domain and then interpolate back, it generated errors because of the changing of grid resolution.

6. Interpolated wind field compare with HRD wind field
The slides shown following are comparisons between interpolated wind field and HRD wind field. HRD wind at Aug :30 and 07:30 are used to interpolate the wind field at 04:30 (slide 7) and HRD wind at Aug :30 and 10:30 are used to interpolate the wind field at 07:30 (slide 9).