Thanks to Jack Glendening and his post from 2 weeks ago, we at FSL found that indeed, the 13km and 20km topography detail are very similar, not as different as previously claimed by us in FSL. The 13km topo shown in the online RUC13 powerpoint is correct, but the actual 20km topo (slide 5) is more detailed than shown. In some cases, as that for the Owens Valley in CA shown by Jack, the 13km topography may be slightly smoother. In other locations, the 13km topography sometimes has slightly more detail, but not on the average.

The reason for this is that different procedures and source datasets
were used for the RUC 13km and the 20km topo. The WRF SI program for the13km topo was used with a 30" USGS topography dataset, and included implicit smoothing. The 20km topo was determined from a 5' mean topography dataset with RUC software that allows more control on smoothing. The 20km topo from the RUC topo routine also is an envelope topography, whereas the 13km topo from the WRF SI is a mean topography.

The 20km topo shown in the previous slide 5 in the RUC13.ppt was from
a 20km version using WRF SI, but is not the actual RUC20 topo, as Jack has pointed out. (correction upcoming to the online RUC13.ppt) We thank Jack again and apologize for not recognizing this 20 vs. 13 topo difference accurately before. FSL will be experimenting with a less smoothed topography in its version of the RUC13 to consider if this would be useful for a possible upgrade to the RUC13 well after next week's implementation.

Stan Benjamin