Urban canopy models with 33 categories landuse data

[Z_wendy]

Hi,
I'm learning the urban canopy models of WRF. Now I have modified the landuse data and it has 33 categories, including Lo-Res, Hi-Res and Commercial. I am a little confused about the parameters in URBPARM.TBL. For example, when BEM is considered, diurnal heating profile of heat generated by equipments (HSEQUIP) is needed. It may be inappropriate to set one diurnal heating profile, because the equipment of residential and conmmercial buildings usually have the different running time. I have the same doubts about some other parameters, such as Thickness of each building wall layer (DDZB). So how can I set the parameters of different urban types seperately? Any ideas?
Besides, it seems that I can't handle the problems in setting the parameter "eta_levels" in namelist.input. I am not sure if it's appropriate to ask the question here. But I would be appreciative if someone gives a guidance.

Thanks

 

[Ming Chen]

Hi,
You raised a good question. Note that those parameters specified in URBPARM.TBL are empirical, and they can be adjusted based on specific case.
For the vertical levels, REAL program can produce vertical levels based on p_top_requested and e_vert. If you need to change the levels, it is probably better to start from the eta levels generated by REAL. Below is a sample settings we use for 15-km run over conus:
eta_levels = 1.00000 , 0.99307 , 0.98348 , 0.97105 , 0.95551 ,
0.93651 , 0.91363 , 0.88644 , 0.85460 , 0.81855 ,
0.77877 , 0.73579 , 0.69016 , 0.64246 , 0.59329 ,
0.54573 , 0.50104 , 0.45908 , 0.41972 , 0.38281 ,
0.34824 , 0.31589 , 0.28563 , 0.25735 , 0.23096 ,
0.20635 , 0.18343 , 0.16209 , 0.14226 , 0.12384 ,
0.10677 , 0.09095 , 0.07633 , 0.06282 , 0.05036 ,
0.03889 , 0.02835 , 0.01868 , 0.00983 , 0.00000
For this case, we set p_top_requested = 3000 and e_vert= 40.

 

[Z_wendy]

Thank you for the reply.

For the vertical levels, I am still confused. What's the basis to decide the p_top_requested and e_vert? Are the two parameters related to the grid resolution (dx, dy)? When the grid resolution (dx, dy) of the inner nest is equal to 300m in BEM, I wonder if you can recommend the values of p_top_requested and e_vert (vertical levels).

Thanks

 

[Ming Chen]

Hi,
p_top_requested and e_vert actually determine the vertical resolution.Higher p_top and smaller e_vert yield larger dz in the vertical. There is no strict rule about how to set these two variables. In our cases we often set p_top = 3000 (or 5000) and e_vert to be around 40 for dx >=3km.
For very high resolution case like dx=300, one must ensure that dz < dx, which implies that e_vert should be large enough. For real data case, p_top still needs to be high enough (e.g., 30 hPa, 50 Hpa) to ensure correct simulation of physical processes in the troposphere.