Urban canopy parameters for BEP

[NinglvLi]

Hello ,


I’m running WRF-Urban with the BEP multilayer UCM for 1 km urban microclimate simulations. I noticed that even for BEP, different papers/documentation list different “urban morphology/canopy parameters”: some describe BEP inputs in street-canyon/building-scale terms (e.g., road width, building width, street direction, building height distribution as in URBPARM.TBL), while others provide grid-scale gridded UCPs via the URB_PARAM array (e.g., plan area fraction λp, area-weighted mean building height, building surface density/ratio λb, and height distribution).


Since my simulations are at 1 km resolution, I would like to use grid-scale (gridded) morphology inputs rather than LCZ-based lookup tables. However, I cannot find a clear “minimum required” list of parameters that BEP actually reads/needs in this gridded-input configuration.


Could you please clarify for WRF version [your WRF version]:

1. When BEP is enabled, what is the minimum set of gridded urban morphology fields that must be provided (e.g., FRC_URB2D and specific URB_PARAM indices)?
2. If certain fields are missing, does BEP fall back to URBPARM.TBL defaults, or will it fail?
3. Is there an official document (users guide/tech note) that explicitly maps BEP-required fields between URBPARM.TBL and URB_PARAM (especially for street parameters and building height distribution)?

Any pointers to the relevant documentation or code references would be greatly appreciated.


Best regards,

 

[Ming Chen]

Please see my answers below:

Hello ,


I’m running WRF-Urban with the BEP multilayer UCM for 1 km urban microclimate simulations. I noticed that even for BEP, different papers/documentation list different “urban morphology/canopy parameters”: some describe BEP inputs in street-canyon/building-scale terms (e.g., road width, building width, street direction, building height distribution as in URBPARM.TBL), while others provide grid-scale gridded UCPs via the URB_PARAM array (e.g., plan area fraction λp, area-weighted mean building height, building surface density/ratio λb, and height distribution).


Since my simulations are at 1 km resolution, I would like to use grid-scale (gridded) morphology inputs rather than LCZ-based lookup tables. However, I cannot find a clear “minimum required” list of parameters that BEP actually reads/needs in this gridded-input configuration.


Could you please clarify for WRF version [your WRF version]:

1. When BEP is enabled, what is the minimum set of gridded urban morphology fields that must be provided (e.g., FRC_URB2D and specific URB_PARAM indices)?

• FRC_URB2D and parameters from URBPARM.TBL are required to run BEP.

1. If certain fields are missing, does BEP fall back to URBPARM.TBL defaults, or will it fail?

Can you specify what fields might be missing? Generally, BEP will use default values (mainly from URBPARM.TBL).

1. Is there an official document (users guide/tech note) that explicitly maps BEP-required fields between URBPARM.TBL and URB_PARAM (especially for street parameters and building height distribution)?

I am not aware of such documents specifically maps BEP-required fields between URBPARM.TBL and URB_PARAM. But the two papers below may provide some helpful information:

Salamanca, F., and A. Martilli, 2010: A new building energy model coupled with an urban canopy parameterization for urban climate simulations––part II. Validation with one dimension off–line simulations. Theor. Appl. Climatol., 99, 345–356.
doi:10.1007/s00704-009-0143-8


Martilli A, Clappier A, and Rotach M.W., 2002: An urban surface exchange parameterization for mesoscale models. Bound.-Layer Meteorol., 104, 261–304.
doi:10.1023/A:1016099921195

Any pointers to the relevant documentation or code references would be greatly appreciated.


Best regards,