Estimating roughness length from canopy height

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hschlaer
Posts: 2
Joined: Tue Apr 27, 2021 5:42 pm

Estimating roughness length from canopy height

Post by hschlaer » Mon May 17, 2021 8:43 pm

Hey there WRF experts,

I'm running simulations where I increase tree height in a specific land use category. However, I'm having trouble figuring out how to change Z0MIN and Z0MAX in VEGPARM.TBL to reflect the increased canopy height. I read a general rule of thumb that roughness length is about one-tenth of canopy height, but I can't find information on the units used in the VEGPARM table or how adjustments are made for seasonal growing patterns in Z0MIN and Z0MAX. Could someone direct me to where I might find this information?

Thanks!

Hannah

Ming Chen
Posts: 1456
Joined: Mon Apr 23, 2018 9:42 pm

Re: Estimating roughness length from canopy height

Post by Ming Chen » Mon May 24, 2021 10:24 pm

Hannah,
I am sorry that I have no answer to your question. I talked to our land model expert and he told me the values are mostly empirical. They derive these values based on in-situ observations and satellite remote sensing. We use them as is and never really explore how they are specified.
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