MYNN TKE budget

[hanyuanl]

Hello,
I'm using the em_seabreeze2d_x case with MYNN level3 in WRF 4.2. I noticed the TKE budget terms (QBUOY. QDISS etc) had magnitudes that were way too big. For example, QBUOY near surface was way larger than 1 after being nominalized by w_star^3/Zi. I went through the code and found the QBUOY was multiplied by delt, which I don't quite understand the reason for. After I removed the *delt part in the code, the magnitude seemed to be normal. I wonder if this is the correct way to do it? If not, can you briefly explain the reason why the code was that way?

Thanks, and best,
Liu

 

[Ming Chen]

Would you please take a look at this paper:
Nakanishi, M., and H. Niino, 2009: Development of an improved turbulence closure model for the atmospheric boundary layer. J. Meteor. Soc. Japan, 87, 895–912. doi:10.2151/jmsj.87.895
I remember this paper describes the MYNN PBL and many details in the codes can be found here.