The average wind and the wind at the moment are almost the same

[kairat_boss]

I ran WRF with output_diagnostics=1, to get averaged wind values every 20 min. But comparing the results of momentary wind U10, V10, and averaged U10MEAN, V10MEAN I get very close values. According to the observation data, the average wind is always less than the momentary wind. Can anyone explain it?

 

[kwerner]

Hi,
Can you provide some additional information - such as some plots or files with the output values you're getting? Can you also attach your namelist.input file and let us know which version of WRF you're using? Thanks!

 

[kairat_boss]

I am using WRF version 4.3. I have attached plots in the Compare_WRF_and_WRFMEAN.pdf file. It is confusing that averaged wind is greater than momentary wind for meteostation Alm-004 (you can see this in the file). Also, I have attached namelist.input file. Thank you for your reply.

 

[kwerner]

Hi,
Thanks for sending that, and I just want to let you know I haven't forgotten about you. I have been busy preparing for and conducting the WRF tutorial we just held last week and have been out of the office this week. I will get back to this very soon. Thank you so much for your patience!

 

[kwerner]

I have a few questions/comments:

1. Which domains are these plots made from? The most different U2 and U2MEAN is from meteostation Alm-004 - which domain have you plotted for that figure?

2. Is it possible that the mean and instant values are more different if the output interval becomes longer? Currently it is set to 20 min. What if the interval is hourly? Can you test this?

3. Regarding the set-up, you have 33 of the 45 levels located under 900 mb, and very few levels above that until the model top at 50 mb. This is not a good setup for the model. Although it may or may not change the outcome of the mean calculation, it would not be something we would recommend to simulate real atmospheric flows. The model needs more levels from 900 mb to 50 mb to properly represent the flow.