Overestimated Kdown in Shanghai by WRF

[sunt05]

@sunt05 I have done a case with setting all the urban grids to 100% cropland. Here are the results.

Originally posted by @zhenkunl in https://github.com/Urban-Meteorology-Reading/WRF-SUEWS/issues/45#issuecomment-517764562

[sunt05]

As far as I know, SUEWS doesn't use SMOIS in the wrfinput, but use SOILMOIST_SUEWS which is assigned values by ourselves instead. This is timeseries of moisture of grass, which has a 100% fraction in my case.

Originally posted by @zhenkunl in https://github.com/Urban-Meteorology-Reading/WRF-SUEWS/issues/45#issuecomment-517890037

[sunt05]

Yes it should be our Soilmoist_suews. I assume that is the deficit. Please can you set that to a larger values e.g.100 to see if that is limiting things. Please Also check the LAI.

Best wishes Sue

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Prof Sue Grimmond Meteorology, University of Reading

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From: Zhenkun Li notifications@github.com Sent: Saturday, August 3, 2019 4:20:14 AM To: Urban-Meteorology-Reading/WRF-SUEWS WRF-SUEWS@noreply.github.com Cc: Sue Grimmond c.s.grimmond@reading.ac.uk; Mention mention@noreply.github.com Subject: Re: [Urban-Meteorology-Reading/WRF-SUEWS] WRF-SUEWS evaluation in Shanghai case (#45)

As far as I know, SUEWS doesn't use SMOIS in the wrfinput, but use SOILMOIST_SUEWS which is assigned values by ourselves instead. This is timeseries of moisture of grass, which has a 100% fraction in my case. [4925C956-9035-4AE5-BDC9-B06D626BD9D5]https://user-images.githubusercontent.com/12846201/62406546-4cf5f500-b5e0-11e9-9868-67af5c0c6b0f.png

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Originally posted by @suegrimmond in https://github.com/Urban-Meteorology-Reading/WRF-SUEWS/issues/45#issuecomment-517901358

[sunt05]

As far as I know, SUEWS doesn't use SMOIS in the wrfinput, but use SOILMOIST_SUEWS which is assigned values by ourselves instead. This is timeseries of moisture of grass, which has a 100% fraction in my case.

Originally posted by @zhenkunl in #45 (comment)

Given the very small changes in the soilmoist shown in your figure: ~0.1 mm in 3 days, it is not surprising that LH would be so low: 1 mm day-1 ≈ 30 W m-2 (equivalent latent heat flux). So I think some surface conductance related parameters (and others) might need to be looked into in this case.

However, as our purpose is to see if surface latent flux would affect incoming solar radiation, I suggest you use the more common Noah to examine the effect: make sure you will see a large LH.

[sunt05]

@zhenkunl can you calculate the transmissivity using WRF produced Kdown following Ao et al. (2016)? See their eons 2–4. Or, can you upload the Kdown data produced by WRF? I'd like to have a look.

[zhenkunl]

I set the initial soilmoist_SUEWS to higher values to get larger LH. This can be seen from output, however, it looks LH doesn't affect SWDOWN.

[sunt05]

Thanks for the plot of transmissivity. Compared with Figure 4 in Ao et al. (2016), the transmissivity by WRF is apparently larger by ~0.1. We may consider to "brutally" suppress Kdown at the SUEWS side.

[suegrimmond]

I.e. acknowledging urban aerosols

[zhenkunl]

How can we take into account the effect of haze?

[suegrimmond]

We have a plan.

[sunt05]

can be addressed by supplying a local correction factor based on observations of kdown.