[RegCNET] 10 km run

[gaoxj at cma.gov.cn]

Hi Csaba,

Seems you are doing the highest resolution simulation by RegCM3. I think we do not have such experiences before. I have some suggestions, but do not know whether they will work or not.

1. Generally, people say that the ratio for the driven resolution to RCM resolution is better to be in the range of 3-5, 10 is the maximum. There should be some references on this, but I do not have in hand. Maybe you can try the double-nesting, from 2.5 degrees to say 50 km first, then from 50 to 10?

2. CRU is in the resolution of 0.5 deg. It smoothes the precip peak. Meanwhile, over mountain areas, it tends to under-estimate the real precip because no weather stations there. What about try to evaluate the model by some station data?

3. A critical issue is that RegCM3 is hydro-statistic. Some people say a model like that can go to 10 km, some said not and you need a non-hydro-statistic one. I have no idea about this. Maybe others have?

Good luck.

Regards,

Gao

----- Original Message ----- 
From: "Torma Csaba" <delivitez at nimbus.elte.hu>
To: <regcnet at lists.ictp.it>
Sent: Wednesday, March 14, 2007 6:20 PM
Subject: [RegCNET] 10 km run


> Dear RegCM Users,
> 
> We just started to use RegCM3 driven by ERA40 2.5 degree resolution ICBC
> data for a European subregion containing the Carpathian Basin and Hungary.
> 
> Our grid resolution is 10 km.
> 
> In the precipitation pattern we found big biases as compared to the CRU
> data, especially during summer (convective events cause too much
> precipitation). We tried to use both Emanuel and Grell convective schemes,
> but the result was quite the same: the precipition was overestimated by
> the model with a factor of about 2.
> 
> We suspect that the 10 km resolution causes this overestimation. Using 25
> km grid resolution the result is much more realistic, but we would like to
> use 10 km grid spacing. Is there any possible solution for this
> overestimation? Any suggestion is welcome!
> 
> Thanks in advance.
> 
> Kind regards,
> Csaba TORMA
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