Strange wind data in small area over Alps in CCLM5 output – in #9: CCLM

in #9: CCLM

<p> Hi Michael, </p> <p> to my opinion, the problem is independent of the CCLM5 sub-version. <br/> I see it also in the results of some of my 1-year (1999) test runs that I carried out in order to find a suitable model setup for the <span class="caps"> FPS </span> Convection runs. <br/> These tests had been perforemd with CCLM5-0-10. <br/> And I think I identified the responsible Namelist-parameter by checking a variety of the test runs. <br/> It seems to be: <br/> hd_corr_u_in <br/> that I set to the value of 1., since the experiment with this value showed a positive impact on precipitation by reducing the wet bias over mountainous areas. <br/> The value used in <span class="caps"> COSMO </span> _DE and, thus, also im my reference setup of the tests, is 0.1 <br/> The coded default is 0.25. </p> <p> Only those of my experiments that used hd_corr_u_in=1. show the strange U_10M data in the region you mentioned. <br/> I tested also hd_corr_u_in=0.0; no such strange values. </p> <p> I have to admit, while analyzing the results of my tests I focused on <span class="caps"> TOT </span> _PREC and T_2M. I never looked at the wind components. </p> <p> Would it be possbile that you perform a short test by putting the hd_corr_u_in value back to 0.1? (myself, I can’t run jobs presently!!!) <br/> I assume you will see an impact very soon. <br/> I see the U_10M “hotspot” already after the first hour (my storage interval is 1 hour). </p> <p> However, some questions remain: <br/> - why only U and not V? What really “happens” in the code? <br/> - why only in this small area and not also elsewhere? <br/> - would the change of hd_corr_u_in from 1 back to 0.1 also have an impact on other variables, e.g. <span class="caps"> TOT </span> _PREC and T_2M? If yes, how strong? </p> <p> Hans-Juergen </p>

  @hans-jürgenpanitz in #b666805

<p> Hi Michael, </p> <p> to my opinion, the problem is independent of the CCLM5 sub-version. <br/> I see it also in the results of some of my 1-year (1999) test runs that I carried out in order to find a suitable model setup for the <span class="caps"> FPS </span> Convection runs. <br/> These tests had been perforemd with CCLM5-0-10. <br/> And I think I identified the responsible Namelist-parameter by checking a variety of the test runs. <br/> It seems to be: <br/> hd_corr_u_in <br/> that I set to the value of 1., since the experiment with this value showed a positive impact on precipitation by reducing the wet bias over mountainous areas. <br/> The value used in <span class="caps"> COSMO </span> _DE and, thus, also im my reference setup of the tests, is 0.1 <br/> The coded default is 0.25. </p> <p> Only those of my experiments that used hd_corr_u_in=1. show the strange U_10M data in the region you mentioned. <br/> I tested also hd_corr_u_in=0.0; no such strange values. </p> <p> I have to admit, while analyzing the results of my tests I focused on <span class="caps"> TOT </span> _PREC and T_2M. I never looked at the wind components. </p> <p> Would it be possbile that you perform a short test by putting the hd_corr_u_in value back to 0.1? (myself, I can’t run jobs presently!!!) <br/> I assume you will see an impact very soon. <br/> I see the U_10M “hotspot” already after the first hour (my storage interval is 1 hour). </p> <p> However, some questions remain: <br/> - why only U and not V? What really “happens” in the code? <br/> - why only in this small area and not also elsewhere? <br/> - would the change of hd_corr_u_in from 1 back to 0.1 also have an impact on other variables, e.g. <span class="caps"> TOT </span> _PREC and T_2M? If yes, how strong? </p> <p> Hans-Juergen </p>
HP replied

Hi Michael,

to my opinion, the problem is independent of the CCLM5 sub-version.
I see it also in the results of some of my 1-year (1999) test runs that I carried out in order to find a suitable model setup for the FPS Convection runs.
These tests had been perforemd with CCLM5-0-10.
And I think I identified the responsible Namelist-parameter by checking a variety of the test runs.
It seems to be:
hd_corr_u_in
that I set to the value of 1., since the experiment with this value showed a positive impact on precipitation by reducing the wet bias over mountainous areas.
The value used in COSMO _DE and, thus, also im my reference setup of the tests, is 0.1
The coded default is 0.25.

Only those of my experiments that used hd_corr_u_in=1. show the strange U_10M data in the region you mentioned.
I tested also hd_corr_u_in=0.0; no such strange values.

I have to admit, while analyzing the results of my tests I focused on TOT _PREC and T_2M. I never looked at the wind components.

Would it be possbile that you perform a short test by putting the hd_corr_u_in value back to 0.1? (myself, I can’t run jobs presently!!!)
I assume you will see an impact very soon.
I see the U_10M “hotspot” already after the first hour (my storage interval is 1 hour).

However, some questions remain:
- why only U and not V? What really “happens” in the code?
- why only in this small area and not also elsewhere?
- would the change of hd_corr_u_in from 1 back to 0.1 also have an impact on other variables, e.g. TOT _PREC and T_2M? If yes, how strong?

Hans-Juergen

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