CCLM for Middle East with ERA Interim – in #9: CCLM

in #9: CCLM

<p> Dear Simon, </p> <p> if you have a look into the <span class="caps"> YUCHKDAT </span> file of your INT2LM run you will see <br/> that the field “PP” (pressure perturbation) is undefined in the uppermost layer (search for “laf” and/or “lbfd” strings; <br/> there you find the PP values). That is deadly! <br/> The reason certainly is that you used the old reference atmosphere (irefatm=1), which makes no sense for <br/> a model domain height of 30 km, since, for the old reference atmosphere, the reference temperature T0 is decreasing steadily, <br/> and it might become negative (below absolute Zero) if the top of the model domain is too high. <br/> Thus, you have to use the new reference atmosphere, which you get if you set irefatm=2 in Namelist “lmgrid”. <br/> The new ref. atmosphere is much closer to the standard atmosphere. <br/> And there are, in principle, no restrictions with respect to the top height of the model domain. <br/> The only restriction is the top height of the driving large-scale model. </p> <p> Best regards </p> <p> Hans-Juergen </p>

  @hans-jürgenpanitz in #ed2163b

<p> Dear Simon, </p> <p> if you have a look into the <span class="caps"> YUCHKDAT </span> file of your INT2LM run you will see <br/> that the field “PP” (pressure perturbation) is undefined in the uppermost layer (search for “laf” and/or “lbfd” strings; <br/> there you find the PP values). That is deadly! <br/> The reason certainly is that you used the old reference atmosphere (irefatm=1), which makes no sense for <br/> a model domain height of 30 km, since, for the old reference atmosphere, the reference temperature T0 is decreasing steadily, <br/> and it might become negative (below absolute Zero) if the top of the model domain is too high. <br/> Thus, you have to use the new reference atmosphere, which you get if you set irefatm=2 in Namelist “lmgrid”. <br/> The new ref. atmosphere is much closer to the standard atmosphere. <br/> And there are, in principle, no restrictions with respect to the top height of the model domain. <br/> The only restriction is the top height of the driving large-scale model. </p> <p> Best regards </p> <p> Hans-Juergen </p>
HP replied

Dear Simon,

if you have a look into the YUCHKDAT file of your INT2LM run you will see
that the field “PP” (pressure perturbation) is undefined in the uppermost layer (search for “laf” and/or “lbfd” strings;
there you find the PP values). That is deadly!
The reason certainly is that you used the old reference atmosphere (irefatm=1), which makes no sense for
a model domain height of 30 km, since, for the old reference atmosphere, the reference temperature T0 is decreasing steadily,
and it might become negative (below absolute Zero) if the top of the model domain is too high.
Thus, you have to use the new reference atmosphere, which you get if you set irefatm=2 in Namelist “lmgrid”.
The new ref. atmosphere is much closer to the standard atmosphere.
And there are, in principle, no restrictions with respect to the top height of the model domain.
The only restriction is the top height of the driving large-scale model.

Best regards

Hans-Juergen

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