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<p>Hi Carlos,<br></p>
<p class="default-style">thanks for sharing your scripts. I revised my code and finally I found the bug. In vinth2p_ecmwf I used as <em>tbot</em> the surface geopotential instead of bottom temperature. After providing the right surface temperature and surface geopotential as orog*9.81 I get reasonable geopotential heights.</p>
<p class="default-style">Best regards, <br></p>
<p class="default-style">Markus<br></p>
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Il 14/11/2022 14:17 Carlos Marques <cafm@ua.pt> ha scritto:
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<p>Hi,</p>
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<p>Attached there are two scripts that I used to compute Geopotential for CMIP6 model MPI-ESM1.2-LR and to interpolate after to pressure levels.</p>
<p>Also attached there are 3 figures that compare the geopotential computed and interpolated to pressure levels with NCL with that provided by MPI. You may see that they compare fairly well.</p>
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<p>You should check that every variable is what NCL's expects (units, coordinates ordering, etc. ). I think that for example you P0 is in hPa, but NCL expects that to be in Pa.</p>
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<p>I don't think that you can compute and interpolate to pressure levels without the surface geopotential.</p>
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<p>Hope that helps.<br></p>
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<br>C. A. F. Marques
<br>CESAM & Physics Department
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<span style="font-family: Calibri,sans-serif; font-size: small;"><span style="font-size: 11pt;">University of Aveiro</span></span>
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<span style="font-family: Calibri,sans-serif; font-size: small;"><span style="font-size: 11pt;">3810-193 Aveiro. Portugal<br></span></span>
</div><a id="LPNoLP" target="_blank" href="http://www.cesam.ua.pt/cafmarques" rel="noopener">http://www.cesam.ua.pt/cafmarques</a>
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<span style="font-size: 11pt; color: #000000; font-family: Calibri, sans-serif;"><strong>From:</strong> ncl-talk <ncl-talk-bounces@mailman.ucar.edu> on behalf of markus mingel via ncl-talk <ncl-talk@mailman.ucar.edu><br><strong>Sent:</strong> Monday, November 14, 2022 12:42:27 PM<br><strong>To:</strong> ncl-talk@ucar.edu<br><strong>Subject:</strong> [ncl-talk] Computing geopotential height</span>
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<p class="default-style">Hi All,<br></p>
<p class="default-style">I am trying to derive the geopotential height of a given CMIP6 model from its air temperature and humidity. <br></p>
<p class="default-style">Firstly, I compute the geopotential in the native hybrid coordinates using the NCL function cz2ccm, then I interpolate the just computed geopotential to some pressure levels using vinth2p_ecmwf.</p>
<p class="default-style">The comparison of the geopotential computed with my script (attached) with the zg downloaded from ESGF shows large differences, so I was wondering if anyone could suggest me what's wrong in my script? </p>
<p class="default-style">Besides, when the variable phis (surface geopotential (m^2/sec^2)) is not available as input, which values I should use? Is it possible to compute it in anyway with NCL?<br></p>
<p class="default-style">Thanks into advance for help,<br></p>
<p class="default-style">Best,<br></p>
<p class="default-style">Markus<br></p>
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