<div dir="ltr"><div>Generally, NCL's wrf_* functions are direct interfaces to the fortran subroutines written by members of the WRF project. NCL developers did not write the WRF or RIP subroutines. <br></div><div><br></div><div>Likely, the answer to your questions would have to come from a WRF support group.</div><div><br></div><div>One possible group is <a href="https://forum.mmm.ucar.edu/phpBB3/"><b>here</b></a></div><div><br></div><div><b>Good Luck</b><br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Nov 19, 2020 at 6:39 AM Nan Yang via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu">ncl-talk@mailman.ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">Hello,</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px"><br></div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">I am using wrf_user_getvar to calculate cloud top temperature (ctt) from WRF outputs.</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">I've checked the wrf_fctt.f source code. The cloud-top temperature is calculated by interpolating the temperature to the level of unit optical depth (or a threshold) into the cloud, similar to RIP, but the absorption cross-section for cloud ice and cloud water are obtained from Dudhia (1989) in RIP, while in ncl:</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">ABSCOEFI = .272D0  ! cloud ice absorption coefficient in m^2/g</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">ABSCOEF = .145D0   ! cloud water absorption coefficient in m^2/g</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">I want to know why ctt is calculated this way, and where the constants come from.</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">Is there any reference paper for the ncl wrf_ctt calculation?</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px"><br></div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">Thanks,</div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px"><br></div><div style="margin:8px 0px 0px;font-family:Helvetica,"Hiragino Sans GB",微软雅黑,"Microsoft YaHei UI",SimSun,SimHei,arial,sans-serif;font-size:16px">Nan Yang</div></div>_______________________________________________<br>
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