<div dir="ltr"><div>Hi,<br></div><div><br></div><div>I suggest looking at the following resources to compute this. Take note of the version of NCL used in these resources.</div><div><br></div><div>[1] For computing shear and stretching deformation:</div><div><a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/shear_stretch_deform.shtml" target="_blank">https://www.ncl.ucar.edu/Document/Functions/Contributed/shear_stretch_deform.shtml</a><br></div><div><br></div><div>[2] For computing absolute vorticity:</div><div>First compute the relative vorticity using spherical harmonics:</div><div><a href="https://www.ncl.ucar.edu/Applications/vort.shtml" target="_blank">https://www.ncl.ucar.edu/Applications/vort.shtml</a><br></div><div><br></div><div>Then, you can add the coriolis parameter this way:</div><div><br></div><div><div> vr = vr + <a href="http://www.ncl.ucar.edu/Document/Functions/Built-in/conform.shtml" target="_blank"><b>conform</b></a>(vr, flat, 2) ) ; flat matched the '2-th' dimension of 'vr'</div><div><div> vr@long_name = "absolute vorticity"</div><div> vr@units = "per second<div> <a href="http://www.ncl.ucar.edu/Document/Functions/Contributed/copy_VarCoords.shtml" target="_blank"><b>copy_VarCoords</b></a>(u, vr)</div></div></div></div><div><br></div><div>[3] NCL also provides a way to compute the coriolis parameter:</div><div><a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml">https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml</a><br></div><div><br></div><div>or you can also do it this way:</div><div><pre style="color:rgb(0,0,0);white-space:pre-wrap"> <font face="arial, sans-serif"> W = 7.292e-5 ; (1/s) ; earth ang rotation
rad = 4.*atan(1.)/180.
f = 2.*W*sin(lat*rad) ; (1/s) ; coriolis parameter</font></pre></div><div><br></div><div>Then, applying Brown's indicator equation is pretty straighforward. </div><div><br></div><div>Sincerely,</div><div><br clear="all"><div><div dir="ltr" class="m_4344722752365683298gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><font face="comic sans ms, sans-serif"><b><u>Lyndz</u></b></font><br><div><br></div></div></div></div></div></div></div></div></div></div></div><br><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 30, 2019 at 7:32 PM Ehsan Taghizadeh <<a href="mailto:ehsantaghizadeh@yahoo.com" target="_blank">ehsantaghizadeh@yahoo.com</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 class="m_4344722752365683298gmail-m_3398883253474480888yahoo-style-wrap" style="font-family:"bookman old style","new york",times,serif;font-size:16px"><div>Dears,</div><div>I hope this email finds you well.<br>As you know, there is various indicators for CAT (Clear Air Turbulence), like <i>Richardson number (Ri)</i> or <i>Brown's indicator</i>, etc. I've found attached script for <i>Ri</i>. May I ask if anyone has any script to compute <span><i style="color:rgb(0,0,0);font-family:"bookman old style","new york",times,serif;font-size:16px">Brown's indicator</i></span>, or other CAT indicators in NCL?</div><div>I'll be thankful if I hear from you.</div><div>Sincerely</div><div>Ehsan</div><div><br></div><div><img title="Inline image" alt="Inline image" class="m_4344722752365683298gmail-m_3398883253474480888yahoo-inline-image" style="max-width:412px;width:100%"><br><span></span><br></div></div></div>_______________________________________________<br>
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