<div dir="ltr">Thanks a lot Rick!<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Aug 20, 2019 at 3:12 PM Rick Brownrigg <<a href="mailto:brownrig@ucar.edu">brownrig@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 dir="ltr"><div>Hi,</div><div><br></div><div>Below is the NCL for the function. I see that "g" is defined, but never referenced (?), so no it is not part of the computation.<br></div><div><br></div><div>Rick</div><div><font size="2"><span style="font-family:monospace"><br></span></font></div><div><font size="2"><span style="font-family:monospace">;-------------------------------<br>undef("eady_growth_rate")<br>function eady_growth_rate(th:numeric, u:numeric, z:numeric, lat:numeric, opt[1]:integer, ndimz[1]:integer)<br>;<br>; Maximum Eady Growth Rate <br>;<br>; Reference: <br>; R. S. Lindzen and Brian Farrell, 1980: <br>; A Simple Approximate Result for the Maximum Growth Rate of Baroclinic Instabilities. <br>; J. Atmos. Sci., 37, 1648–1654. <br>; <a href="http://dx.doi.org/10.1175/1520-0469(1980)037" target="_blank">http://dx.doi.org/10.1175/1520-0469(1980)037</a><1648:ASARFT><a href="http://2.0.CO" target="_blank">2.0.CO</a>;2<br>;<br>; Simmonds, I., and E.-P. Lim (2009): <br>; Biases in the calculation of Southern Hemisphere mean baroclinic eddy growth rate <br>; Geophys. Res. Lett., 36, L01707 <br>; doi:10.1029/2008GL036320<br>;<br>; Vallis, G.K. (2006) <br>; Atmospheric and Oceanic Dynamics: Fundamentals and Large-Scale Circulation<br>; Cambridge Univ. Press, New York.<br>; <br>; Nomenclature<br>; th - potential temperature (K)<br>; <a href="http://glossary.ametsoc.org/wiki/potential_temperature" target="_blank">http://glossary.ametsoc.org/wiki/potential_temperature</a><br>; <a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/pot_temp.shtml" target="_blank">https://www.ncl.ucar.edu/Document/Functions/Contributed/pot_temp.shtml</a><br>; u - zonal wind components (m/s) ; same dimensionality as 'th'<br>; z - height (m)<br>; lat - latitude of each grid point ; same dimensionality as 'th' <br>; opt - =0 (egr only); <br>; ndimz- dimension of 'th' for which vertical gradient is to be calculated<br>; th(:), wspd(:), z(:) ..... ndimz=0<br>; th(:,:,:) , z(:) or z(:,:,:) and the left is the vertical dim, ndimz=0<br>; th(:,:,:,:), z(:) or z(:,:,:,:) and the left is the time dimension <br>; and the next is height, ndimz=1 <br>;<br>;<br>local dimth, dimu, dimz, dimth, dimlat, rankth, ranku, rankz, rankth, ranklat \<br> , u_shear, brunt, fcor, g, omega, con, rad, egr<br>begin<br> ; dimension checking<br> dimu = dimsizes(u)<br> dimz = dimsizes(z)<br> dimth = dimsizes(th)<br> dimlat = dimsizes(lat)<br><br> ranku = dimsizes(dimu) <br> rankz = dimsizes(dimz) <br> rankth = dimsizes(dimth)<br> ranklat = dimsizes(dimlat) <br><br> if (.not.(rankth.eq.ranku .and. rankth.eq.rankz .and. rankth.eq.ranklat) \<br> .and. all(dimth.eq.dimu) .and. all(dimth.eq.dimz) .and. all(dimth.eq.dimlat)) then<br> print("eady_growth_rate: th, u, lat and must have the same rank & sizes")<br> print("ranku="+ranku+" rankth="+rankth+" rankz="+rankz+" ranklat="+ranklat)<br> print(dimth)<br> print(dimu) <br> print(dimz) <br> print(dimlat) <br> exit<br> end if<br><br> brunt = brunt_vaisala_atm(th, z, 0, ndimz)<br><br> dudz = center_finite_diff_n(u , z, False, 0, ndimz) <br><br> copy_VarCoords(u, dudz)<br> dudz@long_name = "vertical gradient of the zonal wind (zonal wind shear): du/dz"<br> dudz@units = "1/s"<br> ;print("eady_growth_rate: dudz: min="+min(dudz)+" max="+max(dudz))<br><br> g = 9.80665 ; m/s2 ; gravity at 45 deg lat used by the WMO<br> con = 0.3098<br> fcor = coriolis_param(lat) ; (1/s) ; coriolis parameter<br> ; prevent 1/0<br> if (any(brunt.eq.0)) then<br> if (.not.isatt(brunt,"_FillValue")) then<br> if (typeof(brunt).eq."double") then<br> brunt@_FillValue = 1d20<br> else<br> brunt@_FillValue = 1e20<br> end if<br> end if<br> brunt = where(brunt.eq.0, brunt@_FillValue, brunt)<br> end if<br><br> egr = con*abs(fcor)*abs(dudz)/brunt<br> egr@long_name = "maximum eady growth rate"<br> egr@units = ""<br> copy_VarCoords(u, egr)<br><br> if (opt.eq.0) then<br> return (egr)<br> else if (opt.eq.1) then<br> return ( [/egr, dudz /] )<br> else if (opt.eq.2) then<br> return ( [/egr, dudz, brunt /] )<br> end if<br> end if<br> end if<br><br>end</span></font></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Aug 20, 2019 at 6:47 AM Rohit Ghosh via ncl-talk <<a href="mailto:ncl-talk@ucar.edu" target="_blank">ncl-talk@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 dir="ltr">
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">Hello,</p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap"><br></p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">I am going to use the eady_growth_rate function from ncl. In the description of the function I find the gravitation term (g) is multiplied while calculating the Eady growth rate. Unfortunately, I could not find g multiplied in any references of Eady growth rate. Moreover, multiplication of g would not give the units of Eady growth rate (1/s). Could you please confirm that if it is a typo error or this multiplication is really done inside the script? That would be very helpful.</p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap"><br></p><p style="margin:0px;text-indent:0px;white-space:pre-wrap"><a href="https://www.ncl.ucar.edu/Document/Functions/Contributed/eady_growth_rate.shtml" target="_blank">https://www.ncl.ucar.edu/Document/Functions/Contributed/eady_growth_rate.shtml</a></p><p style="margin:0px;text-indent:0px;white-space:pre-wrap"><br></p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">Thank you very much.</p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap"><br></p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">Look forward to your response.</p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap"><br></p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">Regards,</p>
<p style="margin:0px;text-indent:0px;white-space:pre-wrap">Rohit</p></div>
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