Thanks Matthias. I sure do appreciate the help. That produced some interesting results, but it didn't seem accurate (arrows pointing in some rather bizarre directions). Perhaps though this is a data problem, and I need to grab different GRIB files? Currently, I'm using GRIBs from the NCEP server:<br>
<a href="ftp://polar.ncep.noaa.gov/pub/waves/latest_run/">ftp://polar.ncep.noaa.gov/pub/waves/latest_run/</a><br><br>-Nathan<br>
<br><br><div class="gmail_quote">On Wed, Nov 4, 2009 at 7:53 AM, Matthias Fripp <span dir="ltr"><<a href="mailto:matthias.fripp@eci.ox.ac.uk">matthias.fripp@eci.ox.ac.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="word-wrap: break-word;">How about this:<div><br></div><div>set gxout vector</div><div>display cos(DIRPWsfc * 3.14159/180); sin(DIRPWsfc * 3.14159/180)</div><div><br></div><div>This converts the wave direction from degrees to radians, and then calculates its u and v components.</div>
<div><br></div><font color="#888888"><div>Matthias</div></font><div><div></div><div class="h5"><div><br><div><div>On Nov 4, 2009, at 2:38 PM, Nathan Cool wrote:</div><br><blockquote type="cite">Thanks, but I'm not trying to display "wind" vector arrows; instead, I'm trying to display the primary wave direction.<br>
<br>The vars in the Grib are:<br>------------------------<br><div> DIRPWsfc 0 107,1,1 ** surface Primary wave direction [deg]<br> DIRSWsfc 0 109,1,1 ** surface Secondary wave direction [deg]<br> HTSGWsfc 0 100,1,1 ** surface Sig height of wind waves and swell [m]<br>
PERPWsfc 0 108,1,1 ** surface Primary wave mean period [s]<br> PERSWsfc 0 110,1,1 ** surface Secondary wave mean period [s]<br> UGRDsfc 0 33,1,1 ** surface u wind [m/s]<br> VGRDsfc 0 34,1,1 ** surface v wind [m/s]<br>
WDIRsfc 0 31,1,1 ** surface Wind direction [deg]<br> WINDsfc 0 32,1,1 ** surface Wind speed [m/s]<br> WVDIRsfc 0 101,1,1 ** surface Direction of wind waves [deg]<br> WVPERsfc 0 103,1,1 ** surface Mean period of wind waves [s]</div>
<br>...and I can see that others have been able to show the primary wave direction (DIRPWsfc) using vector arrows, as is the case on the FNMOC models like this one:<br> <a href="https://www.fnmoc.navy.mil/ww3_cgi/dynamic/ww3.w.npac.sig_wav_ht.000.gif" target="_blank">https://www.fnmoc.navy.mil/ww3_cgi/dynamic/ww3.w.npac.sig_wav_ht.000.gif</a><br>
<br>Do you know how this can be done?<br><br> Thanks,<br><br>-Nathan<br><br><br><div class="gmail_quote">On Tue, Nov 3, 2009 at 9:58 PM, sushant puranik <span dir="ltr"><<a href="mailto:sushantpuranik@gmail.com" target="_blank">sushantpuranik@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi<br>I am able to generate wind direction. try his <br>'set arrscl 1 30'<br>'set cthick 5'<br>
'set arrowhead 0.10'<br>'set clevs 3 5 10 15 20 25'<br>'set ccols 0 4 1 2 3 5 12'<br>'set gxout vector'<br> 'd skip(UGRDsfc,2,2);skip(VGRDsfc,2,2);skip(sqrt(UGRDsfc*UGRDsfc+VGRDsfc*VGRDsfc),2,2)'<br>
'run <a href="http://cbar.gs" target="_blank">cbar.gs</a>'<br>'printim wind(m/s)'<br><br>with the help of such script i am able to generate output which is attached with this mail.<br> <br>all the best.<div>
<div></div><div><br><br><div class="gmail_quote">On Tue, Nov 3, 2009 at 9:45 PM, Nathan Cool <span dir="ltr"><<a href="mailto:nathan@nathancool.com" target="_blank">nathan@nathancool.com</a>></span> wrote:<br> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Good morning everyone,<br><br>I'm generating wave analysis models, but I'm having a tough time showing the mean-wave (or primary) wave direction arrows. <br> <br> The vars in the Grib are:<br> -------------------------------------------------<br>
DIRPWsfc 0 107,1,1 ** surface Primary wave direction [deg]<br> DIRSWsfc 0 109,1,1 ** surface Secondary wave direction [deg]<br> HTSGWsfc 0 100,1,1 ** surface Sig height of wind waves and swell [m]<br> PERPWsfc 0 108,1,1 ** surface Primary wave mean period [s]<br>
PERSWsfc 0 110,1,1 ** surface Secondary wave mean period [s]<br> UGRDsfc 0 33,1,1 ** surface u wind [m/s]<br> VGRDsfc 0 34,1,1 ** surface v wind [m/s]<br> WDIRsfc 0 31,1,1 ** surface Wind direction [deg]<br> WINDsfc 0 32,1,1 ** surface Wind speed [m/s]<br>
WVDIRsfc 0 101,1,1 ** surface Direction of wind waves [deg]<br> WVPERsfc 0 103,1,1 ** surface Mean period of wind waves [s]<br> <br>For displaying wind vector arrows it's straightforward as there are U and V variables (UGRDsfc and VGRDsfc) for the zonal and meridional components. Displaying primary wave direction though seems more elusive, yet I see it done on many models such as the following:<br>
<a href="https://www.fnmoc.navy.mil/ww3_cgi/dynamic/ww3.w.npac.sig_wav_ht.000.gif" target="_blank">https://www.fnmoc.navy.mil/ww3_cgi/dynamic/ww3.w.npac.sig_wav_ht.000.gif</a><br><br>...which was generated using GrADS by FNMOC.<br>
<br> Any help you can provide would be greatly appreciated, and thank you for your time.<br><font color="#888888"><br>--<br>Nathan Cool<br><a href="mailto:nathan@nathancool.com" target="_blank">nathan@nathancool.com</a><br>
</font></blockquote></div><br><br clear="all"><br></div></div><font color="#888888">-- <br>Sushant Puranik<br>Junior Research Fellow<br>Dept. of Atmospheric & Space Sciences,<br>University of Pune,<br>Pune-07,<br>India.<br>
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