<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span>Hi</span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span>While writing variables to a text, you can create a loop for related variables and use 'gxout' command. As an example you can look at the following simple example to write precipitation in the text file for 200 time steps.</span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; ">However before using this example, you have to create .ctl file based on your grib files. You can use wgrib to open a grib file, and use grib2ctl to make a .ctl file from the grib files (you can also make .ctl file manually, for some variables it is not a big deal. But you need to get information from the grib
files using wgrib). Then, use gribmap to create .idx file from the .ctl file. After creating all of these files, run the following script. </div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><br></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; ">(For documentation on all of the above commands, look the tutorials and online documentation available in the link <a href="http://grads.iges.org/grads/gadoc/" style="font-size: 16px; ">http://grads.iges.org/grads/gadoc/</a>). I hope this is helpful. </div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span><br></span></div><div><span><div>'open c:\dummy.ctl'</div><div><br></div><div>'set gxout print'</div><div><br></div><div>'set lat 38 42'</div><div>'set lon -105 -96'</div><div><br></div><div>lat = 38.5625</div><div><br></div><div>lon =
-104.1875</div><div><br></div><div>'set t 1'</div><div>count = 1</div><div>while (count <= 200)</div><div>'set t' count</div><div><br></div><div>'d apcp'</div><div>pcp=subwrd(result,20)</div><div><br></div><div>dummy = write('data'',count"<span class="Apple-tab-span" style="white-space: pre; "> </span>"pcp)<br></div><div><br></div><div>count = count + 1</div><div>endwhile</div><div><br></div><div><br></div><div><br></div><div><br></div></span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span> </span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "> </div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><font class="Apple-style-span" color="#0000ff"><font style="font-size:medium;background-color:transparent;" size="2"><span style="font-family: arial; ">Sincerely,<br>Anil Acharya <br></span></font><span
style="font-family: arial; "><font class="Apple-style-span" size="2"><i>Research Associate</i></font></span></font></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><font size="2" color="#0000ff"><span style="font-family: arial; "><i>Idaho Water Center, </i></span></font><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: small; font-family: arial; "><i>University of Idaho</i></span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span style="font-style: italic; font-family: arial; "><font class="Apple-style-span" size="2" color="#0000ff">322 E Front Street, Suite 324F</font></span></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><span style="font-style: italic; font-family: arial; "><font class="Apple-style-span" size="2" color="#0000ff">Boise, Idaho, 83702</font></span></div><div
style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><font class="Apple-style-span" color="#0000ff" face="arial" size="2"><i><br></i></font></div><div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt; "><br></div> <div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; "> <div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; "> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> "gradsusr-request@gradsusr.org" <gradsusr-request@gradsusr.org><br> <b><span style="font-weight: bold;">To:</span></b> gradsusr@gradsusr.org <br> <b><span style="font-weight: bold;">Sent:</span></b> Wednesday, November 23, 2011 10:22 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> gradsusr Digest, Vol 21, Issue 66<br> </font> <br>Send gradsusr mailing list submissions
to<br> <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br><br>To subscribe or unsubscribe via the World Wide Web, visit<br> <a href="http://gradsusr.org/mailman/listinfo/gradsusr" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>or, via email, send a message with subject or body 'help' to<br> <a ymailto="mailto:gradsusr-request@gradsusr.org" href="mailto:gradsusr-request@gradsusr.org">gradsusr-request@gradsusr.org</a><br><br>You can reach the person managing the list at<br> <a ymailto="mailto:gradsusr-owner@gradsusr.org" href="mailto:gradsusr-owner@gradsusr.org">gradsusr-owner@gradsusr.org</a><br><br>When replying, please edit your Subject line so it is more specific<br>than "Re: Contents of gradsusr digest..."<br><br><br>Today's Topics:<br><br> 1. (no subject) (Alireza Azargoun)<br> 2. writing
results & variables to a text file (Alireza Azargoun)<br> 3. Re: Specialized Display Question (Jeff Duda)<br> 4. Re: Specialized Display Question (Jeff Duda)<br><br><br>----------------------------------------------------------------------<br><br>Message: 1<br>Date: Wed, 23 Nov 2011 20:25:27 +0330<br>From: Alireza Azargoun <<a ymailto="mailto:alireza.azargoun@gmail.com" href="mailto:alireza.azargoun@gmail.com">alireza.azargoun@gmail.com</a>><br>Subject: [gradsusr] (no subject)<br>To: <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>Message-ID:<br> <CAKuuxT4OhrFz40sbjnuWCUbJBMH55fnmJh3geTJLT5XQz3=<a ymailto="mailto:03g@mail.gmail.com" href="mailto:03g@mail.gmail.com">03g@mail.gmail.com</a>><br>Content-Type: text/plain; charset="iso-8859-1"<br><br>Dear GrADS users<br>Hi everybody<br><br>I have about 200 grib2 files ( 1.grb2 ~ 200.grb ) . i need to
read a<br>temperature of a city (lat, lon, lev, time are constant in all files) . how<br>i can read this files using a while loop!? ( I receive this error when i<br>write a while. Unknown Command: while )<br> and how can i write these data to a text file!? I've searched all grads<br>option for a command that writes variables in a text file! but i couldn't<br>find it!<br><br>Thanks in advance,<br>Alireza<br>Sharif University of Technology<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <a href="http://gradsusr.org/pipermail/gradsusr/attachments/20111123/3f4a31b4/attachment-0001.html" target="_blank">http://gradsusr.org/pipermail/gradsusr/attachments/20111123/3f4a31b4/attachment-0001.html</a> <br><br>------------------------------<br><br>Message: 2<br>Date: Wed, 23 Nov 2011 20:33:25 +0330<br>From: Alireza Azargoun <<a ymailto="mailto:alireza.azargoun@gmail.com"
href="mailto:alireza.azargoun@gmail.com">alireza.azargoun@gmail.com</a>><br>Subject: [gradsusr] writing results & variables to a text file<br>To: GrADS Users Forum <<a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a>><br>Message-ID:<br> <CAKuuxT6WpbvCRhmwu+8QhzgytddHWGHYVtmh4sNV7FCE=+<a ymailto="mailto:X0cA@mail.gmail.com" href="mailto:X0cA@mail.gmail.com">X0cA@mail.gmail.com</a>><br>Content-Type: text/plain; charset="iso-8859-1"<br><br>Dear GrADS users<br>Hi everybody<br><br>I have about 200 grib2 files ( 1.grb2 ~ 200.grb ) . i need to read a<br>temperature of a city (lat, lon, lev, time are constant in all files) . how<br>i can read this files using a while loop!? ( I receive this error when i<br>write a while. Unknown Command: while )<br> and how can i write these data to a text file!? I've searched all grads<br>option for a command that writes variables in
a text file! but i couldn't<br>find it!<br><br>Thanks in advance,<br>Alireza<br>Sharif University of Technology<br><br><br>-- <br>Alireza Azargoun<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <a href="http://gradsusr.org/pipermail/gradsusr/attachments/20111123/230c6444/attachment-0001.html" target="_blank">http://gradsusr.org/pipermail/gradsusr/attachments/20111123/230c6444/attachment-0001.html</a> <br><br>------------------------------<br><br>Message: 3<br>Date: Wed, 23 Nov 2011 11:17:20 -0600<br>From: Jeff Duda <<a ymailto="mailto:jeffduda319@gmail.com" href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>><br>Subject: Re: [gradsusr] Specialized Display Question<br>To: GrADS Users Forum <<a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a>><br>Message-ID:<br> <CAAig09B2+<a
ymailto="mailto:7mFXvdFHCwEj7ogt3z5OmckfDKVtNHerEJ_u6CVgw@mail.gmail.com" href="mailto:7mFXvdFHCwEj7ogt3z5OmckfDKVtNHerEJ_u6CVgw@mail.gmail.com">7mFXvdFHCwEj7ogt3z5OmckfDKVtNHerEJ_u6CVgw@mail.gmail.com</a>><br>Content-Type: text/plain; charset="iso-8859-1"<br><br>Mason,<br>I haven't looked at your script, but here are the answers to your questions.<br><br>You got the error from CDIFF when setting lev statically because it needs<br>the vertical dimension to be varying in order to work. On the other hand,<br>typing the expression in manually does not require the vertical dimension<br>to vary. To see why this works, look through the top section of the<br>variables page <<a href="http://www.iges.org/grads/gadoc/variable.html#names" target="_blank">http://www.iges.org/grads/gadoc/variable.html#names</a>> on the<br>Grads site. Basically, you can use parentheses to tag a field with a<br>spatiotemporal (and/or ensemble) offset or
specification. For example, 'd<br>tmpprs(z+1)' tells Grads to plot tmpprs one vertical level away from where<br>the current vertical dimension is set (this works for both fixed and<br>varying vertical dimension settings). So if you have two pressure levels<br>at 850 and 800 mb, if your lev is set to 850, 'd tmpprs(z+1)' will plot<br>temperatures at 800 mb. 'd tmpprs(z-1)' plots tmpprs one level down. You<br>can specify the level, too. Say you want to plot 500 mb heights and MSLP.<br>The following lines of code to do that are equivalent:<br>'set lev 500'<br>'d hgtprs'<br>'set lev 1000'<br>'d mslmamsl'<br><br>OR<br><br>'set lev 500'<br>'d hgtprs'<br>'d mslmamsl(lev=1000)'<br><br>OR<br>(assume lev is set to something other than 500 or 1000)<br>'d hgtprs(lev=500)'<br>'d mslmamsl(lev=1000)'<br><br>Thus, this command: 'd (theta(z+1)-theta(z-1)) /<br>(hgtprs(z+1)-hgtprs(z-1))', tells grads to plot an approximation of
the<br>vertical derivative of theta in the same way that CDIFF would do it. It's<br>just that CDIFF requires a varying vertical dimension if you use Z as the<br>argument, which means you pretty much can't use it to display a vertical<br>derivative on a single pressure surface in a horizontal cross section<br>(sorry, that just came to me, so I apologize for the confusion).<br><br>To compute potential temperature using the formula you have, use the pow()<br>function instead of the carrot. Thus, potprs = tmpprs*pow(1000/lev,2/7)<br>(with your vertical dimension varying over all the levels you want to have<br>potential temperature defined) will give you a grid of potential<br>temperatures.<br><br>Here's my suggestion for how to plot the vertical temperature gradient at<br>850 mb given NARR data (assuming I remember the variable names):<br><br>'set x 1 (whatever last index is)'<br>'set y 1 (whatever last index is)'<br>'set lev 1000 (however high
you want, but make sure it includes the level<br>above the one you want to view the gradient on)'<br>'define theta = tmpprs*pow(1000/lev,2/7)'<br>'set lev 850'<br>'d (theta(z+1)-theta(z-1)) / (hgtprs(z+1)-hgtprs(z-1))'<br><br>Jeff<br><br>On Wed, Nov 23, 2011 at 12:44 AM, Rowell, Mason D.<br><<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>>wrote:<br><br>> All,<br>><br>> Well I appear to still have issues. I can define theta like I discovered<br>> I can, but then I can't just use this in Jeff's vertical derivative<br>> expression (the one that will work), given that its value at z+1 and z-1 is<br>> not defined. I thought I was being clever getting around that, but it<br>> claims I am not setting lev right, and I don't know why. Script is<br>> attached. Any ideas?<br>><br>> Mason<br>> ------------------------------<br>> *From:* <a
ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>> behalf of Rowell, Mason D. [<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>]<br>> *Sent:* Tuesday, November 22, 2011 11:21 PM<br>><br>> *To:* GrADS Users Forum<br>> *Subject:* Re: [gradsusr] Specialized Display Question<br>><br>> Apparently it won't take lev in my potential temp expression, even<br>> though it is set to the right lev I need, but If I define hgt = 850 for<br>> example, use that to set lev, then use hgt in my expression, it takes it.<br>> The issue with defining potential temp. from NARR data is solved then (I<br>> knew it shouldn't have been challenging). Now I just need to
confirm that<br>> Jeff's second method for cdiff (given it still doesn't take the first<br>> method provided) does indeed approximate the vertical deriv. for the<br>> central level, as I would assume it does if I know the method like I think<br>> I do.<br>><br>> Mason<br>> ------------------------------<br>> *From:* <a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>> behalf of Rowell, Mason D. [<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>]<br>> *Sent:* Tuesday, November 22, 2011 10:58 PM<br>> *To:* GrADS Users Forum<br>> *Subject:* Re: [gradsusr] Specialized Display Question<br>><br>> Jeff,<br>><br>> Well the
expression given second will work with lev set statically<br>> before entering the command (doesn't make sense to me to enter it after<br>> given the level about which to compute a central difference would have to<br>> be known first), but the first expression (w/ lev first set) gives 'Error<br>> from CDIFF: Specified dimension non varying', which is what I thought I<br>> would get out of cdiff given lev is set statically. Though the second<br>> command may suffice for my purposes. As I said I was able to get it to<br>> work, after having set lev, so I assume the display is appropriate for the<br>> lev I choose and no other (I'd imagine it would have to be if the<br>> expression is working as it appears, that is the central difference about<br>> the set lev, with this approximation valid for the state of the derivative<br>> at the center, ie the level about which the central difference is<br>> computed). The
syntax is new to me so it is good to learn. Now I just need<br>> to get a potential temperature expression to display for me.<br>><br>> Mason<br>> ------------------------------<br>> *From:* <a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>> behalf of Jeff Duda [<a ymailto="mailto:jeffduda319@gmail.com" href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>]<br>> *Sent:* Tuesday, November 22, 2011 8:41 PM<br>> *To:* GrADS Users Forum<br>> *Subject:* Re: [gradsusr] Specialized Display Question<br>><br>> Mason,<br>> You can use the cdiff command in the z direction to display variables<br>> (unfortunately, you can't use it to define variables). However, you can<br>>
approximate the vertical derivative by copying the method that cdiff uses.<br>> If you have geopotential height, then you have all you need to compute a<br>> vertical derivative with respect to height coordinates. You can display<br>> the vertical derivative of theta by either of the following:<br>><br>> 'd cdiff(theta,z)'<br>> 'd (theta(z+1)-theta(z-1)) / (hgtprs(z+1)-hgtprs(z-1))<br>><br>> If you want to just view the gradient on one pressure surface, set the<br>> level that surface, then enter the command.<br>><br>> Jeff<br>><br>> On Tue, Nov 22, 2011 at 7:54 PM, Rowell, Mason D. <<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a><br>> > wrote:<br>><br>>> All,<br>>><br>>> Is it possible to display the vertical derivative of some quantity (like<br>>> say temp or potential temp) on a pressure surface? I know I have
height in<br>>> my NARR data, but it is specific to a pressure level (i.e. HGTprs). What I<br>>> would need is the height just above the current pressure level and below it<br>>> in order to get cdiff of say theta and z. I'm not sure how to set the<br>>> dimensions to do this...I would be okay with just getting this quantity for<br>>> display at some level height, it doesn't have to be on a pressure surface.<br>>><br>>> Mason<br>>> _______________________________________________<br>>> gradsusr mailing list<br>>> <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>>> <a href="http://gradsusr.org/mailman/listinfo/gradsusr" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>>><br>><br>><br>><br>> --<br>> Jeff Duda<br>> Grad student - PhD, Meteorology<br>> University of Oklahoma School of
Meteorology - Center for Analysis and<br>> Prediction of Storms<br>><br>><br>> _______________________________________________<br>> gradsusr mailing list<br>> <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>> <a href="http://gradsusr.org/mailman/listinfo/gradsusr" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>><br>><br><br><br>-- <br>Jeff Duda<br>Grad student - PhD, Meteorology<br>University of Oklahoma School of Meteorology - Center for Analysis and<br>Prediction of Storms<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <a href="http://gradsusr.org/pipermail/gradsusr/attachments/20111123/5301872c/attachment-0001.html" target="_blank">http://gradsusr.org/pipermail/gradsusr/attachments/20111123/5301872c/attachment-0001.html</a> <br><br>------------------------------<br><br>Message: 4<br>Date: Wed, 23 Nov
2011 11:22:14 -0600<br>From: Jeff Duda <<a ymailto="mailto:jeffduda319@gmail.com" href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>><br>Subject: Re: [gradsusr] Specialized Display Question<br>To: GrADS Users Forum <<a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a>><br>Message-ID:<br> <CAAig09DhoBAqCSWBLySCc+fN+iO=<a ymailto="mailto:n8gWY_zvZuA0WV4o10uQOA@mail.gmail.com" href="mailto:n8gWY_zvZuA0WV4o10uQOA@mail.gmail.com">n8gWY_zvZuA0WV4o10uQOA@mail.gmail.com</a>><br>Content-Type: text/plain; charset="iso-8859-1"<br><br>Mason,<br>I "corrected" your script file and reattached it here. Basically you were<br>a little quote-happy with your definitions in the first half of the<br>script. Other than that you coded it in a way that would work. Hopefully<br>you understand why certain variables don't need to be in quotes.<br><br>Jeff<br><br>On
Wed, Nov 23, 2011 at 11:17 AM, Jeff Duda <<a ymailto="mailto:jeffduda319@gmail.com" href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>> wrote:<br><br>> Mason,<br>> I haven't looked at your script, but here are the answers to your<br>> questions.<br>><br>> You got the error from CDIFF when setting lev statically because it needs<br>> the vertical dimension to be varying in order to work. On the other hand,<br>> typing the expression in manually does not require the vertical dimension<br>> to vary. To see why this works, look through the top section of the<br>> variables page <<a href="http://www.iges.org/grads/gadoc/variable.html#names" target="_blank">http://www.iges.org/grads/gadoc/variable.html#names</a>> on<br>> the Grads site. Basically, you can use parentheses to tag a field with a<br>> spatiotemporal (and/or ensemble) offset or specification. For example, 'd<br>>
tmpprs(z+1)' tells Grads to plot tmpprs one vertical level away from where<br>> the current vertical dimension is set (this works for both fixed and<br>> varying vertical dimension settings). So if you have two pressure levels<br>> at 850 and 800 mb, if your lev is set to 850, 'd tmpprs(z+1)' will plot<br>> temperatures at 800 mb. 'd tmpprs(z-1)' plots tmpprs one level down. You<br>> can specify the level, too. Say you want to plot 500 mb heights and MSLP.<br>> The following lines of code to do that are equivalent:<br>> 'set lev 500'<br>> 'd hgtprs'<br>> 'set lev 1000'<br>> 'd mslmamsl'<br>><br>> OR<br>><br>> 'set lev 500'<br>> 'd hgtprs'<br>> 'd mslmamsl(lev=1000)'<br>><br>> OR<br>> (assume lev is set to something other than 500 or 1000)<br>> 'd hgtprs(lev=500)'<br>> 'd mslmamsl(lev=1000)'<br>><br>> Thus, this command: 'd (theta(z+1)-theta(z-1)) /<br>>
(hgtprs(z+1)-hgtprs(z-1))', tells grads to plot an approximation of the<br>> vertical derivative of theta in the same way that CDIFF would do it. It's<br>> just that CDIFF requires a varying vertical dimension if you use Z as the<br>> argument, which means you pretty much can't use it to display a vertical<br>> derivative on a single pressure surface in a horizontal cross section<br>> (sorry, that just came to me, so I apologize for the confusion).<br>><br>> To compute potential temperature using the formula you have, use the pow()<br>> function instead of the carrot. Thus, potprs = tmpprs*pow(1000/lev,2/7)<br>> (with your vertical dimension varying over all the levels you want to have<br>> potential temperature defined) will give you a grid of potential<br>> temperatures.<br>><br>> Here's my suggestion for how to plot the vertical temperature gradient at<br>> 850 mb given NARR data (assuming I
remember the variable names):<br>><br>> 'set x 1 (whatever last index is)'<br>> 'set y 1 (whatever last index is)'<br>> 'set lev 1000 (however high you want, but make sure it includes the level<br>> above the one you want to view the gradient on)'<br>> 'define theta = tmpprs*pow(1000/lev,2/7)'<br>> 'set lev 850'<br>> 'd (theta(z+1)-theta(z-1)) / (hgtprs(z+1)-hgtprs(z-1))'<br>><br>> Jeff<br>><br>><br>> On Wed, Nov 23, 2011 at 12:44 AM, Rowell, Mason D. <<br>> <a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>> wrote:<br>><br>>> All,<br>>><br>>> Well I appear to still have issues. I can define theta like I<br>>> discovered I can, but then I can't just use this in Jeff's vertical<br>>> derivative expression (the one that will work), given that its value at z+1<br>>> and z-1 is not defined. I thought I
was being clever getting around that,<br>>> but it claims I am not setting lev right, and I don't know why. Script is<br>>> attached. Any ideas?<br>>><br>>> Mason<br>>> ------------------------------<br>>> *From:* <a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>>> behalf of Rowell, Mason D. [<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>]<br>>> *Sent:* Tuesday, November 22, 2011 11:21 PM<br>>><br>>> *To:* GrADS Users Forum<br>>> *Subject:* Re: [gradsusr] Specialized Display Question<br>>><br>>> Apparently it won't take lev in my potential temp expression, even<br>>> though it is
set to the right lev I need, but If I define hgt = 850 for<br>>> example, use that to set lev, then use hgt in my expression, it takes it.<br>>> The issue with defining potential temp. from NARR data is solved then (I<br>>> knew it shouldn't have been challenging). Now I just need to confirm that<br>>> Jeff's second method for cdiff (given it still doesn't take the first<br>>> method provided) does indeed approximate the vertical deriv. for the<br>>> central level, as I would assume it does if I know the method like I think<br>>> I do.<br>>><br>>> Mason<br>>> ------------------------------<br>>> *From:* <a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>>> behalf of
Rowell, Mason D. [<a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>]<br>>> *Sent:* Tuesday, November 22, 2011 10:58 PM<br>>> *To:* GrADS Users Forum<br>>> *Subject:* Re: [gradsusr] Specialized Display Question<br>>><br>>> Jeff,<br>>><br>>> Well the expression given second will work with lev set statically<br>>> before entering the command (doesn't make sense to me to enter it after<br>>> given the level about which to compute a central difference would have to<br>>> be known first), but the first expression (w/ lev first set) gives 'Error<br>>> from CDIFF: Specified dimension non varying', which is what I thought I<br>>> would get out of cdiff given lev is set statically. Though the second<br>>> command may suffice for my purposes. As I said I was able to get it to<br>>> work, after having set
lev, so I assume the display is appropriate for the<br>>> lev I choose and no other (I'd imagine it would have to be if the<br>>> expression is working as it appears, that is the central difference about<br>>> the set lev, with this approximation valid for the state of the derivative<br>>> at the center, ie the level about which the central difference is<br>>> computed). The syntax is new to me so it is good to learn. Now I just need<br>>> to get a potential temperature expression to display for me.<br>>><br>>> Mason<br>>> ------------------------------<br>>> *From:* <a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a> [<a ymailto="mailto:gradsusr-bounces@gradsusr.org" href="mailto:gradsusr-bounces@gradsusr.org">gradsusr-bounces@gradsusr.org</a>] on<br>>> behalf of Jeff Duda [<a
ymailto="mailto:jeffduda319@gmail.com" href="mailto:jeffduda319@gmail.com">jeffduda319@gmail.com</a>]<br>>> *Sent:* Tuesday, November 22, 2011 8:41 PM<br>>> *To:* GrADS Users Forum<br>>> *Subject:* Re: [gradsusr] Specialized Display Question<br>>><br>>> Mason,<br>>> You can use the cdiff command in the z direction to display variables<br>>> (unfortunately, you can't use it to define variables). However, you can<br>>> approximate the vertical derivative by copying the method that cdiff uses.<br>>> If you have geopotential height, then you have all you need to compute a<br>>> vertical derivative with respect to height coordinates. You can display<br>>> the vertical derivative of theta by either of the following:<br>>><br>>> 'd cdiff(theta,z)'<br>>> 'd (theta(z+1)-theta(z-1)) / (hgtprs(z+1)-hgtprs(z-1))<br>>><br>>> If you want to just view the
gradient on one pressure surface, set the<br>>> level that surface, then enter the command.<br>>><br>>> Jeff<br>>><br>>> On Tue, Nov 22, 2011 at 7:54 PM, Rowell, Mason D. <<br>>> <a ymailto="mailto:Mason.D.Rowell-1@ou.edu" href="mailto:Mason.D.Rowell-1@ou.edu">Mason.D.Rowell-1@ou.edu</a>> wrote:<br>>><br>>>> All,<br>>>><br>>>> Is it possible to display the vertical derivative of some quantity (like<br>>>> say temp or potential temp) on a pressure surface? I know I have height in<br>>>> my NARR data, but it is specific to a pressure level (i.e. HGTprs). What I<br>>>> would need is the height just above the current pressure level and below it<br>>>> in order to get cdiff of say theta and z. I'm not sure how to set the<br>>>> dimensions to do this...I would be okay with just getting this quantity for<br>>>> display at some level
height, it doesn't have to be on a pressure surface.<br>>>><br>>>> Mason<br>>>> _______________________________________________<br>>>> gradsusr mailing list<br>>>> <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>>>> <a href="http://gradsusr.org/mailman/listinfo/gradsusr" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>>>><br>>><br>>><br>>><br>>> --<br>>> Jeff Duda<br>>> Grad student - PhD, Meteorology<br>>> University of Oklahoma School of Meteorology - Center for Analysis and<br>>> Prediction of Storms<br>>><br>>><br>>> _______________________________________________<br>>> gradsusr mailing list<br>>> <a ymailto="mailto:gradsusr@gradsusr.org" href="mailto:gradsusr@gradsusr.org">gradsusr@gradsusr.org</a><br>>> <a
href="http://gradsusr.org/mailman/listinfo/gradsusr" target="_blank">http://gradsusr.org/mailman/listinfo/gradsusr</a><br>>><br>>><br>><br>><br>> --<br>> Jeff Duda<br>> Grad student - PhD, Meteorology<br>> University of Oklahoma School of Meteorology - Center for Analysis and<br>> Prediction of Storms<br>><br>><br><br><br>-- <br>Jeff Duda<br>Grad student - PhD, Meteorology<br>University of Oklahoma School of Meteorology - Center for Analysis and<br>Prediction of Storms<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <a href="http://gradsusr.org/pipermail/gradsusr/attachments/20111123/27bbe0c1/attachment.html" target="_blank">http://gradsusr.org/pipermail/gradsusr/attachments/20111123/27bbe0c1/attachment.html</a> <br>-------------- next part --------------<br>A non-text attachment was scrubbed...<br>Name: meso_proj_ms_fr_jdduda.gs<br>Type: application/octet-stream<br>Size:
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