[gradsusr] gradsusr Digest, Vol 8, Issue 33
Brian.Hoeth at noaa.gov
Brian.Hoeth at noaa.gov
Wed Oct 20 14:03:12 EDT 2010
Jennifer,
Your suggestions worked, thank you very much!
Brian Hoeth
NWS Spaceflight Meteorology Group
Johnson Space Center
Houston, TX
281-483-3246
----- Original Message -----
From: gradsusr-request at gradsusr.org
Date: Wednesday, October 20, 2010 10:46 am
Subject: gradsusr Digest, Vol 8, Issue 33
To: gradsusr at gradsusr.org
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> Today's Topics:
>
> 1. Re: Trouble displaying data from netcdf file (Jennifer Adams)
> 2. spatial plot form a time series of multiple stations
> (Thomas W. Collow)
> 3. Re: CDIFF Versus HDIVG? (Eric Altshuler)
> 4. Re: Visualize Wind Vectors (Nena Carina Espa?ola)
> 5. cdiff function (Adrian Scherzinger)
> 6. Re: cdiff function (Jeffrey Duda)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 19 Oct 2010 16:44:19 -0400
> From: Jennifer Adams <jma at cola.iges.org>
> Subject: Re: [gradsusr] Trouble displaying data from netcdf file
> To: GrADS Users Forum <gradsusr at gradsusr.org>
> Message-ID: <83639431-6BF9-4621-99DA-9F2FB4479837 at cola.iges.org>
> Content-Type: text/plain; charset="us-ascii"
>
> In the ncdump output, you have this:
> float mslp(record, levels_1, y, x) ;
>
> which means the variable has 4 dimensions, so you need to change your
>
> variable declaration in the descriptor file from
> mslp=>mslp 1 Y,X Mean Sea Level Pressure (Pa)
> to
> mslp=>mslp 1 t,z,y,x Mean Sea Level Pressure (Pa)
>
> Similar changes may be required for other variables. Also, it isn't
>
> necessary to alias the variable name to the identical thing. The
> native varname is compliant with GrADS requirements, so you can
> change
> "mslp=>mslp" to just "mslp".
>
> --Jennifer
>
> On Oct 19, 2010, at 3:00 PM, Brian.Hoeth at noaa.gov wrote:
>
> > Hello,
> >
> > I'm having troubles displaying data from a netcdf file. I'm sure
>
> > there is an error in my index file, but I just don't know what I'm
>
> > missing?
> >
> > I've attached the output of ncdump -c (ncdump.txt), my control file
>
> > (adas_ncdf.ctl), and my grads session (gradsout.txt).
> >
> > Thanks in advance for your help!> > Brian Hoeth
> > NWS Spaceflight Meteorology Group
> > Johnson Space Center
> > Houston, TX
> > 281-483-3246
> >
> >
> >
> >
> > <
> > adas_ncdf
> > .ctl
> > >
> > <
> > gradsout
> > .txt><ncdump.txt>_______________________________________________
> > gradsusr mailing list
> > gradsusr at gradsusr.org
> >
>
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org
>
>
>
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> ------------------------------
>
> Message: 2
> Date: Tue, 19 Oct 2010 16:55:45 -0400 (EDT)
> From: "Thomas W. Collow" <tcollow at eden.rutgers.edu>
> Subject: [gradsusr] spatial plot form a time series of multiple
> stations
> To: gradsusr at gradsusr.org
> Message-ID: <209816879.4383.1287521744847.JavaMail.tomcat at aveo>
> Content-Type: text/plain; charset=ISO-8859-1
>
> I asked a similar question awhile back but perhaps did not make it
> clear enough what I am trying to do.
>
> I have several ARM/CART files for soil moisture data for about 12
> different stations over the central USA. Each file is a netcdf file
> for 24 different times (every hour for one day). I am able to
> template each of the files that are for the same station to make a
> time series say over one month. So for each of the 12 different
> stations I can make a monthly time series. What I would like to do is
> create a spatial plot of this data which would involve me taking one
> point from each of the 12 files and plotting it on a single map in
> GrADS. Each point would have a different latitude and longitude
> depending on the file but it would be at the same time. I have
> created a control file for each station which allows me to display the
> station time series in GrADS using the xdfopen command. The command
> sdfopen did not work in opening the control file. Also there was no
> latitude/ longitude dimension, only time and depth. The latitude and
> longitude are known and are put in for the y!
> def and xdef parameters respectively.
>
> Here is a control file for opening the time series of one station (ARM_E4)
>
> DSET ^ARM_files/sgpswatsE4.b1.201008%d2.000700.cdf
> OPTIONS template
> OPTIONS zrev
> TITLE ARM Data
> UNDEF -9999
> XDEF time 01 levels -98.329
> YDEF time 01 levels 37.953
> ZDEF depth 8 levels 175 125 85 60 35 25 15 5
> TDEF time 720 linear 00Z01aug2010 1hr
> VARS 2
> watcont_W=>smw 8 99 water content west
> watcont_E=>sme 8 99 water content east
> ENDVARS
>
> For station E9 (ARM_E9)
> DSET ^ARM_files/sgpswatsE9.b1.201008%d2.000700.cdf
> OPTIONS template
> OPTIONS zrev
> TITLE ARM Data
> UNDEF -9999
> XDEF time 01 levels -97.266
> YDEF time 01 levels 37.133
> ZDEF depth 8 levels 175 125 85 60 35 25 15 5
> TDEF time 720 linear 00Z01aug2010 1hr
> VARS 2
> watcont_W=>smw 8 99 water content west
> watcont_E=>sme 8 99 water content east
> ENDVARS
>
> This is one approach I took, here is a GrADS script I tried to use to
> plot these two stations on a spatial map.
>
> reinit
> set mpdset hires
> xdfopen ARM_E4
> xdfopen ARM_E9
> set lat 25 45
> set lon -105 -85
> set T 1
> set z 8
> set gxout grfill
> d smw
> d smw.2
>
>
> However, all this did was plot two points on a map in the right
> locations but GrADS is treating them as entirely different variables
> and it seems two maps were made with one map on top of the other.
> Therefore it looks like one map but it really isn?t. How do I treat
> these as one variable on one map for two or more stations? Thanks
>
> Tom
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 19 Oct 2010 19:58:16 -0400 (EDT)
> From: Eric Altshuler <ela at cola.iges.org>
> Subject: Re: [gradsusr] CDIFF Versus HDIVG?
> To: GrADS Users Forum <gradsusr at gradsusr.org>
> Message-ID:
> <1541734297.2667.1287532696811.JavaMail.root at mail.iges.org>
> Content-Type: text/plain; charset=utf-8
>
> Hello Robert,
>
> Your expressions for du and dv are incorrect for calculating
> divergence. I assume you copied the expressions from the grads
> documentation page for cdiff, where an example is presented for
> calculating vorticity. However, the expressions are different when
> calculating divergence. Use the following:
>
> du = cdiff(ugrdprs,x)
> dv = cdiff(vgrdprs*cos(lat*3.1416/180),y)
>
> I based these expressions on the formula for divergence in spherical
> coordinates given in Holton's book, in the appendix on vector analysis
> (I have the 4th edition, but older editions should have the same appendix).
>
> As an aside, I think it's possible to obtain more accurate
> approximations for divergence and vorticity than those given in the
> grads documentation, because the factor cos(lat) can be taken outside
> the derivative operator and differentiated analytically rather than
> using finite differencing. Using the product rule of differentiation
> and a bit of algebra, I have derived the following sequence of
> calculations for these quantities (my definitions of intermediate
> quantities are different, but the end result is the same):
>
> pi=3.14159265359
> dtr=pi/180
> a=6.371e6
> dx=a*cos(dtr*lat)*dtr*cdiff(lon,x)
> dy=a*dtr*cdiff(lat,y)
> div=cdiff(u,x)/dx+cdiff(v,y)/dy-v*tan(dtr*lat)/a
> vor=cdiff(v,x)/dx-cdiff(u,y)/dy+u*tan(dtr*lat)/a
> def1=cdiff(u,x)/dx-cdiff(v,y)/dy-v*tan(dtr*lat)/a
> def2=cdiff(v,x)/dx+cdiff(u,y)/dy+u*tan(dtr*lat)/a
>
> In these formulas, substitute your wind variable names for u and v.
> In addition to divergence and vorticity, there are also calculations
> of the components of deformation, def1 and def2, and total deformation
> is equal to mag(def1,def2). These formulas (in terms of continuous
> fields) can also be found in Bluestein (1992), "Synoptic-Dynamic
> Meteorology in Midlatitudes", Vol. I, p. 111.
>
> Best regards,
>
> Eric L. Altshuler
> Assistant Research Scientist
> Center for Ocean-Land-Atmosphere Studies
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705-3106
> USA
>
> E-mail: ela at cola.iges.org
> Phone: (301) 902-1257
> Fax: (301) 595-9793
>
> ----- Original Message -----
> From: "Robert N LeeJoice" <rnleejoi at nps.edu>
> To: gradsusr at gradsusr.org
> Sent: Tuesday, October 19, 2010 3:27:26 PM
> Subject: [gradsusr] CDIFF Versus HDIVG?
>
>
> I was wondering if there is a difference in the differencing scheme
> between CDIFF and HDIVG. I ask because I did a modified example from
> the documentation, i.e., divergence vice vorticity. The documentation
> states that CDIFF uses centered differencing. HDIVG says the same. The
> images suggest something else unless I?m missing something.
>
> CDIFF file
> if(var='DIV')
> 'run bluewhitered.gs -2.0 .5 10'
> 'define dv = cdiff(vgrdprs,x)'
> 'define dx = cdiff(lon,x)*3.1416/180'
> 'define du = cdiff(ugrdprs*cos(lat*3.1416/180),y)'
> 'define dy = cdiff(lat,y)*3.1416/180'
> 'display (du/dx+dv/dy)*1e5/(6.37e6*cos(lat*3.1416/180))'
> 'run cbarn.gs 0.8 1 10.4 4.7'
> endif
>
> HDIVG file
> if(var='DIV')
> 'run bluewhitered.gs -2.0 .5 10'
> 'd 1e5*hdivg(ugrdprs,vgrdprs)'
> 'run cbarn.gs 0.8 1 10.4 4.7'
> Endif
>
> Here are the images in order...
>
> Thank you for any comments,
>
> Robert LeeJoice
> PhD Candidate, Naval Postgraduate School
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 20 Oct 2010 13:41:09 +0800
> From: Nena Carina Espa?ola <nena at asti.dost.gov.ph>
> Subject: Re: [gradsusr] Visualize Wind Vectors
> To: GrADS Users Forum <gradsusr at gradsusr.org>
> Message-ID: <4CBE80F5.9000303 at asti.dost.gov.ph>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Daniele,
>
> Thanks for the help.
>
> I am still figuring out how to convert my station data into GrADS
> binary
> as I am very new to GrADS. I already posted my problem yesterday but
>
> nobody has answered it yet.
>
>
> I do not know how to create a binary with more than one surface
> variable. I was able to create a binary for one variable only and
> most
> examples I find use only one variable. Now I have three, and data is
>
> hourly. Here's a sample:
> YEAR MO DA HO STNID LATITUDE LONGITUDE
> PRESSURE
> DIR SPEED
> 2010 09 08 08 98132 20.800283 121.847534 1012.3
>
> 160 12
> 2010 09 08 08 98133 19.283147 121.463012 1008.5
>
> 120 8
> 2010 09 08 08 98134 20.454293 121.963806 1009.2
>
> 140 12
> 2010 09 08 08 98222 17.582765 120.387268 1008.1
>
> 220 4
> 2010 09 08 08 98223 18.185845 120.58239 1006.6
>
> 250 10
> 2010 09 08 08 98232 18.360782 121.658935 1009.5
>
> 90 4
> 2010 09 08 08 98233 17.629364 121.70288 1008.1
>
> 0 0
> 2010 09 08 08 98324 15.328294 119.980087 1007.2
>
> 270 2
> 2010 09 08 08 98325 16.051192 120.333195 1007.3
>
> 360 4
> 2010 09 08 08 98327 16.607768 121.265259 1007.5
>
> 190 4
>
> Thanks again. :-)
>
>
> On Friday, 15 October, 2010 05:52 PM, Daniele Gandini wrote:
> > Hi Nena.
> >
> > Here a simple formula to have U and V in m/s from wind speed (velv)
> and direction (dirv):
> >
> > 'set gxout barb'
> > 'd -velv*cos((dirv-90)/180*3.14);-velv*cos(dirv/180*3.14)'
> >
> > To display these data with OACRES function first you must create a
> base grid file
> > with a "dummy" constant value for example and then you can
> interpolate wind data:
> >
> > 'vel=oacres(dummy.1,velv.2,4,3,3,1)'
> > 'd vel'
> > 'run cbarn.gs'
> >
> > Good luck.
> >
> > Daniele
> >
> > ----- Messaggio originale -----
> > Da: "Nena Carina Espa?ola"<nena at asti.dost.gov.ph>
> > A: "GrADS Users Forum"<gradsusr at gradsusr.org>
> > Inviato: Venerd?, 15 ottobre 2010 5:32:26
> > Oggetto: [gradsusr] Visualize Wind Vectors
> >
> >
> > Hello Guys!
> >
> > I am trying to create a visualization of the wind vectors. I am not
> sure where to begin as my data is not split into U and V components.
> Here's a snippet of the sample data I have. These are from 24 weather
> stations in the Philippines. Can I also interpolate these scattered
> data to create a gridded data using the OACRES function?
> >
> >
> >
> > Station ID Latitude Longitude Wind Speed (m/s) Wind Direction
> (degrees)
> > 12 15.721279 121.522293 0.8 204
> > 70 7.135233 124.814758 2.21 148
> > 72 6.960916 126.212082 6.34 286
> > 73 9.282162 123.244572 9.6 20
> > 74 8.997093 124.883595 1.54 85
> > 75 9.217067 124.713134 3.84 89
> > Thanks,
> >
> > Nena
> >
> >
>
> --
> *GRID OPERATIONS TEAM*
> Advanced Science & Technology Institute
> Department Of Science & Technology
> ASTI Bldg., C.P. Garcia Ave., Technology Park Complex
> U.P. Campus, Diliman, Quezon City, PHILIPPINES 1101
> Tel No: +63 2 4269760
> Email: nena at asti.dost.gov.ph <>
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>
> Message: 5
> Date: Wed, 20 Oct 2010 15:18:30 +0200
> From: Adrian Scherzinger <adrian.scherzinger at meteotest.ch>
> Subject: [gradsusr] cdiff function
> To: gradsusr at gradsusr.org
> Message-ID: <4CBEEC26.2020009 at meteotest.ch>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi
> I am looking for a function similar to cdiff, BUT instead of
> "The result value at each grid point is the value at the grid point
> plus
> one minus the value at the grid point minus one."
> i need a funktion that calculates:
> "The result value at each grid point is the value at the grid point
> minus the value at the grid point minus one."
>
> This is my problem:
> Each timestep of my mm5 precipitation data set contains the integral
> of
> the precipitation since t=1. I want to plot a bar graph with the
> precipitation of each hour (not the integral). If I want to get the
> value only at time X, I need to calculate (rain at t=x)-(rain at t=x-1).
> cdiff(rain,t) is not the solution.
>
> Thanks for your help
> Adrian
>
> --
> ___________________________
> Adrian Scherzinger
> Stv. Leiter Wetterprognosen
>
> Genossenschaft METEOTEST
> Fabrikstrasse 14, CH-3012 Bern
> Tel +41 (0)31 307 26 26
> Fax +41 (0)31 307 26 10
> adrian.scherzinger at meteotest.ch
>
>
> ********************************************************************
> 0900 57 61 52 (CHF 3.13/Min) im direkten Dialog mit dem Prognostiker
> METEOFON - das pers?nliche Wettertelefon von METEOTEST (05-18 Uhr)
> ********************************************************************
>
>
>
> ------------------------------
>
> Message: 6
> Date: Wed, 20 Oct 2010 10:40:06 -0500
> From: Jeffrey Duda <jdduda at iastate.edu>
> Subject: Re: [gradsusr] cdiff function
> To: GrADS Users Forum <gradsusr at gradsusr.org>
> Message-ID:
> <AANLkTiku13b3nOh64Vq2VzhuFcN8GbW8LOgfpw0dNuDs at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Adrain,
> Indeed, the CDIFF function won't help you here, but it sounds like
> you have
> answered your own question. All you need to do is (quoted from your
> message): "(rain at t=x)-(rain at t=x-1)" and almost in that exact syntax.
> Whatever your "rain" variable is called (I'll call it "rain" in this
> example), just do 'd rain(t=x) - rain(t=x-1)', or if you want to do this
> over a range of values, do either
>
> 'set t t1 t2'
> 'd tloop(rain-rain(t-1))'
>
> OR
>
> 'set t t1 t2'
> 'define rainvariable = rain-rain(t-1)'
> 'd rainvariable'
>
> That should work.
>
> Jeff Duda
>
> On Wed, Oct 20, 2010 at 8:18 AM, Adrian Scherzinger <
> adrian.scherzinger at meteotest.ch> wrote:
>
> > Hi
> > I am looking for a function similar to cdiff, BUT instead of
> > "The result value at each grid point is the value at the grid point
> plus
> > one minus the value at the grid point minus one."
> > i need a funktion that calculates:
> > "The result value at each grid point is the value at the grid point
> > minus the value at the grid point minus one."
> >
> > This is my problem:
> > Each timestep of my mm5 precipitation data set contains the
> integral of
> > the precipitation since t=1. I want to plot a bar graph with the
> > precipitation of each hour (not the integral). If I want to get the
> > value only at time X, I need to calculate (rain at t=x)-(rain at t=x-1).
> > cdiff(rain,t) is not the solution.
> >
> > Thanks for your help
> > Adrian
> >
> > --
> > ___________________________
> > Adrian Scherzinger
> > Stv. Leiter Wetterprognosen
> >
> > Genossenschaft METEOTEST
> > Fabrikstrasse 14, CH-3012 Bern
> > Tel +41 (0)31 307 26 26
> > Fax +41 (0)31 307 26 10
> > adrian.scherzinger at meteotest.ch
> >
> >
> > ********************************************************************
> > 0900 57 61 52 (CHF 3.13/Min) im direkten Dialog mit dem Prognostiker
> > METEOFON - das pers?nliche Wettertelefon von METEOTEST (05-18 Uhr)
> > ********************************************************************
> >
> > _______________________________________________
> > gradsusr mailing list
> > gradsusr at gradsusr.org
> >
> >
>
>
>
> --
> Jeff Duda
> Iowa State University
> Meteorology Graduate Student
> 3134 Agronomy Hall
> www.meteor.iastate.edu/~jdduda
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