GEMPAK 5.2 New Feature FAQ Peggy Bruehl Unidata Program Center Last Updated 9/19/94 In order to use some of the new functionality available in GEMPAK 5.2, you must learn new ways of specifying some GEMPAK parameters. To make this easier, I've written this document of questions and answers. This file assumes a working knowledge of GEMPAK, and only covers functionality new to GEMPAK 5.2. I encourage you to read this document carefully. It is located in the $NAWIPS/README directory, as well as the GEMPAK ftp directory, and it is available on-line at the Unidata WWW server. (Open URL http://www.unidata.ucar.edu/, click on GEMPAK, click on Userful GEMPAK Information.) I will be updating this document periodically, so please check the "Last Updated" date on the on-line versions. Questions about the new XW driver --------------------------------- 1) How do I use multiple GEMPAK X-windows? This is a great new feature of GEMPAK 5.2. In the old days, the only way you could have two GEMPAK XW's running at the same time was to run two sessions of the GEMPAK application program in two different windows. Well, you can still do this, but now you don't have to do it that way. Let's say I want to plot a surface chart map of the US, and I also want to view a smaller region, perhaps the east coast, in more detail. First I start by running the GEMPAK surface mapping program, SFMAP. I set the parameters to give me my surface chart over the US. I'll use the Hurricane Bob data set that is distributed with the code: GEMPAK-SFMAP> AREA Data area us GAREA Graphics area usnps SFPARM Surface parameter list skyc;tmpf;wsym;rmsl;;dwpf;p03i;brbk:.7:2 DATTIM Date/time 910819/1800 SFFILE Surface data file $GEMPAKHOME/data/hrcbob.sfc COLORS Color list 1;2;3;4;5;6;7;8;9;10;11;12 MAP Map color/dash/width 15/1/2 LATLON Line color/dash/width/label/inc 0 MARKER Marker color/type/size/width/hw 0 TITLE Title color/line/title 1/-2 CLEAR Clear screen flag YES PANEL Panel location/color/dash/width 0 DEVICE Device|name xw PROJ Map projection/angles/margins nps FILTER Filter data factor .6 TEXT Text size/font/width/hw flag 1.3/23//HW SKPMIS Skip missing data flag no GEMPAK-SFMAP> I run the program and get the surface chart. Now, I want to also see a close up over the east coast, but I don't want to lose the US map. I take advantage of the new format for DEVICE (type "phelp device" for the on-line help description): GEMPAK-SFMAP>dis AREA Data area us GAREA Graphics area east SFPARM Surface parameter list skyc;tmpf;wsym;rmsl;;dwpf;p03i;brbk:.7:2 DATTIM Date/time 910819/1800 SFFILE Surface data file $GEMPAKHOME/data/hrcbob.sfc COLORS Color list 1;2;3;4;5;6;7;8;9;10;11;12 MAP Map color/dash/width 15/1/2 LATLON Line color/dash/width/label/inc 0 MARKER Marker color/type/size/width/hw 0 TITLE Title color/line/title 1/-2 CLEAR Clear screen flag YES PANEL Panel location/color/dash/width 0 DEVICE Device|name xw | East PROJ Map projection/angles/margins nps FILTER Filter data factor .6 TEXT Text size/font/width/hw flag 1.3/23//HW SKPMIS Skip missing data flag no GEMPAK-SFMAP> I run the program again, and now a second window with the name East pops up. Before I draw to this window, I can re-size it to make both windows fit on the screen. (You can re-size the first window, too, but you'll have to re-run the program with the US map settings to re-draw the graphic in the smaller window.) Now I enter to plot the second map, and voila! I have two GEMPAK windows, a US view and a close up view. I can generate up to 5 different GEMPAK XW's at a time. I control which window I draw to by the name in the DEVICE variable. DEVICE = XW without a name results in a window called GEMPAK 5.2. (If I ask for a sixth window, I get an error message telling me "[GEMPLT -45] NWINDW - Too many windows."). 2) Great, but now what if I want to get rid of one of those windows I just created. Can I do that? Of course! You just need to run the program GPCLOSE. Exit out of SFMAP (don't worry, GEMPAK will remember all of your variable settings) and run GPCLOSE. Specify which window you'd like to close in the DEVICE variable (DEVICE = XW | East) and run the program. The named window will close. If you want to close all your windows, just run the GPEND program as usual. 3) OK, but in the New Features document, I read something about inputting the graphics area with the mouse. Instead of looking at the whole east coast, I want to select just the spot where Bob is hitting. How does that work? Oh, you're going to love this! First re-draw the US surface chart to focus it as the active window. Now at the GEMPAK prompt, use the CURSOR command and give it the argument GAREA (because we want to use the CURSOR to define a new GAREA): GEMPAK-SFMAP>cursor garea Hit return, and go back to the XW containing the US surface chart. Position your cursor over the general area of interest, press and hold the left mouse button down and draw the "rubber-band box" to cover the area you'd like to select. When the box is the right size, let go of the mouse button. Now go back to the SFMAP program and display the variable settings: GEMPAK-SFMAP>dis AREA Data area us GAREA Graphics area 34.2;-85.4;41.7;-71.3 SFPARM Surface parameter list skyc;tmpf;wsym;rmsl;;dwpf;p03i;brbk:.7:2 DATTIM Date/time 910819/1800 SFFILE Surface data file $GEMPAKHOME/data/hrcbob.sfc COLORS Color list 1;2;3;4;5;6;7;8;9;10;11;12 MAP Map color/dash/width 15/1/2 LATLON Line color/dash/width/label/inc 0 MARKER Marker color/type/size/width/hw 0 TITLE Title color/line/title 1/-2 CLEAR Clear screen flag YES PANEL Panel location/color/dash/width 0 DEVICE Device|name xw PROJ Map projection/angles/margins nps FILTER Filter data factor .6 TEXT Text size/font/width/hw flag 1.3/23//HW SKPMIS Skip missing data flag no GEMPAK-SFMAP> You'll notice that the GAREA variable is now set to a region defined by the lower left and upper right lat/lon's of the box you just drew. Change the DEVICE variable to reflect a new XW and run the program: GEMPAK-SFMAP>device = xw | closeup You should now have a second window, named closeup, covering the region you selected with your mouse! You may want to turn the FILTER factor down a bit, particularly if you've selected a relatively small area. You can use the CURSOR command with CXSTNS to select a cross section line for SNCROSS and GDCROSS, and you can use CURSOR with GPOINT to select a grid point for GDPROF, GDTHGT and GDTSER. In these cases, you'll have to select the point or line from a map drawn with a mapping program (SFMAP, GDCNTR, GPMAP, etc), and then run a *different* program to use the CXSTNS or GPOINT that you defined with the mouse. Try it, and you'll see what I mean. 4) I also read about animation in the New Features list. How do I do that? This is another great new feature of GEMPAK 5.2. Not only can I generate multiple windows with the new XW driver, I can actually generate a series of pixmaps (frames) in a single window, and then loop over them. Let's use the model data available from the Hurricane Bob data set, and look at surface pressure contours for the east coast: GEMPAK-GDCNTR>dis GDATTIM Grid date/time all GLEVEL Grid level 0 GVCORD Grid vertical coordinate pres GFUNC Scalar grid pres GDFILE Grid file $GEMPAKHOME/data/hrcbob.grd CINT Contour interval/min/max 0 LINE Line color/type/width/label 5/1/2 MAP Map color/dash/width 15/1/2 TITLE Title color/line/title 1/-2 DEVICE Device|name xw PROJ Map projection/angles/margins nps GAREA Graphics area east CLEAR Clear screen flag y PANEL Panel location/color/dash/width 0 TEXT Text size/font/width/hw flag 1.3/23//hw SCALE Scalar scale/vector scale 999 LATLON Line color/dash/width/label/inc 0 HILO Color/sym/rng/rad/cnt/int? HLSYM HILO txt size/posn/font/wdth/hw CLRBAR BC/clr/ornt/anch/x;y/ln;wd/freq CONTUR Subbox/smooth 3/0 SKIP Scalar/vect_x;vect_y 0 FINT Fill interval/min/max 0 FLINE Fill colors 31-18--1 CTYPE Contour type: C/F c GEMPAK-GDCNTR> Note that I have set GDATTIM=ALL. I could have also set it to LIST, and I would get a list of all the grid times in the file. Since I want to generate a loop, I'll leave it as ALL. Simply run the program and you'll see five pixmaps (frames) loaded into the XW. To loop through these pixmaps, all you need to do is type: GEMPAK-GDCNTR> ;loop at the GEMPAK prompt. Your frames will start to loop. To stop the looping, put your mouse inside the XW and click the left mouse button once. Pretty easy! You can also command the frames to step forward ( ;step ), step backward ( ;back ) and loop in reverse ( ;reverse ). You can abbreviate these commands too ( ;l ;s ;b ;r ). You also have control over the "dwell rate", meaning how quickly the frames loop. The dwell rates vary from ";1" slowest to ";5" fastest. ";3" is the default. 4) Wow, can I color fill those contours? You bet: GEMPAK-GDCNTR> ctype = c/f GEMPAK-GDCNTR> fline = 31-18--1 GEMPAK-GDCNTR> clrbar = 1 6) Only GDCNTR? Of course not! You can generate a loop using any of these programs: GDCNTR, GDPROF, GDSTREAM, GDWIND, SFMAP, SNMAP and SNPROF. The secret to generating a loop of pixmaps (frames) is to specify multiple times in the GDATTIM or DATTIM variable. In all of these programs, you can specify a list of times, a range of times, ALL, or LIST. List will give you a list of times to choose from and a prompt. At the prompt, you can input a single time, list of times, range of times or ALL. 7) I have a special data set that has two times associated with each grid. For example: NUM TIME1 TIME2 LEVL1 LEVL2 VCORD PARM 1 940831/0000F000 940831/0000F006 500 PRES AVET 2 940831/0000F006 940831/0000F012 500 PRES AVET 3 940831/0000F012 940831/0000F018 500 PRES AVET 4 940831/0000F018 940831/0000F024 500 PRES AVET When I use GDATTIM=LIST, I don't get my list of two times per grid. What gives? Well, unfortunately, the LIST and ALL options don't support grids with two times (YET!). The good news is you can still loop over these grids, you just have to specify a list of times in the GDATTIM variable: GDATTIM = F000:F006;F006:F012;F012:F018;F018:F024 Satellite Display and Overlay ----------------------------- 1) Is it true that I can now display satellite imagery with GEMPAK? How? Yes, you can display satellite imagery stored in the McIDAS AREA format. That means that you can display your AREA files ingested from the Unidata McIDAS channel directly in a GEMPAK window. It does not matter if you have ingested your AREA files on a PC or on a UNIX machine. The following GEMPAK programs will drop and navigate a satellite image stored in a McIDAS AREA file: SFMAP SNMAP GDCNTR GDWIND GDMAP GDPLOT GDSTREAM GPMAP To drop an image, simply specify the file name (including path) as the graphics area GAREA, and specify the projection, PROJ, as SAT. Here's and example from GPMAP: GEMPAK-GPMAP>dis MAP Map color/dash/width 23 GAREA Graphics area $AREA/AREA0172 PROJ Map projection/angles/margins sat LATLON Line color/dash/width/label/inc 0 PANEL Panel location/color/dash/width 0 TITLE Title color/line/title 1/-1/940919/12 Water Vapor CLEAR Clear screen flag yes DEVICE Device|name xw|1 GEMPAK-GPMAP> Note that I used the $AREA environment variable to point to the directory that holds my AREA files. This environment variable is in your Gemenviron file, which gets sourced when you log in. Now here's the really exciting news...You can overlay traditional GEMPAK graphics on top of these images! For example, here's how I would overlay temperature contours from the initialization field of the aviation model with the appropriate satellite image: GEMPAK-GDCNTR>dis GDATTIM Grid date/time 940919/00F00 GLEVEL Grid level 500 GVCORD Grid vertical coordinate PRES GFUNC Scalar grid tmpk GDFILE Grid file /var/data/ldm/gempak/hds/94091900_a.gem CINT Contour interval/min/max LINE Line color/type/width/label 4/1/2/ MAP Map color/dash/width 23 TITLE Title color/line/title 1/-1 DEVICE Device|name xw|1 PROJ Map projection/angles/margins sat GAREA Graphics area $AREA/AREA0178 CLEAR Clear screen flag yes PANEL Panel location/color/dash/width 0 TEXT Text size/font/width/hw flag 1/21//hw SCALE Scalar scale/vector scale 999 LATLON Line color/dash/width/label/inc 0 HILO Color/sym/rng/rad/cnt/int? HLSYM HILO txt size/posn/font/wdth/hw CLRBAR BC/clr/ornt/anch/x;y/ln;wd/freq 1 CONTUR Subbox/smooth 1 SKIP Scalar/vect_x;vect_y FINT Fill interval/min/max 2/16/46 FLINE Fill colors 0;23-15 CTYPE Contour type: C/F c GEMPAK-GDCNTR> Now, you can go ahead and overlay another contour field, or a vector field on the graphic, without having to re-drop the image and obscure the temperature contours. Simply set CLEAR=NO. The program will get the navigation from the AREA file, but it will not drop the image: GEMPAK-GDWIND>dis GDATTIM Grid date/time 940919/00F00 GLEVEL Grid level 500 GVCORD Grid vertical coordinate PRES GVECT Vector grid wind GDFILE Grid file /var/data/ldm/gempak/hds/94091900_a.gem GAREA Graphics area $AREA/AREA0178 SKIP Scalar/vect_x;vect_y WIND Wind symbol/siz/wdth/typ/hdsz bk26 REFVEC Mag;x;y;text size/font/width/HW; MAP Map color/dash/width 23 LATLON Line color/dash/width/label/inc 0 PANEL Panel location/color/dash/width 0 TITLE Title color/line/title 1// DEVICE Device|name xw|1 PROJ Map projection/angles/margins sat CLEAR Clear screen flag n SCALE Scalar scale/vector scale 999 TEXT Text size/font/width/hw flag 1/21//hw GEMPAK-GDWIND> Here's a really important point. YOU are responsible for matching up the date and time of the data (in this case, the aviation model 940919/00F00 temperature field) with the time of the satellite image! There is no code in GEMPAK that will do the time verification for you. That means that you can easily overlay Hurricane Bob observational or model data on top of today's 12Z water vapor image. It is your job to avoid this. (with knowledge, comes power, and responsibilty!) 2) Can I loop over satellite images? Yes! You can loop over several satellite images much the same way as you can loop over regular GEMPAK images (;loop, ;step, ;back, ;reverse). Simply list the images you'd like to loop over on the GAREA input line: GEMPAK-GPMAP> MAP Map color/dash/width 23 GAREA Graphics area $AREA/AREA0178;$AREA/AREA0179;$AREA/AREA0170;$AREA/AREA0171 PROJ Map projection/angles/margins sat LATLON Line color/dash/width/label/inc 0 PANEL Panel location/color/dash/width 0 TITLE Title color/line/title CLEAR Clear screen flag yes DEVICE Device|name xw|1 GEMPAK-GPMAP> Note that I am using real time data, since there are no sample AREA files available for Hurricane Bob (yet!). The bad news is that you are limited to a 72 character input line for GAREA. I recognize that this is a significant limitation. I am working on a package for the contrib directory that will use a program, mcInfo, written by Tom Yoksas of the UPC, to open each AREA file, extract the date/time, and then create a link using a 2 digit time and a single letter (w=water vapor, vi=visible, ir=infrared) as a filename. Combined with a shorter environment variable ($AR), each file name will only take 7 characters. This will give you up to 10 AREA files per loop ($AR/w12). A better solution is the use of wild cards in the input line. For example GAREA=$AREA/AREA017* will get all the water vapor AREA files in a single directory. This solution, or something like it, is under consideration at NMC. I'll keep you posted. More bad news...wouldn't it be nice if the default title for each frame in this loop would be the time of the image? Unfortunately, this is not possible, yet. However, it is on my list, and we'll be looking at how to implement this in the near future. This looping functionality will work with all the GEMPAK programs that can drop a statellite image. For example, with SFMAP: AREA Data area 10;-125;50;-20 GAREA Graphics area $AREA/AREA0178;$AREA/AREA0179;$AREA/AREA0170;$AREA/AREA0171 SFPARM Surface parameter list SKYC;TMPF;WSYM;PMSL;;DWPF;BRBK DATTIM Date/time 940919/00;940919/03;940919/06;940919/09 SFFILE Surface data file /var/data/ldm/gempak/surface/sao/940919.gem COLORS Color list 1;2;3;4;5;6;7 MAP Map color/dash/width 23 LATLON Line color/dash/width/label/inc 0 MARKER Marker color/type/size/width/hw 0 TITLE Title color/line/title 1/-1 CLEAR Clear screen flag yes PANEL Panel location/color/dash/width 0 DEVICE Device|name xw PROJ Map projection/angles/margins sat FILTER Filter data factor .7 TEXT Text size/font/width/hw flag 1/21//hw SKPMIS Skip missing data flag NO GEMPAK-SFMAP> Again, it is the users responsibility to be sure that the times between the AREA files and the observational data match up. There is no time verification in any of these routines. 3) Can I display NEXRAD products in GEMPAK? Not yet. Our distinquished colleague Jim Cowie of COMET is currently working on a program to convert NEXRAD products into an AREA format. We will keep you informed on the progress. 4) Anything else I should know about this? Yes, there are a few things: A) Try not to leave your GEMPAK XWindow open and unused on your workstation for hours on end. Occaisionally we've seen trouble with the message queues becoming corrupted on Sun Solaris after leaving the window running for >3 hours. B) You can get the satellite navigation (without dropping the satellite image) for a map by specifying an AREA file name in GAREA and SAT in PROJ, but setting CLEAR=NO. This navigation may be useful in constructing some graphics. C) Currently NTRANS can not display or loop graphics with satellite imagery. D) Be patient with the satellite display and overlay functionality. It is brand new to GEMPAK, and it doesn't have the maturity of the rest of the package. We are looking for ways to improve this functionality, and would appreciate hearing from you if you have suggestions. E) We are considering the following improvements: -Better filename specification on GAREA input line. -Cursor interrogation of imagery (returning earth referencing information, pixel values, calibrated values, etc.) -Extracting the date/time information from the AREA file for time verification, and default title extraction -Access to NEXRAD and Wetnet products. New GEMPAK pograms ------------------ 1) There's a new GEMPAK program called GDVINT. What does it do? GDVINT is used to interpolate gridded data on one vertical coordinate to a different vertical coordinate. The allowable coordinates are PRES, THTA, SGMA, HGHT, and ZAGL. GDVINT will interpolate the entire horizontal domain of the grid, or subset the grid by latitude/longitude or grid point numbers if desired. It also handles interpolation to below-ground coordinates by either assigning missing values or surface values depending on the user's choice. Additionally, GDVINT will transfer uninterpolated grids from the input file to the output file. This allows the user to interpolate from a PRES to THTA grid, but also transfer the NONE coordinate grids to the output file. See the on-line help file for more detailed information about how to use the program, including examples. 2) There's a new GEMPAK program called GDTHGT. What does it do? GDTHGT is a user contributed program that draws a vertical time section at a location in a grid field. (Just like the time option in SNCROSS.) The location is specified by setting GPOINT. Gridded data are interpolated to the time-section plane at regular intervals of time specified in GDATTIM. The grid vertical coordinate (GVCORD) may be PRES, THTA, or HGHT, depending on what is available in the grid file. A scalar and/or vector field may be specified. Vectors are displayed as arrows or barbs, scalars as contours. See the on-line help file for more information and examples (phelp gdthgt). 3) There's a new GEMPAK program called GDPLOT. What does it do? GDPLOT is a combination of GDCNTR and GDWIND. It draws contour lines (or color fill) through a scalar grid computed using the GEMPAK grid diagnostic functions. Then it draws a vector grid using wind barbs or arrows. It can present any number of time periods. It can also produce any number of contours or vectors on each frame. This program was originally written to simplify constructing META files for use with Ntrans. Ntrans is a GUI-based animator and viewer for previously generated GEMPAK graphics. With GDPLOT, you can quickly generate a series of graphics with multiple scalar and vector fields over all times in a file. Most often this program is used in a script. This is exactly the sort of thing you want to do to pre-generate graphics and store them in a META file for use with Ntrans. After GDPLOT was written, time looping functionality was added to GDCNTR and GDWIND, making some of the new GDPLOT functionality unnecessary. However, GDPLOT still has the ability to overlay contours and vectors from a single run, which can save time. On the other hand GDPLOT is rather complicated to run, so it remains best used from scripts. First I'll explain how it works, then we'll go through an example: GFUNC may contain exclamation points to delimit any number of sets of contour specifications. GVECT may contain exclamation points to delimit any number of sets of vector plot specifications. GLEVEL, GVCORD, PANEL, SKIP, SCALE, GFUNC, CTYPE, CONTUR, CINT, TITLE, LINE, FINT, FLINE, GVECT, WIND, REFVEC, HILO, and HLSYM may contain exclamation points to delimit specifications for the plots specified in GFUNC and GVECT. For example, let's say I want to generate 500mb heights and wind barbs, over the east coast during Hurricane Bob. Here's my settings for GDPLOT: GDFILE Grid file $GEMDATA/hrcbob.grd GDATTIM Grid date/time first GLEVEL Grid level 500 ! 500 GVCORD Grid vertical coordinate PRES ! PRES PANEL Panel location/color/dash/width 0 SKIP Scalar/vect_x;vect_y SCALE Scalar scale/vector scale -1 ! GFUNC Scalar grid hght ! CTYPE Contour type: C/F c ! CONTUR Subbox/smooth 1 CINT Contour interval/min/max 4 ! LINE Line color/type/width/label 20/1/2 ! FINT Fill interval/min/max FLINE Fill colors HILO Color/sym/rng/rad/cnt/int? HLSYM HILO txt size/posn/font/wdth/hw CLRBAR BC/clr/ornt/anch/x;y/ln;wd/freq 1 GVECT Vector grid !wind WIND Wind symbol/siz/wdth/typ/hdsz !bk26 REFVEC Mag;x;y;text size/font/width/HW; TITLE Title color/line/title 5//~ @ HEIGHTS AND VORTICITY ! TEXT Text size/font/width/hw flag 1/21//hw CLEAR Clear screen flag yes GAREA Graphics area east PROJ Map projection/angles/margins nps MAP Map color/dash/width 23 LATLON Line color/dash/width/label/inc 0 DEVICE Device|name xw| Example GEMPAK-GDPLOT> The secret to understanding how this program works to pay attention to the "!"s. The "!" is the delimiter between fields. Note that the first "field" is the 500mb heights, scaled by 10**-1, with a contour interval of 4, in color 20. The second "field" is the 500mb wind in knots in color 26. See that all the variables that correspond to the first field (heights) come before the "!". All the variables that correspond to the second field (winds) come after the "!". In the case of GLEVEL and GVCORD, we could have left off the second specification of "! 500" and "! PRES", because if there is no trailing "!", the last specification will be repeated for subsequent plots. Now lets get a little more complicated. Let's plot the vorticity field too, and let's color fill the areas of high vorticity: GEMPAK-GDPLOT>dis GDFILE Grid file $GEMDATA/hrcbob.grd GDATTIM Grid date/time first GLEVEL Grid level 500 GVCORD Grid vertical coordinate PRES PANEL Panel location/color/dash/width 0 SKIP Scalar/vect_x;vect_y SCALE Scalar scale/vector scale 5 !-1 ! GFUNC Scalar grid (avor(wnd)) ! hght ! CTYPE Contour type: C/F c/f ! c ! CONTUR Subbox/smooth 1 CINT Contour interval/min/max 2/0/99 ! 4 ! LINE Line color/type/width/label 7/5/1/1 ! 20/1/2 ! FINT Fill interval/min/max 2/16/46 FLINE Fill colors 0;23-15 HILO Color/sym/rng/rad/cnt/int? 2;6/X;N/10-99;10-99 HLSYM HILO txt size/posn/font/wdth/hw 2 CLRBAR BC/clr/ornt/anch/x;y/ln;wd/freq 1 GVECT Vector grid ! ! wind WIND Wind symbol/siz/wdth/typ/hdsz ! ! bk26 REFVEC Mag;x;y;text size/font/width/HW; TITLE Title color/line/title 5//~ @ HEIGHTS AND VORTICITY ! TEXT Text size/font/width/hw flag 1/21//hw CLEAR Clear screen flag yes GAREA Graphics area east PROJ Map projection/angles/margins nps MAP Map color/dash/width 23 LATLON Line color/dash/width/label/inc 0 DEVICE Device|name xw | Example GEMPAK-GDPLOT> And here's the printout we get when we run it: GEMPAK-GDPLOT>r PARAMETERS FOR GDPLOT: Grid file: $GEMDATA/hrcbob.grd TIMES: 910819/0000F000 GRID IDENTIFIER: PLOT LEVEL VCORD PARM WPARM 1 500 PRES (AVOR(WND)) 2 500 PRES HGHT 3 500 PRES WIND GAREA: east Parameters requested: GDFILE,GDATTIM,GLEVEL,GVCORD,PANEL,SKIP,SCALE,GFUNC, CTYPE,CONTUR,CINT,LINE,FINT,FLINE,HILO,HLSYM,CLRBAR,GVECT,WIND,REFVEC,TITLE, TEXT,CLEAR,GAREA,PROJ,MAP,LATLON,DEVICE. GEMPAK-GDPLOT> Each layer of the plot is numbered and summarized for you. Remember to plot the color filled contours first, so that other lines are not obscured. This program can be very finicky about the variable settings. I don't recommend that GEMPAK beginners use GDPLOT very much. However, I do recommend GDPLOT for those of you developing scripts. In fact, the general release of Ntrans will include several sample scripts for generating META files. Many of these scripts use GDPLOT, and they can serve as examples for you. 4) There is a new program called NAGRIB. What does it do? NAGRIB is a GEMPAK program which will convert GRIB messages into GEMPAK grids and store them in a GEMPAK grid file. This program will either read the grid navigation from the "GDS" (grid definition section) included in the GRIB message, or it can take it from the grid navigation table, $GEMTBL/grdnav.tbl. NOTE: This program will not work on GRIB messages broadcast as part of the Family of Servies (FOS) and ingested by the LDM. These messages have a WMO header attached to the GRIB message. If you would like to decode FOS data, please see the README file for the LDM4-GEMPAK Bridge software. Questions about miscellaneous things ------------------------------------ 1) What is this LDM4-GEMPAK Bridge thing? The LDM4-GEMPAK Bridge is a set of real-time decoders to convert raw data into GEMPAK format. Currently there are decoders for surface SAO's (satogem), synoptic reports (sytogem), upper air reports (uatogem), GRIB data (gribtogem), and NLDN lightning data (nldntogem). These decoders were written by various people in the community, and are now supported by the UPC. They are intended to be run on-demand by the Unidata Local Data Manager (LDM), but can be run on the command line as well. In order to build these decoders, you must have a copy of the LDM library (libldm.a) built on your computer. The LDM is freely available from the UPC (and it's even available as binaries, so you can pick up a copy of libldm.a for your platform). Please see the file Bridge.general in the README directory of the GEMPAK 5.2 distribution for more information. 2) What are the EZ-Scripts? The EZ-Scripts are scripts for producing standard GEMPAK plots from a simple, GEMPAK-ignorant interface. They were written by Brad Coleman, SOO at the Seattle Forecast office. They are included in the GEMPAK5.2 distribution in the $GEMPAKHOME/scripts/ezscripts directory. Please see the file gempak.ezscripts in the README directory of the GEMPAK 5.2 distribution for more information. 3) Did I read that there are now program-specific NTS files? What's an NTS file? What's the difference between these NTS files and the files in the $GEMPAKHOME/defaults directory? Can I make my own NTS files? Well, you're just full of questions, aren't you ;-) ? An NTS file is a text file that contains the current settings of some or all of the GEMPAK variables. Each time you run GEMPAK, the file gemglb.nts in your current directory gets read in and all the variables on your screen get set to what they were the last time you ran GEMPAK. When you are done running GEMPAK, the last thing that the program does is to write the values of all the current variables to the file gemglb.nts. The next time you run GEMPAK, the gemglb.nts file gets read in again, and all the variables are set to what they were. And so on, and so on... This is why when you run GDCNTR to make temperature contours, and then run GDWIND to overlay wind barbs, most of the variables are already set for you. The current variable settings are always stored and read from the file gemglb.nts. Gemglb.nts has variable settings for EVERY variable used in GEMPAK. In addition, the settings for just the variables in the current program are written to the file last.nts. Last.nts is always written, but only is read unless you specifically ask for it. For example, let's say I run GDCNTR in my home directory, and get all the variables set-up to do a plot. Now a colleague wants to make a similar plot, but he's not very familiar with GEMPAK, and would like to see how I made the plot. So he runs GDCNTR and reads in *my* last.nts: GEMPAK-GDCNTR> restore /home/peggy/last.nts Now, as long as my colleague has read permission in my directory, he can read in all my settings for GDCNTR. Up until recently, most GEMPAK users only used the two NTS files, gemglb.nts and last.nts. In GEMPAK 5.2, there are now NTS files that define standard settings for each GEMPAK program. These files make standard or default settings program- specific. For example, in SFMAP, you will probably want to specify the date and time yourself, but for SFGRAM, you will probably always want DATTIM=ALL. So, in the file sfgram.nts, DATTIM is set to ALL. To read in these program specific settings, simply type "restore" at the GEMPAK prompt: GEMPAK-SFMAP> restore The environment variable GEMNTS points to the directory where the NTS files are kept. Without an argument, "restore" reads in the NTS file for the current GEMPAK program. In this case, it reads in $GEMNTS/sfmap.nts. You will see the following variable settings after you run the restore command: GEMPAK-SFMAP>display AREA Data area GAREA Graphics area SFPARM Surface parameter list skyc;tmpf;wsym;rmsl;ptnd;dwpf;p03i;brbk:.7:2 DATTIM Date/time SFFILE Surface data file COLORS Color list 1;2;3;25;5;6;7;9 MAP Map color/dash/width 3/1/1 LATLON Line color/dash/width/label/inc 0 MARKER Marker color/type/size/width/hw 0 TITLE Title color/line/title 1/-2 CLEAR Clear screen flag YES PANEL Panel location/color/dash/width 0 DEVICE Device|name xw PROJ Map projection/angles/margins nps FILTER Filter data factor yes TEXT Text size/font/width/hw flag 1.3/23//HW SKPMIS Skip missing data flag no GEMPAK-SFMAP> In addition to keeping track of default values for some variables, these NTS files also blank out the variables that you need to set each time you run the program. This reminds you which variables you need to set in order to run the program. You can imagine how useful these NTS files might be, both for experienced and novice GEMPAK users. There are two sets of NTS files included in your GEMPAK distribution, the $GEMPAKHOME/nts directory, and the $GEMPAKHOME/defaults directory. There isn't much difference between the files in these two directories. You should set your $GEMNTS environment variable to one or the other (or your own) directory: (in the C-shell) setenv GEMNTS $GEMPAKHOME/defaults The defaults/ directory was added as a contribution to GEMPAK 5.1 by Unidata, and the nts/ directory was created by NMC. In addition to NTS files for most GEMPAK programs, the Unidata defaults/ directory contains a few special NTS files: area.eur GAREA and PROJ for Europe area.na GAREA and PROJ for North America area.nhemi GAREA and PROJ for the northern hemisphere area.npac GAREA and PROJ for the north Pacific snprof.skewt Specification for a Skew-T Log-P plot To read in any of these special NTS files, you must give the name of the file: GEMPAK-SFMAP> restore area.na You'll note that the area.* NTS files ONLY re-set the GAREA and PROJ variables, leaving the other settings as is. After running GEMPAK for a while, you may find that you have your own personal favorite colors, line types, areas, etc. You can create your own NTS directory with NTS files defining these settings (and the standard NTS files too, if you like). To generate an NTS file, start with the "save" command. Set up the GEMPAK program the way you like it, and then: GEMPAK-SFMAP> save my.nts Now, you'll have a text file in your current directory called "my.nts". You can edit this file, since it is just text, and remove or blank out any settings that you don't want. You can call your NTS files anything you'd like. At this point, you may want to set your $GEMNTS environment variable to point at your own directory: (in the C-shell) setenv GEMNTS /home/peggy/gempak.defaults You can add this command to your .cshrc file, after you source the other GEMPAK environment variables: ... source /home/gempak/Gemenviron setenv GEMNTS /home/peggy/gempak.defaults ... Questions about availability and support of GEMPAK -------------------------------------------------- 1) How do I get GEMPAK version 5.2? GEMPAK and the related software is available by Unidata license to U.S. colleges and universities at no charge. Please contact support@unidata.ucar.edu for more information. If you are a SOO in the National Weather Service, you must contact Ron Miller of COMET at rmiller@comet.ucar.edu. If you are a NOAA employee you must contact the Transition Project at the National Meteorological Center. If you work for a private company, you must contact a group called COSMIC at service@cossack.cosmic.uga.edu or (706) 542-3265. 2) If I have a problem running or installing GEMPAK version 5.2, where can I go for help? You have several ways to go about getting help with GEMPAK problems: A) GEMPAK has an on-line help facility. At any GEMPAK prompt, simply type "phelp" and the name of the variable or program you are interested in. The command "help" works too, but with "phelp" the output is paged. If the topic is a long one, you don't want scrolling off your screen before you can read it. So, lets say I'm running GDCNTR and I don't know how to specify the GLEVEL parameter. I simply ask for help on GLEVEL: GEMPAK-GDCNTR>phelp glevel GLEVEL GLEVEL is the vertical level for the grid. Grids may contain two levels separated by a colon. If the grid to be selected contains only one level, the colon and second level may be omitted. In this case, the second level is stored in the grid file as -1. Note that the vertical coordinate system for GLEVEL is specified by GVCORD. The value in GLEVEL may be overridden by specifying @GLEVEL with the grids to be found. For example, the following two computations are identical: GFUNC = SUB (TMPF@850,TMPF@500) GFUNC = LDF (TMPF) and GLEVEL = 850:500. GEMPAK-GDCNTR> B ) In addition to the on-line help, there is also a Users Manual for GEMPAK. The latest version of the manual for GEMPAK 5.2 is not available yet, however many questions can be answered with the old manual. Most of the meat of the manual is just hard copies of the on-line help files. There are a few extra chapters though, which provide additional information on getting started using GEMPAK, observational and gridded data parameters and diagnostics, and installation and maintenance information. C ) Unidata makes past copies of all GEMPAK support questions available over the internet. So, by using either a Gopher or Web (MOSAIC, LYNX) client, you can connect to the Unidata database of GEMPAK and "gembud" mail messages. For example, let's say you have a question about how to use a full map projection, and you can't figure out how to do it with the manual or the on-line help. There's a good chance that someone before you has had a similar question, so you connect to the Unidata gopher via "gopher gopher.unidata.ucar.edu" or the Unidata Web server by opening URL http://www.unidata.ucar.edu/. Select the GEMPAK category, and follow the path down to the string searchable archives. You'll find an archive for GEMPAK user support mail, and an archive for "gembud" mail. Select the support archive and type in a string to search for. For example, I would type "full and map and projection". The default on these searches is "or" so I specify "and" to narrow my search to messages contain all three of these words. This search is case insensitive. In response to my search I get quite a few responses. Select the first one or two messages and read them to see if they are appropriate to your question. Reading a few messages may help you narrow or shift your search to more appropriate key words. You can keep searching over and over again for help with any of your questions. Even if you don't find the answer to your exact question, it will help you in formulating your question more precisely, which will help me in the next step... D ) Finally, if you can't solve your problem yourself, Unidata sites can contact Unidata support. If you do send a question to me, please be as complete as possible. Send me copies of your input variables, and definitely send me an exact copy of any error messages you receive. If you are installing GEMPAK and see an error, send me a copy of the make log. It is much much easier to answer a question when too much information is provided, than to have to try to guess what the problem is first, and then solve it. E ) If you are a NWS SOO and have a question, you should follow the procedure set up by Ron Miller of COMET. If your software comes from NMC or COSMIC, you must follow the support procedure that they have set up. 3) What is the "gembud" mailing list? "gembud" is a special interest mailing list for GEMPAK users. It is administered by Unidata. You do not have to be a Unidata site to subscribe to the mailing list. The "gembud" mailing list is a great place to start a scientific discussion relating to GEMPAK functions, or inquire if any fellow GEMPAK users have implemented an enhancement. It also is the place where you will hear about new releases, patches, and the availability of community and Unidata contributed software. However, "gembud" is not the place to ask rudimentary questions about GEMPAK. For example a question about how to make a basic contour plot is not really appropriate for the whole community to receive. I will quickly answer that question for you, and it is doubtful that many others on the list will benefit from the answer to that kind of question. Messages sent to "gembud" go to approximately 200 users, so its best to keep the content to items of wide interest. If in doubt about a topic, you are encouraged to send a copy of your message to me first, and I'll be happy to advise you if it is appropriate. Conversely, if you ask a question directly to me that is better posed to the "gembud" community, I'll certainly let you know. NWS SOO's have their own mailing list administered by Ron Miller. Ron will act as a gateway between the two mailing lists. If a topic is brought up on your mailing list that is of general interest to all of gembud, he will forward it to the "gembud" list. The same will happen for messages of interest to SOO's that appear on the "gembud" mailing list.