ATM350 HW 5
Due: Friday, May 3, end of day
Preparation: As always, start by creating a homework folder (hw5) in your atm350
directory, and then change its permissions so it is readable, writable, and executable
only by you. Then cd into that directory.
1. Using the upper air data files with the naming convention
$GEMDATA/YYMMDD.ua, plot a 12Z sounding for your RAOB city using the
GEMPAK program snprof (choose 00Z or a different day if the report was missing
for your site). Be sure to save a settings file once you are happy with your plot, and
output your plot to a gif file with the naming convention
YYMMDDHH_<site>_sndg.gif
snprof works differently from other GEMPAK programs in that you can plot
multiple variables at once separated by semicolons. For a sounding, you will need to
plot temperature (°C, thick red line) and dew point (°C, thick green line). The line
color can be changed using the parameter
line = <1st_variable_color>;<2nd_variable_color>/line type/line thickness
You will also need to set the plot type (ptype) as a Skew-T, and you should use the
parameters thtaln, thteln, and mixrln to create guide lines for dry adiabats,
pseudoadiabats, and mixing ratio, respectively. These lines are drawn using the
same convention as the parameter line.
Finally, using the parameter stndex, you should pick at least two variables/indices
separated by semicolons to have GEMPAK calculate and list above the Skew-T (this
is done automatically once you have chosen the variables for stndex).
The online GEMPAK user guide PDF has a section on the use of snprof, as well as
snmap, which follows:
2. Using the upper air data file in $GEMDATA/YYMMDD.ua, plot a 500-mb
observation plot from 12Z over the continental U.S. using snmap. You should
organize your RAOB data as depicted below:
TEMP (°C)
HEIGHT (DECAMETERS)
WIND BARB
Td DEPRESSION (°C)
Note: In order to plot height in decameters, you are allowed to simply use the
asterisk (*) for multiplication within snparm (e.g., hght*.1)
When you are happy with your plot, save a settings file, and output a gif with the
naming convention YYMMDDHH_500.gif
3. Using a GFS 12Z initialization (F000) found in
/nmc2/gempak/YYMMDDHH_gfs_255.gem
plot a cross section using the GEMPAK program gdcross. In your cross section, you
should plot potential temperature contoured every 3 K, relative humidity (color fill),
OR vertical motion (omega). Make your cross section starting from your ASOS
station, and ending at any ASOS location at least three large U.S. states away in any
direction (e.g., ALB>RDU). Feel free to draw your cross section through any
interesting synoptic feature, like a jet or a front.
Set yaxis = 1000/200 to plot your cross section from 1000 mb to 200 mb.
Note that you cannot use exclamation points between your variables in gdcross, so
you must run gdcross two times to plot two variables on top of each other. If you
are using a color fill, you should plot that first, so that contours can be plotted on top
of the color fill. In order to plot two variables, you must set clear=yes for the first
variable plotted, and clear=no for the second variable. Finally, be sure to keep your
device the same for each time gdcross is run, so that the two variables will be plotted
on the same gif. You should save two settings files, one for each variable plotted,
once you are happy with your plot, so that it is quicker to run gdcross for both of the
variables you wish to plot. This is actually easier done using a script, which you may
also do.
Your graphic should have the naming convention YYMMDDHH_xsec.gif.
4. Create your own map discussion set of 16 loops using NMAP2. Center each map
over the CONUS. Have a mix of image (satellite and radar), real-time surface/upper
air, and model grid plots. For your surface maps, overlay ship and buoy obs and
display METARs only from the top of the hour (i.e. no 20/40 off hour times). For your
gridded model data loops, choose among the A1.standard products … the ones
ending in ral are good ones to use. Be sure you have at least two examples of
satellite, radar, and model data in your loops—and be sure to use examples of NAM
and GFS model data. Once you have perfected your loops, save your settings as a
stored process file, nmap_briefing.spf. We will use these spf files to load your loops
to check your work. Load no more than 12 frames per loop.