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NCL Graphics: WRF plotting - titles

This page documents the various resources you can set to add, customize, or remove titles associated with WRF plotting functions.

Here are the title attributes recognized by wrf_contour and wrf_vector:

  • MainTitle - Sets a main title at the top left corner of the page that is 1.5 times larger than the other titles.

    Default = "  "

  • MainTitlePos - Indicates the position of the main title.

    Default = "Left" ("Left" / "Center" / "Right")

  • InitTime - If True, will put the model start time at the top right of your page using the START_DATE or SIMULATION_START_DATE global attribute on the file.

    Default = True

  • ValidTime - If True, will look for a TimeLabel attribute set by the user, and will use this as an additional title to appear under the "Init: " label at the top of the page.

    Default = True

  • TimeLabel - see ValidTime

    No default is provided.

  • TimePos - Indicates whether to right or left justify the InitTime and ValidTime labels.

    Default = "right" ("right" / "left")

  • Footer - Indicates whether to add a footer title at the bottom lower left of the page.

    The footer will include two lines of text including the TITLE global attribute, the distance in kilometers, the spatial and level dimension sizes, and various physics parameters that were used to create the WRF output file.

    Default = True

  • FieldTitle - By default, a field title will be added to the upper left area just above the plot for each contour and/or vector plot that is overlaid. You can set this resource for any of the overlay plots if you want to change this title.

    This string will also be used as part of the cnInfoLabel string or labelbar title (lbTitleString).

    The default is the variable's "description" and "units" attributes.

  • UnitLabel - This string will be appended after FieldTitle, in parentheses.

    The default is the variable's "units" attribute, if any.

  • SubFieldTitle - This string will be appended after the FieldTitle, before UnitLabel.

    There is no default.

  • PlotLevelID (default is " at " opts@PlotLevelId)

  • NoHeaderFooter - If True, all of the titles at the top right and lower left of the page and the main title at the upper left will be turned off. This will not affect the field title(s) just above the plot. See NoTitles below.

    This is useful if you need to panel plots later using gsn_panel.

    Default = True

  • FontHeightF - This sets the base font height for all titles. The MainTitle will be 1.5 times the base font height.

    Default = 0.01

wrf_map_overlays adds left-justified titles just above the plot for every plot that is overlaid.

Here are the resources that allow you to customize these titles:

  • CommonTitle - If True, allows you to replace the left-justified field title(s) with your own title via PlotTitle.

    Default = False

  • PlotTitle - see CommonTitle

  • NoTitles - If True, removes the left-justified field title(s) just above the plot.

    Default = False

If you want far more customization of titles in your plot, then you may want to consider using the gsn_csm functions for plotting WRF data.

For a more complete suite of examples using NCL to plot WRF-ARW data, we recommend that you visit the WRF-ARW Online Tutorial.

wrf_title_1.ncl: This is a simple filled contour plot of the HGT variable read off a WRF output file. The title at the top right of the page is from the global attribute "START_DATE" or "SIMULATION_START_DATE".

The left title just above the plot is from the variable's "description" and "units" attributes.

The title above the labelbar is also from the variable's "description" and "units" attributes.

The first line at the lower left of the page is from the global attribute "TITLE".
The second line is constructed using global attributes that describe the various spatial and level dimension sizes, the distance in kilometers, and the various physics used (MP_PHYSICS, BL_PBL_PHYSICS, CU_PHYSICS).

wrf_title_2.ncl: This script is based on wrf_title_1.ncl, and shows how to change or add titles on a WRF plot.

To change/add titles at the top right and left sides of the page, set these two resources before calling wrf_contour:

Adds a title just below the "Init" title, preceded by the word "Valid: " 

  res@TimeLabel = "Desired title for time label"
Adds adds a slightly larger title at the top left side of the page. This title will be 1.5 times larger than the other WRF titles. 

  res@MainTitle = "Desired main title"

To change the left-justified title just above the plot, set these two resources before calling wrf_map_overlays: 

  pltres@CommonTitle = True
  pltres@PlotTitle   = "Desired plot title"

Note: you cannot change the "Init" time label at this time. See the next script for an example of how to turn it off.

wrf_title_3.ncl: This script is based on wrf_title_1.ncl and shows how to turn off the three sets of titles that are added.

wrf_contour: 

  res@NoHeaderFooter = True   ; Turn off the top right "Init" title
                                     ; and the two bottom footer titles.

wrf_map_overlays: 

  pltres@NoTitles = True     ; Turn off the left title just above the plot

wrf_title_4.ncl: By default, the variable's description and units will appear twice on a color contour plot: just above the plot and above the labelbar (see first frame).

The second frame turns off the labelbar title and slightly changes the title just above the plot: 

  res@FieldTitle = "SEA LEVEL PRESSURE"  ; Change variable description
  res@UnitLabel  = "mb"                  ; Change variable units
  res@lbTitleOn  = False                 ; Turn off labelbar title
The third frame adds extra text to the field title, just before the units, and increases the size of both titles using the special FontHeightF resource. 

  res@SubFieldTitle = "[extra text b/f units]"
Note: the two footer strings were turned off in all plots by setting: 

  res@Footer = False
wrf_title_5.ncl: This example is a more elaborate one that shows how the left titles above the plot are stacked when you overlay more than one plot.

The first frame overlays wind vectors on sea level pressure (blue contour lines) on surface tempature (filled contours).

The second frame overlays wind vectors on surface dew point temperature (filled contours).

A main title was added with res@MainTitle and the wind vector title was changed using res@FieldTitle.

wrf_title_6.ncl: This example shows a typical WRF-ARW plot with several overlays (temperature, sea level pressure, and vectors), with the various WRF titles annotated.