Usage

Basic Usage

The first step in plotting diagnostic variable to find what all variables are supported by wrfplot application. This is required as the application would accept variable names only in certain string format. Therefore, you should list and review the name of variable by issuing the following command in the terminal:

wrfplot --list-vars

Invoking the above command will produce the following output:

****    ****    ****    ****    ****    ****    ****
Variables starting with 'u_' are upper air variable availabe at 925, 850, 700, 600, 500, 400, 300 and 200 hPa heights...
****    ****    ****    ****    ****    ****    ****

Variable "slp"   --> Mean Sea Level Pressure (hPa)
Variable "winds"   --> Surface (10M) Wind Speed and Direction (Kt)
Variable "rh2"   --> 2m Relative Humidity (%)
Variable "T2"   --> 2m Temperature (°C)
Variable "mcape"   --> CAPE Maximum ($J kg^{1}$)
Variable "mcin"   --> Minimum Convective Inhibition ($J kg^{1}$)
Variable "lcl"   --> Lifting Condensation Level (Meters)
Variable "lfc"   --> Level of Free Convection (Meters)
Variable "ctt"   --> Cloud Top Temperature (°C)
Variable "low_cloudfrac"   --> Low Cloud Coverage (%)
Variable "mid_cloudfrac"   --> Medium Cloud Coverage (%)
Variable "high_cloudfrac"   --> High Cloud Coverage (%)
Variable "mdbz"   --> Maximum Reflectivity (dBZ)
Variable "helicity"   --> Storm Relative Helicity ($m^{2} s^{-2}$)
Variable "pw"   --> Precipitable Water ($kg m^{-2}$)
Variable "td2"   --> 2m Dew Point Temperature (°C)
Variable "ppn_accum"   --> Accumulated Precipitation (mm)
Variable "ppn_conv"   --> Convective Precipitation (mm)
Variable "ppn"   --> Precipitation/ Rain (mm)
Variable "updraft_helicity"   --> Updraft Helicity ($m^{2} s^{-2}$)
Variable "u_theta_e"   --> Equivalent Potential Temperature (°C)
Variable "u_avo"   --> Absolute Vorticity ($10^{-5} s^{-1}$)
Variable "u_dbz"   --> Reflectivity (dBz)
Variable "u_geopotential"   --> Geopotential - Mass Grid ($m^{2} s^{-2}$)
Variable "u_omg"   --> Omega ($Pa s^{-1}s$)
Variable "u_pressure"   --> Full Model Pressure (hPa)
Variable "u_pvo"   --> Potential Vorticity (PVU)
Variable "u_td"   --> Dew Point Temperature (°C)
Variable "u_rh"   --> Relative Humidity (%)
Variable "u_theta"   --> Potential Temperature (°C)
Variable "u_temp"   --> Temperature (°C)
Variable "u_tv"   --> Virtual Temperature (°C)
Variable "u_twb"   --> Wet Bulb Temperature (°C)
Variable "u_winds"   --> Wind Speed and Direction (Kt)
Variable "u_cin"   --> Convective Inhibition ($J kg^{1}$)
Variable "u_cape"   --> Convective Available Potential Energy ($J kg^{1}$)

The above console print has two names. One with quote and the other is without. The name within quote such as "slp" is called short variable, and without a quote is called long variable. You can read through a list to take note of what parameter you want to plot. For example, if you need to plot 2m Relative Humidity, then you need to remember the sort variable name in the first quote “” i.e, “rh2”. With this, we will proceed ahead to plot “rh2” variable. To plot any variable, there are minimum three arguments required to be provided. They are --vars, --input and --output. Details of these would be discussed later.

Plotting Surface Variable

All the variables which does not start with u_ string are surface variable. Now, let's go ahead and start plotting the variable “2m Relative Humidity” named as “rh2”:

wrfplot --vars "rh2" --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

Where:

--vars to indicate name of variable to plot
--input is path to wrfout netCDF file
--output is path to directory where final image files are required to be saved. The directory will be created if it does not exist

Executing the above command will produce the following output in the terminal indicating the progress of plots and location of files saved in local filesystem.

*** Initialising plotting for variable : "rh2" ***

        Plotting "rh2" for Time : "13-05-2021_05:30" UTC                                                                                 
          Image saved at : "../../test/wrfout_data/output_images/rh2_13-05-2021_05_30.png"                            
        Plotting "rh2" for Time : "13-05-2021_08:30" UTC                                                                                 
          Image saved at : "../../test/wrfout_data/output_images/rh2_13-05-2021_08_30.png"                            
        Plotting "rh2" for Time : "13-05-2021_11:31" UTC                                                                                 
          Image saved at : "../../test/wrfout_data/output_images/rh2_13-05-2021_11_31.png"                            
        Plotting "rh2" for Time : "13-05-2021_14:30" UTC                                                                                 
          Image saved at : "../../test/wrfout_data/output_images/rh2_13-05-2021_14_30.png"                            
        Plotting "rh2" for Time : "13-05-2021_17:30" UTC                                                                                 
          Image saved at : "../../test/wrfout_data/output_images/rh2_13-05-2021_17_30.png"                            

Plotting process completed. It took 0H:0M:9.682410S

The plotted output for variable will look like below:

Image title — Sample Relative Humidity Plot

Plotting Upper Atmospheric Variables

wrfplot supports a few upper atmospheric variables. These variables are indicated with u_ tag for ease of identification. By default, the plot for upper atmospheric variables would be plotted for 925, 850, 700, 600, 500, 400, 300 & 200 hPa. The upper levels can be controlled using --ulevels though. If you want to plot upper winds, you can specify the variable with the following command:

wrfplot --vars "u_winds" --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

Plot Variable at Specific Level(s)

When plotting upper level variable, wrfplot will plot all the predefined levels viz., 925, 850, 700, 600, 500, 400, 300 & 200 hPa. You can control the level at which variable is required to be plotted using --ulevels argument. For example, if you need to plot at 800 and 750 hpa levels only, then you can apply the following command:

wrfplot --vars "u_winds" --ulevels "800,750" --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

Remember that the level values are to be separated by ,. That should produce the following output in the terminal:

Using user provided upper level(s) : "800.0,750.0"

*** Initialising plotting for variable : "u_winds" ***

        Plotting "u_winds" for level "800.0" hPa and Time : "13-05-2021_05:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_800.0_13-05-2021_05_30.png"                  
        Plotting "u_winds" for level "800.0" hPa and Time : "13-05-2021_08:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_800.0_13-05-2021_08_30.png"                  
        Plotting "u_winds" for level "800.0" hPa and Time : "13-05-2021_11:31" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_800.0_13-05-2021_11_31.png"                  
        Plotting "u_winds" for level "800.0" hPa and Time : "13-05-2021_14:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_800.0_13-05-2021_14_30.png"                  
        Plotting "u_winds" for level "800.0" hPa and Time : "13-05-2021_17:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_800.0_13-05-2021_17_30.png"                  
        Plotting "u_winds" for level "750.0" hPa and Time : "13-05-2021_05:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_750.0_13-05-2021_05_30.png"                  
        Plotting "u_winds" for level "750.0" hPa and Time : "13-05-2021_08:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_750.0_13-05-2021_08_30.png"                  
        Plotting "u_winds" for level "750.0" hPa and Time : "13-05-2021_11:31" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_750.0_13-05-2021_11_31.png"                  
        Plotting "u_winds" for level "750.0" hPa and Time : "13-05-2021_14:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_750.0_13-05-2021_14_30.png"                  
        Plotting "u_winds" for level "750.0" hPa and Time : "13-05-2021_17:30" UTC                                                       
          Image saved at : "../../test/wrfout_data/output_images/u_winds_750.0_13-05-2021_17_30.png"                  

Plotting process completed. It took 0H:0M:6.948402S

Create Animation (GIF)

You can also create an animation of your plots using --gif option. Example command is given below:

wrfplot --vars "rh2" --gif --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

This would produce an animated gif image as shown below:

Control Animation Speed

By default, the speed of the animation is kept as 0.5 sec. If you wish to increase or decrease the speed, you can do so by with --gif-speed option as indicated below where speed is increased to 0.25 sec:

wrfplot --vars "rh2" --gif --gif-speed 0.25 --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

This would increase the speed of animation as shown in the sample image file.

Control Contour Levels

The default contour levels of each variable set based on a variable type. For example, Relative Humidity variable will have 10 levels from 0 to 100 with an interval of 10. If you wish to change these intervals for specific variable, you may do so with --clevels argument. Levels are to be in ascending order and separated by ','. For example, 24,26,28,30,32,34,36. Example plot to change temperature level to highlight the temperature range of interest will be as follows:

wrfplot --vars "rh2" --clevels '0,10,20,30,32,34,36,38,40,42,44,46' --input ../../test/wrfout_data/wrfout_d01_2021-05-13_00_00_00 --output ../../test/wrfout_data/output_images

After executing the command with --clevels argument, the plot would look like this:

this can be compared with the default clevels set by the wrfplot as shown below: