Plot a plan position indicator (ppi)

Source: R/plot.ppi.R

Plot a plan position indicator (PPI) generated with project_to_ppi using ggplot

# S3 method for ppi
plot(
  x,
  param,
  xlim,
  ylim,
  zlim = c(-20, 20),
  ratio = 1,
  na.value = "transparent",
  ...
)

Arguments

x

An object of class ppi.

param

The scan parameter to plot, see details below.

xlim

Range of x values to plot.

ylim

Range of y values to plot.

zlim

The range of parameter values to plot. Defaults to parameter specific limits for plotting, not full range of data.

ratio

Aspect ratio between x and y scale.

na.value

ggplot argument setting the plot color of NA values

...

Arguments passed to low level ggplot function.

Value

No return value, side effect is a plot.

Details

Available scan parameters for plotting can by printed to screen by summary(x). Commonly available parameters are:

  • DBZH, DBZ: (Logged) reflectivity factor (dBZ)

  • TH, T: (Logged) uncorrected reflectivity factor (dBZ)

  • VRADH, VRAD: Radial velocity (m/s). Radial velocities towards the radar are negative, while radial velocities away from the radar are positive

  • RHOHV: Correlation coefficient (unitless). Correlation between vertically polarized and horizontally polarized reflectivity factor

  • PHIDP: Differential phase (degrees)

  • ZDR: (Logged) differential reflectivity (dB) The scan parameters are named according to the OPERA data information model (ODIM), see Table 16 in the ODIM specification.

Examples

# \donttest{
# load an example scan:
data(example_scan)

# print to screen the available scan parameters:
summary(example_scan)
#>                   Polar scan (class scan)
#> 
#>      parameters:  DBZH VRADH RHOHV ZDR PHIDP 
#> elevation angle:  0.5 deg
#>            dims:  480 bins x 360 rays

# make ppi for the scan
ppi <- project_as_ppi(example_scan)

# plot the default scan parameter, which is reflectivity "DBZH":
plot(ppi)


# plot the radial velocity parameter:
plot(ppi, param = "VRADH")


# change the range of reflectivities to plot, from -10 to 10 dBZ:
plot(ppi, param = "DBZH", zlim = c(-10, 10))


# change the scale name and colour scheme, using viridis colors:
plot(ppi, param = "DBZH", zlim = c(-10, 10)) + viridis::scale_fill_viridis(name = "dBZ")
#> Scale for fill is already present.
#> Adding another scale for fill, which will replace the existing scale.

# }