bioRad (version 0.7.1)

map: Map a plan position indicator (ppi) on a map

Description

Plots a plan position indicator (ppi) on a base layer using ggmap::ggmap().

Usage

map(x, ...)
# S3 method for ppi
map(
  x,
  map,
  param,
  alpha = 0.7,
  xlim,
  ylim,
  zlim = c(-20, 20),
  ratio,
  radar_size = 3,
  radar_color = "red",
  n_color = 1000,
  palette = NA,
  ...
)

Value

A ggmap object (a classed raster object with a bounding box attribute).

Arguments

x

A ppi object.

...

Arguments passed to ggmap::ggmap().

map

Basemap to use, result of a call to download_basemap().

param

Character. Scan parameter to plot, e.g. DBZH or VRADH. See summary.param() for commonly available parameters.

alpha

Numeric. Transparency of the data, value between 0 and 1.

xlim

Numeric vector of length 2. Range of x values (degrees longitude) to plot.

ylim

Numeric vector of length 2. Range of y values (degrees latitude) to plot.

zlim

Numeric vector of length 2. The range of values to plot.

ratio

Numeric. Aspect ratio between x and y scale, by default \(1/cos(latitude radar * pi/180)\).

radar_size

Numeric. Size of the symbol indicating the radar position.

radar_color

Character. Color of the symbol indicating the radar position.

n_color

Numeric. Number of colors (>=1) to use in the palette.

palette

Character vector. Hexadecimal color values defining the plot color scale, e.g. output from viridisLite::viridis().

Methods (by class)

• map(ppi): Plot a ppi object on a map.

Details

Available scan parameters for mapping 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.

See Also

• download_basemap()

• project_as_ppi()

Examples

# Project a scan as a ppi
ppi <- project_as_ppi(example_scan)
# \donttest{
# Create a basemap that matches the extent of the ppi
basemap <- download_basemap(ppi, maptype = "toner-lite")

# Map the radial velocity of the ppi onto the basemap
map(ppi, map = basemap, param = "VRADH")

# Extend the plotting range of velocities, from -50 to 50 m/s
map(ppi, map = basemap, param = "VRADH", zlim = c(-50, 50))

# Map the reflectivity
map(ppi, map = basemap, param = "DBZH")

# Change the color palette to Viridis colors
map(ppi, map = basemap, param = "DBZH", palette = viridis::viridis(100), zlim=c(-10,10))

# Give the data more transparency
map(ppi, map = basemap, param = "DBZH", alpha = 0.3)

# Change the appearance of the symbol indicating the radar location
map(ppi, map = basemap, radar_size = 5, radar_color = "blue")

# Crop the map
map(ppi, map = basemap, xlim = c(12.4, 13.2), ylim = c(56, 56.5))
# }