quiver: Vectors of ocean currents velocities

In satin: Visualisation and Analysis of Ocean Data Derived from Satellites

Vectors of ocean currents velocities

Description

Plot vectors of ocean current velocities of varying size or color for Copernicus data.

Usage

quiver(u, v, period = 1, depth = 1, xlim = NULL, ylim = NULL, scale = 1, 
       length = 0.05, colarrow = NULL, scheme = "default", ra.pos = NULL, 
       ra.speed = NULL, map = NULL, map.col = "grey", map.outline = "black", 
       colbar = FALSE, main = NULL, main.pos = "topright", add2map = FALSE, ...) 

Arguments

u	a satin object with eastward ocean current velocities (in m/s).
v	a satin object with northward ocean current velocities (in m/s).
period	an integer referring to the image number to plot.
depth	an integer referring to a depth level.
xlim	minimum and maximum longitude values for the map.
ylim	minimum and maximum latitude values for the map.
scale	this argument controls the arrow length.
length	this value controls the size of the arrow head.
colarrow	color(s) for the arrows; see details.
scheme	color scheme for the arrows. Either: "default" or a vector of valid color names.
ra.pos	position (lon, lat) for a reference arrow.
ra.speed	speed (in m/s) of the reference arrow. The mean is used by default.
map	a user defined map of class "SpatialPolygons".
map.col	color for the map.
map.outline	color for the map outline.
colbar	logical. If TRUE a color bar is added to the plot.
main	title for the map, defaults to the corresponding selected image period.
main.pos	position for the title: "topright", "topleft", "bottomright" or "bottomleft".
add2map	a logical value. If FALSE an entire new plot is created. If TRUE ocean current velocity arrows are added to an existing plot.
...	further arguments to pass to arrows.

Details

Usage and behavior of this function closely resembles that of plot.satin. It differs in that two different satin objects are needed, one for each component of ocean current velocities. Also, the ocean current vectors can be overlayed to an existing plot of another variable, as the temperature, for instance.

Value

A map of the ocean current velocities is produced.

Author(s)

Héctor Villalobos

Examples

if(interactive()){
# import copernicus data with potential temperatures and ocean current velocities
oc <- read.cmems("global-reanalysis-phy-001-030-daily_1560792767602_GC_2013-14.nc")

# Default plot
quiver(u = oc$uo, v = oc$vo)

# Using default colors for the arrows, color bar and reference arrow
quiver(u = oc$uo, v = oc$vo, colarrow = TRUE, colbar = TRUE,
       ra.pos = c(-108, 30))

# Adding custom map and colors, and plotting another period and depth level
quiver(u = oc$uo, v = oc$vo, image = 4, depth = 10, colbar = TRUE,
       colarrow = TRUE, scheme = c("mediumblue", "lightcyan", "red"), 
       map = dmap, ra.pos = c(-108, 30), ra.speed = 0.2)


# Overlay arrows to an existing plot of the potential temperature
plot(oc$thetao, map = dmap, xlim = c(-112, -108), ylim = c(24, 28), 
     colbar = FALSE)
quiver(u = oc$uo, v = oc$vo, colarrow = TRUE, ra.pos = c(-108.5, 27), 
       ra.speed = 0.15, main = "", length=0.02, scale = 0.7, add2map = TRUE)	   
}

satin documentation built on Sept. 23, 2022, 1:06 a.m.