advectionFspiral: Spiraling advection field

In CoSMoS: Complete Stochastic Modelling Solution

Description

Provides an advection field corresponding to a spiral motion to/from a specified reference point (sink).

Usage

advectionFspiral(spacepoints, x0, y0, a, b, rotation = 1)

Arguments

spacepoints	vector of coordinates (2 x d), where d is the number of locations/grid points
x0	x coordinate of reference point (sink)
y0	y coordinate of reference point (sink)
a	parameter controlling the x component of rotational velocity
b	parameter controlling the y component of rotational velocity
rotation	parameter controlling the rotational direction. The following combinations hold: if a > 0, b > 0, and direction = 1: spiraling CLOCKWISE TO (x0, y0) if a < 0, b < 0, and direction = 1: spiraling COUNTER-CLOCKWISE FROM (x0, y0) if a > 0, b > 0, and direction = 2: spiraling COUNTER-CLOCKWISE TO (x0, y0) if a < 0, b < 0, and direction = 2: spiraling CLOCKWISE FROM (x0, y0)

References

Papalexiou, S.M., Serinaldi, F., Porcu, E. (2021). Advancing Space-Time Simulation of Random Fields: From Storms to Cyclones and Beyond. Water Resources Research, 57, e2020WR029466, doi: 10.1029/2020WR029466

Examples

library(ggquiver)
library(ggplot2)
## specify coordinates
m = 25
aux <- seq(0, m - 1, length = m)
coord <- expand.grid(aux, aux)

af <- advectionFspiral(spacepoints = coord,
                        x0 = floor(m / 2),
                        y0 = floor(m / 2),
                        a = 3,
                        b = 2,
                        rotation = 1)

## visualize advection field
dta <- data.frame(lon = coord[ ,1], lat = coord[ ,2], u = af[ ,1], v = af[ ,2])
ggplot(dta, aes(x = lon, y = lat, u = u, v = v)) +
geom_quiver() +
theme_light()

CoSMoS documentation built on May 30, 2021, 1:06 a.m.