advectionFspiral function

Spiraling advection field

Spiraling advection field

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

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)

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()

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, tools:::Rd_expr_doi("10.1029/2020WR029466")