advectionFspiralCE {CoSMoS}

Spiraling advection field satisfying continuity equation

Description

Provides an advection field corresponding to a spiral motion to/from a specified reference point (sink) satisfying continuity equation (from John Burkardt's website).

Usage

advectionFspiralCE(spacepoints, a, C)

Arguments

spacepoints

vector of coordinates (2 x d), where d is the number of locations/grid points

a

parameter controlling the intensity of rotational velocity (a > 0 clokwise; a < 0 conter-clockwise)

C

parameter ranging in (0, 2*pi)

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 <- advectionFspiralCE(spacepoints = coord,
                        a = 5,
                        C = 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()