Ks: Calculates Total Wavenumber for Stationary Rossby Waves (Ks)

In raytracing: Rossby Wave Ray Tracing

Calculates Total Wavenumber for Stationary Rossby Waves (Ks)

Description

Ks ingests the time-mean zonal wind (u) and calculates the Total Wavenumber for Stationary Rossby waves (Ks) in mercator coordinates (see: Hoskins and Ambrizzi, 1993). Stationary Rossby waves are found when zonal wave number (k) is constant along the trajectory, which leads to wave frequency (omega) zero. In this code Ks is used to distinguish the total wavenumber for Stationary Rossby Waves (Ks) from the total wavenumber for Rossby waves (K), and zonal wave number (k). Ks returns a list with Ks in mercator coordinates (ksm).

Usage

Ks(
  u,
  lat = "lat",
  lon = "lon",
  uname = "uwnd",
  ofile,
  a = 6371000,
  plots = FALSE,
  show.warnings = FALSE
)

Arguments

u	String indicating the input data filename. The file to be passed consists in a netCDF file with only time-mean zonal wind at one pressure level, latitude in ascending order (not a requisite), and longitude from 0 to 360. It is required that the read dimensions express longitude (in rows) x latitude (in columns). u also can be a numerical matrix with time-mean zonal wind at one pressure level, latitude in ascending order (not a requisite), and longitude from 0 to 360. It is required that the read dimensions express longitude (in rows) x latitude (in columns).
lat	String indicating the name of the latitude field. If u is a matrix, lat must be numeric.
lon	String indicating the name of the longitude field.If u is a matrix, lon must be numeric from 0 to 360.
uname	String indicating the variable name field
ofile	String indicating the file name for store output data. If missing, will not return a netCDF file
a	Numeric indicating the Earth's radio (m)
plots	Logical, if TRUE will produce filled.countour plots
show.warnings	Logical, if TRUE will warns about NaNs in sqrt(<0)

Value

list with one vector (lat) and 1 matrix (Ksm)

Examples

{
# u is NetCDF and lat and lon characters
input <- system.file("extdata",
                     "uwnd.mon.mean_200hPa_2014JFM.nc",
                      package = "raytracing")
Ks <- Ks(u = input, plots = TRUE)
Ks$ksm[] <- ifelse(Ks$ksm[] >= 16 |
                   Ks$ksm[] <= 0, NA, Ks$ksm[])
cores <- c("#ff0000","#ff5a00","#ff9a00","#ffce00","#f0ff00")
graphics::filled.contour(Ks$ksm[, -c(1:5, 69:73)] ,
                         col = rev(colorRampPalette(cores, bias = 0.5)(20)),
                         main = "Ks")
}

raytracing documentation built on June 7, 2022, 1:09 a.m.