betam {raytracing}

Calculates Meridional Gradient of the Absolute Vorticity (beta) in mercator coordinates (betam)

Description

betam ingests the time-mean zonal wind (u), transform it in mercator coordinates (um) and then calculates the meridional gradient of the absolute vorticity (beta) in mercator coordinates (betam) using equation Karoly (1983). betam returns a list with the u, betam, and lat for being ingested in Ktotal, Ks, ray or ray_source.

Usage

betam(
  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, it 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 2 matrices (u and betam)

Examples

{
# u is NetCDF and lat and lon characters
input <- system.file("extdata",
                     "uwnd.mon.mean_200hPa_2014JFM.nc",
                      package = "raytracing")
b <- betam(u = input, plots = TRUE)
cores <- c("#ff0000","#ff5a00","#ff9a00","#ffce00","#f0ff00")
graphics::filled.contour(b$betam/10e-12,
                         zlim = c(0, 11),
                         col = rev(colorRampPalette(cores)(24)),
                         main = "Beta Mercator (*10e-11)")
# u, lat and lon as numeric
input <- system.file("extdata",
                     "uwnd.mon.mean_200hPa_2014JFM.bin",
                      package = "raytracing")
u <- readBin(input,
             what = numeric(),
             size = 4,
             n = 144*73*4)
lat <- seq(-90, 90, 2.5)
lon <- seq(-180, 180 - 1, 2.5)
u <- matrix(u,
            nrow = length(lon),
            ncol = length(lat))
graphics::filled.contour(u, main = "Zonal Wind Speed [m/s]")
}