compute_dist: Compute distance between points on the globe

In jonasbhend/geoutils: package to read in and analyse climate model output in NetCDF format

Description

This function computes distances between an arbitrary number of points on the globe

Usage

compute_dist(lon, lat, lon0, lat0, Rearth = 6371)

Arguments

lon,lat	points from which distance is measured (in degree)
lon0,lat0	points to which distance is measured (in degree)
Rearth	Earth's radius (defaults to 6371km)

Value

Distance between points in km

Examples

## read in some netcdf data
tas <- readNetCDF(system.file("extdata", "annual_CRUTEMv3_1961-90.nc", package="geoutils"), varname="temp")
lons <- attr(tas, 'lon')
lats <- attr(tas, 'lat')
## compute distance from greenwich
gdist <- compute_dist(lons, lats, 0, 50)

## set up new netcdf object for plotting
gdist <- as.matrix(gdist)
class(gdist) <- 'NetCDF'
attr(gdist, 'lon') <- lons
attr(gdist, 'lat') <- lats

## plot the distances
plot(gdist, type='mean', ti=1)
map(add=T, interior=F)

jonasbhend/geoutils documentation built on May 19, 2019, 7:27 p.m.