earth_surf: Surface of 1 dg by 1 dg Cells of the Earth

In marelac: Tools for Aquatic Sciences

Description

earth_surf computes the surface of 1d by 1dg grid cells as a function of latitude.

Based on data that give the surface distance per 1 dg change in lat/lon from http://en.wikipedia.org/wiki/Latitude

earth_dist calculates the distance between two (lat, lon) points

Usage

earth_surf(lat = 0, lon = 0)
earth_dist(alat, alon, blat, blon, method = 1) 

Arguments

lat	latitude (-90 - +90).
lon	longitude - not used.
alat	first latitude (-90 - +90).
alon	first longitude (-180, 180).
blat	second latitude (-90 - +90).
blon	second longitude (-180, 180).
method	an integer indicating the formula to use, either the spherical law of cosines (1) or the haversine formula (2)

Value

Surface of the grid cell, in m2.

Distance between the points (alat, alon), (blat, blon), m.

Author(s)

Karline Soetaert <[e-mail]>

See Also

Bathymetry, Oceans

Examples

 earth_surf(seq(0, 90, by = 15))

 SURF <- outer(X = Bathymetry$x,
               Y = Bathymetry$y,
               FUN <- function(X, Y) earth_surf(Y, X))

 earth_dist(10, 80, 10, 81)
 earth_dist(20, 80, 20, 81)

 SURF <- outer(X = Bathymetry$x,
               Y = Bathymetry$y,
               FUN <- function(X, Y) earth_surf(Y, X))

 sum(SURF)                                   #is: 510,072,000  km2

# the surface of the Oceans, m2
 sum(SURF*(Bathymetry$z < 0))                  # is: 3.58e14

# the volume of the Oceans, m3
- sum(SURF*Bathymetry$z*(Bathymetry$z < 0))    # is: 1.34e+18

# the surface area at several depths
SurfDepth <- vector()

dseq <- seq(-7500, -250, by = 250)

for (i in 2:length(dseq)) {
  ii <- which (Bathymetry$z > dseq[i-1] & Bathymetry$z <= dseq[i])
  SurfDepth[i-1]<-sum(SURF[ii])
}

plot(dseq[-1], SurfDepth, xlab = "depth, m", log = "y",
     ylab = "m2", main = "Surface at ocean depths")

marelac documentation built on Feb. 12, 2020, 3 a.m.