1d:T7a6,# Surface of 1 dg by 1 dg Cells of the Earth `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 [https://en.wikipedia.org/wiki/Latitude](https://en.wikipedia.org/wiki/Latitude) `earth_dist` calculates the distance between two (lat, lon) points ```r 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`) ## Returns Surface of the grid cell, in $m2$. Distance between the points (alat, alon), (blat, blon), m. ## Author(s) Karline Soetaert ## Examples ```r 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") ``` ## See Also `Bathymetry`, `Oceans`

earth_surf function