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May 17, 2017 20:19
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An example of the robinson maps often used to represent global modelling data
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library(raster) | |
library(maps) | |
library(maptools) | |
library(sf) | |
library(scales) | |
# set coordinate systems | |
robinson = CRS(" +proj=robin +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs") | |
latlon = CRS("+init=epsg:4326") | |
# set the colours for the map | |
# red and blues in this case for temperatures | |
cols = dichromat_pal("DarkRedtoBlue.12")(12) | |
cols = gradient_n_pal(cols)(seq(0, 1, length = 15)) | |
# load data | |
data("wrld_simpl") | |
# download a file here: https://data.giss.nasa.gov/gistemp/maps/ | |
temp = raster("amaps.nc") # I downloaded the map for April 2017 | |
# create grid lines | |
pts=SpatialPoints(rbind(c(-180,-90), | |
c(-180,90), | |
c(180,90), | |
c(180,-90)), | |
CRS("+init=epsg:4326")) | |
gl = gridlines(pts, easts = seq(-180,180,180), norths = seq(-90,90,90), ndiscr = 100) | |
bb = gridlines(pts, easts = seq(-180,180,360), norths = seq(-90,90,180), ndiscr = 100) | |
# reproject grid lines and bounding box | |
gl_robinson = spTransform(gl, robinson) | |
bb_robinson = spTransform(bb, robinson) | |
# transform the wold map and data | |
wrld_robinson = spTransform(wrld_simpl, robinson) | |
# reproject the gridded data | |
temp_robinson = trim(projectRaster(temp, crs = robinson, over = TRUE)) | |
temp_robinson[temp_robinson>7] = 7 # zlim otherwise makes these missing values | |
par(mar=c(5,0,3,0)) | |
plot(temp_robinson, | |
xaxt = "n", | |
yaxt = "n", | |
bty = "n", | |
zlim = c(-7,7), | |
col = cols, | |
box = FALSE, | |
horiz = TRUE, | |
legend.args=list(text=expression('Temperature Anomaly (' * degree * 'C)'), | |
side = 3, | |
font = 2, | |
line = 2, | |
cex = 1.5)) | |
lines(wrld_robinson, col = "grey25") | |
lines(gl_robinson, col = "grey25") | |
lines(bb_robinson, lwd = 2) | |
mtext(text = "April 2017 - Anomaly vs 1951-1980", | |
line = 1, | |
side = 3, | |
cex = 1.5) |
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