Sea ice vignette

Get sea ice data at ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/shapefiles.

Install rnoaa

Install and load rnoaa into the R session.

If you're on Windows, you may have to install Rtools. Run devtools::has_devel(). If you get a TRUE, you're okay. If not, install Rtools.

install.packages("devtools")
library(devtools)
ropensci::install_github("ropensci/rnoaa")

library('rnoaa')
library('plyr')

Look at data.frame's for a series of years for Feb, South pole

urls <- sapply(seq(1979,1990,1), function(x) seaiceeurls(yr=x, mo='Feb', pole='S'))
out <- lapply(urls, seaice)

head(out[[1]])

##       long     lat order  hole piece group id
## 1 -2125000 1950000     1 FALSE     1   0.1  0
## 2 -2050000 1950000     2 FALSE     1   0.1  0
## 3 -2050000 1925000     3 FALSE     1   0.1  0
## 4 -1950000 1925000     4 FALSE     1   0.1  0
## 5 -1950000 1900000     5 FALSE     1   0.1  0
## 6 -1875000 1900000     6 FALSE     1   0.1  0

Map a single year/month/pole combo

urls <- seaiceeurls(mo='Apr', pole='N', yr=1990)
out <- seaice(urls)

library('ggplot2')
ggplot(out, aes(long, lat, group=group)) +
   geom_polygon(fill="steelblue") +
   theme_ice()

Map all years for April only for North pole

urls <- seaiceeurls(mo='Apr', pole='N')[1:10]
out <- lapply(urls, seaice)

names(out) <- seq(1979,1988,1)
df <- ldply(out)
library('ggplot2')
ggplot(df, aes(long, lat, group=group)) +
  geom_polygon(fill="steelblue") +
  theme_ice() +
  facet_wrap(~ .id)