# EXAMPLE R-CODE FOR ACCESSING NETCDF FILES
# by Karsten Steinhaeuser, March 2009

# Load the ncdf library
library(ncdf)

### TEMPERATURE ###

# open the netCDF file for reading
ncdata <- open.ncdf("air.2m.1950-1999.nc")

# print metadata
print(ncdata)

# get latitude coordinates
lat <- get.var.ncdf(ncdata,"lat")
# get longitude coordinates
lon <- get.var.ncdf(ncdata,"lon")
# get time axis
time <- get.var.ncdf(ncdata,"time")

# read air temperature data into an array
air <- get.var.ncdf(ncdata,"air")

# close the netCDF file
close.ncdf(ncdata);

# BEGIN ANALYSIS HERE...

# Example: convert temperature from Kelvin to Degrees Celsius
air <- air-273;

### PRECIPITATION ###

# open the netCDF file for reading
ncdata <- open.ncdf("prate.sfc.1950-1999.nc")

# print metadata
print(ncdata)

# get latitude coordinates
lat <- get.var.ncdf(ncdata,"lat")
# get longitude coordinates
lon <- get.var.ncdf(ncdata,"lon")
# get time axis
time <- get.var.ncdf(ncdata,"time")

# read air temperature data into an array
prate <- get.var.ncdf(ncdata,"prate")

# close the netCDF file
close.ncdf(ncdata);

# BEGIN ANALYSIS HERE...

# Example: convert precipitation from kilograms per square meter per second
#          to millimeters per day
prate <- prate*86400;