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Spatial rainfall or precipitation data

5 messages · Barry Rowlingson, Matthew Landis, Robert J. Hijmans +1 more

Barry Rowlingson
# 
On Tue, Sep 13, 2011 at 3:57 PM, luca candeloro
<luca.candeloro at gmail.com> wrote:
you could try the IRI Data Library:

http://iridl.ldeo.columbia.edu/

 the interface is a bit clunky but persevere. There's definitely
rainfall data in there over space and time, but it does concentrate on
Africa and tropical areas for backing up disease research.

Barry
Matthew Landis
#
On 9/13/2011 10:57 AM, luca candeloro wrote:
Luca, I haven't used the TRMM binary data specifically, but I've read in 
similar files into R.  It's a little tricky to go from binary data to 
something you can visualize, e.g. with the raster package.  I found that 
there was a fair bit of trial and error.

# This gives a vector of values
trmm.data <- readBin(file(trmm.data.file, open = 'rb'), size = 2, 
endian='little')

# If it looks like nonsense, you might try setting endian to 'swap' or 
'big',  or changing the 'size'

# assign to a raster layer
# The array might have to be transposed to work right
trmm.array <- array(trmm.data, dim = c(1440, 400))

trmm.raster <- raster(trmm.array, xmn = -180, xmx = 180, ymn = -50, ymx 
= 50,
     crs = '+proj=longlat +datum=WGS84 +ellps=WGS84')

plot(trmm.raster)
# If image doesn't look right, you might look into the rotate() and 
flip() functions in the raster package.

Good luck.

M