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I am having difficulties in R getting climate data from a netCDF file into the right format for further analysis. I am working with gridded global data on Standardized Precipitation Index (downloaded from here and want to aggregate the monthly values for each grid-cells to an annual average.

Now the issue is that in the file the data is organised as TXY, where T are the number of months since January 1960 and X and Y are longitude and latitude respectively. As a result, when I load the file into R with,

library(raster)
spi<-brick("data.nc") 

I get the following dimensions:

class       : RasterBrick 
dimensions  : 144, 441, 63504, 58  (nrow, ncol, ncell, nlayers)
resolution  : 1, 2.5  (x, y)
extent      : 228, 669, 0, 360  (xmin, xmax, ymin, ymax)
coord. ref. : NA 
data source : data.nc 
names       : X.66.25, X.63.75, X.61.25, X.58.75, X.56.25, X.53.75,... 
degree_north: -66.25, 76.25 (min, max)
varname     : aprod 

So annoyingly, the monthly observations are on the columns whereas the latitude coordinates are on the layers. Which I don't find very useful and makes processing the data rather difficult.

Therefore I wondered, if there is a way in which I can change the dimensions to a more conventional format? With the data of interest on the layers.

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That particular data source (IRI data library) allows reordering in its language, e.g. append

[ X Y ] REORDER

data link

  • I didn't dare to venture into Expert Mode. Many thanks. – HorseOfTheYear Oct 22 '15 at 10:36

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