Strange spatial reference system netCDF
Dear Maurizio,
an attempt to do something along this line is:
f = "tas_rcp85_land-rcm_eur_12km_01_mon_198012-208011.nc"
library(stars)
r = read_ncdf(f, ncsub = cbind(start = c(1, 1, 1, 1), count = c(418,
406, 3, 1)), eps=1e-3)
rx = read_stars(f, proxy = TRUE) # only for the crs!
st_crs(r) = st_crs(rx)
r0 = stars:::st_transform_proj.stars(r, 4326)
png("x.png")
plot(r0[,,,1], border = NA, axes = TRUE, reset = FALSE)
library(rnaturalearth)
plot(ne_coastline(returnclass = "sf"), add = TRUE, col = 'orange')
Note that the output object time stamps respect the 360-day calendar
(using pkg PCICt).
You'll find some discussion, and the output image, here:
https://github.com/r-spatial/stars/issues/175
Feel free to post follow-up questions here, or to github.
On 5/2/19 6:49 PM, Maurizio Marchi wrote:
Dear list, I'm working with large netCDF files from the UK Climate Projections portal ( https://www.metoffice.gov.uk/research/collaboration/ukcp). More in detail I'm reading with the ncdf4 library this <http://data.ceda.ac.uk/badc/ukcp18/data/land-rcm/eur/12km/rcp85/01/tas/mon/latest/> file. Once loaded O can easily handle it but it is a strange reference system as follow: rotated_latitude_longitude[] grid_mapping_name: rotated_latitude_longitude longitude_of_prime_meridian: 0 earth_radius: *6371229* grid_north_pole_latitude: 39.25 grid_north_pole_longitude: 198 north_pole_grid_longitude: 0 If I load the .nc file in QGIS I see that the SR is "+proj=longlat +a=6371229 +b=6371229 +no_defs" where the values associated to *a* and *b* variables are the earth radius. Even if QGIS can read it, the raw file isn't projected properly (it seems tha QGIS is not able to handle such projection). Finally, using the ncdf4+raster libraries, I can easily generate e raster image but then I'm not able to understand I could I re project this raster in WGS84 reference system. Any helps? Cheers -- Maurizio Marchi, PhD Forest Science - Ecological Mathematics Skype ID: maurizioxyz linux user 552742 #EUFGIS national Focal point for Italy #Annals of Silvicultural Research Associated Editor https://scholar.google.it/citations?hl=en&user=_2X6fu8AAAAJ <https://scholar.google.it/citations?hl=en&user=_2X6fu8AAAAJ*> [[alternative HTML version deleted]]
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