I am wondering about how to proportionally split or subset the gridded dataset in
netCDF format where data sources were provided by
European Climate Assessments and dataset (link for data source). However,
E-OBS climate gridded dataset were given for each
15 years climate observation throughout Europe and working with big
netCDF format grid data in R always cause memory problem in my site when I tried to treat all missing values. After decompressing grid data in
netCDF format (download link of grid data), I used
raster::stack to import whole gridded data, then I tried to treat missing values in this grid data because I need to do some statistics on this temperature observation later on, but it caused memory problem. So here is what in R:
mydat <- raster::stack("~/data/tg_0.25deg_reg_1980-1994_v17.0.nc") > print(mydat) File C:\Users\jvrat\Documents\stella\data\tg_0.25deg_reg_1980-1994_v17.0.nc (NC_FORMAT_CLASSIC): 1 variables (excluding dimension variables): short tg[longitude,latitude,time] long_name: mean temperature units: Celsius standard_name: air_temperature _FillValue: -9999 scale_factor: 0.00999999977648258 3 dimensions: longitude Size:464 long_name: Longitude values units: degrees_east standard_name: longitude latitude Size:201 long_name: Latitude values units: degrees_north standard_name: latitude time Size:5479 *** is unlimited *** long_name: Time in days units: days since 1950-01-01 00:00 standard_name: time 5 global attributes: Ensembles_ECAD: 17.0 Conventions: CF-1.4 References: http://www.ecad.eu\nhttp://www.ecad.eu/download/ensembles/ensembles.php\nhttp://www.ecad.eu/download/ensembles/Haylock_et_al_2008.pdf history: Wed Apr 4 11:17:28 2018: ncks -a -d time,10957,16435 tg_0.25deg_regular_1.nc tg_0.25deg_reg_1980-1994_v17.0.nc Wed Apr 4 11:16:02 2018: ncks -a --mk_rec_dmn time tg_0.25deg_regular.nc tg_0.25deg_regular_1.nc NCO: 4.6.7 mydat <- raster::reclassify(mydat, cbind(NA, -999)) Error: cannot allocate vector of size 2.9 Gb
To avoid this memory problem, perhaps I can try to split original gridded data in
netCDF format in
10 years and
5 years observation or equally split the grid data by each
5 years climate data observation (originally it was 15 years climate data observation for whole Europe). But doing this way is not feasible and desired.
I want to either convert this
netCDF file to plain text tabular data in
ASCII format (extract plain text data of Germany grid from chosen
netCDF grid data). I can use
R to work with this data manipulation, then I will use its output data (plain text data in
ArcGIS desk for different interpolation.
I need to extract plain text data of Germany grid with
0.25 degree resolution from original
netCDF files where 15 years climate observation for whole Europe were stored in each
nc file. I need all grid data in
ASCII format or
csv format because I can import them with
ArcGIS desktop and apply respective geospatial analysis. I need to find a solution how to get this task done that I specified above. Any idea please?
How can I make this happen this extraction or possible coercion of
netCDF data? Is that doable in R? Any more thoughts?