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how to obtain data of long years included NetCDF file for a " small-time range"?

Asked by Behzad Navidi on 20 Sep 2019
Latest activity Commented on by Behzad Navidi on 25 Sep 2019
I have a NetCDF file from GPCC (GLOBAL PRECIPITATION CLIMATOLOGY CENTRE). this file include precipitation from 1800 to 2016 at 0.5 deere grids for all around the globe in a monthly format. I only want data from 1982 to 2015. how to cut this range from NetCDF file? if it possible I need a related code or function. I write the nv(disp) information of my file below.
Format:
netcdf4_classic
Global Attributes:
Original_Source = 'http://www.dwd.de/en/FundE/Klima/KLIS/int/GPCC/GPCC.htm
is the webpage and the data is at ftp://ftp.dwd.de/pub/data/gpcc/download.html'
Reference = 'Users of the data sets are kindly requested to give feed back and to refer to GPCC publications on this webpage: http://www.dwd.de/bvbw/appmanager/bvbw/dwdwwwDesktop/?_nfpb=true&_pageLabel=_dwdwww_klima_umwelt_datenzentren_wzn&T12404518261141645246564gsbDocumentPath=Content%2FOeffentlichkeit%2FKU%2FKU4%2FKU42%2Fteaser__product__access.html&_state=maximized&_windowLabel=T12404518261141645246564&lastPageLabel=_dwdwww_klima_umwelt_datenzentren_wzn'
original_source = 'ftp://ftp-anon.dwd.de/pub/data/gpcc/html/fulldata_download.html'
Conventions = 'CF 1.0'
dataset_title = 'Global Precipitation Climatology Centre (GPCC)'
References = 'https://www.esrl.noaa.gov/psd/data/gridded/data.gpcc.html'
title = 'GPCC Full Data Reanalysis Version 2018 0.5x0.5 Monthly Total'
history = 'Created 09/2018 based on V2018 data obtained via ftp'
data_modified = '2019-03-12'
_NCProperties = 'version=2,netcdf=4.6.3,hdf5=1.10.5'
Dimensions:
lat = 360
lon = 720
nbnds = 2
time = 1512 (UNLIMITED)
Variables:
lat
Size: 360x1
Dimensions: lat
Datatype: single
Attributes:
long_name = 'Latitude'
units = 'degrees_north'
standard_name = 'latitude'
axis = 'Y'
coordinate_defines = 'point'
actual_range = [89.75 -89.75]
lon
Size: 720x1
Dimensions: lon
Datatype: single
Attributes:
long_name = 'Longitude'
units = 'degrees_east'
standard_name = 'longitude'
actual_range = [0.25 359.75]
axis = 'X'
coordinate_defines = 'point'
time
Size: 1512x1
Dimensions: time
Datatype: double
Attributes:
long_name = 'Time'
units = 'days since 1800-1-1 00:00:00'
delta_t = '0000-01-00 00:00:00'
avg_period = '0000-01-00 00:00:00'
standard_name = 'time'
axis = 'T'
coordinate_defines = 'start'
actual_range = [33237 79227]
precip
Size: 720x360x1512
Dimensions: lon,lat,time
Datatype: single
Attributes:
missing_value = -9.969209968386869e+36
units = 'mm'
var_desc = 'Precipitation'
level_desc = 'Surface'
parent_stat = 'Observations'
long_name = 'GPCC Monthly total of precipitation'
valid_range = [0 8000]
statistic = 'Total'
level = 'Surface'
actual_range = [0 4552.4302]
dataset = 'GPCC Precipitation 0.5degree V2018 Full Reanalysis'

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1 Answer

Answer by Chad Greene
on 25 Sep 2019
 Accepted Answer

You can load only the time range of interest by specifying the start indices when you call ncread.
Start by using ncdateread to get a time vector. Something like
t = ncdateread(filename,'time');
Then figure out which index starts the time range of interest:
ind = find(t>=datetime('jan 1, 1982'),1,'first');
Then load the gridded data, specifying the starting indices for each dimension of the precipitation data cube:
P = ncread(filename,'precip',[1 1 ind]);

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