使用 cdo（气候数据运算符）在每日时间步长中存储的变量的月度总和

Question

I have a nc file of 40 years for a variable recorded at daily temporal resolution. I would like to sum these over monthly intervals and have tried the following:

cdo monsum inputfile.nc outputfile.nc

Although this runs with no error, I only get one frame in the output file. I would expect a much larger file.

I am thinking this might be some issue with time in the input file.

Copied info from ncdump-h input file :

dimensions:
       time = UNLIMITED ; // (14975 currently)
       longitude = 40 ;
       latitude = 66 ;
variables:
       double time(time) ;
               time:standard_name = "time" ;
               time:units = "days since 1979-1-1 00:00:00" ;
               time:calendar = "proleptic_gregorian" ;
               time:axis = "T" ;
       double longitude(longitude) ;
               longitude:standard_name = "projection_x_coordinate" ;
               longitude:long_name = "longitude" ;
               longitude:units = "degrees_east" ;
               longitude:axis = "X" ;
       double latitude(latitude) ;
               latitude:standard_name = "projection_y_coordinate" ;
               latitude:long_name = "latitude" ;
               latitude:units = "degrees_north" ;
               latitude:axis = "Y" ;
       int crs ;
               crs:proj4 = "+proj=longlat +datum=WGS84" ;
       float variable(time, latitude, longitude) ;
               variable :grid_mapping = "crs" ;
               variable :_FillValue = -3.4e+38f ;
               variable :missing_value = -3.4e+38f ;
               variable :proj4 = "+proj=longlat +datum=WGS84" ;
               variable :min = 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0. ;
               variable :max = 6.5701843261719, 8.62581787109377, 6.24334106445315, 8.29082641601565, 7.59359130859377, 10.0182434082031, 9.76052246093752, 9.95830688476565, 10.3648010253906, 12.8482604980469, 13.1276489257813, 13.1267333984375, 10.9829345703125, 9.82497558593752, 10.1014953613281, 11.8195434570313, 13.9579711914063, 10.0517211914063, 9.37850341796877, 11.3964782714844, 13.0114074707031, 14.4672180175781, 11.4755798339844, 10.6639953613281, 11.3891540527344, 11.9616943359375, 13.7388854980469, 5.56426391601565, 7.07705078125002, 7.64479980468752, 8.25527343750002 ; // global attributes:
               :CDI = "Climate Data Interface version 1.9.10 (https://mpimet.mpg.de/cdi)" ;
               :Conventions = "CF-1.4" ;
               :created_by = "R, packages ncdf4 and raster (version 3.4-10)" ;
               :date = "2021-10-06 11:52:06" ;
               :history = "Mon Oct 18 13:50:40 2021: cdo setreftime,1979-01-01,00:00:00 kdd_AR_1979_2019.nc kdd_AR_1979_2019_adj.nc\n",

Help is much appreciated. Sorry for not being to provide a straightforward reproducible example. I can share the data via we-transfer or such if needed. Thanks!

Answer 1

CDO uses the attribute proj_params to identify the proj parameters. The corresponding attribute in your file is proj4. You need to rename this attribute to apply the proj parameters automatically:

ncrename -a crs@proj4,proj_params file.nc

I found this answer here from Uwe Schulzweida

Once you have done that I hope you can process the file with cdo correctly, let me know if it works.

Answer 2

Thanks for Adrian Tompkins who lead me straight to the answer. I had to fix the time axis of the merged file used here as input. This is possible using the settaxis operator