How to edit global attributes in netcdf file with NCO

Question

I am trying to edit one of the global attributes in my netcdf file:

START_DATE = "2016-05-12_00:00:00"

I want to change the date string to another date. How do you do this with the nco package?

I've seen that I can use

ncatted [-a ...] [-D dbg_lvl] [-h] [-l path] [-O] [-o out.nc] [-p path] [-R] [-r] in.nc [[out.nc]]

I've read the docs, but there are limited examples shown.

This is how I used it:

ncatted -O -h -a START_DATE,,m,c,"2016-06-12_00:00:00" wrfchemi_d01.nc wrfnew.nc

Upon checking the output with ncdump, the global attribute did not change as seen here:

// global attributes:
        :TITLE = " OUTPUT FROM *             PROGRAM:WRF-Chem V4.1.2 MODEL" ;
        :START_DATE = "2016-05-12_00:00:00" ;
        :WEST-EAST_GRID_DIMENSION = 70 ;
        :SOUTH-NORTH_GRID_DIMENSION = 70 ;
        :BOTTOM-TOP_GRID_DIMENSION = 51 ;
        :DX = 25000.f ;
        :DY = 25000.f ;
        :AERCU_OPT = 0 ;
        :AERCU_FCT = 1.f ;
        :IDEAL_CASE = 0 ;
        :DIFF_6TH_SLOPEOPT = 0 ;
        :AUTO_LEVELS_OPT = 2 ;
        :DIFF_6TH_THRESH = 0.1f ;
        :DZBOT = 50.f ;
        :DZSTRETCH_S = 1.3f ;
        :DZSTRETCH_U = 1.1f ;
        :GRIDTYPE = "C" ;
        :DIFF_OPT = 1 ;
        :KM_OPT = 4 ;
        :DAMP_OPT = 3 ;
        :DAMPCOEF = 0.2f ;
        :KHDIF = 0.f ;
        :KVDIF = 0.f ;
        :MP_PHYSICS = -1 ;
        :RA_LW_PHYSICS = 1 ;
        :RA_SW_PHYSICS = 1 ;
        :SF_SFCLAY_PHYSICS = 2 ;
        :SF_SURFACE_PHYSICS = 2 ;
        :BL_PBL_PHYSICS = 2 ;
        :CU_PHYSICS = 5 ;
        :SF_LAKE_PHYSICS = 0 ;
        :SURFACE_INPUT_SOURCE = 1 ;
        :SST_UPDATE = 0 ;
        :GRID_FDDA = 0 ;
        :GFDDA_INTERVAL_M = 0 ;
        :GFDDA_END_H = 0 ;
        :GRID_SFDDA = 0 ;
        :SGFDDA_INTERVAL_M = 0 ;
        :SGFDDA_END_H = 0 ;
        :HYPSOMETRIC_OPT = 2 ;
        :USE_THETA_M = 1 ;
        :GWD_OPT = 0 ;
        :SF_URBAN_PHYSICS = 0 ;
        :SF_SURFACE_MOSAIC = 0 ;
        :SF_OCEAN_PHYSICS = 0 ;
        :WEST-EAST_PATCH_START_UNSTAG = 1 ;
        :WEST-EAST_PATCH_END_UNSTAG = 69 ;
        :WEST-EAST_PATCH_START_STAG = 1 ;
        :WEST-EAST_PATCH_END_STAG = 70 ;
        :SOUTH-NORTH_PATCH_START_UNSTAG = 1 ;
        :SOUTH-NORTH_PATCH_END_UNSTAG = 69 ;
        :SOUTH-NORTH_PATCH_START_STAG = 1 ;
        :SOUTH-NORTH_PATCH_END_STAG = 70 ;
        :BOTTOM-TOP_PATCH_START_UNSTAG = 1 ;
        :BOTTOM-TOP_PATCH_END_UNSTAG = 50 ;
        :BOTTOM-TOP_PATCH_START_STAG = 1 ;
        :BOTTOM-TOP_PATCH_END_STAG = 51 ;
        :GRID_ID = 1 ;
        :PARENT_ID = 1 ;
        :I_PARENT_START = 1 ;
        :J_PARENT_START = 1 ;
        :PARENT_GRID_RATIO = 1 ;
        :DT = 150.f ;
        :CEN_LAT = 14.60003f ;
        :CEN_LON = 120.98f ;
        :TRUELAT1 = 14.6f ;
        :TRUELAT2 = 14.6f ;
        :MOAD_CEN_LAT = 14.60003f ;
        :STAND_LON = 120.98f ;
        :POLE_LAT = 90.f ;
        :POLE_LON = 0.f ;
        :GMT = 0.f ;
        :JULYR = 2016 ;
        :JULDAY = 133 ;
        :MAP_PROJ = 1 ;
        :MAP_PROJ_CHAR = "Lambert Conformal" ;
        :MMINLU = "USGS" ;
        :NUM_LAND_CAT = 28 ;
        :ISWATER = 16 ;
        :ISLAKE = 28 ;
        :ISICE = 24 ;
        :ISURBAN = 1 ;
        :ISOILWATER = 14 ;
        :HYBRID_OPT = 2 ;
        :ETAC = 0.2f ;

Can someone show me how its done for this simple change?

Thanks!

How to edit global attributes in netcdf file with NCO

Answers (1)

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