Remove xtime variable from ocean climatology

[hollyhan]

This PR address the issue created by @trhille (#463) on having the xtime variable in the processed ocean climatology thermal forcing file in the ismip6_forcing landice test group.

closes #463

[trhille]

Thanks @hollyhan. Have you tested this? I'm approving by inspection, but am also happy to test this tomorrow when Cori is back up.

[hollyhan]

Thanks @hollyhan. Have you tested this? I'm approving by inspection, but am also happy to test this tomorrow when Cori is back up.

@trhille - I haven't tested it, thanks to Cori being down. It was an easy/straightforward fix to make, but it would be great to test it if it's not too much for you. Thanks so much, trevor!

[xylar]

This looks right to me, too. But I would prefer not to merge until someone has done some testing.

[trhille]

I tested this on Cori and it worked as expected. Thanks for taking care of this @hollyhan!

[hollyhan]

Testing
I've also tested on my macbook, and it worked as expected. Below is the result of ncdump-ing the ocean forcing file processed from the test:

(dev_compass_1.2.0-alpha.3_openmpi) pn2034311:process_thermal_forcing hollyhan$ ncdump -v xtime Thwaites4km_obs_TF_1995-2017_8km_x_60m.nc 
ncdump: xtime: No such variable


(dev_compass_1.2.0-alpha.3_openmpi) pn2034311:process_thermal_forcing hollyhan$ ncdump -h Thwaites4km_obs_TF_1995-2017_8km_x_60m.nc 
netcdf Thwaites4km_obs_TF_1995-2017_8km_x_60m {
dimensions:
	Time = UNLIMITED ; // (1 currently)
	nCells = 98341 ;
	nISMIP6OceanLayers = 30 ;
variables:
	double ismip6shelfMelt_zOcean(nISMIP6OceanLayers) ;
		ismip6shelfMelt_zOcean:units = "meters" ;
		ismip6shelfMelt_zOcean:bounds = "z_bnds" ;
		ismip6shelfMelt_zOcean:standard_name = "depth" ;
		ismip6shelfMelt_zOcean:positive = "up" ;
		ismip6shelfMelt_zOcean:axis = "Z" ;
	double ismip6shelfMelt_3dThermalForcing(Time, nCells, nISMIP6OceanLayers) ;
		ismip6shelfMelt_3dThermalForcing:units = "degrees_celsius" ;
		ismip6shelfMelt_3dThermalForcing:long_name = "thermal forcing, the difference between the temperature and the local freezing point" ;
		ismip6shelfMelt_3dThermalForcing:cell_measures = "area: area" ;
		ismip6shelfMelt_3dThermalForcing:coordinates = "lat lon" ;

// global attributes:
		:history = "Thu Dec 22 10:16:00 2022: /Users/hollyhan/miniconda3/envs/dev_compass_1.2.0-alpha.3_openmpi/bin/compass run\n",
			"Thu Dec 22 10:16:00 2022: ncks -O -t 2 --no_tmp_fl --hdr_pad=10000 --gaa remap_script=ncremap --gaa remap_hostname=pn2034311.lanl.gov --gaa remap_version=5.1.3 --rgr lat_nm_out=lat --rgr lon_nm_out=lon --map_fl=map_ismip6_8km_to_Thwaites4km_bilinear.nc /Users/hollyhan/Downloads/JUNK/landice/ismip6_forcing/ocean_thermal_obs/process_thermal_forcing/obs_thermal_forcing_1995-2017_8km_x_60m.nc remapped.nc" ;
		:remap_script = "ncremap" ;
		:remap_hostname = "pn2034311.lanl.gov" ;
		:remap_version = "5.1.3" ;
		:NCO = "netCDF Operators version 5.1.3 (Homepage = http://nco.sf.net, Code = http://github.com/nco/nco)" ;
		:title = "Regridded version of obs_thermal_forcing_1995-2017_8km_x_60m.nc" ;
		:map_file = "map_ismip6_8km_to_Thwaites4km_bilinear.nc" ;
		:input_file = "/Users/hollyhan/Downloads/JUNK/landice/ismip6_forcing/ocean_thermal_obs/process_thermal_forcing/obs_thermal_forcing_1995-2017_8km_x_60m.nc" ;
}