CDO

I have this NetCDF file from Germany DWD Deutscher Wetterdienst: https://opendata.dwd.de/climate_environment/CDC/grids_germany/daily/Project_TRY/air_temperature_mean/TT_201001_daymean.nc.gz

However, I don't know why this netCDF has Lat and Lon axes in 2D.

double lon(y, x) ;
    double lat(y, x) ;

The result from ncdump is below:

```
ncdump -h TT_20100101_daymean.nc
netcdf TT_20100101_daymean {
dimensions:
x = 720 ;
y = 938 ;
time = UNLIMITED ; // (31 currently)
bnds = 2 ;
variables:
double lon(y, x) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude coordinate" ;
lon:units = "degrees_east" ;
lon:_CoordinateAxisType = "Lon" ;
double lat(y, x) ;
lat:standard_name = "latitude" ;
lat:long_name = "latitude coordinate" ;
lat:units = "degrees_north" ;
lat:_CoordinateAxisType = "Lat" ;
double time(time) ;
time:standard_name = "time" ;
time:long_name = "time" ;
time:bounds = "time_bnds" ;
time:units = "hours since 2010-1-1 00:00:00" ;
time:calendar = "proleptic_gregorian" ;
time:axis = "T" ;
double time_bnds(time, bnds) ;
double datum(time) ;
datum:long_name = "Date and time in UTC" ;
datum:units = "YYYYMMDDHH" ;
datum:_FillValue = 9999. ;
datum:missing_value = 9999. ;
short temperature(time, y, x) ;
temperature:standard_name = "air_temperature" ;
temperature:long_name = "mean temperature at 2 m height" ;
temperature:units = "degC" ;
temperature:coordinates = "lat lon" ;
temperature:add_offset = 0.f ;
temperature:scale_factor = 0.1f ;
temperature:_FillValue = 9999s ;
temperature:missing_value = 9999s ;

// global attributes:
:CDI = "Climate Data Interface version 1.7.0 (http://mpimet.mpg.de/cdi)" ;
:Conventions = "CF-1.4" ;
:source = "surface and satellite observations, cosmo_090213_4.8_clm17" ;
:institution = "Deutscher Wetterdienst" ;
:title = "Temperature daily gridded dataset" ;
:project_id = "TRY-advancement" ;
:realization = "v1.0" ;
:contact = "Stefan Kraehenmann, stefan.kraehenmann@dwd.de" ;
:creation_date = "2016-01-23 06:07:57" ;
:CDO = "Climate Data Operators version 1.7.0 (http://mpimet.mpg.de/cdo)" ;
:history = "Wed Jun 22 10:24:12 2016: ncatted -a history,global,d,c, TT_201001_daymean.nc temp.nc" ;
}
```

Typically, I see another netCDF file has Lat and Long axes in 1D, e.g:

```
dimensions:
lat = 360 ;
lon = 720 ;
variables:

float lat(lat) ;
        lat:units = "degrees_north" ;
        lat:long_name = "latitude" ;
    float lon(lon) ;
        lon:units = "degrees_east" ;
        lon:long_name = "longitude" ;
```

Anyone knows why the netCDF file Lat and Long axes in 2D and the CRS of this netCDF file?
I don't know what is the correct way for getting the values of lat and long variables in 2D array.
It will be great, if anyone can point me to the netCDF document which has this information about 2D Lat Long axes.