I figured out the answer some time ago but I hope this will help other people that are dipping their toes into the NetCDF file format.
I found that the easiest way to create a new NetCDF file containing several GeoTIFF files is using GDAL and then using NCO and CDO tools (Provided by unidata) to add the appropriate metadata.
First you convert the GeoTIFF´s to NetCDF using:
gdal_translate -of netCDF -co "FOMRAT=NC4" foo.tif foo.nc
This creates a netCDF in NC4 format (which is the newest version at this time) with some basic metadata like coordinate system, pixel size etc.
Then I rename the variable information to what I want it to be (In my case SST) with the appropriately registered long and short name From the unidata convention page):
ncrename -v Band1,SST foo.nc
ncatted -O -a long_name,SST,o,c,sea_surface_temperature foo.nc
The first renames the variable Band1 to the wanted variable SST.
The second adds the long name of the SST variable.
In my case I added time data to the new nc file using:
ncap2 -Oh -s "tin=$d;" -S mean.nco foo.nc new_foo.nc
where the mean.nco file looks as follows:
/***.nco ncap2 script***/
defdim("time",1);
time[time]=tin;
time@long_name="Time";
time@units="days since 2000-00-00 00:00:00";
time@standard_name="time";
time@axis="T";
time@coordinate_defines="point";
time@calendar="standard";
/***SST_M@long_name="Sea surface temperature mean";
SST_M@units="Celsius"
/***********/
This adds the third coordinate time where T=$d, which in my case was the january or 1. Then this time is set to the file using:
cdo settime,$d new_foo.nc newer_foo.nc
Finally all the files converted to NetCDF are joined together using:
cdo mergetime folder_containing_all_nc/*.nc final.nc
This joins all files with the appropriate timestamp to one file. This can be with several parameters in one file.
Hope this helps someone.
Greetings,
Frans
Best Answer
If you have access to the 3D Analyst extension, instead of downloading NetCDF grids, you could download ASCII grids (GEBCO offers both options). You can use the ASCII 3D to Feature Class tool to create a feature layer, and then use the Spline or Krigging tools to create your bathymetric rasters.