I am sorry, but I have some difficulties in understanding your
I don't understand why the aggregation type is "joinExisting" and not
"joinNew", if you define an aggregation variable "time". Is there
already a dimension "time" in your netCDF data files or not?
Could you please attach a ncdump -h of one netCDF file?
If there's no dimension "time" in your netCDF file and you want to add
it, then I miss the units declaration inside the variable tag, something
<attribute name="units" value="seconds since 2000-01-01"/>