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--op_typ’
The ‘-y op_typ’ switch allows specification of many different
types of operations
Set op_typ to the abbreviated key for the corresponding operation:
NCO assumes coordinate variables represent grid axes, e.g.,
longitude.
The only rank-reduction which makes sense for coordinate variables
is averaging.
Hence NCO implements the operation type requested with
‘-y’ on all non-coordinate variables, but not on coorniate
variables.
When an operation requires a coordinate variable to be reduced in
rank, i.e., from one dimension to a scalar or from one dimension to
a degenerate (single value) array, then NCO
always averages the coordinate variable regardless of the
arithmetic operation type performed on the non-coordinate variables.
avgsqravgavgsqrmaxminrmsrmssdnsqrtttl
The mathematical definition of each arithmetic operation is given below. See