CONSERV performs a global modification of the coupling field.
This analysis requires the source and target grid mesh areas to be
defined in the areas.nc file or transferred to the coupler with oasis_write_area (see section
). For a correct CONSERV operation,
overlapping grid cells on the source grid or on the target grid
must be masked. In the namcouple, CONSERV requires
one input line with one argument and one optional argument:
# CONSERV operation
- $CMETH is the method desired with the following choices
- with $CMETH = GLOBAL, the field is integrated on both
source and target grids, without considering values of masked
points, and the residual (target - source) is uniformly
distributed on the target grid; this option ensures global
conservation of the field;
- with $CMETH = GLBPOS, the same operation is performed
except that the residual is distributed proportionally to the
value of the original field; this option ensures the global
conservation of the field and does not change the sign of the
- with $CMETH = BASBAL, the operation is analogous to
GLOBAL except that the non masked surface of the source
and the target grids are taken into account in the calculation
of the residual; this option does not ensure global conservation
of the field but ensures that the energy received is
proportional to the non masked surface of the target grid;
- with $CMETH = BASPOS, the non masked surface of the
source and the target grids are taken into account and the
residual is distributed proportionally to the value of the
original field; therefore, this option does not ensure global
conservation of the field but ensures that the energy received
is proportional to the non masked surface of the target grid and
it does not change the sign of the field.
- $CONSOPT is an optional argument specifying the
algorithm. $CONSOPT can be bfb, gather, lsum16, lsum8,
ddpdd, reprosum or opt. Details on the perfromance of these different options can also be found in () and references there in.
- The bfb option is the default for CONSOPT and uses the reprosum option (see below).
- The gather option computes global sums by gathering a decomposed array
onto the root process before doing an index ordered sum. This is guaranteed to produce
identical results for different numbers of processors and decompositions but is expensive
both with respect to performance and memory use. This is equivalent to the bfb option in previous OASIS versions.
- The lsum16 option computes a local sum at quadruple precision before doing
an MPI reduction on the local sums at quadruple precision. This is likely to be
bit-for-bit for different numbers of processors and decompostions but that's not guaranteed.
This is just like lsum8 but at quadruple precision and a little slower.
- The lsum8 option computes a local sum at double precision before doing
an MPI reduction on the local sums at double precision. This is NOT likely to be
bit-for-bit for different numbers of processors and decompostions. This is just like lsum16
but at double precision and faster.
- The ddpdd option is a parallel double-double algorithm using a single scalar
reduction. It should behave between lsum8 and lsum16 with respect to performance and
reproducibility. See ().
- The reprosum option is a fixed point method based on ordered double integer sums
that requires two scalar reductions per global sum. The cost of reprosum will be higher than
some of the other methods but it will be bit-for-bit for different processor counts or
different decompostions except in extremely rare cases and the cost is significantly less
than the gather option. See ().
- The opt option carries out the global sum using the fastest algorithm generally available. Currently,
this is set to lsum8.
- SUBGRID: UNUSED
BLASNEW performs a scalar multiply or scalar add to any
destination field. This is the equivalent of BLASOLD on the
destination side. The prior feature that supported linear
combinations of the current coupling field with any other fields
after the interpolation has been deprecated.
This analysis requires the same input line(s) as BLASOLD.
- MASKP: UNUSED
- REVERSE: UNUSED
CHECKOUT calculates the global minimum, the maximum and the
sum of the target field values (not weighted by the grid cell area)
and prints them to the OASIS3-MCT debug file (for the master process
of the target component model only). These informations are found in
the debug file of the master process of the target model under the
attribute “diags”. This operation does not
transform the field. CHECKOUT operation can significantly slow down the simulation.
It should not be used in production mode.
The generic input line is as for CHECKIN (see above).
- GLORED: UNUSED