As mentioned in the previous sections, surface boundary conditions are contained within array and defined on the MOM grid. If option coupled is enabled, the same set is also contained within array defined on the atmosphere grid. The array only exists if option coupled is enabled. The total number of surface boundary conditions numsbc is partitioned into numosbc for the ocean and numasbc for the atmosphere. Surface boundary conditions are chosen from a list of possibilities maintained within module sbc_info. The module contains two routines: setup_sbc selects a particular surface boundary condition from the list of possible ones and a sequence of ordered calls to setup_sbc builds the desired ordered list of surface boundary conditions. The other routine index_of_sbc returns the index of any surface boundary condition within the ordered list. The ordering of surface boundary conditions is the same in array and array ; the only difference is that one set is on the MOM grid and the other is on the atmosphere grid.