Wrap MPAS longitude values to [0,2pi) range

doc/ChangeLog

@@ -1,5 +1,69 @@
 ===============================================================
 
+Tag name:
+Originator(s): gdicker
+Date: Jul 18, 2024
+One-line Summary: Address run failures due to MPAS-A longitudes
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1095
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+ - Wrap MPAS-A longitudes to [0,2pi) range: https://github.com/ESCOMP/CAM/issues/1094
+
+Describe any changes made to build system: N/A
+
+Describe any changes made to the namelist: N/A
+
+List any changes to the defaults for the boundary datasets: N/A
+
+Describe any substantial timing or memory changes: N/A
+
+Code reviewed by:
+
+List all files eliminated: N/A
+
+List all files added and what they do: N/A
+
+List all existing files that have been modified, and describe the changes:
+M       src/dynamics/mpas/dyn_grid.F90
+ - Modifies setup_time_invariant to ensure lonCell values are in [0,2pi) range
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
+
+derecho/intel/aux_cam:
+
+izumi/nag/aux_cam:
+
+izumi/gnu/aux_cam:
+
+CAM tag used for the baseline comparison tests if different than previous
+tag:
+
+Summarize any changes to answers, i.e.,
+- what code configurations:
+- what platforms/compilers:
+- nature of change (roundoff; larger than roundoff but same climate; new
+  climate):
+
+If bitwise differences were observed, how did you show they were no worse
+than roundoff?
+
+If this tag changes climate describe the run(s) done to evaluate the new
+climate in enough detail that it(they) could be reproduced, i.e.,
+- source tag (all code used must be in the repository):
+- platform/compilers:
+- configure commandline:
+- build-namelist command (or complete namelist):
+- MSS location of output:
+
+MSS location of control simulations used to validate new climate:
+
+URL for AMWG diagnostics output used to validate new climate:
+
+===============================================================
+
 Tag name: cam6_3_148
 Originator(s): brianpm, courtneyp, eaton
 Date: Wed 21 Feb 2024

src/dynamics/mpas/dyn_grid.F90

@@ -453,6 +453,8 @@ subroutine setup_time_invariant(fh_ini)
    type(mpas_pool_type),   pointer :: meshPool
    real(r8), pointer     :: rdzw(:)
    real(r8), allocatable :: dzw(:)
+   integer, pointer :: nCells
+   real(r8), dimension(:), pointer :: lonCell
 
    integer :: k, kk
    integer :: ierr
@@ -473,6 +475,7 @@ subroutine setup_time_invariant(fh_ini)
    call mpas_pool_get_dimension(meshPool, 'nEdgesSolve', nEdgesSolve)
    call mpas_pool_get_dimension(meshPool, 'nVerticesSolve', nVerticesSolve)
    call mpas_pool_get_dimension(meshPool, 'nVertLevels', nVertLevelsSolve) ! MPAS always solves over the full column
+   call mpas_pool_get_dimension(meshPool, 'nCells', nCells)
 
    ! check that number of vertical layers matches MPAS grid data
    if (plev /= nVertLevelsSolve) then
@@ -482,6 +485,17 @@ subroutine setup_time_invariant(fh_ini)
                            ') does not match plev ('//int2str(nVertLevelsSolve)//').')
    end if
 
+   ! Ensure longitudes are within the [0,2*pi) range, and only remap values that
+   ! are outside the range. Some non-simple physics in CAM require this
+   ! longitude range, the MPAS-A dycore does not require any specific range for
+   ! lonCell
+   call mpas_pool_get_array(meshPool, 'lonCell', lonCell)
+   do k=1,nCells
+      if (lonCell(k) < 0._r8 .or. lonCell(k) >= (2._r8 * pi)) then
+         lonCell(k) = lonCell(k) - (2._r8 * pi) * floor(lonCell(k) / (2._r8 * pi))
+      end if
+   end do
+
    ! Initialize fields needed for reconstruction of cell-centered winds from edge-normal winds
    ! Note: This same pair of calls happens a second time later in the initialization of
    !       the MPAS-A dycore (in atm_mpas_init_block), but the redundant calls do no harm