Make diagnostic default missing value same as other parts of the model.

mom-ocean#334

src/framework/MOM_diag_mediator.F90

@@ -176,7 +176,7 @@ module MOM_diag_mediator
   integer :: next_free_diag_id
 
   !default missing value to be sent to ALL diagnostics registrations
-  real :: missing_value = 1.0e+20
+  real :: missing_value = -1.0e+34
 
   !> Control structure for each possible coordinate
   type(diag_remap_ctrl), dimension(REGRIDDING_NUM_TYPES) :: diag_remap_cs
@@ -696,7 +696,6 @@ subroutine post_data_3d(diag_field_id, field, diag_cs, is_static, mask)
   type(diag_type), pointer :: diag => null()
   integer :: nz, i, j, k
   real, dimension(:,:,:), allocatable :: remapped_field
-  real :: missing_value
   logical :: staggered_in_x, staggered_in_y
 
   if (id_clock_diag_mediator>0) call cpu_clock_begin(id_clock_diag_mediator)