Merge pull request NOAA-EMC#83 from NOAA-GFDL/master

rebase dev/emc with master updates

.github/pull_request_template.md

@@ -0,0 +1,23 @@
+**Description**
+
+Include a summary of the change and which issue is fixed. Please also include
+relevant motivation and context. List any dependencies that are required for
+this change.
+
+Fixes # (issue)
+
+**How Has This Been Tested?**
+
+Please describe the tests that you ran to verify your changes. Please also note
+any relevant details for your test configuration (e.g. compiler, OS).  Include
+enough information so someone can reproduce your tests.
+
+**Checklist:**
+
+Please check all whether they apply or not
+- [ ] My code follows the style guidelines of this project
+- [ ] I have performed a self-review of my own code
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] I have made corresponding changes to the documentation
+- [ ] My changes generate no new warnings
+- [ ] Any dependent changes have been merged and published in downstream modules

tools/coarse_graining.F90

@@ -112,6 +112,12 @@ subroutine compute_nx_coarse(npx, coarsening_factor, nx_coarse)
     integer :: nx
 
     nx = npx - 1
+
+    if (coarsening_factor < 1) then
+       write(error_message, *) 'Invalid coarsening_factor chosen'
+       call mpp_error(FATAL, error_message)
+    endif
+
     if (mod(nx, coarsening_factor) > 0) then
        write(error_message, *) 'coarse_graining_init: coarsening_factor does not evenly divide the native resolution.'
        call mpp_error(FATAL, error_message)