From 15a480e9dd2c37a79852fd6238fc615cf2726287 Mon Sep 17 00:00:00 2001
From: Bill Sacks <sacks@ucar.edu>
Date: Tue, 15 Oct 2024 21:25:47 -0600
Subject: [PATCH 1/2] Use xgrid for aoflux calculation unless atm & ocn are on
 the same grid

Resolves ESCOMP/CMEPS#502
---
 cime_config/namelist_definition_drv.xml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/cime_config/namelist_definition_drv.xml b/cime_config/namelist_definition_drv.xml
index 375b4e7f..be078a46 100644
--- a/cime_config/namelist_definition_drv.xml
+++ b/cime_config/namelist_definition_drv.xml
@@ -925,7 +925,10 @@
       default: ogrid
     </desc>
     <values>
-      <value>ogrid</value>
+      <value>xgrid</value>
+      <!-- xgrid introduces unnecessary cost and complexity if atm & ocn are on the same
+      grid, so fall back to ogrid in that case -->
+      <value samegrid_atm_ocn='true'>ogrid</value>
     </values>
   </entry>
   <entry id="ocn_surface_flux_scheme">

From e649244fba5968d5d376288eaea004d595e7d0f7 Mon Sep 17 00:00:00 2001
From: Bill Sacks <sacks@ucar.edu>
Date: Tue, 15 Oct 2024 21:46:51 -0600
Subject: [PATCH 2/2] Add a test with aoflux_grid = ogrid

---
 cime_config/testdefs/testlist_drv.xml                  | 10 ++++++++++
 .../testmods_dirs/drv/aoflux_ogrid/user_nl_cpl         |  1 +
 2 files changed, 11 insertions(+)
 create mode 100644 cime_config/testdefs/testmods_dirs/drv/aoflux_ogrid/user_nl_cpl

diff --git a/cime_config/testdefs/testlist_drv.xml b/cime_config/testdefs/testlist_drv.xml
index e17b2ffc..948bd267 100644
--- a/cime_config/testdefs/testlist_drv.xml
+++ b/cime_config/testdefs/testlist_drv.xml
@@ -65,6 +65,16 @@
     </options>
   </test>
 
+  <test compset="X" grid="f19_g17" name="ERS_D_Ln9" testmods="drv/aoflux_ogrid">
+    <machines>
+      <machine name="derecho" compiler="intel" category="aux_cmeps"/>
+    </machines>
+    <options>
+      <option name="wallclock"> 00:40:00 </option>
+      <option name="comment">The default aoflux_grid is now xgrid; include a debug test with different atm/ocn grids with aoflux_grid=ogrid to make sure that option continues to work.</option>
+    </options>
+  </test>
+
   <!-- ======================================= -->
   <!-- B compsets -->
   <!-- ======================================= -->
diff --git a/cime_config/testdefs/testmods_dirs/drv/aoflux_ogrid/user_nl_cpl b/cime_config/testdefs/testmods_dirs/drv/aoflux_ogrid/user_nl_cpl
new file mode 100644
index 00000000..91228d3f
--- /dev/null
+++ b/cime_config/testdefs/testmods_dirs/drv/aoflux_ogrid/user_nl_cpl
@@ -0,0 +1 @@
+aoflux_grid = "ogrid"