From aac3760ba256cf655b5f727ca9919f218c47c3ac Mon Sep 17 00:00:00 2001
From: Bill Sacks <sacks@ucar.edu>
Date: Sun, 25 Jan 2026 22:34:58 -0700
Subject: [PATCH 1/3] For histaux_atm2med: put Sa_co2prog and Sa_co2diag on a
 single file each

These two CO2 fields were both being output to both file4 (3-hourly) and
file5 (daily). Based on comments from Keith Lindsay, I'm keeping
prognostic CO2 just on the 3-hourly file and diagnostic CO2 just on the
daily file:

"The suffix prog in co2prog indicates that it represents CO2 that has
been prognostically computed. In CAM, it comes from a tracer/constituent
that is advected and has surface fluxes from the surface BGC components.
It typically has high frequency temporal variability, e.g., a diurnal
cycle over land. That is why it is in a 3-hourly stream for datm, you
want to represent this variability.

In contrast, co2diag is a diagnostic (not prognostic) quantity that is
either a constant or a smoothly varying function of time, such as
1%/year increase or monthly or annual timeseries read from a file. So
daily resolution is sufficient to represent it."
---
 cime_config/namelist_definition_drv.xml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cime_config/namelist_definition_drv.xml b/cime_config/namelist_definition_drv.xml
index abd806f6..0e8d2e09 100644
--- a/cime_config/namelist_definition_drv.xml
+++ b/cime_config/namelist_definition_drv.xml
@@ -1478,7 +1478,7 @@
       Auxiliary mediator a2x dynamic, radiation, and precipitation fields history output every 3 hours
     </desc>
     <values>
-      <value>Sa_z:Sa_topo:Sa_u:Sa_v:Sa_tbot:Sa_ptem:Sa_shum:Sa_dens:Sa_pbot:Sa_pslv:Faxa_lwdn:Faxa_rainc:Faxa_rainl:Faxa_snowc:Faxa_snowl:Faxa_swndr:Faxa_swvdr:Faxa_swndf:Faxa_swvdf:Sa_co2diag:Sa_co2prog</value>
+      <value>Sa_z:Sa_topo:Sa_u:Sa_v:Sa_tbot:Sa_ptem:Sa_shum:Sa_dens:Sa_pbot:Sa_pslv:Faxa_lwdn:Faxa_rainc:Faxa_rainl:Faxa_snowc:Faxa_snowl:Faxa_swndr:Faxa_swvdr:Faxa_swndf:Faxa_swvdf:Sa_co2prog</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file4_history_option">
@@ -1543,7 +1543,7 @@
     <group>MED_attributes</group>
     <desc>Auxiliary mediator a2x aerosol and ghg history output daily or endofrun</desc>
     <values>
-      <value>Faxa_bcph:Faxa_ocph:Faxa_dstwet:Faxa_dstdry:Sa_co2prog:Sa_co2diag</value>
+      <value>Faxa_bcph:Faxa_ocph:Faxa_dstwet:Faxa_dstdry:Sa_co2diag</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file5_history_option">

From 727bfab2b04f81356dd1154bc7fb96dd410534dc Mon Sep 17 00:00:00 2001
From: Bill Sacks <sacks@ucar.edu>
Date: Sun, 25 Jan 2026 22:39:19 -0700
Subject: [PATCH 2/3] Add Faxa_ndep to histaux_atm2med file 5 (daily)

Daily sounds more than sufficient temporal resolution based on
discussion in https://github.com/escomp/ctsm/issues/1844
---
 cime_config/namelist_definition_drv.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cime_config/namelist_definition_drv.xml b/cime_config/namelist_definition_drv.xml
index 0e8d2e09..f74504b0 100644
--- a/cime_config/namelist_definition_drv.xml
+++ b/cime_config/namelist_definition_drv.xml
@@ -1543,7 +1543,7 @@
     <group>MED_attributes</group>
     <desc>Auxiliary mediator a2x aerosol and ghg history output daily or endofrun</desc>
     <values>
-      <value>Faxa_bcph:Faxa_ocph:Faxa_dstwet:Faxa_dstdry:Sa_co2diag</value>
+      <value>Faxa_bcph:Faxa_ocph:Faxa_dstwet:Faxa_dstdry:Faxa_ndep:Sa_co2diag</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file5_history_option">

From e2b3924ecae8f78cd2d8066b626b1d59b084f360 Mon Sep 17 00:00:00 2001
From: Bill Sacks <sacks@ucar.edu>
Date: Sun, 25 Jan 2026 22:46:28 -0700
Subject: [PATCH 3/3] Change atm2med file5 to be daily rather than 3-hourly

My sense from the description and file name is that this file is
intended to be daily but was accidentally set to 3-hourly. It was
changed from daily to 3-hourly in
https://github.com/ESCOMP/CMEPS/pull/378 and I think that may have been
a mistake, but I'll confirm that. (That PR fixed the description of
file5 to say that it is daily, but at the same time changed the output
frequency to 3-hourly instead of daily.)
---
 cime_config/namelist_definition_drv.xml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/cime_config/namelist_definition_drv.xml b/cime_config/namelist_definition_drv.xml
index f74504b0..429d42c0 100644
--- a/cime_config/namelist_definition_drv.xml
+++ b/cime_config/namelist_definition_drv.xml
@@ -1552,7 +1552,7 @@
     <group>MED_attributes</group>
     <desc>history option type</desc>
     <values>
-      <value>nhours</value>
+      <value>ndays</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file5_history_n">
@@ -1561,7 +1561,7 @@
     <group>MED_attributes</group>
     <desc>history option span</desc>
     <values>
-      <value>3</value>
+      <value>1</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file5_doavg">
@@ -1579,7 +1579,7 @@
     <group>MED_attributes</group>
     <desc>Number of time samples per file.</desc>
     <values>
-      <value>2</value>
+      <value>1</value>
     </values>
   </entry>
   <entry id="histaux_atm2med_file5_auxname">