From 034b7a21477af1d4bf14aee4dbf420990c485653 Mon Sep 17 00:00:00 2001
From: Peter Hjort Lauritzen <pel@ucar.edu>
Date: Fri, 20 Feb 2026 08:18:31 -0700
Subject: [PATCH] ne16pg3 configuration LT and MT out-of-the-box

---
 bld/namelist_files/namelist_defaults_cam.xml | 13 ++++++++-----
 doc/ChangeLog                                | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/bld/namelist_files/namelist_defaults_cam.xml b/bld/namelist_files/namelist_defaults_cam.xml
index 343693e6d8..75acdede44 100644
--- a/bld/namelist_files/namelist_defaults_cam.xml
+++ b/bld/namelist_files/namelist_defaults_cam.xml
@@ -184,6 +184,8 @@
 <ncdata hgrid="ne16np4"  nlev="126" waccmx="1" aquaplanet="1"                  >atm/waccm/ic/waccmx_aqua_ne16np4_126L_c191108.nc</ncdata>
 <ncdata hgrid="ne16np4"  nlev="126" waccmx="1" aquaplanet="1" ionosphere="none">atm/waccm/ic/waccmx4_neutral_aquap_ne16np4_126lev_c200827.nc</ncdata>
 <ncdata hgrid="ne16np4"  nlev="130" waccmx="1"     >atm/waccm/ic/FX2000_ne16pg3_spinup01.cam.i.0002-01-01_c251215.nc</ncdata>
+<ncdata hgrid="ne16np4"  nlev="58"                 >atm/cam/inic/se/FHISTC_LTso_ne16pg3_ne16pg3_mg17.i.c260220.nc</ncdata>
+<ncdata hgrid="ne16np4"  nlev="93"                 >atm/cam/inic/se/FHISTC_MTso_ne16pg3_ne16pg3_mg17.i.c260220.nc</ncdata>
 
 <ncdata hgrid="ne30np4"  nlev="26"                 >atm/cam/inic/se/ape_topo_cam4_ne30np4_L26_c171020.nc</ncdata>
 <ncdata hgrid="ne30np4"  nlev="26"  aquaplanet="1" >atm/cam/inic/se/ape_cam4_ne30np4_L26_c170417.nc</ncdata>
@@ -3207,7 +3209,8 @@
 <se_hypervis_subcycle                                                           > 3 </se_hypervis_subcycle>
 <se_hypervis_subcycle  waccm_phys="1"  model_top="mt"                           > 3 </se_hypervis_subcycle>
 <se_hypervis_subcycle  waccm_phys="1"                                           > 2 </se_hypervis_subcycle>
-<se_hypervis_subcycle  hgrid="ne16np4"                                          > 4 </se_hypervis_subcycle>
+<se_hypervis_subcycle  hgrid="ne16np4"                                          > 3 </se_hypervis_subcycle>
+<se_hypervis_subcycle  hgrid="ne16np4"  model_top="lt"                          > 1 </se_hypervis_subcycle>
 <se_hypervis_subcycle  hgrid="ne16np4"  waccm_phys="1"            model_top="none"> 10 </se_hypervis_subcycle>
 <se_hypervis_subcycle  hgrid="ne16np4"  waccm_phys="1" waccmx="0" model_top="none"> 9 </se_hypervis_subcycle>
 <se_hypervis_subcycle  hgrid="ne30np4"  waccm_phys="1" waccmx="0" model_top="none"> 8 </se_hypervis_subcycle>
@@ -3249,16 +3252,16 @@
 <se_max_hypervis_courant se_refined_mesh="1" hypervis_type="scalar" > 1.9 </se_max_hypervis_courant>
 
 <se_nu>-1</se_nu>
-<se_nu hgrid="ne16np4" waccm_phys="1" waccmx="0">6.e15</se_nu>
-<se_nu hgrid="ne16np4" model_top="ht"           >6.e15</se_nu>
+<se_nu hgrid="ne16np4">6.e15</se_nu>
 <se_nu waccmx="1">5.e15</se_nu>
 
 <se_nu_div> -1 </se_nu_div>
-<se_nu_div hgrid="ne16np4" waccm_phys="1" waccmx="0">6.e15</se_nu_div>
-<se_nu_div hgrid="ne16np4" model_top="ht"           >6.e15</se_nu_div>
+<se_nu_div hgrid="ne16np4">6.e15</se_nu_div>
 <se_nu_div waccmx="1"> 10.e15 </se_nu_div>
 
 <se_nu_p>-1 </se_nu_p>
+<se_nu_p hgrid="ne16np4">6.e15</se_nu_p>
+<se_nu_p waccmx="1">5.e15</se_nu_p>
 
 <se_nu_top                                   > 1.25e5 </se_nu_top>
 <se_nu_top waccmx="1"                        > 1.0e6 </se_nu_top>
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 0f657a4d25..5721933d64 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,23 @@
+Tag name: cam6_4_???
+Originator(s): pel
+Date: 20 Feb 2026
+One-line Summary: MT & LT ne16pg3 namelist defaults for dycore and inic
+Github PR URL: https://github.com/ESCOMP/CAM/pull/1470
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+
+ Issue #1487
+ - 2 degree (ne16pg3) out-of-the-box LT and MT functionality
+
+Describe any changes made to build system: N/A
+
+Describe any changes made to the namelist:
+
+	Change ncdata and dycore parameters
+	Fix se_nu_p bug for ne16pg3 in namelist
+
+Answer changes expected for all ne16 regression tests.
+
 ===============================================================
 
 Tag name: cam6_4_153