From 3085dfc349098436b4b64b11cbcf0fe2b631011f Mon Sep 17 00:00:00 2001
From: Neil Barton <103681022+NeilBarton-NOAA@users.noreply.github.com>
Date: Mon, 12 Dec 2022 15:58:34 -0500
Subject: [PATCH] ATM 3DVAR with and without IAU (#1113)

This is the first of a series of PRs to addresses issue https://github.com/NOAA-EMC/global-workflow/issues/947 (cycling the S2SW app with 3DVAR). Using the ATM app, 3DVAR with IAU did not cycle out-of-the-box. This PR includes changes to successfully cycle ATM with 3DVAR with and without IAU.

Refs: #947
---
 parm/config/config.base.emc.dyn | 19 ++++++++++++++-----
 ush/parsing_namelists_FV3.sh    |  1 +
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/parm/config/config.base.emc.dyn b/parm/config/config.base.emc.dyn
index 62d7ff59ef..b0ef126500 100755
--- a/parm/config/config.base.emc.dyn
+++ b/parm/config/config.base.emc.dyn
@@ -297,11 +297,6 @@ export IAU_OFFSET=6
 export DOIAU_ENKF=${DOIAU:-"YES"}   # Enable 4DIAU for EnKF ensemble
 export IAUFHRS_ENKF="3,6,9"
 export IAU_DELTHRS_ENKF=6
-# Check if cycle is cold starting, DOIAU off, or free-forecast mode
-if [[ "$MODE" = "cycled" && "$SDATE" = "$CDATE" && $EXP_WARM_START = ".false." ]] || [[ "$DOIAU" = "NO" ]] || [[ "$MODE" = "forecast-only" && $EXP_WARM_START = ".false." ]] ; then
-  export IAU_OFFSET=0
-  export IAU_FHROT=0
-fi
 
 # Use Jacobians in eupd and thereby remove need to run eomg
 export lobsdiag_forenkf=".true."
@@ -350,6 +345,20 @@ if [ $DOHYBVAR = "YES" ]; then
     fi
 fi
 
+# if 3DVAR and IAU 
+if [[ ${DOHYBVAR} == "NO" && ${DOIAU} == "YES"  ]]; then
+    export IAUFHRS="6"
+    export IAU_FHROT="3"
+    export IAU_FILTER_INCREMENTS=".true."
+    export IAUFHRS_ENKF="6"
+fi
+
+# Check if cycle is cold starting, DOIAU off, or free-forecast mode
+if [[ "$MODE" = "cycled" && "$SDATE" = "$CDATE" && $EXP_WARM_START = ".false." ]] || [[ "$DOIAU" = "NO" ]] || [[ "$MODE" = "forecast-only" && $EXP_WARM_START = ".false." ]] ; then
+  export IAU_OFFSET=0
+  export IAU_FHROT=0
+fi
+
 # turned on nsst in anal and/or fcst steps, and turn off rtgsst
 export DONST="YES"
 if [ $DONST = "YES" ]; then export FNTSFA="        "; fi
diff --git a/ush/parsing_namelists_FV3.sh b/ush/parsing_namelists_FV3.sh
index 41fdb04f1b..c9dc9cd1bc 100755
--- a/ush/parsing_namelists_FV3.sh
+++ b/ush/parsing_namelists_FV3.sh
@@ -396,6 +396,7 @@ if [ $DOIAU = "YES" ]; then
   iau_delthrs  = ${IAU_DELTHRS}
   iau_inc_files= ${IAU_INC_FILES}
   iau_drymassfixer = .false.
+  iau_filter_increments = ${IAU_FILTER_INCREMENTS:-".false."}
 EOF
 fi