Updated change log

doc/ChangeLog

@@ -1,4 +1,67 @@
 ===============================================================
+Tag name: ctsm5.1.dev091
+Originator(s): rgknox (Ryan Knox,[email protected])
+Date: Fri Apr 22 14:11:50 EDT 2022
+One-line Summary: clm decomp method is now passed to fates to enabled mimics coupling
+
+Purpose and description of changes
+----------------------------------
+
+This is a small changeset, which only adds the passing of a text based flag to FATES, that defines which soil decomposition method is active. This setting is needed by FATES, so that it can pass specific boundary conditions to CLM (and potentially ELM in the future). This change was necessitated because MIMICS requires a Nitrogen to lignin-carbon ratio in the litter flux, yet other decomposition schemes do not. Moreover, the generation of this boundary condition is not trivial, so it is worth it to avoid its computation if mimics is not on.  This change should have NO impact on any tests.
+
+
+Significant changes to scientifically-supported configurations
+--------------------------------------------------------------
+
+Does this tag change answers significantly for any of the following physics configurations?
+(Details of any changes will be given in the "Answer changes" section below.)
+
+    [Put an [X] in the box for any configuration with significant answer changes.]
+
+[ ] clm5_1
+
+[ ] clm5_0
+
+[ ] ctsm5_0-nwp
+
+[ ] clm4_5
+
+
+Bugs fixed or introduced
+------------------------
+
+None
+
+
+Notes of particular relevance for users
+---------------------------------------
+
+None, this does not currently have an affect on any functionality, it simply lays groundwork for FATES-MIMICS coupling.  There are no changes to memory usage or run-time.
+
+
+Notes of particular relevance for developers:
+---------------------------------------------
+
+No changes in testing. These changes will enable completion (or progress) on CTSM #1643
+
+Testing summary:
+----------------
+
+  regular tests (aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing):
+
+    cheyenne ---- aux_clm, PASS, b4b against ctsm5.1.dev090
+    izumi ------- aux_clm, PASS, b4b against ctsm5.1.dev090
+
+
+Answer changes
+--------------
+None
+
+Pull Requests that document the changes (include PR ids): #1700
+(https://github.com/ESCOMP/ctsm/pull/1700)
+
+===============================================================
+===============================================================
 Tag name: ctsm5.1.dev090
 Originator(s): samrabin (Sam Rabin)
 Date: Thu Mar 31 15:03:34 MDT 2022

doc/ChangeSum

@@ -1,5 +1,6 @@
 Tag                   Who      Date  Summary
 ============================================================================================================================
+    ctsm5.1.dev091   rgknox 04/22/2022 clm decomp method is now passed to fates to enabled mimics coupling
     ctsm5.1.dev090 samrabin 03/31/2022 Fix misleading name of "gddplant"
     ctsm5.1.dev089    sacks 03/31/2022 For CLM45 apply peaklai to aleaf in grainfill
     ctsm5.1.dev088 samrabin 03/28/2022 Add outputs for annual crop sowing and harvest dates