Update Icepack, update documentation, minor bibtex and gptl updates (CICE-Consortium#1015)

Update Icepack to #51695d08d92c20 April 4, 2025. Includes
- Update derecho gnu and code coverage capability
- Update Copyright
- Fix bug with calc_Tsfc=F, set_sfcflux arguments reversed in icepack_therm_vertical.F90
- Fix negative silicate bgc bug
- Update of Mosaic forcing option

Comment out gptl pid check in ice_memusage_gptl.c. The check is not needed, and the arbitrary value of 999999 occasionally fails because on many systems the upper limit is higher. This has not come up in CICE, but it has been noted in other models' use of gptl, https://cerfacs.fr/site-oasis/forum/oa_main.php?c=177.

Update documentation regarding history variable units and cona and conb history variable conversion terms.

Update sphinx-bibtex version in doc requirements. Readthedocs now works with the latest version.

Author: apcraig

cicecore/cicedyn/infrastructure/ice_memusage_gptl.c

@@ -179,10 +179,12 @@ int ice_memusage_gptl (int *size, int *rss, int *share, int *text, int *datastac
   */
 
   pid = (int) getpid ();
-  if (pid > 999999) {
-    fprintf (stderr, "get_memusage: pid %d is too large\n", pid);
-    return -1;
-  }
+  /* tcraig, not needed and can be problematic
+  **  if (pid > 999999) {
+  **    fprintf (stderr, "get_memusage: pid %d is too large\n", pid);
+  **    return -1;
+  **  }
+  */
 
   sprintf (file, "%s%d%s", head, pid, tail);
   if ((fd = fopen (file, "r")) < 0) {

doc/requirements.txt

@@ -1,5 +1,5 @@
 #
 #
-sphinxcontrib-bibtex<2.0.0
+sphinxcontrib-bibtex
 #
 #

doc/source/cice_index.rst

@@ -7,7 +7,9 @@ Index of primary variables and parameters
 
 This index defines many (but not all) of the symbols used frequently in the CICE model
 code.  All quantities in the code are expressed in MKS units (temperatures may take
-either Celsius or Kelvin units).  Deprecated parameters are listed at the end.
+either Celsius or Kelvin units).  Deprecated parameters are listed at the end.  Units are
+as defined inside the model.  Units on history files may be different and are documented
+in history file metadata.
 
 Namelist variables are partly included here, but they are fully documented in 
 section :ref:`tabnamelist`. 
@@ -110,6 +112,8 @@ section :ref:`tabnamelist`.
    "cm_to_m", "cm to meters conversion", "0.01"
    "coldice", "value for constant albedo parameterization", "0.70"
    "coldsnow", "value for constant albedo parameterization", "0.81"
+   "cona", "history units conversion variable, multiplication term", "1.0"
+   "conb", "history units conversion variable, additive term", "0.0"
    "conduct", "conductivity parameterization", ""
    "congel", "basal ice growth", "m"
    "conserv_check", "if true, check conservation", ""

doc/source/user_guide/ug_implementation.rst

@@ -1366,6 +1366,13 @@ another that is multiplied by :math:`a_i`, representing an average over
 the grid cell area. Our naming convention attaches the suffix “_ai" to
 the grid-cell-mean variable names.
 
+The units of the variables on the history file may not match internal model units.  For
+netCDF files, variable units are defined in metadata.  History variable conversion from
+internal model units is carried out by the ``cona`` and ``conb`` arguments defined in 
+subroutine **define_hist_field**.  ``cona`` and ``conb`` are multiplicative and additive 
+terms respectively that are hardwired into the source code to convert model units to
+history units.
+
 Beginning with CICE v6, history variables requested by the Sea Ice Model Intercomparison 
 Project (SIMIP) :cite:`Notz16` have been added as possible history output variables (e.g. 
 ``f_sithick``, ``f_sidmassgrowthbottom``, etc.). The lists of