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Merge branch 'concepts/doc-pressure-unit' into 'concepts/main' (!14)
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doc, ice_history: correct units for 'sigP' and improve doc for stress variables (CICE-Consortium#817)

Closes #20
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phil-blain committed Feb 8, 2024
2 parents 2ee4e61 + 372fd62 commit a8764db
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Showing 5 changed files with 21 additions and 9 deletions.
2 changes: 1 addition & 1 deletion cicecore/cicedyn/analysis/ice_history.F90
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Expand Up @@ -1323,7 +1323,7 @@ subroutine init_hist (dt)
"sig2 is instantaneous" // trim(description), c1, c0, &
ns1, f_sig2)

call define_hist_field(n_sigP,"sigP","1",gridstr2d, gridstr, &
call define_hist_field(n_sigP,"sigP","N/m",gridstr2d, gridstr, &
"ice pressure", &
"sigP is instantaneous" // trim(description), c1, c0, &
ns1, f_sigP)
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7 changes: 4 additions & 3 deletions doc/source/cice_index.rst
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Expand Up @@ -620,7 +620,8 @@ either Celsius or Kelvin units). Deprecated parameters are listed at the end.
"shear", "strain rate II component", "1/s"
"shlat", "southern latitude of artificial mask edge", "30\ :math:`^\circ`\ N"
"shortwave", "flag for shortwave parameterization (‘ccsm3’ or ‘dEdd’)", ""
"sig1(2)", "principal stress components (diagnostic)", ""
"sig1(2)", "principal stress components :math:`\sigma_{n,1}`, :math:`\sigma_{n,2}` (diagnostic)", ""
"sigP", "internal ice pressure", "N/m"
"sil", "silicate concentration", "mmol/m\ :math:`^3`"
"sinw", "sine of the turning angle in water", "0."
"Sinz", "ice salinity profile", "ppt"
Expand Down Expand Up @@ -660,8 +661,8 @@ either Celsius or Kelvin units). Deprecated parameters are listed at the end.
"strax(y)", "wind stress components from data", "N/m\ :math:`^2`"
"strength", "ice strength", "N/m"
"stress12", "internal ice stress, :math:`\sigma_{12}`", "N/m"
"stressm", "internal ice stress, :math:`\sigma_{11}-\sigma_{22}`", "N/m"
"stressp", "internal ice stress, :math:`\sigma_{11}+\sigma_{22}`", "N/m"
"stressm", "internal ice stress, :math:`\sigma_{11}-\sigma_{22}` (:math:`\sigma_2` in the doc)", "N/m"
"stressp", "internal ice stress, :math:`\sigma_{11}+\sigma_{22}` (:math:`\sigma_1` in the doc)", "N/m"
"strintx(y)U", "divergence of internal ice stress, x(y)", "N/m\ :math:`^2`"
"strocnx(y)U", "ice–ocean stress in the x(y)-direction (U-cell)", "N/m\ :math:`^2`"
"strocnx(y)T", "ice–ocean stress, x(y)-dir. (T-cell)", "N/m\ :math:`^2`"
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3 changes: 3 additions & 0 deletions doc/source/conf.py
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Expand Up @@ -38,6 +38,9 @@
'sphinxcontrib.bibtex',
]

# Name of the bibliography file for sphinxcontrib.bibtex.
bibtex_bibfiles = ['master_list.bib']

# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']

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16 changes: 12 additions & 4 deletions doc/source/science_guide/sg_dynamics.rst
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Expand Up @@ -449,8 +449,8 @@ Rheology
********

For convenience we formulate the stress tensor :math:`\bf \sigma` in
terms of :math:`\sigma_1=\sigma_{11}+\sigma_{22}`,
:math:`\sigma_2=\sigma_{11}-\sigma_{22}`, and introduce the
terms of :math:`\sigma_1=\sigma_{11}+\sigma_{22}` (``stressp``),
:math:`\sigma_2=\sigma_{11}-\sigma_{22}` (``stressm``), and introduce the
divergence, :math:`D_D`, and the horizontal tension and shearing
strain rates, :math:`D_T` and :math:`D_S` respectively:

Expand All @@ -468,8 +468,16 @@ where
.. math::
\dot{\epsilon}_{ij} = {1\over 2}\left({{\partial u_i}\over{\partial x_j}} + {{\partial u_j}\over{\partial x_i}}\right)
CICE can output the internal ice pressure which is an important field to support navigation in ice-infested water.
The internal ice pressure (``sigP``) is the average of the normal stresses multiplied by :math:`-1` and
Note that :math:`\sigma_1` and :math:`\sigma_2` are not to be confused with the normalized principal stresses,
:math:`\sigma_{n,1}` and :math:`\sigma_{n,2}` (``sig1`` and ``sig2``), which are defined as:

.. math::
\sigma_{n,1}, \sigma_{n,2} = \frac{1}{P} \left( \frac{\sigma_1}{2} \pm \sqrt{\left(\frac{\sigma_2}{2}\right)^2 + \sigma_{12}^2} \right)
where :math:`P` is the ice strength.

In addition to the normalized principal stresses, CICE can output the internal ice pressure which is an important field to support navigation in ice-infested water.
The internal ice pressure (``sigP``) is the average of the normal stresses (:math:`\sigma_{11}`, :math:`\sigma_{22}`) multiplied by :math:`-1` and
is therefore simply equal to :math:`-\sigma_1/2`.

.. _stress-vp:
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2 changes: 1 addition & 1 deletion doc/source/user_guide/ug_implementation.rst
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Expand Up @@ -1207,7 +1207,7 @@ directory in **iceh\_ic.[timeID].nc(da)**. Several history variables are
hard-coded for instantaneous output regardless of the ``hist_avg`` averaging flag, at
the frequency given by their namelist flag.

The normalized principal components of internal ice stress are computed
The normalized principal components of internal ice stress (``sig1``, ``sig2``) are computed
in *principal\_stress* and written to the history file. This calculation
is not necessary for the simulation; principal stresses are merely
computed for diagnostic purposes and included here for the user’s
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