From c874ad708863bb4e4bdb647766bb4e2e308ba0c5 Mon Sep 17 00:00:00 2001 From: Grant Firl Date: Wed, 14 Aug 2024 16:26:40 -0400 Subject: [PATCH] update forcing_method 1 in chap_cases --- scm/doc/TechGuide/chap_cases.rst | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/scm/doc/TechGuide/chap_cases.rst b/scm/doc/TechGuide/chap_cases.rst index 20cf32a99..4faf7ba22 100644 --- a/scm/doc/TechGuide/chap_cases.rst +++ b/scm/doc/TechGuide/chap_cases.rst @@ -351,7 +351,8 @@ Optional arguments: #. ``--save_comp (-sc)``: flag to create UFS reference file for comparison -#. ``--use_nearest (-near)``: flag to indicate using the nearest UFS history file gridpoint +#. ``--use_nearest (-near)``: flag to indicate using the nearest UFS history file gridpoint for calculation + of forcing; only valid for use with -fm=1 or -fm=3 #. ``--forcing_method (-fm)``: method used to calculate forcing (1=total tendencies from UFS dycore, 2=advective terms calculated from UFS history files, 3=total time tendency terms calculated), default=2 @@ -363,6 +364,27 @@ Optional arguments: #. ``--geostrophic (-geos)``: flag to turn on geostrophic wind forcing +Notes Regarding Implemented Forcing Methods + +The ``--forcing_method`` option hides some complexity that should be understood when running this script since +each method has a particular use case and produces potentially very different forcing terms. Forcing method 1 is +designed to be used in concert with the three-dimensional UFS. I.e., the UFS must be run with diagnostic tendencies +activated so that the `nophysics` term is calculated and output for all grid points. This diagnostic term +represents the tendency produced for each state variable by the UFS between calls to the "slow" physics. This +includes the tendency due to advection, but also any tendencies due to other non-physics processes, e.g. "fast" +physics, coupling to external components, data assimilation, etc. Within the SCM, this diagnostic is used as the +forcing term for each state variable. Although one can achieve results as close as possible between a UFS column +and the single column model using this method, it will NOT be bit-for-bit for many reasons. Some of these reasons +include: diagnostic output is not typically instantaneous for every timestep, the UFS' vertical coordinate is +semi-Lagrangian and includes a remapping step as the surface pressure changes for each column, whereas the SCM +uses a Eulerian vertical coordinate without the vertical remapping step, and some interpolation happens in the +UFS_case_gen.py script due to the UFS initial conditions and history files using different grids. This method +can only be used when the UFS has been configured and run with the anticipation of running the SCM using this +forcing method afterward because it requires considerable extra disk space for the additional output. + + + + .. _`ufsforcingensemblegenerator`: UFS_forcing_ensemble_generator.py