From 10f63eed1158a45e144094ec514ab02c11a864df Mon Sep 17 00:00:00 2001
From: Manda Chasteen <chasteen@ucar.edu>
Date: Wed, 10 Aug 2022 15:02:06 -0600
Subject: [PATCH] Fix PV registry descriptions

In the Registry, the pv_vertex, pv_edge, and pv_cell variables are described as
"absolute vorticity/rho_zz", but the density component was previously removed
from the model code. This request updates the descriptions and units of these
variables to be consistent with the absolute vertical vorticity.

In Line 4816 of mpas_atm_time_integration.F (v7.3): "the original definition of
pv_edge had a factor of 1/density. We have removed that factor given that it was
not integral to any conservation property of the system"

Relative vertical vorticity is calculated beginning at Line 5606 (in v7.3) as:

      do iVertex=vertexStart,vertexEnd
         vorticity(1:nVertLevels,iVertex) = 0.0
         do i=1,vertexDegree
            iEdge = edgesOnVertex(i,iVertex)
            s = edgesOnVertex_sign(i,iVertex) * dcEdge(iEdge)
!DIR$ IVDEP
            do k=1,nVertLevels
               vorticity(k,iVertex) = vorticity(k,iVertex) + s * u(k,iEdge)
            end do
         end do
!DIR$ IVDEP
         do k=1,nVertLevels
            vorticity(k,iVertex) = vorticity(k,iVertex) * invAreaTriangle(iVertex)
         end do
      end do

(with 'u' as the uncoupled normal component of horizontal velocity), and
planetary vorticity is added to get absolute vorticity at Line 5754:

            pv_vertex(k,iVertex) = (fVertex(iVertex) + vorticity(k,iVertex))

Thus, pv_vertex is the absolute vertical vorticity at a vertex.
---
 src/core_atmosphere/Registry.xml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/core_atmosphere/Registry.xml b/src/core_atmosphere/Registry.xml
index e4cf270af4..72072c058a 100644
--- a/src/core_atmosphere/Registry.xml
+++ b/src/core_atmosphere/Registry.xml
@@ -1565,8 +1565,8 @@
                 <var name="vorticity" type="real" dimensions="nVertLevels nVertices Time" units="s^{-1}"
                      description="Relative vorticity at vertices"/>
 
-                <var name="pv_edge" type="real" dimensions="nVertLevels nEdges Time" units="s^{-1} kg^{-1} m^3"
-                     description="absolute vorticity/rho_zz averaged to the cell edge from the vertices"/>
+                <var name="pv_edge" type="real" dimensions="nVertLevels nEdges Time" units="s^{-1}"
+                     description="absolute vertical vorticity averaged to the cell edge from the vertices"/>
 
                 <var name="rho_edge" type="real" dimensions="nVertLevels nEdges Time" units="kg m^{-3}"
                      description="rho_zz averaged from cell centers to the cell edge"/>
@@ -1574,11 +1574,11 @@
                 <var name="ke" type="real" dimensions="nVertLevels nCells Time" units="m^2 s^{-2}"
                      description="Kinetic energy at a cell center"/>
 
-                <var name="pv_vertex" type="real" dimensions="nVertLevels nVertices Time" units="s^{-1} kg^{-1} m^3"
-                     description="absolute vorticity/rho_zz at a vertex"/>
+                <var name="pv_vertex" type="real" dimensions="nVertLevels nVertices Time" units="s^{-1}"
+                     description="absolute vertical vorticity at a vertex"/>
 
-                <var name="pv_cell" type="real" dimensions="nVertLevels nCells Time" units="s^{-1} kg^{-1} m^3"
-                     description="absolute vorticity/rho_zz averaged to the cell center from the vertices"/>
+                <var name="pv_cell" type="real" dimensions="nVertLevels nCells Time" units="s^{-1}"
+                     description="absolute vertical vorticity averaged to the cell center from the vertices"/>
 
                 <!-- reconstructed horizontal velocity vectors at cell centers -->
                 <var name="uReconstructX" type="real" dimensions="nVertLevels nCells Time" units="m s^{-1}"