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(*)Parenthesize Zanna_Bolton for FMAs
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  Added parentheses to 2 expressions in the Zanna_Bolton code and rearranged
another line so that the u- and v-discretizations introduce terms in the same
order so that the Zanna_Bolton code will exhibit rotationally consistent
solutions when fused-multiply-adds are enabled.  All answers are bitwise
identical in cases without FMAs, but answers could change with FMAs enabled in
cases that use the Zanna-Bolton parameterization.
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@Hallberg-NOAA
Hallberg-NOAA committed Jul 29, 2024
1 parent 49419f7 commit 03dc6f9
Showing 1 changed file with 16 additions and 20 deletions.
36 changes: 16 additions & 20 deletions src/parameterizations/lateral/MOM_Zanna_Bolton.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -484,21 +484,21 @@ subroutine compute_c_diss(G, GV, CS)
if (CS%Klower_shear == 0) then
do j=js-1,je+1 ; do i=is-1,ie+1
shear = sqrt(CS%sh_xx(i,j,k)**2 + 0.25 * ( &
(CS%sh_xy(I-1,J-1,k)**2 + CS%sh_xy(I,J ,k)**2) &
+ (CS%sh_xy(I-1,J ,k)**2 + CS%sh_xy(I,J-1,k)**2) &
))
((CS%sh_xy(I-1,J-1,k)**2) + (CS%sh_xy(I,J ,k)**2)) &
+ ((CS%sh_xy(I-1,J ,k)**2) + (CS%sh_xy(I,J-1,k)**2)) &
))
CS%c_diss(i,j,k) = 1. / (1. + shear * CS%ICoriolis_h(i,j))
enddo; enddo

! sqrt(sh_xx**2 + sh_xy**2 + vort_xy**2)
elseif (CS%Klower_shear == 1) then
do j=js-1,je+1 ; do i=is-1,ie+1
shear = sqrt(CS%sh_xx(i,j,k)**2 + 0.25 * ( &
((CS%sh_xy(I-1,J-1,k)**2 + CS%vort_xy(I-1,J-1,k)**2) &
+ (CS%sh_xy(I,J,k)**2 + CS%vort_xy(I,J,k)**2)) &
+ ((CS%sh_xy(I-1,J,k)**2 + CS%vort_xy(I-1,J,k)**2) &
+ (CS%sh_xy(I,J-1,k)**2 + CS%vort_xy(I,J-1,k)**2)) &
))
((CS%sh_xy(I-1,J-1,k)**2 + CS%vort_xy(I-1,J-1,k)**2) &
+ (CS%sh_xy(I,J,k)**2 + CS%vort_xy(I,J,k)**2)) &
+ ((CS%sh_xy(I-1,J,k)**2 + CS%vort_xy(I-1,J,k)**2) &
+ (CS%sh_xy(I,J-1,k)**2 + CS%vort_xy(I,J-1,k)**2)) &
))
CS%c_diss(i,j,k) = 1. / (1. + shear * CS%ICoriolis_h(i,j))
enddo; enddo
endif
Expand Down Expand Up @@ -583,10 +583,10 @@ subroutine compute_stress(G, GV, CS)
if (vort_sh_scheme_1) then
! It is assumed that B.C. is applied to sh_xy and vort_xy
vort_sh = 0.25 * ( &
((G%areaBu(I-1,J-1) * CS%vort_xy(I-1,J-1,k)) * CS%sh_xy(I-1,J-1,k) + &
(G%areaBu(I ,J ) * CS%vort_xy(I ,J ,k)) * CS%sh_xy(I ,J ,k)) + &
((G%areaBu(I-1,J ) * CS%vort_xy(I-1,J ,k)) * CS%sh_xy(I-1,J ,k) + &
(G%areaBu(I ,J-1) * CS%vort_xy(I ,J-1,k)) * CS%sh_xy(I ,J-1,k)) &
(((G%areaBu(I-1,J-1) * CS%vort_xy(I-1,J-1,k)) * CS%sh_xy(I-1,J-1,k)) + &
((G%areaBu(I ,J ) * CS%vort_xy(I ,J ,k)) * CS%sh_xy(I ,J ,k))) + &
(((G%areaBu(I-1,J ) * CS%vort_xy(I-1,J ,k)) * CS%sh_xy(I-1,J ,k)) + &
((G%areaBu(I ,J-1) * CS%vort_xy(I ,J-1,k)) * CS%sh_xy(I ,J-1,k))) &
) * G%IareaT(i,j)
endif

Expand Down Expand Up @@ -717,10 +717,8 @@ subroutine compute_stress_divergence(u, v, h, diffu, diffv, dx2h, dy2h, dx2q, dy
! but here is the discretization of div(S)
do j=js,je ; do I=Isq,Ieq
h_u = 0.5 * (G%mask2dT(i,j)*h(i,j,k) + G%mask2dT(i+1,j)*h(i+1,j,k)) + h_neglect
fx = -((G%IdyCu(I,j)*(Mxx(i,j) - &
Mxx(i+1,j)) + &
G%IdxCu(I,j)*(dx2q(I,J-1)*Mxy(I,J-1) - &
dx2q(I,J) *Mxy(I,J))) * &
fx = -((G%IdyCu(I,j)*(Mxx(i,j) - Mxx(i+1,j)) + &
G%IdxCu(I,j)*(dx2q(I,J-1)*Mxy(I,J-1) - dx2q(I,J)*Mxy(I,J))) * &
G%IareaCu(I,j)) / h_u
diffu(I,j,k) = diffu(I,j,k) + fx
if (save_ZB2020u) &
Expand All @@ -730,10 +728,8 @@ subroutine compute_stress_divergence(u, v, h, diffu, diffv, dx2h, dy2h, dx2q, dy
! Evaluate 1/h y.Div(h S) (Line 1517 of MOM_hor_visc.F90)
do J=Jsq,Jeq ; do i=is,ie
h_v = 0.5 * (G%mask2dT(i,j)*h(i,j,k) + G%mask2dT(i,j+1)*h(i,j+1,k)) + h_neglect
fy = -((G%IdyCv(i,J)*(dy2q(I-1,J)*Mxy(I-1,J) - &
dy2q(I,J) *Mxy(I,J)) + & ! NOTE this plus
G%IdxCv(i,J)*(Myy(i,j) - &
Myy(i,j+1))) * &
fy = -((G%IdxCv(i,J)*(Myy(i,j) - Myy(i,j+1)) + &
G%IdyCv(i,J)*(dy2q(I-1,J)*Mxy(I-1,J) - dy2q(I,J)*Mxy(I,J))) * &
G%IareaCv(i,J)) / h_v
diffv(i,J,k) = diffv(i,J,k) + fy
if (save_ZB2020v) &
Expand Down

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