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Added units to comments in MOM_grid_initialization
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  Added a description of the units to the comments for each of the real
variables in MOM_grid_initialization and MOM_shared_initialization.  Only
comments are changed, and all answers are bitwise identical.
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@Hallberg-NOAA @marshallward
Hallberg-NOAA authored and marshallward committed Jan 18, 2023
1 parent 3f82a92 commit 4be437a
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Showing 2 changed files with 75 additions and 66 deletions.
139 changes: 74 additions & 65 deletions src/initialization/MOM_grid_initialize.F90
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Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,7 @@ subroutine set_grid_metrics_from_mosaic(G, param_file, US)
real, dimension(2*G%isd-3:2*G%ied+1,2*G%jsd-2:2*G%jed+1) :: tmpU ! East face supergrid spacing [L ~> m]
real, dimension(2*G%isd-2:2*G%ied+1,2*G%jsd-3:2*G%jed+1) :: tmpV ! North face supergrid spacing [L ~> m]
real, dimension(2*G%isd-3:2*G%ied+1,2*G%jsd-3:2*G%jed+1) :: tmpZ ! Corner latitudes or longitudes [degN] or [degE]
real, dimension(:,:), allocatable :: tmpGlbl ! A global array of axis labels
real, dimension(:,:), allocatable :: tmpGlbl ! A global array of axis labels [degrees_N] or [km] or [m]
character(len=200) :: filename, grid_file, inputdir
character(len=64) :: mdl = "MOM_grid_init set_grid_metrics_from_mosaic"
type(MOM_domain_type), pointer :: SGdom => NULL() ! Supergrid domain
Expand Down Expand Up @@ -361,8 +361,8 @@ subroutine set_grid_metrics_cartesian(G, param_file, US)
! Local variables
integer :: i, j, isd, ied, jsd, jed, IsdB, IedB, JsdB, JedB, I1off, J1off
integer :: niglobal, njglobal
real :: grid_latT(G%jsd:G%jed), grid_latB(G%JsdB:G%JedB)
real :: grid_lonT(G%isd:G%ied), grid_lonB(G%IsdB:G%IedB)
real :: grid_latT(G%jsd:G%jed), grid_latB(G%JsdB:G%JedB) ! Axis labels [degrees_N] or [km] or [m]
real :: grid_lonT(G%isd:G%ied), grid_lonB(G%IsdB:G%IedB) ! Axis labels [degrees_E] or [km] or [m]
real :: dx_everywhere, dy_everywhere ! Grid spacings [L ~> m].
real :: I_dx, I_dy ! Inverse grid spacings [L-1 ~> m-1].
real :: PI
Expand Down Expand Up @@ -498,13 +498,17 @@ subroutine set_grid_metrics_spherical(G, param_file, US)
type(param_file_type), intent(in) :: param_file !< Parameter file structure
type(unit_scale_type), intent(in) :: US !< A dimensional unit scaling type
! Local variables
real :: PI, PI_180! PI = 3.1415926... as 4*atan(1)
real :: PI ! PI = 3.1415926... as 4*atan(1) [nondim]
real :: PI_180 ! The conversion factor from degrees to radians [radians degree-1]
integer :: i, j, isd, ied, jsd, jed
integer :: is, ie, js, je, Isq, Ieq, Jsq, Jeq, IsdB, IedB, JsdB, JedB
integer :: i_offset, j_offset
real :: grid_latT(G%jsd:G%jed), grid_latB(G%JsdB:G%JedB)
real :: grid_lonT(G%isd:G%ied), grid_lonB(G%IsdB:G%IedB)
real :: dLon, dLat, latitude, dL_di
real :: grid_latT(G%jsd:G%jed), grid_latB(G%JsdB:G%JedB) ! Axis labels [degrees_N]
real :: grid_lonT(G%isd:G%ied), grid_lonB(G%IsdB:G%IedB) ! Axis labels [degrees_E]
real :: dLon ! The change in longitude between successive grid points [degrees_E]
real :: dLat ! The change in latitude between successive grid points [degrees_N]
real :: dL_di ! dLon rescaled from degrees to radians [radians]
real :: latitude ! The latitude of a grid point [degrees_N]
character(len=48) :: mdl = "MOM_grid_init set_grid_metrics_spherical"

is = G%isc ; ie = G%iec ; js = G%jsc ; je = G%jec
Expand All @@ -517,7 +521,7 @@ subroutine set_grid_metrics_spherical(G, param_file, US)

! Calculate the values of the metric terms that might be used
! and save them in arrays.
PI = 4.0*atan(1.0); PI_180 = atan(1.0)/45.
PI = 4.0*atan(1.0) ; PI_180 = atan(1.0)/45.

call get_param(param_file, mdl, "SOUTHLAT", G%south_lat, &
"The southern latitude of the domain.", units="degrees_N", &
Expand Down Expand Up @@ -639,19 +643,23 @@ subroutine set_grid_metrics_mercator(G, param_file, US)
integer :: I_off, J_off
type(GPS) :: GP
character(len=48) :: mdl = "MOM_grid_init set_grid_metrics_mercator"
real :: PI, PI_2! PI = 3.1415926... as 4*atan(1), PI_2 = (PI) /2.0
real :: y_q, y_h, jd, x_q, x_h, id
real :: PI, PI_2 ! PI = 3.1415926... as 4*atan(1), PI_2 = (PI) /2.0 [nondim]
real :: y_q, y_h ! Latitudes of a point [radians]
real :: id ! The i-grid space positions whose longitude is being sought [gridpoints]
real :: jd ! The j-grid space positions whose latitude is being sought [gridpoints]
real :: x_q, x_h ! Longitudes of a point [radians]
real, dimension(G%isd:G%ied,G%jsd:G%jed) :: &
xh, yh ! Latitude and longitude of h points in radians.
xh, yh ! Latitude and longitude of h points in radians [radians]
real, dimension(G%IsdB:G%IedB,G%jsd:G%jed) :: &
xu, yu ! Latitude and longitude of u points in radians.
xu, yu ! Latitude and longitude of u points in radians [radians]
real, dimension(G%isd:G%ied,G%JsdB:G%JedB) :: &
xv, yv ! Latitude and longitude of v points in radians.
xv, yv ! Latitude and longitude of v points in radians [radians]
real, dimension(G%IsdB:G%IedB,G%JsdB:G%JedB) :: &
xq, yq ! Latitude and longitude of q points in radians.
xq, yq ! Latitude and longitude of q points in radians [radians]
real :: fnRef ! fnRef is the value of Int_dj_dy or
! Int_dj_dy at a latitude or longitude that is
real :: jRef, iRef ! being set to be at grid index jRef or iRef.
! being set to be at grid index jRef or iRef [gridpoints]
real :: jRef, iRef ! The grid index at which fnRef is evaluated [gridpoints]
integer :: itt1, itt2
logical, parameter :: simple_area = .true.
integer :: is, ie, js, je, Isq, Ieq, Jsq, Jeq, IsdB, IedB, JsdB, JedB
Expand Down Expand Up @@ -860,8 +868,8 @@ end subroutine set_grid_metrics_mercator

!> This function returns the grid spacing in the logical x direction in [L ~> m].
function ds_di(x, y, GP)
real, intent(in) :: x !< The longitude in question
real, intent(in) :: y !< The latitude in question
real, intent(in) :: x !< The longitude in question [radians]
real, intent(in) :: y !< The latitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters

real :: ds_di ! The returned grid spacing [L ~> m]
Expand All @@ -874,8 +882,8 @@ end function ds_di

!> This function returns the grid spacing in the logical y direction in [L ~> m].
function ds_dj(x, y, GP)
real, intent(in) :: x !< The longitude in question
real, intent(in) :: y !< The latitude in question
real, intent(in) :: x !< The longitude in question [radians]
real, intent(in) :: y !< The latitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters

real :: ds_dj ! The returned grid spacing [L ~> m]
Expand All @@ -887,16 +895,17 @@ function ds_dj(x, y, GP)
end function ds_dj

!> This function returns the contribution from the line integral along one of the four sides of a
!! cell face to the area of a cell, assuming that the sides follow a linear path in latitude and
!! longitude (i.e., on a Mercator grid).
!! cell face to the area of a cell, in [radians2], assuming that the sides follow a linear path in
!! latitude and longitude (i.e., on a Mercator grid).
function dL(x1, x2, y1, y2)
real, intent(in) :: x1 !< Segment starting longitude, in degrees E.
real, intent(in) :: x2 !< Segment ending longitude, in degrees E.
real, intent(in) :: y1 !< Segment ending latitude, in degrees N.
real, intent(in) :: y2 !< Segment ending latitude, in degrees N.
real, intent(in) :: x1 !< Segment starting longitude [radians]
real, intent(in) :: x2 !< Segment ending longitude [radians]
real, intent(in) :: y1 !< Segment starting latitude [radians]
real, intent(in) :: y2 !< Segment ending latitude [radians]
! Local variables
real :: dL
real :: r, dy
real :: dL ! A contribution to the spanned area the surface of the sphere [radian2]
real :: r ! A contribution from the range of latitudes, including trigonometric factors [radians]
real :: dy ! The spanned range of latitudes [radians]

dy = y2 - y1

Expand All @@ -914,22 +923,24 @@ end function dL
!! Newton's method that were used to polish the root.
function find_root( fn, dy_df, GP, fnval, y1, ymin, ymax, ittmax)
real :: find_root !< The value of y where fn(y) = fnval that will be returned
real, external :: fn !< The external function whose root is being sought
real, external :: dy_df !< The inverse of the derivative of that function
type(GPS), intent(in) :: GP !< A structure of grid parameters
real, intent(in) :: fnval !< The value of fn being sought
real, intent(in) :: y1 !< A first guess for y
real, intent(in) :: ymin !< The minimum permitted value of y
real, intent(in) :: ymax !< The maximum permitted value of y
real, external :: fn !< The external function whose root is being sought [gridpoints]
real, external :: dy_df !< The inverse of the derivative of that function [radian gridpoint-1]
type(GPS), intent(in) :: GP !< A structure of grid parameters
real, intent(in) :: fnval !< The value of fn being sought [gridpoints]
real, intent(in) :: y1 !< A first guess for y [radians]
real, intent(in) :: ymin !< The minimum permitted value of y [radians]
real, intent(in) :: ymax !< The maximum permitted value of y [radians]
integer, intent(out) :: ittmax !< The number of iterations used to polish the root
! Local variables
real :: y, y_next
real :: ybot, ytop, fnbot, fntop
real :: y, y_next ! Successive guesses at the root position [radians]
real :: ybot, ytop ! Brackets bounding the root [radians]
real :: fnbot, fntop ! Values of fn at the bounding values of y [gridpoints]
real :: dy_dfn ! The inverse of the local derivative of fn with y [radian gridpoint-1]
real :: dy ! The jump to the next guess of y [radians]
real :: fny ! The difference between fn(y) and the target value [gridpoints]
integer :: itt
character(len=256) :: warnmesg

real :: dy_dfn, dy, fny

! Bracket the root. Do not use the bounding values because the value at the
! function at the bounds could be infinite, as is the case for the Mercator
! grid recursion relation. (I.e., this is a search on an open interval.)
Expand Down Expand Up @@ -1022,40 +1033,40 @@ function find_root( fn, dy_df, GP, fnval, y1, ymin, ymax, ittmax)
find_root = y
end function find_root

!> This function calculates and returns the value of dx/di, where x is the
!! longitude in Radians, and i is the integral north-south grid index.
!> This function calculates and returns the value of dx/di in [radian gridpoint-1],
!! where x is the longitude in Radians, and i is the integral east-west grid index.
function dx_di(x, GP)
real, intent(in) :: x !< The longitude in question
real, intent(in) :: x !< The longitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters
real :: dx_di
real :: dx_di ! The derivative of zonal position with the grid index [radian gridpoint-1]

dx_di = (GP%len_lon * 4.0*atan(1.0)) / (180.0 * GP%niglobal)

end function dx_di

!> This function calculates and returns the integral of the inverse
!! of dx/di to the point x, in radians.
!! of dx/di to the point x, in radians [gridpoints]
function Int_di_dx(x, GP)
real, intent(in) :: x !< The longitude in question
real, intent(in) :: x !< The longitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters
real :: Int_di_dx
real :: Int_di_dx ! A position in the global i-index space [gridpoints]

Int_di_dx = x * ((180.0 * GP%niglobal) / (GP%len_lon * 4.0*atan(1.0)))

end function Int_di_dx

!> This subroutine calculates and returns the value of dy/dj, where y is the
!! latitude in Radians, and j is the integral north-south grid index.
!> This subroutine calculates and returns the value of dy/dj in [radian gridpoint-1],
!! where y is the latitude in Radians, and j is the integral north-south grid index.
function dy_dj(y, GP)
real, intent(in) :: y !< The latitude in question
real, intent(in) :: y !< The latitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters
real :: dy_dj
real :: dy_dj ! The derivative of meridional position with the grid index [radian gridpoint-1]
! Local variables
real :: PI ! 3.1415926... calculated as 4*atan(1)
real :: PI ! 3.1415926... calculated as 4*atan(1) [nondim]
real :: C0 ! The constant that converts the nominal y-spacing in
! gridpoints to the nominal spacing in Radians.
! gridpoints to the nominal spacing in Radians [radian gridpoint-1]
real :: y_eq_enhance ! The latitude in radians within which the resolution
! is enhanced.
! is enhanced [radians]
PI = 4.0*atan(1.0)
if (GP%isotropic) then
C0 = (GP%len_lon * PI) / (180.0 * GP%niglobal)
Expand All @@ -1074,21 +1085,19 @@ function dy_dj(y, GP)
end function dy_dj

!> This subroutine calculates and returns the integral of the inverse
!! of dy/dj to the point y, in radians.
!! of dy/dj to the point y in radians [gridpoints]
function Int_dj_dy(y, GP)
real, intent(in) :: y !< The latitude in question
real, intent(in) :: y !< The latitude in question [radians]
type(GPS), intent(in) :: GP !< A structure of grid parameters
real :: Int_dj_dy
real :: Int_dj_dy ! The grid position of latitude y [gridpoints]
! Local variables
real :: I_C0 = 0.0 ! The inverse of the constant that converts the
real :: I_C0 ! The inverse of the constant that converts the
! nominal spacing in gridpoints to the nominal
! spacing in Radians.
real :: PI ! 3.1415926... calculated as 4*atan(1)
real :: y_eq_enhance ! The latitude in radians from
! from the equator within which the
! meridional grid spacing is enhanced by
! a factor of GP%lat_enhance_factor.
real :: r
! spacing in Radians [gridpoint radian-1]
real :: PI ! 3.1415926... calculated as 4*atan(1) [nondim]
real :: y_eq_enhance ! The latitude in radians from from the equator within which the meridional
! grid spacing is enhanced by a factor of GP%lat_enhance_factor [radians]
real :: r ! The y grid position in the global index space [gridpoints]

PI = 4.0*atan(1.0)
if (GP%isotropic) then
Expand Down Expand Up @@ -1119,9 +1128,9 @@ end function Int_dj_dy

!> Extrapolates missing metric data into all the halo regions.
subroutine extrapolate_metric(var, jh, missing)
real, dimension(:,:), intent(inout) :: var !< The array in which to fill in halos
real, dimension(:,:), intent(inout) :: var !< The array in which to fill in halos [A]
integer, intent(in) :: jh !< The size of the halos to be filled
real, optional, intent(in) :: missing !< The missing data fill value, 0 by default.
real, optional, intent(in) :: missing !< The missing data fill value, 0 by default [A]
! Local variables
real :: badval
integer :: i,j
Expand Down
2 changes: 1 addition & 1 deletion src/initialization/MOM_shared_initialization.F90
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1309,7 +1309,7 @@ subroutine compute_global_grid_integrals(G, US)
type(unit_scale_type), intent(in) :: US !< A dimensional unit scaling type

! Local variables
real, dimension(G%isc:G%iec, G%jsc:G%jec) :: tmpForSumming
real, dimension(G%isc:G%iec, G%jsc:G%jec) :: tmpForSumming ! Masked and unscaled cell areas [m2]
real :: area_scale ! A scaling factor for area into MKS units [m2 L-2 ~> 1]
integer :: i,j

Expand Down

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