Revert scavenging defaults to POP-based equivalents

rename parameter and add constant non-labile POM contribution.

doc/phys_pkgs/darwin_iron.rst

@@ -97,39 +97,29 @@ The scavenging rate for free iron is
 To select particle-based scavenging following Parekh et al. (2005)
 :cite:`parekh:2005`, define :varlink:`DARWIN_PART_SCAV`.  POM is the
 concentration of particulate organic matter in units of mg/L.  It is
-parameterized in terms of POC, POSi and PIC,
+parameterized in terms of POC, PSi and PIC,
 
 .. math::
 
    \op{POM} = w^{\text{scav}}_{\text{POC}} \op{POC}
-            + w^{\text{scav}}_{\text{POSi}} \op{POSi}
+            + w^{\text{scav}}_{\text{PSi}} \op{PSi}
             + w^{\text{scav}}_{\text{PIC}} \op{PIC}
+            + \op{rPOM}
    \;.
 
-The value for :math:`w^{\text{scav}}_{\text{POC}}` is taken from Rios et al.
-(1998) :cite:`rios:1998` as the weight of as detritus without opal per mol of
-carbon.  :math:`w^{\text{scav}}_{\text{POSi}}` and
-:math:`w^{\text{scav}}_{\text{PIC}}` are just the molecular weights of opal
-(per mol Si) and calcium carbonate, see
+By default, only POC contributes, see
 :numref:`tab_phys_pkgs_darwin_iron_params`.
 
-.. admonition:: deprecated formulations
+.. admonition:: deprecated formulation
 
    The old (and deprecated) formulation of scavenging in terms of POP can be
    recovered by defining :varlink:`DARWIN_PART_SCAV_POP`, in which case
    :math:`\op{POM}` is replaced by
    :math:`\op{POP}\!/R^{\op{POP}:\op{POC}}_{{\text{scav}}}`.  Parameter names
    and defaults are different in this case, see
-   :numref:`tab_phys_pkgs_darwin_scav_pop`.  For comparison: this formulation
-   with its default parameters could also be recovered in the new formulation
-   (with new default parameters) by setting
-   :math:`\op{POM}=w^{\text{scav}}_{\text{POP}} \op{POP}` where
-   :math:`w^{\text{scav}}_{\text{POP}}\approx 15.274` g/mmol P.
-
-   The faulty formulation in terms of POC only that existed before 2022-12-05
-   can be recovered by setting scav_POC_wgt=1, scav_PIC_wgt=0 and
-   scav_POSi_wgt=0 and making sure the product scav_tau*scav_inter has the same
-   value as scav_rat*scav_inter before.
+   :numref:`tab_phys_pkgs_darwin_scav_pop`.  The new formulation with default
+   parameters closely approximates the old formulation with its default
+   parameters when POC:POP is 120:1.
 
 The concentration of free iron, Fe', is determined following Parekh et al.
 (2004) :cite:`parekh:2004` and Dutkiewicz et al. (2005)
@@ -180,9 +170,10 @@ and after each biogeochemical subtimestep.
    :varlink:`scav_tau`      & :math:`\tau_{\op{scav}}`             & 0.2         &                        & factor for converting Th scavenging rates to iron ones
    :varlink:`scav_inter`    & :math:`I_{\op{scav}}`                & 0.079 / day & L\ :sup:`e` mg\ :sup:`-e` s\ :sup:`-1` & intercept of scavenging power law (e=e\ :sub:`scav`)
    :varlink:`scav_exp`      & :math:`e_{\op{scav}}`                & 0.58        &                        & exponent of scavenging power law
-   :varlink:`scav_POC_wgt`  & :math:`w^{\op{scav}}_{\op{POC}}`     & 0.02173     & g/mmol |nbsp| C        & weight POC contributes to POM
-   :varlink:`scav_POSi_wgt` & :math:`w^{\op{scav}}_{\op{POSi}}`    & 0.069       & g/mmol |nbsp| Si       & weight POSi contributes to POM
-   :varlink:`scav_PIC_wgt`  & :math:`w^{\op{scav}}_{\op{PIC}}`     & 0.100       & g/mmol |nbsp| C        & weight PIC contributes to POM
+   :varlink:`scav_POC_wgt`  & :math:`w^{\op{scav}}_{\op{POC}}`     & 0.12728     & g/mmol |nbsp| C        & weight POC contributes to POM
+   :varlink:`scav_PSi_wgt`  & :math:`w^{\op{scav}}_{\op{PSi}}`     & 0.0         & g/mmol |nbsp| Si       & weight PSi contributes to POM
+   :varlink:`scav_PIC_wgt`  & :math:`w^{\op{scav}}_{\op{PIC}}`     & 0.0         & g/mmol |nbsp| C        & weight PIC contributes to POM
+   :varlink:`scav_rPOM`     & :math:`\op{rPOM}`                    & 0.0         & g/m\ :sup:`3`          & concentration of non-labile POM for scavenging
    :varlink:`ligand_tot`    & :math:`L_{\op{T}}`                   & 1E-3        & mmol/m\ :sup:`3`       & total ligand concentration
    :varlink:`ligand_stab`   & :math:`\beta_{\op{stab}}`            & 0.2E6       & m\ :sup:`3`/mmol       & ligand stability rate ratio
    :varlink:`freefemax`     & :math:`\op{Fe}'_{\op{max}}`          & 0.4E-3      & mmol/m\ :sup:`3`       & max concentration of free iron

pkg/darwin/DARWIN_PARAMS.h

@@ -247,8 +247,9 @@ C     scav_tau          :: [1]                 factor to go from Th scavenging r
 C     scav_inter        :: [L^e mg^-e s^-1]    intercept of scavenging power law (e=scav_exp)
 C     scav_exp          :: [1]                 exponent of scavenging power law
 C     scav_POC_wgt      :: [g / mmol C]        weight POC contributes to POM for scavenging
-C     scav_POSi_wgt     :: [g / mmol Si]       weight POSi contributes to POM for scavenging
+C     scav_PSi_wgt      :: [g / mmol Si]       weight PSi contributes to POM for scavenging
 C     scav_PIC_wgt      :: [g / mmol C]        weight PIC contributes to POM for scavenging
+C     scav_degrPOM      :: [g/m3]              concentration of non-labile POM for scavenging
 C     scav_rat          :: [1]                 factor Th to iron for DARWIN_PART_SCAV_POP
 C     scav_R_POPPOC     :: [mmol P / g C]      POP:POC ratio for DARWIN_PART_SCAV_POP
 C     depthfesed        :: [m]                 depth above which to add sediment source (was -1000)
@@ -378,8 +379,9 @@ C     depthdenit        :: [m]             not implemented (depth for denitrific
      &    scav_inter,
      &    scav_exp,
      &    scav_POC_wgt,
-     &    scav_POSi_wgt,
+     &    scav_PSi_wgt,
      &    scav_PIC_wgt,
+     &    scav_degrPOM,
 #else
      &    scav,
 #endif
@@ -497,8 +499,9 @@ C     &    yono2,
       _RL scav_inter
       _RL scav_exp
       _RL scav_POC_wgt
-      _RL scav_POSi_wgt
+      _RL scav_PSi_wgt
       _RL scav_PIC_wgt
+      _RL scav_degrPOM
 #else
       _RL scav
 #endif

pkg/darwin/darwin_check.F

@@ -1724,13 +1724,13 @@ SUBROUTINE DARWIN_CHECK( myThid )
      &' /* solubility of Fe dust */')
       CALL WRITE_0D_RL(ligand_tot,INDEX_NONE,
      &'ligand_tot =',
-     &' /* total ligand concentration (mol/m3) */')
+     &' /* total ligand concentration (mmol/m3) */')
       CALL WRITE_0D_RL(ligand_stab,INDEX_NONE,
      &'ligand_stab =',
-     &' /* ligand stability rate ratio (m3/mol) */')
+     &' /* ligand stability rate ratio (m3/mmol) */')
       CALL WRITE_0D_RL(freefemax,INDEX_NONE,
      &'freefemax =',
-     &' /* max concentration of free iron (mol/m3) */')
+     &' /* max concentration of free iron (mmol/m3) */')
 #ifdef DARWIN_PART_SCAV_POP
       CALL WRITE_0D_RL(scav_rat,INDEX_NONE,
      &'scav_rat =',
@@ -1757,12 +1757,15 @@ SUBROUTINE DARWIN_CHECK( myThid )
       CALL WRITE_0D_RL(scav_POC_wgt,INDEX_NONE,
      &'scav_POC_wgt =',
      &' /* weight of POC in POM for scavenging (g / mmol C) */')
-      CALL WRITE_0D_RL(scav_POSi_wgt,INDEX_NONE,
-     &'scav_POSi_wgt =',
-     &' /* weight of POSi in POM for scavenging (g / mmol Si) */')
+      CALL WRITE_0D_RL(scav_PSi_wgt,INDEX_NONE,
+     &'scav_PSi_wgt =',
+     &' /* weight of PSi in POM for scavenging (g / mmol Si) */')
       CALL WRITE_0D_RL(scav_PIC_wgt,INDEX_NONE,
      &'scav_PIC_wgt =',
      &' /* weight of PIC in POM for scavenging (g / mmol C) */')
+      CALL WRITE_0D_RL(scav_degrPOM,INDEX_NONE,
+     &'scav_degrPOM =',
+     &' /* concentration of non-labile POM for scavenging (g/m3) */')
 #else
       CALL WRITE_0D_RL(scav,INDEX_NONE,
      &'scav =',

pkg/darwin/darwin_forcing.F

@@ -407,8 +407,9 @@ SUBROUTINE DARWIN_FORCING( Ptrdummy,
         scv = scav_rat*scav_inter*(scav_pom**scav_exp)
 #elif defined(DARWIN_PART_SCAV)
         scav_pom = scav_POC_wgt*MAX(0 _d 0, Ptracer(i,j,k,bi,bj,iPOC))
-     &           + scav_POSi_wgt*MAX(0 _d 0, Ptracer(i,j,k,bi,bj,iPOSi))
+     &           + scav_PSi_wgt*MAX(0 _d 0, Ptracer(i,j,k,bi,bj,iPOSi))
      &           + scav_PIC_wgt*MAX(0 _d 0, Ptracer(i,j,k,bi,bj,iPIC))
+     &           + scav_degrPOM
         scv = scav_tau*scav_inter*(scav_pom**scav_exp)
 #else
         scv = scav

pkg/darwin/darwin_read_params.F

@@ -115,8 +115,9 @@ SUBROUTINE DARWIN_READ_PARAMS(iUnit,oUnit,myThid)
      &    scav_inter,
      &    scav_exp,
      &    scav_POC_wgt,
-     &    scav_POSi_wgt,
+     &    scav_PSi_wgt,
      &    scav_PIC_wgt,
+     &    scav_degrPOM,
 #else
      &    scav,
 #endif
@@ -393,12 +394,13 @@ SUBROUTINE DARWIN_READ_PARAMS(iUnit,oUnit,myThid)
       scav_exp = 0.58 _d 0
       scav_R_POPPOC = 1.1321 _d -4
 #elif defined(DARWIN_PART_SCAV)
-      scav_tau = 0.2
+      scav_tau = 0.2 _d 0
       scav_inter = 0.079 _d 0 / pday
       scav_exp = 0.58 _d 0
-      scav_POC_wgt = 0.02173 _d 0
-      scav_POSi_wgt = 0.069 _d 0
-      scav_PIC_wgt = 0.100 _d 0
+      scav_POC_wgt = 0.12728 _d 0
+      scav_PSi_wgt = 0 _d 0
+      scav_PIC_wgt = 0 _d 0
+      scav_degrPOM = 0 _d 0
 #else
       scav = 0.4 _d 0/pyear
 #endif