Introduce option to switch on T- and O2-dependent remineralization in…

… all model versions (#424)

Introduce switch to enable T- and O2-dependent remineralization also for the default model (currently just optional) for the water column

cime_config/namelist_definition_blom.xml

@@ -3872,6 +3872,16 @@
     <desc>Switch for primary production and remineralization throughout the whole water column</desc>
   </entry>
 
+  <entry id="lTO2depremin">
+    <type>logical</type>
+    <category>bgcnml</category>
+    <group>bgcnml</group>
+    <values>
+      <value>.false.</value>
+    </values>
+    <desc>Switch for T- and O2-dependent remineralization of POM</desc>
+  </entry>
+
   <entry id="do_oalk">
     <type>logical</type>
     <category>bgcnml</category>

hamocc/mo_control_bgc.F90

@@ -61,6 +61,7 @@ module mo_control_bgc
   logical           :: with_dmsph             = .false. ! apply DMS with pH dependence
   logical           :: use_M4AGO              = .false. ! run with M4AGO settling scheme
   logical           :: lkwrbioz_off           = .false. ! if true, allow remin and primary prod throughout full water column
+  logical           :: lTO2depremin           = .false. ! Temperature- and O2-dependent remineralization of POM
   integer           :: sedspin_yr_s           = -1      ! start year for sediment spin-up
   integer           :: sedspin_yr_e           = -1      ! end   year for sediment spin-up
   integer           :: sedspin_ncyc           = -1      ! sediment spin-up sub-cycles

hamocc/mo_ocprod.F90

@@ -77,7 +77,8 @@ subroutine ocprod(kpie,kpje,kpke,kbnd,pdlxp,pdlyp,pddpo,omask,ptho,pi_ph,psao,pp
                                 dmsp1,dmsp2,dmsp3,dmsp4,dmsp5,dmsp6,dms_gamma,                     &
                                 fbro1,fbro2,atten_f,atten_c,atten_uv,atten_w,bkopal,bkphy,bkzoo,   &
                                 POM_remin_q10,POM_remin_Tref,opal_remin_q10,opal_remin_Tref,       &
-                                bkphyanh4,bkphyano3,bkphosph,bkiron,ro2utammo,max_limiter
+                                bkphyanh4,bkphyano3,bkphosph,bkiron,ro2utammo,max_limiter,         &
+                                O2thresh_aerob,O2thresh_hypoxic,NO3thresh_sulf
     use mo_biomod,        only: bsiflx0100,bsiflx0500,bsiflx1000,bsiflx2000,bsiflx4000,bsiflx_bot, &
                                 calflx0100,calflx0500,calflx1000,calflx2000,calflx4000,calflx_bot, &
                                 carflx0100,carflx0500,carflx1000,carflx2000,carflx4000,carflx_bot, &
@@ -96,7 +97,7 @@ subroutine ocprod(kpie,kpje,kpke,kbnd,pdlxp,pdlyp,pddpo,omask,ptho,pi_ph,psao,pp
     use mo_control_bgc,   only: dtb,io_stdo_bgc,with_dmsph,                                        &
                                 use_BROMO,use_AGG,use_PBGC_OCNP_TIMESTEP,use_FB_BGC_OCE,           &
                                 use_AGG,use_cisonew,use_natDIC, use_WLIN,use_sedbypass,use_M4AGO,  &
-                                use_extNcycle,lkwrbioz_off
+                                use_extNcycle,lkwrbioz_off,lTO2depremin
     use mo_vgrid,         only: dp_min,dp_min_sink,k0100,k0500,k1000,k2000,k4000,kwrbioz,ptiestu
     use mo_vgrid,         only: kmle
     use mo_clim_swa,      only: swa_clim
@@ -657,26 +658,21 @@ subroutine ocprod(kpie,kpje,kpke,kbnd,pdlxp,pdlyp,pddpo,omask,ptho,pi_ph,psao,pp
               ocetra(i,j,k,izoo14) = ocetra(i,j,k,izoo14)-sterzo14
             endif
 
-            if(ocetra(i,j,k,ioxygen) > 5.e-8) then
-              if (use_M4AGO) then
-                if (.not. use_extNcycle) then
-                  ! M4AGO comes with O2-lim
-                  o2lim  = ocetra(i,j,k,ioxygen)/(ocetra(i,j,k,ioxygen) + bkox_drempoc)
-                  pocrem = o2lim*drempoc*POM_remin_q10**((ptho(i,j,k)-POM_remin_Tref)/10.)*ocetra(i,j,k,idet)
-                else
-                  ! nitrogen always accounts for O2-lim - see below
-                  pocrem = drempoc*POM_remin_q10**((ptho(i,j,k)-POM_remin_Tref)/10.)*ocetra(i,j,k,idet)
-                endif
+            if(ocetra(i,j,k,ioxygen) > O2thresh_aerob) then
+              if (lTO2depremin) then
+                ! Both, use_M4AGO and use_extNcycle switch lTO2depremin to true!
+                o2lim  = ocetra(i,j,k,ioxygen)/(ocetra(i,j,k,ioxygen) + bkox_drempoc)
+                pocrem = drempoc*o2lim*POM_remin_q10**((ptho(i,j,k)-POM_remin_Tref)/10.)*ocetra(i,j,k,idet)
               else
                 pocrem = drempoc*ocetra(i,j,k,idet)
               endif
+
               if (.not. use_extNcycle) then
-                pocrem = min(pocrem,0.33*ocetra(i,j,k,ioxygen)/ro2ut)
-                docrem = min( remido*ocetra(i,j,k,idoc),0.33*ocetra(i,j,k,ioxygen)/ro2ut)
+                pocrem = min(pocrem,                    0.33*ocetra(i,j,k,ioxygen)/ro2ut)
+                docrem = min(remido*ocetra(i,j,k,idoc), 0.33*ocetra(i,j,k,ioxygen)/ro2ut)
                 phyrem = min(0.5*dyphy*phythresh,       0.33*ocetra(i,j,k,ioxygen)/ro2ut)
               else
-                o2lim  = ocetra(i,j,k,ioxygen)/(ocetra(i,j,k,ioxygen) + bkox_drempoc)
-                pocrem = min(o2lim*pocrem,              0.33*ocetra(i,j,k,ioxygen)/ro2utammo)
+                pocrem = min(pocrem,                    0.33*ocetra(i,j,k,ioxygen)/ro2utammo)
                 docrem = min(remido*ocetra(i,j,k,idoc), 0.33*ocetra(i,j,k,ioxygen)/ro2utammo)
                 phyrem = min(0.5*dyphy*phythresh,       0.33*ocetra(i,j,k,ioxygen)/ro2utammo)
               endif
@@ -815,7 +811,7 @@ subroutine ocprod(kpie,kpje,kpke,kbnd,pdlxp,pdlyp,pddpo,omask,ptho,pi_ph,psao,pp
         do i = 1,kpie
           do k = merge(1,kwrbioz(i,j)+1,lkwrbioz_off),kpke
             if(omask(i,j) > 0.5) then
-              if(ocetra(i,j,k,ioxygen) < 5.e-7 .and. pddpo(i,j,k) > dp_min) then
+              if(ocetra(i,j,k,ioxygen) < O2thresh_hypoxic .and. pddpo(i,j,k) > dp_min) then
                 if (use_AGG) then
                   avmass = ocetra(i,j,k,iphy) + ocetra(i,j,k,idet)
                 endif
@@ -908,7 +904,7 @@ subroutine ocprod(kpie,kpje,kpke,kbnd,pdlxp,pdlyp,pddpo,omask,ptho,pi_ph,psao,pp
       do i = 1,kpie
         do k = merge(1,kwrbioz(i,j)+1,lkwrbioz_off),kpke
           if(omask(i,j) > 0.5 .and. pddpo(i,j,k) > dp_min) then
-            if(ocetra(i,j,k,ioxygen) < 5.e-7 .and. ocetra(i,j,k,iano3) < 3.e-6) then
+            if(ocetra(i,j,k,ioxygen) < O2thresh_hypoxic .and. ocetra(i,j,k,iano3) < NO3thresh_sulf ) then
 
               if (use_AGG) then
                 avmass = ocetra(i,j,k,iphy)+ocetra(i,j,k,idet)

hamocc/mo_param_bgc.F90

@@ -38,7 +38,7 @@ module mo_param_bgc
                             use_BOXATM,use_CFC,use_PBGC_CK_TIMESTEP,                               &
                             use_sedbypass,with_dmsph,use_PBGC_OCNP_TIMESTEP,ocn_co2_type,use_M4AGO,&
                             do_n2onh3_coupled,use_extNcycle,                                       &
-                            lkwrbioz_off
+                            lkwrbioz_off,lTO2depremin
   use mod_xc,         only: mnproc
 
   implicit none
@@ -98,6 +98,7 @@ module mo_param_bgc
   public :: calcdens,opaldens,orgdens,claydens
   public :: dmsp1,dmsp2,dmsp3,dmsp4,dmsp5,dmsp6,dms_gamma
   public :: POM_remin_q10,opal_remin_q10,POM_remin_Tref,opal_remin_Tref
+  public :: O2thresh_aerob,O2thresh_hypoxic,NO3thresh_sulf
 
   ! extended nitrogen cycle
   public :: q10ano3denit,sc_ano3denit,Trefano3denit,rano3denit,bkano3denit,      &
@@ -276,6 +277,9 @@ module mo_param_bgc
   !********************************************************************
   ! Remineralization and dissolution parameters
   !********************************************************************
+  real, parameter :: O2thresh_aerob   = 5.e-8    ! Above O2thresh_aerob aerob remineralization takes place
+  real, parameter :: O2thresh_hypoxic = 5.e-7    ! Below O2thresh_hypoxic denitrification and sulfate reduction takes place (default model version)
+  real, parameter :: NO3thresh_sulf   = 3.e-6    ! Below NO3thresh_sulf 'sufate reduction' takes place
   real, protected :: remido     = 0.004           ! 1/d - remineralization rate (of DOM)
   ! deep sea remineralisation constants
   real, protected :: drempoc    = 0.025           ! 1/d Aerob remineralization rate detritus
@@ -615,7 +619,7 @@ subroutine read_bgcnamelist()
                          bkoxan2odenit_sed,bkan2odenit_sed,q10dnra_sed,          &
                          bkoxdnra_sed,bkdnra_sed,q10anh4nitr_sed,                &
                          bkoxamox_sed,bkanh4nitr_sed,q10ano2nitr_sed,            &
-                         bkoxnitr_sed,bkano2nitr_sed
+                         bkoxnitr_sed,bkano2nitr_sed,lTO2depremin
 
     if (mnproc.eq.1) then
       write(io_stdo_bgc,*)
@@ -656,7 +660,9 @@ subroutine calc_param_biol()
       bkanh4anmx_sed = bkano2anmx_sed * rnh4anmx/rno2anmx !Half-saturation constant for NH4 limitation of anammox (kmol/m3)
       mufn2o_sed     = 0.11/(50.*1e6*bkoxamox_sed)   !=6.61e-3  0.11/(50*1e6)=2.2e-9 - ~Santoro et al. 2011 with simple MM
       bn2o_sed       = 0.077/(50.*mufn2o_sed)        !=0.2331 - before set to 0.3 - base fraction entering N2O
+      lTO2depremin   = .true.
     endif
+    if (use_M4AGO) lTO2depremin = .true.
   end subroutine calc_param_biol
 
   !********************************************************************
@@ -837,6 +843,7 @@ subroutine write_parambgc()
       call cinfo_add_entry('do_sedspinup',           do_sedspinup)
       call cinfo_add_entry('l_3Dvarsedpor',          l_3Dvarsedpor)
       call cinfo_add_entry('lkwrbioz_off',           lkwrbioz_off)
+      call cinfo_add_entry('lTO2depremin',           lTO2depremin)
       call cinfo_add_entry('use_M4AGO',              use_M4AGO)
       if (use_extNcycle) then
         call cinfo_add_entry('do_n2onh3_coupled',       do_n2onh3_coupled)
@@ -886,6 +893,9 @@ subroutine write_parambgc()
       call pinfo_add_entry('wpoc_const',  wpoc_const*dtbinv)
       call pinfo_add_entry('wcal_const',  wcal_const*dtbinv)
       call pinfo_add_entry('wopal_const', wopal_const*dtbinv)
+      call pinfo_add_entry('O2thresh_aerob', O2thresh_aerob)
+      call pinfo_add_entry('O2thresh_hypoxic',O2thresh_hypoxic)
+      call pinfo_add_entry('NO3thresh_sulf',  NO3thresh_sulf)
       call pinfo_add_entry('drempoc',     drempoc*dtbinv)
       call pinfo_add_entry('dremopal',    dremopal*dtbinv)
       call pinfo_add_entry('dremn2o',     dremn2o*dtbinv)