\(\newcommand{\p}[1]{\frac{\partial }{\partial #1}}\) \(\newcommand{\pp}[2]{\frac{\partial #1}{\partial #2}}\) \(\newcommand{\dd}[2]{\frac{d #1}{d #2}}\) \(\newcommand{\h}{\frac{1}{2}}\) \(\newcommand{\op}[1]{\operatorname{#1}}\)

8.7.3.14. Sediments

The iron sediment source is discussed in Section 8.7.3.15.2.

Two versions of the RADI metamodel for sediments are supported: Defining DARWIN_ALLOW_RADIv1 in DARWIN_OPTIONS.h activates version 1 [SHW+22]; Version 2 [vdZSM+26] is activated by DARWIN_ALLOW_RADIv2. Both require DARWIN_BOTTOM_SINK to be defined.

8.7.3.14.1. RADI v1

Sediment fluxes are based on modeled sinking fluxes of POC and PIC into the bottom, see (8.70).

DIC, alkalinity and oxygen fluxes can be out of the sediment (positive) or burial into the sediment (negative):

\[F^{\mathrm{sed}}_{\mathrm{DIC}} = \left( a_1 \Omega_{\mathrm{C}} c + b_1 F^{\mathrm{sink}}_{\mathrm{POC}} + c_1 F^{\mathrm{sink}}_{\mathrm{PIC}} + d_1 c \right) f^{\mathrm{Tcorr}}_{\mathrm{DIC}}\]

\[F^{\mathrm{sed}}_{\mathrm{ALK}} = \left( a_2 \Omega_{\mathrm{C}} c + b_2 F^{\mathrm{sink}}_{\mathrm{POC}} + c_2 F^{\mathrm{sink}}_{\mathrm{PIC}} + d_2 c \right) f^{\mathrm{Tcorr}}_{\mathrm{ALK}}\]

\[F^{\mathrm{sed}}_{\mathrm{O2}} = \left( a_3 \Omega_{\mathrm{C}} c + b_3 F^{\mathrm{sink}}_{\mathrm{POC}} + c_3 F^{\mathrm{sink}}_{\mathrm{PIC}} + d_3 c \right) f^{\mathrm{Tcorr}}_{\mathrm{O2}}\]

POC and Calcite fluxes are burial-only (always negative):

\[F^{\mathrm{sed}}_{\mathrm{POC}} = \min\left(0, - \left( a_4 \Omega_{\mathrm{C}} c + b_4 F^{\mathrm{sink}}_{\mathrm{POC}} + c_4 F^{\mathrm{sink}}_{\mathrm{PIC}} + d_4 c \right) \right)\]

\[F^{\mathrm{sed}}_{\mathrm{Clc}} = \min\left(0, - \left( a_5 \Omega_{\mathrm{C}} c + b_5 F^{\mathrm{sink}}_{\mathrm{POC}} + c_5 F^{\mathrm{sink}}_{\mathrm{PIC}} + d_5 c \right) \right)\]

DIC, ALK and O2 fluxes are enhanced at higher temperatures:

\[ \begin{align}\begin{aligned}f^{\mathrm{Tcorr}}_{\mathrm{O2}} &= \frac{0.031558 + 0.001428\cdot|T|}{0.0335572}\\f^{\mathrm{Tcorr}}_{\mathrm{DIC}} &= \frac{0.015179 + 0.000795\cdot|T|}{0.016292}\\f^{\mathrm{Tcorr}}_{\mathrm{ALK}} &= \frac{0.015179 + 0.000795\cdot|T|}{0.016292}\end{aligned}\end{align} \]

These are normalized to 1 at \(|T|=1.4\).

Table 8.51 RADI sediment metamodel version 1 parameters
Name	Symbol	Default	Units
sed_a1	\(a_1\)	–0.101
sed_b1	\(b_1\)	1.040
sed_c1	\(c_1\)	0.128
sed_d1	\(d_1\)	0.125
sed_a2	\(a_2\)	–0.225
sed_b2	\(b_2\)	0.581
sed_c2	\(c_2\)	0.273
sed_d2	\(d_2\)	0.211
sed_a3	\(a_3\)	–0.018
sed_b3	\(b_3\)	–0.800
sed_c3	\(c_3\)	0.011
sed_d3	\(d_3\)	–0.033
sed_a4	\(a_4\)	0.000
sed_b4	\(b_4\)	0.027
sed_c4	\(c_4\)	0.012
sed_d4	\(d_4\)	–0.001
sed_a5	\(a_5\)	0.117
sed_b5	\(b_5\)	–0.251
sed_c5	\(c_5\)	0.852
sed_d5	\(d_5\)	–0.127
sed_c	\(c\)	3.17E-5	mmol m^-2 s^-1

8.7.3.14.2. RADI v2

Sediment fluxes into the water column (if positive) or burial into the sediment (if negative) are parametrized in terms of modeled sinking fluxes into the bottom, see (8.70),

\[ \begin{align}\begin{aligned}F^{\mathrm{sed}}_{\mathrm{DIC}} &= a_1 + b_1 |T| + c_1 \Omega_{\mathrm{C}} + d_1 \left( F^{\mathrm{sink}}_{\mathrm{POC}} + F^{\mathrm{sink}}_{\mathrm{plank,C}} \right) + e_1 F^{\mathrm{sink}}_{\mathrm{PIC}}\\F^{\mathrm{sed}}_{\mathrm{ALK}} &= a_2 + b_2 |T| + c_2 \Omega_{\mathrm{C}} + d_2 \left( F^{\mathrm{sink}}_{\mathrm{POC}} + F^{\mathrm{sink}}_{\mathrm{plank,C}} \right) + e_2 F^{\mathrm{sink}}_{\mathrm{PIC}}\\F^{\mathrm{sed}}_{\mathrm{O2}} &= a_3 + b_3 |T| + c_3 \Omega_{\mathrm{C}} + d_3 \left( F^{\mathrm{sink}}_{\mathrm{POC}} + F^{\mathrm{sink}}_{\mathrm{plank,C}} \right) + e_3 F^{\mathrm{sink}}_{\mathrm{PIC}}\\F^{\mathrm{sed}}_{\mathrm{NO3}} &= a_4 + b_4 \left( F^{\mathrm{sink}}_{\mathrm{PON}} + F^{\mathrm{sink}}_{\mathrm{plank,N}} \right) + c_4 F_{\mathrm{DIC}} + d_4 F_{\mathrm{O2}}\\ &\quad + e_4 |T| F_{\mathrm{DIC}} + f_4 |T| F_{\mathrm{O2}} + g_4 F_{\mathrm{DIC}} F_{\mathrm{O2}}\\F^{\mathrm{sed}}_{\mathrm{PO4}} &= a_5 + b_5 |T| + c_5 \Omega_{\mathrm{C}} + d_5 \left( F^{\mathrm{sink}}_{\mathrm{POP}} + F^{\mathrm{sink}}_{\mathrm{plank,P}} \right) + e_5 F^{\mathrm{sink}}_{\mathrm{PIC}}\\F^{\mathrm{sed}}_{\mathrm{NH4}} &= a_6 + b_6 |T| + c_6 \Omega_{\mathrm{C}} + d_6 \left( F^{\mathrm{sink}}_{\mathrm{PON}} + F^{\mathrm{sink}}_{\mathrm{plank,N}} \right) + e_6 F^{\mathrm{sink}}_{\mathrm{PIC}}\end{aligned}\end{align} \]

Table 8.52 RADI sediment metamodel version 2 parameters
Name	Symbol	Default
sed_globala1	\(a_1\)	2.07E-5
sed_globalb1	\(b_1\)	–5.64E-7
sed_globalc1	\(c_1\)	–5.42E-6
sed_globald1	\(d_1\)	1.45
sed_globale1	\(e_1\)	4.19E-1
sed_globala2	\(a_2\)	1.55E-5
sed_globalb2	\(b_2\)	–2.94E-7
sed_globalc2	\(c_2\)	–6.55E-6
sed_globald2	\(d_2\)	5.83E-1
sed_globale2	\(e_2\)	1.38E-1
sed_globala3	\(a_3\)	–1.35E-5
sed_globalb3	\(b_3\)	5.08E-8
sed_globalc3	\(c_3\)	1.79E-6
sed_globald3	\(d_3\)	–1.07
sed_globale3	\(e_3\)	–4.47E-1
sed_globala4	\(a_4\)	3.0E-6
sed_globalb4	\(b_4\)	–7.14E-1
sed_globalc4	\(c_4\)	1.94E-1
sed_globald4	\(d_4\)	2.81E-1
sed_globale4	\(e_4\)	–2.21E-2
sed_globalf4	\(f_4\)	–2.97E-2
sed_globalg4	\(g_4\)	–3.20E2
sed_globala5	\(a_5\)	–2.42E-7
sed_globalb5	\(b_5\)	1.54E-8
sed_globalc5	\(c_5\)	–4.77E-8
sed_globald5	\(d_5\)	1.64
sed_globale5	\(e_5\)	1.20E-2
sed_globala6	\(a_6\)	–3.87E-6
sed_globalb6	\(b_6\)	9.15E-8
sed_globalc6	\(c_6\)	–7.26E-7
sed_globald6	\(d_6\)	1.73
sed_globale6	\(e_6\)	1.51E-1

8.7.3.14.3. Diagnostics

Diagnostics available with DARWIN_ALLOW_RADIv1:

Table 8.53 RADI sediment model version 1 diagnostic fields
Name	Code	Units	Description
DICFsed	`SM______U1`	mmol C/m²/s	DIC sediment flux, \(F^{\mathrm{sed}}_{\mathrm{DIC}}\)
ALKFsed	`SM______U1`	meq/m²/s	ALK sediment flux, \(F^{\mathrm{sed}}_{\mathrm{ALK}}\)
O2Fsed	`SM______U1`	mmol O₂ /m²/s	O₂ sediment flux, \(F^{\mathrm{sed}}_{\mathrm{O2}}\)
POCFbur	`SM______U1`	mmol C/m²/s	POC buried flux, \(F^{\mathrm{sed}}_{\mathrm{POC}}\) (negative!)
CALFbur	`SM______U1`	mmol C/m²/s	Calcite buried flux, \(F^{\mathrm{sed}}_{\mathrm{CAL}}\) (negative!)
sedFlPOC	`SM_P____U1`	mmol C/m²/s	POC flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{POC}}\)
sedFlPIC	`SM_P____U1`	mmol C/m²/s	PIC flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{PIC}}\)
TcorrO2	`SM_P____M1`	1	Temperature correction factor for diffusive O₂ flux
TcorrALK	`SM_P____M1`	1	Temperature correction factor for diffusive ALK flux
TcorrDIC	`SM_P____M1`	1	Temperature correction factor for diffusive DIC flux
OmegCbot	`SM_P____M1`	1	Calcite saturation ratio above the seabed

Diagnostics available with DARWIN_ALLOW_RADIv2:

Table 8.54 RADI sediment model version 2 diagnostic fields
Name	Code	Units	Description
DICFsed	`SM______U1`	mmol C/m²/s	DIC sediment flux, \(F^{\mathrm{sed}}_{\mathrm{DIC}}\)
ALKFsed	`SM______U1`	meq/m²/s	ALK sediment flux, \(F^{\mathrm{sed}}_{\mathrm{ALK}}\)
O2Fsed	`SM______U1`	mmol O₂ /m²/s	O₂ sediment flux, \(F^{\mathrm{sed}}_{\mathrm{O2}}\)
NO3Fsed	`SM______U1`	mmol N/m²/s	NO3 sediment flux, \(F^{\mathrm{sed}}_{\mathrm{NO3}}\)
PO4Fsed	`SM______U1`	mmol P/m²/s	PO4 sediment flux, \(F^{\mathrm{sed}}_{\mathrm{PO3}}\)
NH4Fsed	`SM______U1`	mmol N/m²/s	NH4 sediment flux, \(F^{\mathrm{sed}}_{\mathrm{NH4}}\)
sedFlPOC	`SM_P____U1`	mmol C/m²/s	POC flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{POC}}\)
sedFlPIC	`SM_P____U1`	mmol C/m²/s	PIC flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{PIC}}\)
sedFlPOP	`SM_P____U1`	mmol P/m²/s	POP flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{POP}}\)
sedFlPON	`SM_P____U1`	mmol N/m²/s	PON flux from water column to sediment, \(F^{\mathrm{sink}}_{\mathrm{PON}}\)
sedFplkC	`SM_P____U1`	mmol C/m²/s	C flux from bottom sink plankton to sed, \(F^{\mathrm{sink}}_{\mathrm{plank,C}}\)
sedFplkN	`SM_P____U1`	mmol N/m²/s	N flux from bottom sink plankton to sed, \(F^{\mathrm{sink}}_{\mathrm{plank,N}}\)
sedFplkP	`SM_P____U1`	mmol P/m²/s	P flux from bottom sink plankton to sed, \(F^{\mathrm{sink}}_{\mathrm{plank,P}}\)
OmegCbot	`SM_P____M1`	1	Calcite saturation ratio above the seabed