Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Updates to Tech Note Photosynthesis chapter #1440

Merged
merged 3 commits into from
Jul 28, 2021
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Original file line number Diff line number Diff line change
Expand Up @@ -1197,7 +1197,7 @@ The saturated thickness is
\Delta z_{sat} = z_{bedrock} - z_{\nabla},

where the water table :math:`z_{\nabla}` is determined by finding the
irst soil layer above the bedrock depth (section :numref:`Depth to Bedrock`)
first soil layer above the bedrock depth (section :numref:`Depth to Bedrock`)
in which the volumetric water content drops below a specified threshold.
The default threshold is set to 0.9.

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -47,25 +47,27 @@ Stomatal resistance
-----------------------

CLM5 calculates stomatal conductance using the Medlyn stomatal conductance model (:ref:`Medlyn et al. 2011<Medlynetal2011>`).
Previous versions of CLM calculated leaf stomatal resistance is using the Ball-Berry conductance
Previous versions of CLM calculated leaf stomatal resistance using the Ball-Berry conductance
model as described by :ref:`Collatz et al. (1991)<Collatzetal1991>` and implemented in global
climate models (:ref:`Sellers et al. 1996<Sellersetal1996>`). The Medlyn model
calculates stomatal conductance (i.e., the inverse of resistance) based on net leaf
photosynthesis, the vapor pressure deficit, and the CO\ :sub:`2` concentration at the leaf surface.
photosynthesis, the leaf-to-air vapor pressure difference, and the CO\ :sub:`2` concentration at the leaf surface.
Leaf stomatal resistance is:

.. math::
:label: 9.1

\frac{1}{r_{s} } =g_{s} = g_{o} + 1.6(1 + \frac{g_{1} }{\sqrt{D}}) \frac{A_{n} }{{c_{s} \mathord{\left/ {\vphantom {c_{s} P_{atm} }} \right. \kern-\nulldelimiterspace} P_{atm} } }
\frac{1}{r_{s} } =g_{s} = g_{o} + 1.6(1 + \frac{g_{1} }{\sqrt{D_{s}}}) \frac{A_{n} }{{c_{s} \mathord{\left/ {\vphantom {c_{s} P_{atm} }} \right. \kern-\nulldelimiterspace} P_{atm} } }

where :math:`r_{s}` is leaf stomatal resistance (s m\ :sup:`2`
:math:`\mu`\ mol\ :sup:`-1`), :math:`g_{o}` is the minimum stomatal conductance
(:math:`\mu` mol m :sup:`-2` s\ :sup:`-1`), :math:`A_{n}` is leaf net
photosynthesis (:math:`\mu`\ mol CO\ :sub:`2` m\ :sup:`-2`
s\ :sup:`-1`), :math:`c_{s}` is the CO\ :sub:`2` partial
pressure at the leaf surface (Pa), :math:`P_{atm}` is the atmospheric
pressure (Pa), and :math:`D` is the vapor pressure deficit at the leaf surface (kPa).
pressure (Pa), and :math:`D_{s}=(e_{i}-e{_s})/1000` is the leaf-to-air vapor pressure difference at the leaf surface (kPa)
where :math:`e_{i}` is the saturation vapor pressure (Pa) evaluated at the leaf temperature
:math:`T_{v}` , and :math:`e_{s}` is the vapor pressure at the leaf surface (Pa).
:math:`g_{1}` is a plant functional type dependent parameter (:numref:`Table Plant functional type (PFT) stomatal conductance parameters`)
and are the same as those used in the CABLE model (:ref:`de Kauwe et al. 2015 <deKauwe2015>`).

Expand Down Expand Up @@ -153,7 +155,7 @@ describe the implementation, modified here. In its simplest form, leaf
net photosynthesis after accounting for respiration (:math:`R_{d}` ) is

.. math::
:label: 9.3
:label: 9.2

A_{n} =\min \left(A_{c} ,A_{j} ,A_{p} \right)-R_{d} .

Expand All @@ -162,7 +164,7 @@ The RuBP carboxylase (Rubisco) limited rate of carboxylation
s\ :sup:`-1`) is

.. math::
:label: 9.4
:label: 9.3

A_{c} =\left\{\begin{array}{l} {\frac{V_{c\max } \left(c_{i} -\Gamma _{\*} \right)}{c_{i} +K_{c} \left(1+{o_{i} \mathord{\left/ {\vphantom {o_{i} K_{o} }} \right. \kern-\nulldelimiterspace} K_{o} } \right)} \qquad {\rm for\; C}_{{\rm 3}} {\rm \; plants}} \\ {V_{c\max } \qquad \qquad \qquad {\rm for\; C}_{{\rm 4}} {\rm \; plants}} \end{array}\right\}\qquad \qquad c_{i} -\Gamma _{\*} \ge 0.

Expand All @@ -171,7 +173,7 @@ RuBP (i.e., the light-limited rate) :math:`A_{j}` (:math:`\mu` \ mol
CO\ :sub:`2` m\ :sup:`-2` s\ :sup:`-1`) is

.. math::
:label: 9.5
:label: 9.4

A_{j} =\left\{\begin{array}{l} {\frac{J_{x}\left(c_{i} -\Gamma _{\*} \right)}{4c_{i} +8\Gamma _{\*} } \qquad \qquad {\rm for\; C}_{{\rm 3}} {\rm \; plants}} \\ {\alpha (4.6\phi )\qquad \qquad {\rm for\; C}_{{\rm 4}} {\rm \; plants}} \end{array}\right\}\qquad \qquad c_{i} -\Gamma _{\*} \ge 0.

Expand All @@ -181,7 +183,7 @@ C\ :sub:`4` plants :math:`A_{p}` (:math:`\mu` \ mol
CO\ :sub:`2` m\ :sup:`-2` s\ :sup:`-1`) is

.. math::
:label: 9.6
:label: 9.5

A_{p} =\left\{\begin{array}{l} {3T_{p\qquad } \qquad \qquad {\rm for\; C}_{{\rm 3}} {\rm \; plants}} \\ {k_{p} \frac{c_{i} }{P_{atm} } \qquad \qquad \qquad {\rm for\; C}_{{\rm 4}} {\rm \; plants}} \end{array}\right\}.

Expand Down Expand Up @@ -212,7 +214,7 @@ photosynthetically active radiation absorbed by the leaf. A common
expression is the smaller of the two roots of the equation

.. math::
:label: 9.7
:label: 9.6

\Theta _{PSII} J_{x}^{2} -\left(I_{PSII} +J_{\max } \right)J_{x}+I_{PSII} J_{\max } =0

Expand All @@ -227,7 +229,7 @@ with 4.6 :math:`\mu`\ mol J\ :sup:`-1`, the light utilized in
electron transport is

.. math::
:label: 9.8
:label: 9.7

I_{PSII} =0.5\Phi _{PSII} (4.6\phi )

Expand All @@ -244,7 +246,7 @@ The model uses co-limitation as described by :ref:`Collatz et al. (1991, 1992)
smaller root of the equations

.. math::
:label: 9.9
:label: 9.8

\begin{array}{rcl} {\Theta _{cj} A_{i}^{2} -\left(A_{c} +A_{j} \right)A_{i} +A_{c} A_{j} } & {=} & {0} \\ {\Theta _{ip} A^{2} -\left(A_{i} +A_{p} \right)A+A_{i} A_{p} } & {=} & {0} \end{array} .

Expand Down Expand Up @@ -282,19 +284,19 @@ The parameters :math:`V_{c\max 25}`,
:math:`T_{v}` (K), as:

.. math::
:label: 9.10
:label: 9.9

\begin{array}{rcl} {V_{c\max } } & {=} & {V_{c\max 25} \; f\left(T_{v} \right)f_{H} \left(T_{v} \right)} \\ {J_{\max } } & {=} & {J_{\max 25} \; f\left(T_{v} \right)f_{H} \left(T_{v} \right)} \\ {T_{p} } & {=} & {T_{p25} \; f\left(T_{v} \right)f_{H} \left(T_{v} \right)} \\ {R_{d} } & {=} & {R_{d25} \; f\left(T_{v} \right)f_{H} \left(T_{v} \right)} \\ {K_{c} } & {=} & {K_{c25} \; f\left(T_{v} \right)} \\ {K_{o} } & {=} & {K_{o25} \; f\left(T_{v} \right)} \\ {\Gamma } & {=} & {\Gamma _{25} \; f\left(T_{v} \right)} \end{array}

.. math::
:label: 9.11
:label: 9.10

f\left(T_{v} \right)=\; \exp \left[\frac{\Delta H_{a} }{298.15\times 0.001R_{gas} } \left(1-\frac{298.15}{T_{v} } \right)\right]

and

.. math::
:label: 9.12
:label: 9.11

f_{H} \left(T_{v} \right)=\frac{1+\exp \left(\frac{298.15\Delta S-\Delta H_{d} }{298.15\times 0.001R_{gas} } \right)}{1+\exp \left(\frac{\Delta ST_{v} -\Delta H_{d} }{0.001R_{gas} T_{v} } \right)} .

Expand All @@ -310,7 +312,7 @@ Because :math:`T_{p}` as implemented here varies with
:math:`V_{c\max}` . For C\ :sub:`4` plants,

.. math::
:label: 9.13
:label: 9.12

\begin{array}{l} {V_{c\max } =V_{c\max 25} \left[\frac{Q_{10} ^{(T_{v} -298.15)/10} }{f_{H} \left(T_{v} \right)f_{L} \left(T_{v} \right)} \right]} \\ {f_{H} \left(T_{v} \right)=1+\exp \left[s_{1} \left(T_{v} -s_{2} \right)\right]} \\ {f_{L} \left(T_{v} \right)=1+\exp \left[s_{3} \left(s_{4} -T_{v} \right)\right]} \end{array}

Expand All @@ -321,15 +323,15 @@ with :math:`Q_{10} =2`,
Additionally,

.. math::
:label: 9.14
:label: 9.13

R_{d} =R_{d25} \left\{\frac{Q_{10} ^{(T_{v} -298.15)/10} }{1+\exp \left[s_{5} \left(T_{v} -s_{6} \right)\right]} \right\}

with :math:`Q_{10} =2`, :math:`s_{5} =1.3`
K\ :sup:`-1` and :math:`s_{6} =328.15`\ K, and

.. math::
:label: 9.15
:label: 9.14

k_{p} =k_{p25} \, Q_{10} ^{(T_{v} -298.15)/10}

Expand Down Expand Up @@ -364,7 +366,7 @@ achieved by allowing :math:`\Delta S`\ to vary with growth temperature
according to

.. math::
:label: 9.16
:label: 9.15

\begin{array}{l} {\Delta S=668.39-1.07(T_{10} -T_{f} )\qquad \qquad {\rm for\; }V_{c\max } } \\ {\Delta S=659.70-0.75(T_{10} -T_{f} )\qquad \qquad {\rm for\; }J_{\max } } \end{array}

Expand All @@ -374,7 +376,7 @@ Additionally, the
ratio :math:`J_{\max 25} /V_{c\max 25}` at 25 :sup:`o`\ C decreases with growth temperature as

.. math::
:label: 9.17
:label: 9.16

J_{\max 25} /V_{c\max 25} =2.59-0.035(T_{10} -T_{f} ).

Expand All @@ -394,7 +396,7 @@ When LUNA is on, the :math:`V_{c\max 25}` for sun leaves is scaled to the shaded


.. math::
:label: 9.18
:label: 9.17

\begin{array}{rcl}
{V_{c\max 25 sha}} & {=} & {V_{c\max 25 sha} \frac{i_{v,sha}}{i_{v,sun}}} \\
Expand All @@ -404,7 +406,7 @@ When LUNA is on, the :math:`V_{c\max 25}` for sun leaves is scaled to the shaded
Where :math:`i_{v,sun}` and :math:`i_{v,sha}` are the leaf-to-canopy scaling coefficients of the twostream radiation model, calculated as

.. math::
:label: 9.19
:label: 9.18

i_{v,sun} = \frac{(1 - e^{-(k_{n,ext}+k_{b,ext})*lai_e)} / (k_{n,ext}+k_{b,ext})}{f_{sun}*lai_e}\\
i_{v,sha} = \frac{(1 - e^{-(k_{n,ext}+k_{b,ext})*lai_e)} / (k_{n,ext}+k_{b,ext})}{(1 - f_{sun})*lai_e}
Expand All @@ -427,14 +429,14 @@ are calculated assuming there is negligible capacity to store
CO\ :sub:`2` and water vapor at the leaf surface so that

.. math::
:label: 9.31
:label: 9.19

A_{n} =\frac{c_{a} -c_{i} }{\left(1.4r_{b} +1.6r_{s} \right)P_{atm} } =\frac{c_{a} -c_{s} }{1.4r_{b} P_{atm} } =\frac{c_{s} -c_{i} }{1.6r_{s} P_{atm} }

and the transpiration fluxes are related as

.. math::
:label: 9.32
:label: 9.20

\frac{e_{a} -e_{i} }{r_{b} +r_{s} } =\frac{e_{a} -e_{s} }{r_{b} } =\frac{e_{s} -e_{i} }{r_{s} }

Expand All @@ -444,21 +446,20 @@ terms 1.4 and 1.6 are the ratios of diffusivity of CO\ :sub:`2` to
H\ :sub:`2`\ O for the leaf boundary layer resistance and stomatal
resistance,
:math:`c_{a} ={\rm CO}_{{\rm 2}} \left({\rm mol\; mol}^{{\rm -1}} \right)`, :math:`P_{atm}`
is the atmospheric CO\ :sub:`2` partial pressure (Pa) calculated
from CO\ :sub:`2` concentration (ppmv), :math:`e_{i}` is the
is the atmospheric pressure (Pa), :math:`e_{i}` is the
saturation vapor pressure (Pa) evaluated at the leaf temperature
:math:`T_{v}` , and :math:`e_{a}` is the vapor pressure of air (Pa).
The vapor pressure of air in the plant canopy :math:`e_{a}` (Pa) is
determined from

.. math::
:label: 9.33
:label: 9.21

e_{a} =\frac{P_{atm} q_{s} }{0.622}

where :math:`q_{s}` is the specific humidity of canopy air (kg
kg\ :sup:`-1`, section :numref:`Sensible and Latent Heat Fluxes and Temperature for Vegetated Surfaces`).
Equations and are solved for
Equations :eq:`9.19` and :eq:`9.20` are solved for
:math:`c_{s}` and :math:`e_{s}`

.. math::
Expand All @@ -471,40 +472,51 @@ Equations and are solved for

e_{s} =\frac{e_{a} r_{s} +e_{i} r_{b} }{r_{b} +r_{s} }

Substitution of equation :eq:`9.35` into equation :eq:`9.1` gives an expression for stomatal
resistance (:math:`r_{s}` ) as a function of photosynthesis
(:math:`A_{n}` ), given here in terms of conductance with
:math:`g_{s} =1/r_{s}` and :math:`g_{b} =1/r_{b}`
In terms of conductance with
:math:`g_{s} =1/r_{s}` and :math:`g_{b} =1/r_{b}`

.. math::
:label: 9.36

g_{s}^{2} + bg_{s} + c = 0
e_{s} =\frac{e_{a} g_{b} +e_{i} g_{s} }{g_{b} +g_{s} } .

where

Substitution of equation :eq:`9.36` into equation :eq:`9.1` gives an expression for the stomatal
resistance
(:math:`r_{s}`) as a function of photosynthesis
(:math:`A_{n}` )

.. math::
:label: 9.37

b = 2(g_{o} * 10^{-6} + d) + \frac{(g_{1}d)^{2}}{g_{b}*10^{-6}D}
ag_{s}^{2} + bg_{s} + c = 0

c = (g_{o}*10^{-6})^{2} + [2g_{o}*10^{-6} + d \frac{1-g_{1}^{2}} {D}]d
where

.. math::
:label: 9.38

\begin{array}{l} a = 1 \\

b = -[2(g_{o} * 10^{-6} + d) + \frac{(g_{1}d)^{2}}{g_{b}*10^{-6}D_{l}}] \\

c = (g_{o}*10^{-6})^{2} + [2g_{o}*10^{-6} + d (1-\frac{g_{1}^{2}} {D_{l}})]d \end{array}

and

.. math::
:label: 9.38
:label: 9.39

d = \frac {1.6 A_{n}} {c_{s} / P_{atm} * 10^{6}}

D = \frac {e_{i} - e_{a}} {1000}
D_{l} = \frac {max(e_{i} - e_{a},50)} {1000}


Stomatal conductance, as solved by equation :eq:`9.36` (mol m :sup:`-2` s :sup:`-1`), is the larger of the two roots that satisfy the
quadratic equation. Values for :math:`c_{i}` are given by

.. math::
:label: 9.39
:label: 9.40

c_{i} =c_{a} -\left(1.4r_{b} +1.6r_{s} \right)P_{atm} A{}_{n}

Expand Down