Surface model

Storyboard

The transfer of particles or molecules, such as CO2, between the atmosphere and the ocean involves a more complex mechanism. This process is associated with the formation of a liquid film saturated with particles or molecules, which regulates the movement of new particles to or from the interior of the ocean.

>Model

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Mechanisms

Definition


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Surface layer

Image

To study the transfer of CO2 at the ocean surface, it is necessary to carefully observe the concentration changes in both the air and the water.

In the air, CO2 enters the water, creating a zone of low concentration where it decreases from $C_a$ to $C_{a,0}$. This layer has a thickness ranging from 0.1 to 1 mm.

The CO2 that enters the water initially accumulates at the surface, creating a concentration $C_{w,0}$, which then diffuses into the interior, reaching a lower concentration of $C_w$.

The concentration reduction allows us to define two zones: a very thin one, ranging from 0.02 to 0.2 mm, where the concentration decreases rapidly, and a second zone, spanning from 0.6 to 2 mm, where the concentration decreases more gradually until it reaches the concentration within the water.

Ocean-Atmosphere Interactions of Gases and Particles, Peter S. Liss, Martin T. Johnson (eds.), Springer-Verlag Berlin Heidelberg

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CO2 exchange, speed from water

Note

The gas transfer rate in water ($k_w$) can be modeled using measured data. Firstly, it depends on the rate at which the system removes carbon from the air-water interface, making the transport speed proportional to the relative velocity between the two mediums.

Secondly, there is an effect of ion mobility, which can be described by the schmidt number ($Sc$), representing the relationship between momentum diffusion and particles. However, this dependence is not linear and is influenced by a factor ERROR:9926 that varies between -1/2 and -2/3 depending on the surface roughness.

Finally, the gas transfer rate in water ($k_w$) also depends on the factor beta del transporte aire a agua de CO2 ($\beta$), which in turn is determined by the level of surface roughness.

In summary, the gas the gas transfer rate in water ($k_w$) is described as a function of the velocidad del agua ($u_w$), the velocidad del aire ($u_a$), the schmidt number ($Sc$), the factor beta del transporte aire a agua de CO2 ($\beta$), and ERROR:9926 as follows:

$ k_w = ( u_a - u_w ) \beta Sc ^ n $

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Solubility as a function of Schmidt number

Quote

The mobility of molecules, represented by the gas solubility ($\alpha$), is modeled as a function of particle concentration, characterized by the schmidt number ($Sc$), which in turn is calculated from parameters the viscosidad en masa acuosa ($\eta$), the densidad en capa de masa acuosa ($\rho$), and the constante de difusión en masa acuosa ($D$) using the following expression:

$ Sc =\displaystyle\frac{ \eta }{ \rho D }$



This relationship is visualized in the following diagram:

Ocean-Atmosphere Interactions of Gases and Particles, Peter S. Liss, Martin T. Johnson (eds.), Springer-Verlag Berlin Heidelberg

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Transfer speed

Exercise

The gas transfer rate in air ($k_a$) can be estimated from Fick's law by comparing the constante de difusión en masa acuosa ($D$) with the grosor de la capa superficial ($\delta_c$) as follows:

$ k_a = \displaystyle\frac{ D }{ \delta_c }$

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Transfer speed and resistances

Equation

For the interaction between the atmosphere and the ocean, the air to water transfer resistance of a gas ($R_{ta}$) initially encompasses the transfer resistance in water ($R_w$), followed by the evaporation process $1/\alpha$ with the gas solubility ($\alpha$), and once the gas has passed into the air, the transfer resistance in air ($R_a$) acts upon it:

$ R_{ta} = R_a + \displaystyle\frac{1}{ \alpha } R_w $



Meanwhile, in the interaction between the atmosphere and the ocean, the water to air transfer resistance of a gas ($R_{tw}$) initially includes the transfer resistance in air ($R_a$), followed by the gas solubility ($\alpha$), and once the gas has penetrated the water, the transfer resistance in water ($R_w$) comes into play:

$ R_{tw} = R_w + \alpha R_a $



With these equations, we can formulate the relationships for the transfer velocities.

Therefore, using the total transfer rate of gas in air ($k_{ta}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), we establish the following relationship:

$ \displaystyle\frac{1}{ k_{ta} } = \displaystyle\frac{1}{ k_a } + \displaystyle\frac{1}{ \alpha k_w } $



On the other hand, with the total transfer rate of gas in water ($k_{tw}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), we establish that:

$ \displaystyle\frac{1}{ k_{tw} } = \displaystyle\frac{1}{ k_w } + \displaystyle\frac{ \alpha }{ k_a } $

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Model

Script


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Surface model

Storyboard

The transfer of particles or molecules, such as CO2, between the atmosphere and the ocean involves a more complex mechanism. This process is associated with the formation of a liquid film saturated with particles or molecules, which regulates the movement of new particles to or from the interior of the ocean.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$R_{ta}$
R_ta
Air to water transfer resistance of a gas
s/m
$D$
D
Constante de difusión en masa acuosa
m/s^2
$n$
n
Exponente de Schmidt
-
$\beta$
beta
Factor beta del transporte aire a agua de CO2
-
$C_{a,0}$
C_a0
Gas concentration in the atmosphere
1/m^3
$C_{w,0}$
C_w0
Gas concentration in water
1/m^3
$\alpha$
alpha
Gas solubility
-
$k_a$
k_a
Gas transfer rate in air
m/s
$k_w$
k_w
Gas transfer rate in water
m/s
$\delta_c$
delta_c
Grosor de la capa superficial
m
$Sc$
Sc
Schmidt number
-
$k_{ta}$
k_ta
Total transfer rate of gas in air
m/s
$k_{tw}$
k_tw
Total transfer rate of gas in water
m/s
$R_a$
R_a
Transfer resistance in air
s/m
$R_w$
R_w
Transfer resistance in water
s/m
$u_w$
u_w
Velocidad del agua
m/s
$u_a$
u_a
Velocidad del aire
m/s
$R_{tw}$
R_tw
Water to air transfer resistance of a gas
s/m

Calculations


First, select the equation:   to ,  then, select the variable:   to 

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations

The relationship involving the air to water transfer resistance of a gas ($R_{ta}$), determined by the combination of the transfer resistance in water ($R_w$), the transfer resistance in air ($R_a$), and the gas solubility ($\alpha$), is formulated in the equation:

equation=12240

This includes the relationship of the transfer resistance in air ($R_a$) with the gas transfer rate in air ($k_a$) expressed in:

equation=12236

Additionally, the interaction of the transfer resistance in water ($R_w$) with the gas transfer rate in water ($k_w$) is explained in:

equation=12237

And the connection between the air to water transfer resistance of a gas ($R_{ta}$) and the total transfer rate of gas in air ($k_{ta}$) is specified in:

equation=12239

These elements together provide the basis for defining the relationship for the total transfer rate of gas in air ($k_{ta}$):

equation

The relationship between the water to air transfer resistance of a gas ($R_{tw}$), established through the sums of the transfer resistance in water ($R_w$), the transfer resistance in air ($R_a$), and the gas solubility ($\alpha$), is expressed in the equation:

equation=12241

Including the relationship of the transfer resistance in air ($R_a$) with the gas transfer rate in air ($k_a$) in:

equation=12236

The interaction of the transfer resistance in water ($R_w$) with the gas transfer rate in water ($k_w$) is described in:

equation=12237

And the connection between the water to air transfer resistance of a gas ($R_{tw}$) and the total transfer rate of gas in water ($k_{tw}$) is detailed in:

equation=12238

This provides the basis for establishing the relationship for the total transfer rate of gas in water ($k_{tw}$):

equation


Examples


mechanisms

To study the transfer of CO2 at the ocean surface, it is necessary to carefully observe the concentration changes in both the air and the water.

In the air, CO2 enters the water, creating a zone of low concentration where it decreases from $C_a$ to $C_{a,0}$. This layer has a thickness ranging from 0.1 to 1 mm.

The CO2 that enters the water initially accumulates at the surface, creating a concentration $C_{w,0}$, which then diffuses into the interior, reaching a lower concentration of $C_w$.

The concentration reduction allows us to define two zones: a very thin one, ranging from 0.02 to 0.2 mm, where the concentration decreases rapidly, and a second zone, spanning from 0.6 to 2 mm, where the concentration decreases more gradually until it reaches the concentration within the water.

image

The gas transfer rate in water ($k_w$) can be modeled using measured data. Firstly, it depends on the rate at which the system removes carbon from the air-water interface, making the transport speed proportional to the relative velocity between the two mediums.

Secondly, there is an effect of ion mobility, which can be described by the schmidt number ($Sc$), representing the relationship between momentum diffusion and particles. However, this dependence is not linear and is influenced by a factor ERROR:9926 that varies between -1/2 and -2/3 depending on the surface roughness.

Finally, the gas transfer rate in water ($k_w$) also depends on the factor beta del transporte aire a agua de CO2 ($\beta$), which in turn is determined by the level of surface roughness.

In summary, the gas the gas transfer rate in water ($k_w$) is described as a function of the velocidad del agua ($u_w$), the velocidad del aire ($u_a$), the schmidt number ($Sc$), the factor beta del transporte aire a agua de CO2 ($\beta$), and ERROR:9926 as follows:

equation=12215

The mobility of molecules, represented by the gas solubility ($\alpha$), is modeled as a function of particle concentration, characterized by the schmidt number ($Sc$), which in turn is calculated from parameters the viscosidad en masa acuosa ($\eta$), the densidad en capa de masa acuosa ($\rho$), and the constante de difusión en masa acuosa ($D$) using the following expression:

equation=12216

This relationship is visualized in the following diagram:

image

The gas transfer rate in air ($k_a$) can be estimated from Fick's law by comparing the constante de difusión en masa acuosa ($D$) with the grosor de la capa superficial ($\delta_c$) as follows:

equation=12227

For the interaction between the atmosphere and the ocean, the air to water transfer resistance of a gas ($R_{ta}$) initially encompasses the transfer resistance in water ($R_w$), followed by the evaporation process $1/\alpha$ with the gas solubility ($\alpha$), and once the gas has passed into the air, the transfer resistance in air ($R_a$) acts upon it:

equation=12240

Meanwhile, in the interaction between the atmosphere and the ocean, the water to air transfer resistance of a gas ($R_{tw}$) initially includes the transfer resistance in air ($R_a$), followed by the gas solubility ($\alpha$), and once the gas has penetrated the water, the transfer resistance in water ($R_w$) comes into play:

equation=12241

With these equations, we can formulate the relationships for the transfer velocities.

Therefore, using the total transfer rate of gas in air ($k_{ta}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), we establish the following relationship:

equation=12242

On the other hand, with the total transfer rate of gas in water ($k_{tw}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), we establish that:

equation=12243


model

The concentration gradient between the gas concentration in the atmosphere ($C_{a,0}$) and the gas concentration in water ($C_{w,0}$) depends on the gas solubility ($\alpha$). Therefore, the following relationship is established:

kyon

The gas transfer rate in air ($k_a$) can be estimated from Fick's law by comparing the constante de difusión en masa acuosa ($D$) with the grosor de la capa superficial ($\delta_c$) as follows:

kyon

The gas parameter the gas transfer rate in water ($k_w$) is described in terms of the velocidad del agua ($u_w$), the velocidad del aire ($u_a$), the schmidt number ($Sc$), the factor beta del transporte aire a agua de CO2 ($\beta$), and ERROR:9926 as follows:

kyon

The transfer resistance in air ($R_a$) is defined as the inverse of the gas transfer rate in air ($k_a$). This relationship can be expressed as follows:

kyon

The transfer resistance in water ($R_w$) is defined as the inverse of the gas transfer rate in water ($k_w$). This relationship can be expressed as follows:

kyon

The water to air transfer resistance of a gas ($R_{tw}$) is defined as the inverse of the total transfer rate of gas in water ($k_{tw}$). This relationship can be expressed as follows:

kyon

The air to water transfer resistance of a gas ($R_{ta}$) is defined as the inverse of the total transfer rate of gas in air ($k_{ta}$). This relationship can be expressed as follows:

kyon

For the interaction between the atmosphere and the ocean, the air to water transfer resistance of a gas ($R_{ta}$) initially includes the transfer resistance in water ($R_w$), followed by the evaporation process $1/\alpha$ with the gas solubility ($\alpha$). Once the gas has transferred to the air, the transfer resistance in air ($R_a$) acts on it:

kyon

For the interaction between the atmosphere and the ocean, the water to air transfer resistance of a gas ($R_{tw}$) initially includes the transfer resistance in air ($R_a$), followed by the gas solubility ($\alpha$), and once the gas has penetrated the water, the transfer resistance in water ($R_w$) acts:

kyon

The relationship between the transfer resistance between the atmosphere and the ocean can be expressed in terms of the transfer speeds in both mediums, equating to the inverse of the total transfer speed.

Therefore, with the total transfer rate of gas in water ($k_{tw}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), it is established that:

kyon

The relationship of the transfer resistance between the ocean and the atmosphere can be expressed in terms of the transfer speeds in both mediums, corresponding to the inverse of the total transfer speed.

Thus, using the total transfer rate of gas in air ($k_{ta}$), the gas transfer rate in water ($k_w$), the gas transfer rate in air ($k_a$), and the gas solubility ($\alpha$), the following relationship is established:

kyon


>Model

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