Calculating atmospheric IR absorption Journal Title XX(X):1–7 The Author(s) 0000 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/ToBeAssigned www.sagepub.com/ SAGE Dr Barry D.O. Adams 1 Abstract In this work, we present a program to numerical integrate the atmospheric absorption due to carbon dioxide and water vapour of infrared photons by the atmosphere. Keywords Global Warming, Carbon Dioxide, Water Vapour Introduction In recent years, the hypothesis that human released carbon dioxide will warm planet earth has become an huge issue. There is naturally a large body of work in it. However very few of the calculation tools for the issue are released as open source. In this work we present a program and it results to numerical integrate carbon dioxide and water vapour absorption over frequency, latitude and height, producing a percentage absorption amount for the two green house gases. Input Absorption Lines Spectra absorption lines for many molecules are available on the HITRAN database online. We are interest in the strongest lines for absorbtion by the molecules with the most common isotopes from the ground state, since it is the ground state is far more common than the higher levels. Download the HITRAN frequency, upper and lower quantum states, with the Einstein A Coefficient that gives the absorption strength of the lines. Using the line intersity S, from HITRAN we order the lines from strongest to weakest, and select those starting This work was self funded, Dr Adams is employed in a Back End Developer Role not related to this work Corresponding author: Email: [email protected] Prepared using sagej.cls [Version: 2017/01/17 v1.20]
Global Warming Paper - Draft 1
Mar 22, 2022
Integrations over H20 and CO2 HITRAN lines to determine Infrared absorption in Watts. New Insight and Discussion on effect of Rainfall on Climate Sensitivity
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Journal Title XX(X):1–7 ©The Author(s) 0000 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/ToBeAssigned www.sagepub.com/
SAGE
Dr Barry D.O. Adams1
Abstract In this work, we present a program to numerical integrate the atmospheric absorption due to carbon dioxide and water vapour of infrared photons by the atmosphere.
Keywords Global Warming, Carbon Dioxide, Water Vapour
Introduction
In recent years, the hypothesis that human released carbon dioxide will warm planet earth has become an huge issue. There is naturally a large body of work in it. However very few of the calculation tools for the issue are released as open source. In this work we present a program and it results to numerical integrate carbon dioxide and water vapour absorption over frequency, latitude and height, producing a percentage absorption amount for the two green house gases.
Input Absorption Lines
Spectra absorption lines for many molecules are available on the HITRAN database online. We are interest in the strongest lines for absorbtion by the molecules with the most common isotopes from the ground state, since it is the ground state is far more common than the higher levels. Download the HITRAN frequency, upper and lower quantum states, with the Einstein A Coefficient that gives the absorption strength of the lines. Using the line intersity S, from HITRAN we order the lines from strongest to weakest, and select those starting
This work was self funded, Dr Adams is employed in a Back End Developer Role not related to this work
Corresponding author:
Email: [email protected]
2 Journal Title XX(X)
Table 1. The most prominent absorption lines from ground state
Molecule Wave-number (cm−1) Einstein Coefficient A upper state multiplicity upper state line width air at 1atm nair
CO2 2349.91 140.7 3 v1 = 0,v2 = 0, i2 = 1, v3 = 1, J = 1, r = 1 0.0949 0.69 CO2 686.16 1.023 3 v1 = 0,v2 = 1, i2 = 1, J = 1, r = 1 0.0949 0.69 CO2 3716.56 5.903 3 v1 = 1,v2 = 1, i2 = 0, J = 1, r = 1 0.0949 0.69 H2O 1634.96 7.599 3 v1 = 0, v2 = 1, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1026 0.74 H2O 3693.29 1.031 3 v1 = 1, v2 = 0, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1049 0.71 H2O 3196.09 0.1982 3 v1 = 0, v2 = 2, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1038 0.57 H2O 1601.34 14.79 3 v1 = 0, v2 = 2, v3 = 0, J = 1, Ka = 1, Kc = 1 0.0975 0.61
at ground strength. We find 3 lines for carbon dioxide and 4 for water, and present them in the table below. Where the wave number ν is the frequency divided by the speed of light c
ν = 1
c (1)
Required Equations
The Intensity of radiation in the presence of an absorber is, [2]
I = I0e −NαL (2)
Where N is number density of the absorbing molecule, L the length of the absorbing region, and α the cross section of absorbtion. Tokmakoff also gives for a single spectral line,
α = hν
c B12 (3)
Where ν is the frequency, and B is the Einstein B coefficient. HITRAN gives us the Einstein A coefficent, which is related to B (at equilibrium) by [6]
A21 = 8πhν3
and B12 =
gu gl
B21 (5)
The ratio of lower to upper transition to the upper to lower transition is the ratio of the number of quantum states in the upper and lower states. So
α(ν)ν = c2
8πν2 guA21 (6)
Of course we need the spectral lines for each absorber, labelled M , so
I = I0e −L
) (7)
The input intensity is the Planck Radiation Law of EM emission from a surface at temperature T, [3]
Prepared using sagej.cls
− 1 (8)
The width of the spectra line is commonly approximated as a Lorenzian, due to Natural and Collusional broadaning. [4] In fact the Lorenz shape estimate the tail of absorption, and is often cut off at the edges, but we will not do that here. In HITRAN [5] units, we lose the factor of 4π2 and the line width is proportional to the pressure P , Γ = Pγ, of the line width in table 1.
(ν) = 1
(ν − ν0)2 + Γ2 (9)
Then ν can be approximately the line width Γ HITRAN [5] approximates the line widthΓ for air to
Γ(p, T ) = (fracTrefT ) nair γairp] (10)
So now we have the absorption equation for surface temperature T and Pressure P at each height, so need a model of earths surface temperature and latitude θ, and atmospheric pressure at height h, to complete our input equations. To begin with we will average the temperature over day and night, we need a rough input function of latitude that provides an average surface air temperature, we find this Fuelner at al /citeFeulner, as graph Fig 5, we copy the data for Observations from 1961-1990 which we approcimate place the data points for each 10 degree latitude in the table below. We will then interpolate begin the given points to provide a programmatic function to give a value for any latitude. Given the Pressure P0 and Temperature T0 at the Earths surface we can
find the temperature, T (h) and pressure a P (h) a height h, using a Barometric formula, we use Lente and Osz’s formule [8]
P (h) =
P 1
ν+1
) (12)
where R is the gas constant, RE is the radius of the Earth, m is the mass density of air M = mNA is the molar mass of air. NA IS Avogaro’s constant, g is acceleration due to gravity at the surface, K is Boltzmann’s constant, v is the number of degree of freedom of the average molecule in air ν ≈ 5/2, and m is mass density of air. The formula works to about 30Km, which is around 4 e-folds of exponentionly growth, as the scale height of air pressure is around 7Km. For pressure we just take the average surface pressure a earth surface. The
above equations are enough for CO2 but for water, we need the humdity in the
Prepared using sagej.cls
atmosphere. We assume constant relative humanity the August Roche Magnus equation [9].
Ph20 = 0.61094exp
) (13)
With T in Kelvin. Then the idea gas law will give the density of water vapour.
Results of absorption integration
We release the source code of our calculation at GitHub [10]. We step in 10 meter intervals to 25km, frequencies between 1011 and 3 ∗ 1015 in steps of 105, and a hundred steps in latitude, integrating triply using Simpsons law. We use C02 concentrations from 100 to 1200 and plot the graph of individual and combined contributions from the two gases. It takes around 6 hours on typical modern PC. We find that CO2 matches similar results, but H20 is some six time lower than modern estimates of water which is considered to the primary green house gases at 60% of the total absorption. Green, Newman et al [11], state the individual lines from HITRAN do not well fit the absorption for water vapour, instead a sum of long tails of weaker lines, makes up most of the absorption, and ”however, there is no universally accepted underlying physical model for the source of the continuum absorption.” In our results we find that doubling CO2 from 400ppvm to 800ppvm increases total absorption by 1.1Wm−2, one point one, Watts per square meter. See the figure.
Prepared using sagej.cls
1
2
3
4
5
6
7
Absorb C02 Watts
Absorb H20 Watts
Absorb Both Watts
Table 2. Reconstructed 1961-1990 Average Surface Air Temperature By Latitude
Latitude Temperature Celsius -90 -20 -80 -15 -70 -8 -60 -1 -50 10 -40 16 -30 20 -20 24 -10 26 0 27 10 27 20 25 30 20 40 17 50 7 60 -1 70 -8 80 -15 90 -17
Climate Sensitivity and Rainfall
The usual model of climate sensitivity is to use the Stefan Boltzmann equation to assume the increase in heat absorption all goes into the the heat balance between incoming and outgoing radiation [12]
F2xCO2 =
dF
= 4σT 3T2xCO2 (14)
However we see an additional heat lose mechanism evaporation. At present an average rainfall of 39inch lands upon the earth surface annually [13]. But rainfall increases 7% for each degree warmer it gets [14]. Using the mean temperature of 17.5, and the usual heat of vaporization of water. So multiply the volume of water falling per square meter, 970kg, the specific heat of water times the average 82.5 degree heating plus the heat of vaporization, gets 2.526GJ per year, or 80.11 Watts per square meter, we call Eevap. Adding the increase in rainfall to the energy balance derivative equation gives.
T2xCO2 =
F
4σT 3 + 0.07 ∗ Eevapexp(T − 17.5) ∗ 0.07) (15)
For our 1.1 Watts of additional CO2 absorption from doubling CO2, we get a warming of just .17C. This five times lower than the [12] Climate sensitivity, and we thus find it would make little difference to the modern world to continue Carbon emissions at current levels.
Prepared using sagej.cls
//sites.google.com/site/puenggphysics/home/unit-i/
uchicago.edu/~tokmakoff/TDQMS/Notes/4.3._Abs_Cross-Sec_
2-12-08.pdf
[3] Britannica, T. Editors of Encyclopaedia (Invalid Date). Planck’s radiation law. Encyclopedia Britannica. https://www.britannica.com/science/
Plancks-radiation-law
[4] Kenneth Wood,University of St Andrews , Nebalae, Lecture 8, Line Widths http://www-star.st-and.ac.uk/~kw25/teaching/nebulae/
lecture08_linewidths.pdf
definitions-and-units/
publications/2006-EinsteinA-JQSRT-98.pdf
[7] G. Feulner, S. Rahmstorf, A. Levermann, S. Volkwardt, On the Origin of Surface Air Temperature Difference between Hemispheres in the Earth’s Present-Day Climate, pg 7136-7130 Vol 26 Jounral of Climate (2013)
[8] Lente, G., Osz, K. Barometric formulas: various derivations and comparisons to environmentally relevant observations. ChemTexts 6, 13 (2020). https://doi.org/10.1007/s40828-020-0111-6
[9] https://en.wikipedia.org/wiki/Vapour_pressure_of_water
[10] https://github.com/badams77-cpu/agw
[11] Recent advances in measurement of the water vapour continuum in the far-infrared spectral region Paul D. Green , Stuart M. Newman , Ralph J. Beeby , Jonathan E. Murray , Juliet C. Pickering and John E. Harries June 2012 https://doi.org/10.1098/rsta.2011.0263
[12] https://en.wikipedia.org/wiki/Climate_sensitivity
[13] https://en.wikipedia.org/wiki/Earth_rainfall_climatology
[14] https://phys.org/news/2018-05-higher-temperature-heavier.html
SAGE
Dr Barry D.O. Adams1
Abstract In this work, we present a program to numerical integrate the atmospheric absorption due to carbon dioxide and water vapour of infrared photons by the atmosphere.
Keywords Global Warming, Carbon Dioxide, Water Vapour
Introduction
In recent years, the hypothesis that human released carbon dioxide will warm planet earth has become an huge issue. There is naturally a large body of work in it. However very few of the calculation tools for the issue are released as open source. In this work we present a program and it results to numerical integrate carbon dioxide and water vapour absorption over frequency, latitude and height, producing a percentage absorption amount for the two green house gases.
Input Absorption Lines
Spectra absorption lines for many molecules are available on the HITRAN database online. We are interest in the strongest lines for absorbtion by the molecules with the most common isotopes from the ground state, since it is the ground state is far more common than the higher levels. Download the HITRAN frequency, upper and lower quantum states, with the Einstein A Coefficient that gives the absorption strength of the lines. Using the line intersity S, from HITRAN we order the lines from strongest to weakest, and select those starting
This work was self funded, Dr Adams is employed in a Back End Developer Role not related to this work
Corresponding author:
Email: [email protected]
2 Journal Title XX(X)
Table 1. The most prominent absorption lines from ground state
Molecule Wave-number (cm−1) Einstein Coefficient A upper state multiplicity upper state line width air at 1atm nair
CO2 2349.91 140.7 3 v1 = 0,v2 = 0, i2 = 1, v3 = 1, J = 1, r = 1 0.0949 0.69 CO2 686.16 1.023 3 v1 = 0,v2 = 1, i2 = 1, J = 1, r = 1 0.0949 0.69 CO2 3716.56 5.903 3 v1 = 1,v2 = 1, i2 = 0, J = 1, r = 1 0.0949 0.69 H2O 1634.96 7.599 3 v1 = 0, v2 = 1, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1026 0.74 H2O 3693.29 1.031 3 v1 = 1, v2 = 0, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1049 0.71 H2O 3196.09 0.1982 3 v1 = 0, v2 = 2, v3 = 0, J = 1, Ka = 1, Kc = 1 0.1038 0.57 H2O 1601.34 14.79 3 v1 = 0, v2 = 2, v3 = 0, J = 1, Ka = 1, Kc = 1 0.0975 0.61
at ground strength. We find 3 lines for carbon dioxide and 4 for water, and present them in the table below. Where the wave number ν is the frequency divided by the speed of light c
ν = 1
c (1)
Required Equations
The Intensity of radiation in the presence of an absorber is, [2]
I = I0e −NαL (2)
Where N is number density of the absorbing molecule, L the length of the absorbing region, and α the cross section of absorbtion. Tokmakoff also gives for a single spectral line,
α = hν
c B12 (3)
Where ν is the frequency, and B is the Einstein B coefficient. HITRAN gives us the Einstein A coefficent, which is related to B (at equilibrium) by [6]
A21 = 8πhν3
and B12 =
gu gl
B21 (5)
The ratio of lower to upper transition to the upper to lower transition is the ratio of the number of quantum states in the upper and lower states. So
α(ν)ν = c2
8πν2 guA21 (6)
Of course we need the spectral lines for each absorber, labelled M , so
I = I0e −L
) (7)
The input intensity is the Planck Radiation Law of EM emission from a surface at temperature T, [3]
Prepared using sagej.cls
− 1 (8)
The width of the spectra line is commonly approximated as a Lorenzian, due to Natural and Collusional broadaning. [4] In fact the Lorenz shape estimate the tail of absorption, and is often cut off at the edges, but we will not do that here. In HITRAN [5] units, we lose the factor of 4π2 and the line width is proportional to the pressure P , Γ = Pγ, of the line width in table 1.
(ν) = 1
(ν − ν0)2 + Γ2 (9)
Then ν can be approximately the line width Γ HITRAN [5] approximates the line widthΓ for air to
Γ(p, T ) = (fracTrefT ) nair γairp] (10)
So now we have the absorption equation for surface temperature T and Pressure P at each height, so need a model of earths surface temperature and latitude θ, and atmospheric pressure at height h, to complete our input equations. To begin with we will average the temperature over day and night, we need a rough input function of latitude that provides an average surface air temperature, we find this Fuelner at al /citeFeulner, as graph Fig 5, we copy the data for Observations from 1961-1990 which we approcimate place the data points for each 10 degree latitude in the table below. We will then interpolate begin the given points to provide a programmatic function to give a value for any latitude. Given the Pressure P0 and Temperature T0 at the Earths surface we can
find the temperature, T (h) and pressure a P (h) a height h, using a Barometric formula, we use Lente and Osz’s formule [8]
P (h) =
P 1
ν+1
) (12)
where R is the gas constant, RE is the radius of the Earth, m is the mass density of air M = mNA is the molar mass of air. NA IS Avogaro’s constant, g is acceleration due to gravity at the surface, K is Boltzmann’s constant, v is the number of degree of freedom of the average molecule in air ν ≈ 5/2, and m is mass density of air. The formula works to about 30Km, which is around 4 e-folds of exponentionly growth, as the scale height of air pressure is around 7Km. For pressure we just take the average surface pressure a earth surface. The
above equations are enough for CO2 but for water, we need the humdity in the
Prepared using sagej.cls
atmosphere. We assume constant relative humanity the August Roche Magnus equation [9].
Ph20 = 0.61094exp
) (13)
With T in Kelvin. Then the idea gas law will give the density of water vapour.
Results of absorption integration
We release the source code of our calculation at GitHub [10]. We step in 10 meter intervals to 25km, frequencies between 1011 and 3 ∗ 1015 in steps of 105, and a hundred steps in latitude, integrating triply using Simpsons law. We use C02 concentrations from 100 to 1200 and plot the graph of individual and combined contributions from the two gases. It takes around 6 hours on typical modern PC. We find that CO2 matches similar results, but H20 is some six time lower than modern estimates of water which is considered to the primary green house gases at 60% of the total absorption. Green, Newman et al [11], state the individual lines from HITRAN do not well fit the absorption for water vapour, instead a sum of long tails of weaker lines, makes up most of the absorption, and ”however, there is no universally accepted underlying physical model for the source of the continuum absorption.” In our results we find that doubling CO2 from 400ppvm to 800ppvm increases total absorption by 1.1Wm−2, one point one, Watts per square meter. See the figure.
Prepared using sagej.cls
1
2
3
4
5
6
7
Absorb C02 Watts
Absorb H20 Watts
Absorb Both Watts
Table 2. Reconstructed 1961-1990 Average Surface Air Temperature By Latitude
Latitude Temperature Celsius -90 -20 -80 -15 -70 -8 -60 -1 -50 10 -40 16 -30 20 -20 24 -10 26 0 27 10 27 20 25 30 20 40 17 50 7 60 -1 70 -8 80 -15 90 -17
Climate Sensitivity and Rainfall
The usual model of climate sensitivity is to use the Stefan Boltzmann equation to assume the increase in heat absorption all goes into the the heat balance between incoming and outgoing radiation [12]
F2xCO2 =
dF
= 4σT 3T2xCO2 (14)
However we see an additional heat lose mechanism evaporation. At present an average rainfall of 39inch lands upon the earth surface annually [13]. But rainfall increases 7% for each degree warmer it gets [14]. Using the mean temperature of 17.5, and the usual heat of vaporization of water. So multiply the volume of water falling per square meter, 970kg, the specific heat of water times the average 82.5 degree heating plus the heat of vaporization, gets 2.526GJ per year, or 80.11 Watts per square meter, we call Eevap. Adding the increase in rainfall to the energy balance derivative equation gives.
T2xCO2 =
F
4σT 3 + 0.07 ∗ Eevapexp(T − 17.5) ∗ 0.07) (15)
For our 1.1 Watts of additional CO2 absorption from doubling CO2, we get a warming of just .17C. This five times lower than the [12] Climate sensitivity, and we thus find it would make little difference to the modern world to continue Carbon emissions at current levels.
Prepared using sagej.cls
//sites.google.com/site/puenggphysics/home/unit-i/
uchicago.edu/~tokmakoff/TDQMS/Notes/4.3._Abs_Cross-Sec_
2-12-08.pdf
[3] Britannica, T. Editors of Encyclopaedia (Invalid Date). Planck’s radiation law. Encyclopedia Britannica. https://www.britannica.com/science/
Plancks-radiation-law
[4] Kenneth Wood,University of St Andrews , Nebalae, Lecture 8, Line Widths http://www-star.st-and.ac.uk/~kw25/teaching/nebulae/
lecture08_linewidths.pdf
definitions-and-units/
publications/2006-EinsteinA-JQSRT-98.pdf
[7] G. Feulner, S. Rahmstorf, A. Levermann, S. Volkwardt, On the Origin of Surface Air Temperature Difference between Hemispheres in the Earth’s Present-Day Climate, pg 7136-7130 Vol 26 Jounral of Climate (2013)
[8] Lente, G., Osz, K. Barometric formulas: various derivations and comparisons to environmentally relevant observations. ChemTexts 6, 13 (2020). https://doi.org/10.1007/s40828-020-0111-6
[9] https://en.wikipedia.org/wiki/Vapour_pressure_of_water
[10] https://github.com/badams77-cpu/agw
[11] Recent advances in measurement of the water vapour continuum in the far-infrared spectral region Paul D. Green , Stuart M. Newman , Ralph J. Beeby , Jonathan E. Murray , Juliet C. Pickering and John E. Harries June 2012 https://doi.org/10.1098/rsta.2011.0263
[12] https://en.wikipedia.org/wiki/Climate_sensitivity
[13] https://en.wikipedia.org/wiki/Earth_rainfall_climatology
[14] https://phys.org/news/2018-05-higher-temperature-heavier.html
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