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Ozone Abundance in Earth-like Planets

NTNU Earth Science Department

Shung-wen Hsu

Supervisor： Gu, Pin-Gao

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Outline

• Introduction

• About OZONE LAYER

• The SIMULATION

• Comparing to the Franck Selsis Paper

• Conclusion & Future work

Introduction

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Early Earth Atmosphere• The atmosphere formed when the core, mantle, and

crust differentiated.

• DEGAS with differentiate -- gas released form the Earth.• The original composition in the early Earth atmosphere

is : H2O、 H2、 HCl、 CO、 CO2、 N2…etc

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Index of Life?

• How to find the other life on other planets?

• By oxygen?• We can not be detected oxygen in

planet spectra, but we can detect Ozone.

• Finding creatures live on the land…?

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About OZONE LAYER

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The Stratosphere• Altitude : 10 ~ 50 km• Stable inversion layer

Thermosphere

Mesosphere

Stratosphere

Troposphere

• Locate at the stratosphere

• Heating the atmosphere and cause the inversion layer.

The Ozone layer

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The Formation of Ozone Layer

• Chapman Equations

• Reaction rate :• Fast : (1)、 (3)• Slow : (2)、 (4)• Very slow : (5)

• Timescale between

Chemistry and Transport (dynamical) .

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The Formation of Ozone Layer II• For simplify the equation, we take off the slow

reaction.

• Finally, we got this :

K1/k2 is an inverse ratio to temperature.

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Simulation

• Fortran program

• Isothermal Simulation

• Dynamic Equilibrium Simulation

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Isothermal Simulation• Assume :1. Each layer is well mixed.2. Each layer is independent ( no vertical convection

and heat transport) .3. The ozone do not heat or cool the atmosphere.4. The radiation from the ground does not be

considered.

K1/k2 is an inverse ratio to temperature.

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Isothermal Ozone Abundance

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O3 mixing ratio

• Mixing ratio air

O3

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F、 G、 K star spectra

A Stellar Spectral Flux Library: 1150 - 25000 A (Pickles 1998)

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Different Stellar Spectra in Isothermal Simulation

• We can only find that the F2V star causes higher ozone at altitude above 30km.

• The O3 mixing ratio of G2V is almost the same with the K2V.

• => We can’t get information from isothermal simulation.

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Dynamic Equilibrium Simulation• Assume :1.Each layer is well mixed.2.Each layer is independent.3.The heating effect is caused by ozone

only, and the cooling effect is caused by CO2 only. And I assume heating is equal to cooling in this simulation.

4.The radiation from the ground does not be considered.

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Heating & Cooling Rate

• Heating : caused from ozone absorb and transform UV into thermal energy.

• Cooling : caused from CO2 thermal emission to the space.

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Dynamic Equilibrium Simulation Result I

•Highest temperature

– 305k, 52km.

•The trend of the temperature maybe correct.

•The temperature difference between is much larger in the dynamic equilibrium simulation than a observed data.

Temperature Profile -- Solar Flux

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Dynamic Equilibrium Simulation Result I

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Result II – F,G,K type

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Result II – F,G,K type

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K1/k2 is an inverse ratio to temperature.

So, temperature is high, this effect will cause the [O3] drop, and oppositely, when the temperature is low, the [O3] will be more.

This effect seems to dominate my simulation!!

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Result II – F,G,K type

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Paper of Franck Selsis• DARWIN And The Atmosphere of Terrestrial Planets

K-type,low temperature, high ozone

F-type,High temperature, low ozone

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The Selsis Simulation Spectra of

Planets

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Conclusion & Future Work

• A lot of aspects do not be considered in my simulation, Ex. Scattering、 O3 cooling effect、 catalytic reaction、 incorrect UV flux…etc.

• Make the code complete, and expect the program could reflect the properties of earth-like planet atmosphere more precisely.

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The End

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Evidence in Geology

• Banded iron accumulated between about 1.9 to 3.5 billion years ago.

• Banded iron – the mineral which have not oxidized completely.

• Banded iron can not be found in the rock younger than 1.9 billion year. Banded iron