earth evolution - cfa.harvard.edulkaltenegger/evolutionearthlisa07.pdf · 4 evolution calender •...

1WHAT TIME IS IT THERE?

EARTH EVOLUTION....

D. Aguilar, CfA Press

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Atmosphere evolution & Life...Model based on work by Kasting et al 2004

Kasting et al 2004

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Biomarkers & spectra change over time IMPORTANT: Surface temp change, cloud! coverage

Ref.: based on J. Kasting, Sci. Am., July 2004

Model based on work by Traub et al, Jucks et al, Kasting et al, Pavlov et al, Segura et al.Ref: Kaltenegger et al ApJ 2007

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EVOLUTION CALENDER

• EPOCH 0 - February 12… 3.9 billion years ago • EPOCH 1 – March 17… 3.5 billion years ago• EPOCH 2 – June 5… 2.5 billion years ago• EPOCH 3 – July 16… 2 billion years ago• EPOCH 4 – October 13… 800 million years ago• EPOCH 5 – November 8… 300 million years ago• EPOCH 6 – December 31 (11:59 and 59 seconds to

midnight) ? time period humans occupy today

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EVOLUTION CALENDER

• EPOCH 0 - February 12… 3.9 billion years ago • EPOCH 1 – March 17… 3.5 billion years ago• EPOCH 2 – June 5… 2.5 billion years ago• EPOCH 3 – July 16… 2 billion years ago• EPOCH 4 – October 13… 800 million years ago• EPOCH 5 – November 8… 300 million years ago• EPOCH 6 – December 31 (11:59 and 59 seconds to

midnight) ? time period humans occupy today

REFLECTED

(OPTICAL)

HEAT

(INFRARED)

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EVOLUTION CALENDER

• EPOCH 0 - February 12… 3.9 billion years ago • EPOCH 1 – March 17… 3.5 billion years ago• EPOCH 2 – June 5… 2.5 billion years ago• EPOCH 3 – July 16… 2 billion years ago• EPOCH 4 – October 13… 800 million years ago• EPOCH 5 – November 8… 300 million years ago• EPOCH 6 – December 31 (11:59 and 59 seconds to

midnight) ? time period humans occupy today

REFLECTED

(OPTICAL)

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Instrument Requirementsto detect Earth when it was young & nowRESOLUTION

SPECTROGRAPH:IR

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RESOLUTION

SPECTROGRAPH:VIS

Instrument Requirementsto detect Earth when it was young & now

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OUR MODEL

Radiative Transfer Model developed by W. Traub & K. Jucks

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ocean

stratosphere

vegetation surfaces:e.g. granite,basalt

troposphere

high

Rayleighaerosol

ice, snow

Our model: RT, 24 layers, 4 streams

lowmedium

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Verification of our Model

using disc-integrated spectra of Earth (ground & space based)

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Model Validation: Visible spectrum

Observed Earthshine, reflected from dark side of moon.Ref.: Woolf, Smith, Traub, & Jucks, ApJ 574, p.430, 2002

Rayleigh

Ozone O3

Chlorophyll

Oxygen O2

Water H2O

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ModelValidationnear-IR

Data: Turnbull, Traub, Jucks et al 2006Fig. Kaltenegger, Traub, Jucks et al 2007 (ApJ)

Observed Earthshine, reflected from dark side of moon.

CO2

O2

CH4H2O

H2O H2O

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ModelValidation

mid-IR

TES data; Christensen 2004, Fig. Kaltenegger, Traub, Jucks et al 2007 (ApJ)

N2O

N2O