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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
