Development of an optimal calibration strategy for trace gas - - PowerPoint PPT Presentation

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Development of an optimal calibration strategy for trace gas - - PowerPoint PPT Presentation

Jul 17, 2023 14 likes •456 views

Development of an optimal calibration strategy for trace gas measurements Mark Battle (Bowdoin College) Zane Davis, Ryan Hart, Jayme Woogerd, Jacob Scheckman Eric Sofen Becca Perry John Scheckman, Eric Sofen, Becca Perry, John Carpenter.

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Development of an optimal calibration strategy for trace gas measurements

Mark Battle

(Bowdoin College) Zane Davis, Ryan Hart, Jayme Woogerd, Jacob Scheckman Eric Sofen Becca Perry John Scheckman, Eric Sofen, Becca Perry, John Carpenter.

Special thanks: Britt Stephens (NCAR) Ralph Keeling Special thanks: Britt Stephens (NCAR), Ralph Keeling (SIO), Bill Munger (Harvard) Mary Lou Zeeman (Cornell/Bowdoin)

CompSust09 June 11, 2009

Funding from: DOE, Bowdoin College

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Outline

  • Structure of a measurement program
  • What measurements might tell us

g

  • Example of one such program
  • Call for help
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Measuring the composition of air

  • Precision vs. Accuracy
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Precision vs. Accuracy

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Measuring the composition of air

  • Precision vs. Accuracy
  • Differential measurements
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Benefits of differential measurements

Initial Group 1001 Women Final group Final group 1002 Women

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Benefits of differential measurements

Initial Group Absolute changes Initial # women: 1001 1001 Women Final # women: 1002 Change in women: 0.1% Final group Final group 1002 Women

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Benefits of differential measurements

Initial Group 999 Men 1001 Women Final group Final group 999 Men 999 Men 1002 Women

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Benefits of differential measurements

Initial Group 999 Men 1001 Women Final group Differential changes Final group 999 Men Differential changes Initial gender diff: 2 Final gender diff: 3 999 Men 1002 Women Final gender diff: 3 Change in gender diff: 33%

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Benefits of differential measurements

Initial Group Absolute changes Initial # women: 1001 999 Men 1001 Women Final # women: 1002 Change in women: 0.1% Final group Differential changes Final group 999 Men Differential changes Initial gender diff: 2 Final gender diff: 3 999 Men 1002 Women Final gender diff: 3 Change in gender diff: 33%

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Measuring the composition of air

  • Precision vs. Accuracy
  • Differential measurements
  • Measure samples relative to

“standards”

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Challenges of differential measurements

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Challenges of differential measurements

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Challenges of differential measurements

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Challenges of differential measurements

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Challenges of differential measurements

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Measuring the composition of air

  • Precision vs. Accuracy
  • Differential measurements
  • Measure samples relative to

“standards”

  • Instrumental response
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Impact of instrumental non-linearity

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Metric

Precision & Accuracy

Constraints

I t t ti i i Instrument time is precious Standard air is precious

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In summary:

Optimally combine many analyses of t d d t t i t l many standards to create a virtual standard against which all samples are d measured.

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Connecting to the real world: Connecting to the real world: Measuring O2 and CO2 to constrain the carbon cycle to constrain the carbon cycle

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Where does anthropogenic CO2 end up?

Values for 2000-2006 Canadell et al. PNAS 2007

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How do we know these numbers?

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How do we know these numbers?

  • Record CO2 emissions
  • Measure CO2 in the atmosphere

p

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How do we know these numbers?

  • Record CO2 emissions
  • Measure CO2 in the atmosphere

p

  • Measure CO2 in the oceans
  • Estimate from small-scale land

measurements

  • Infer from spatial pattern and isotopes

p p p

  • f atmospheric CO2
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How do we know these numbers?

  • Record CO2 emissions
  • Measure CO2 in the atmosphere

p

  • Measure CO2 in the oceans
  • Estimate from small-scale land

measurements

  • Infer from spatial pattern and isotopes

p p p

  • f atmospheric CO2
  • Measure atmospheric O2
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The link between O2 and CO2

ΔCO2 = Land biota + Industry + Ocean ΔO = Land biota + Industry ΔO2 = Land biota + Industry

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The link between O2 and CO2

ΔCO2 = Land biota + Industry + Ocean ΔO = Land biota + Industry ΔO2 = Land biota + Industry

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The link between O2 and CO2

ΔCO2 = Land biota + Industry + Ocean ΔO = Land biota + Industry ΔO2 = Land biota + Industry

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Google maps

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The equipment

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The equipment

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Real data

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Real data

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Real data

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Summary

  • Important questions require excellent

atmospheric measurements

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Summary

  • Important questions require excellent

atmospheric measurements

  • Excellent measurements require intelligent

weighting of experimental evidence

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Summary

  • Important questions require excellent

atmospheric measurements

  • Excellent measurements require intelligent

weighting of experimental evidence

  • I have abundant data. Intelligence, on the
  • ther hand…

mbattle@bowdoin edu mbattle@bowdoin.edu

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