FLYSPEC Miniature UVSpectrometer System

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FLYSPECMiniature UV-Spectrometer System

• Taryn Lopez
• Remote Sensing of Volcanic Eruptions

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Related Instruments

• FLYSPEC
• COSPEC
• Mini-DOAS
• MAX-DOAS
• RMDI
• And more

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Related Instruments

• FLYSPEC
• COSPEC
• Mini-DOAS
• MAX-DOAS
• RMDI
• And more

Calibration Cells
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Related Instruments

• FLYSPEC
• COSPEC
• Mini-DOAS
• MAX-DOAS
• RMDI
• And more

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Advantages of FLYSPEC

• Relatively low cost (10 K)
• Portable and field worthy
• Comes ready to use with user-friendly operating
  and data reduction software
• Cal cells and software provide near-real-time SO2
  SCD values

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Disadvantages of FLYSPEC

• More expensive than build-your-own
• Cal cells can leak
• Used only for detection of one species (SO2)
• Black box problem

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FLYSPEC Components
USB Hub
USB2000 Spectrometer
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Ocean Optics Spectrometer
www.oceanoptics.com
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Ocean Optics Spectrometer
www.oceanoptics.com
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Ocean Optics Spectrometer
www.oceanoptics.com
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Remote sensing theory
The Beer-Lambert Law
A Absorption ? Wavelength Io Incident
light I Transmitted light s Absorption
x-section N Concentration L Path length
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Application of Beers Law
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Application of Beers Law
Io
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Application of Beers Law
Io
I
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Solve this equation for NL
The Beer-Lambert Law
A Absorption ? Wavelength Io Incident
light I Transmitted light s Absorption
x-section N Concentration L Path length
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Wahner et al., Chem. Phys. Letters, 1988
Weibring, Diploma Thesis, 1986
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FLYSPEC Deployment

• Traverse Mode
• Stationary Scanning Mode
• Static (Pointing) Mode

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Traverse Mode
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Insert Fourpeaked Gas Flight Data
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Stationary Scanning Mode
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Static (Pointing) Mode
Branan, Ph.D. Dissertation, 2007
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Emission Rate Calculations

• Scan or traverse measurements of plume UV
  absorption
• Plume width
• Plume velocity (wind velocity)
• Conversion factor

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A series of measurements are collected by
scanning through the plume
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Plume width is calculated using measured plume
angles and the distance to the source
?
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Wind velocity can be used as a proxy for plume
velocity
Plume velocity in m/s
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SO2 Emission Rate Calculation

• (?C W) V F SO2 emission rate (t/d)
• C SO2 column density (ppmm)
• W plume width (m)
• V plume velocity (m/s)
• F conversion factor (0.00023)

Plume Width (m)
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Challenges

• Large (poorly constrained) error
• Highest signal to noise for clear weather
• Accurate measurements not possible for plumes
  containing ash

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Advancements

• Scanner
• DOAS spectral fitting for detection of multiple
  gas species SO2, BrO, ClO, OClO, O3
• Permanent installations (NOVAC)

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Thank you!