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ring2.psu

"Ring 2":  High-precision, high-accuracy CO 2 mixing ratio measurements in support of the NACP Mid Continent Intensive. Scott Richardson, Natasha Miles, Kenneth Davis (PSU), Eric Crosson (Picarro, Inc.), Scott Denning, Marek Uliasz, Dusanke Zupanski (CSU). ring2.psu.edu. The Ring of Fire.

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ring2.psu

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  1. "Ring 2":  High-precision, high-accuracy CO2 mixing ratio measurements in support of the NACP Mid Continent Intensive Scott Richardson, Natasha Miles, Kenneth Davis (PSU), Eric Crosson (Picarro, Inc.), Scott Denning, Marek Uliasz, Dusanke Zupanski (CSU) ring2.psu.edu

  2. The Ring of Fire The Ring of Towers • Love is a burning thingand it makes a firery ringbound by wild desireI fell in to a ring of fire...I fell in to a burning ring of fireI went down,down,downand the flames went higher.And it burns,burns,burnsthe ring of firethe ring of fire. • CO2 is a burning thingand it makes a warmerringbound by wild desireI fell in to a ring of CO2...I fell in to a burning ring of CO2I went down,down,downand the CO2 went higher.And it burns,burns,burnsthe ring of CO2the ring of CO2.

  3. ChEAS Regional Flux Experiment Domain = LI-820 sampling from 75m above ground on a communications tower. = 40m Sylvania flux tower with high-quality standard gases. = 447m WLEF tower. LI-820, CMDL in situ and flask measurements.

  4. Mid-Continent Intensive • Overall goal: Seek convergence between top-down and bottom-up ecological estimates of the regional flux • Focus on upper Midwest of the U.S.

  5. The role of Ring 2 in the Mid-Continent Intensive • Add regional network of 5 communications-tower based atmospheric CO2 obs in the midcontinent intensive region • April 2007 through October 2008 • In addition to the planned long-term atmospheric CO2 observing network • Tall towers • Aircraft profiles • Well-calibrated CO2 measurements on AmeriFlux towers • The communications towers will “oversample” the atmosphere in the study region for more than a full year • A coupled atmosphere/terrestrial carbon model and a Lagrangian particle dispersion model will be used to conduct an atmospheric inversion and convert these mixing ratio measurements into highly data-constrained regional carbon balance estimates. • This work builds upon the Ring of Towers which deployed similar methodology in a forested region of northern Wisconsin

  6. Ring 2 sites • Kewanee, IL • Centerville, IA • Mead, NE • Round Lake, MN • Highland, WI

  7. Round Lake, MN 100 ft agl 360 ft agl Kewanee, IL 100 ft agl 460 ft agl Mead, NE 100 ft agl 400 ft agl Centerville, IA 100 ft agl 360 ft agl

  8. Cavity Ring-Down Spectroscopy => A laser-based optical technique => Sensitivity Extremely long effective path length Insensitive to optical power fluctuations => Chemical Specificity Able to distinguish individual absorption features => Linearity Beer-Lambert Law

  9. Cavity Ring-Down Spectroscopy • Picarro, Inc. has developed an ultra-sensitive trace gas (CO2, methane, CO) monitoring system. Advantages include: • High precision and accuracy long-term stability: days to weeks 1.5-sec sample precision and accuracy of ≤ 0.2 ppm and in tests • Measurement rate in seconds rather than minutes • No drying is required; water vapor is measured and correction to CO2 is applied • Stable and robust long-term measurement

  10. Predeployment tests • Prior to deployment, the five cavity ring-down systems were tested together with two PSU Ameriflux systems.  • For details on the low-cost systems, see www.amerifluxco2.psu.edu. • Overall agreement ~0.2 ppm

  11. Cavity Ring-Down Spectroscopy • Long-term stability is unknown • Lab tests indicate calibration changed by 0.1–0.2 over 6 weeks between calibrations

  12. Sampling Strategy • Two levels sampled at each tower • 100 ft AGL (15 min every hour) • 360–460 ft AGL (45 min every hour) • Two reference gases • sampled for 15 min each day(time of day changes) • Used to post-process calibrated data (if necessary)

  13. Nighttime 100 ft. level Sunrise Sunset

  14. In-field agreement between sensors first two weeks following deployment

  15. ring2.psu.edu

  16. ring2.psu.edu

  17. ring2.psu.edu Site specific information • Latitude • Longitude • Installation date • Sampling heights • Reference tank information • Calibration date

  18. Summary • Four of five Ring 2 sites installed • Fifth sites to be installed soon • Data available near real-time • Necessary calibration frequency to be determined • Expected to be ~monthly • Network designed to oversample the region • Will be used to calculate the regional flux for comparison with bottom-up methods

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