AN033: Picarro’s New Flux Instrument Captures CO2, CH4 & H2O Fluxes by Measuring Concentrations at 10 Hz with the Best Precision and Lowest Drift

AN033: Picarro’s New Flux Instrument Captures CO2, CH4 & H2O Fluxes by Measuring Concentrations at 10 Hz with the Best Precision and Lowest Drift

Natural ecosystems have long been the focus of flux research, however characterizing the complexities of the urban environment is also critical to understanding global cycles. Wade McGillis from Columbia University's Lamont-Doherty Earth Observatory has deployed the Picarro flux instrument (G2311-f) on the largest greenroof, the main post office building in Manhattan.

Abstract: 

Natural ecosystems have long been the focus of flux research, and while continued investigations into these areas is absolutely necessary for developing accurate climate & ecological models, characterizing the complexities of the urban environment is also critical to understanding global cycles. One research area gaining particular interest is quantifying environmental effects of green practices and technologies such as greenroofs. A partnership of Columbia University, the USPS, and TectaAmerica has undertaken a project where seven greenroofs in New York City are being evaluated for their effectiveness at reducing the heat island effect, reducing the amount of rainwater that reaches the storm drains, improving run-off water quality and functioning as a potential carbon sink. Wade McGillis from Columbia University's Lamont-Doherty Earth Observatory has deployed the Picarro flux instrument (G2311-f) on the largest greenroof, the main post office building in Manhattan. The rooftop ecosystem is dominated by sedum, a plant that is widely used in such applications for its drought tolerance and hardiness. The Picarro flux analyzer has been deployed to help quantify the net flux of water from the roof to the atmosphere, as well as the low level daily CO2 respiration of the plants. Also of interest is discovering if the rooftop garden is a source or sink for methane. To date, the Picarro shows excellent frequency response and low drift, which enables the measurement of low-level fluxes. CO2 fluxes as low as + 2 μmol m-2s-1 are measured even during periods of high latent heat flux up to 64 Wm-2. Diurnal, hourly methane fluxes between + 0.004 and (-)0.01 μmol m-2s-1 are observed with errors typically less than 0.001μmol m-2s-1. As expected for the relatively arid, hot conditions, no discernible trends in methane flux emerged, indicating the roof is not a significant methane source or sink.

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