Vertical Profiles of NOx, O3, and Volatile Organic Compounds in a Deciduous Forest Canopy
Abstract
Vertical profiles of traces gases were made through a deciduous forest canopy as part of the Community Atmosphere-Biosphere Interactions Experiments (CABINEX) conducted in July-August, 2009 at the University of Michigan Biological Station. Measurements of O3, NO, NO2 and VOCs were made from three heights: 6 m, the top of the forest canopy at 20 m, and at a height of 34 m. O3 was continuously monitored from each of these heights. NOx and VOC measurements switched between these sampling heights every 10 minutes. VOCs were measured using a Proton Transfer Reaction Mass Spectrometer (PTR-MS). Measured VOCs include formaldehyde and methylhydroperoxide as well as isoprene and monoterpenes. NO and NO2 were continuously measured using a two channel chemiluminescent instrument. NOx mixing ratios were often significantly greater at the 6 m sampling height compared to the top of the canopy, suggesting NOx emissions from the forest floor. A difference of 50 pptv or greater was measured 44% of the time and frequently observed at night and during the morning. Approximately 40% of the time the differences were less than 10 pptv, implying a well mixed environment. The NOX and VOC profiles and their diel behavior will be presented to illustrate the importance of surface sources and sinks on trace gas mixing ratios within a forest canopy.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.A51G..06J
- Keywords:
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- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE / Biosphere/atmosphere interactions;
- 0322 ATMOSPHERIC COMPOSITION AND STRUCTURE / Constituent sources and sinks;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry