An overview of the 2003 Chemical Emission, Loss, Transformation and Interactions within Canopies (CELTIC) study
Abstract
The Chemical Emission, Loss, Transformation and Interactions within Canopies (CELTIC) study was conducted from June 30 to July 25, 2003 at the Duke Forest FACTS-1 Site. The primary objective of CELTIC is to improve our ability to predict regional air quality (e.g., particulates and ozone) and climate through a quantitative understanding of the processes controlling the exchange of trace gases and aerosols between the atmosphere and vegetation canopies. CELTIC researchers used an unprecedented array of enclosure and whole canopy trace gas and aerosol measurement systems to compile a unique database that is being used to develop and evaluate models of biosphere-atmosphere chemical exchange. Analytical systems included twelve real-time, fast-response and continuous analyzers capable of quantifying key trace gases (>10 VOC species, NH3, PANs, NOy, CO2) and CCN and total particle numbers and chemical composition. The measurements demonstrate that our current understanding of the controlling biological, chemical and physical factors is limited and that current models are not able to accurately simulate observed biosphere-atmosphere exchange of trace gases and particles. Leaf, branch and soil enclosure systems characterized the response of isoprene, monoterpenes, sesquiterpenes, oxygenated VOC, ozone and NOx emission and uptake to changes in chemical (e.g., ozone and CO2) and physical (e.g., temperature, light, soil moisture) conditions. Major findings include observations that 1) isoprene emission increases with elevated ozone, 2) canopy scale isoprene emission increases with elevated CO2, 3) soil and leaf litter are a net sink of oxygenated VOC, and 4) sesquiterpene emissions may be higher than monoterpene emissions under certain environmental conditions. Above canopy fluxes and within canopy vertical profiling systems characterized variations in trace gases (isoprene, monoterpenes, oxygenated VOC, NOx, ozone, CO2, PANs, NH3), particles (numbers, size distribution, chemical composition, CCN) and physical environment (JNO2, UV-B, PAR, temperature, humidity, winds, turbulence). The results include the first above canopy flux measurements of PANs and the chemical components of particles.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AGUFM.A21F..04G
- Keywords:
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- 0312 Air/sea constituent fluxes (3339;
- 4504);
- 0315 Biosphere/atmosphere interactions;
- 0322 Constituent sources and sinks;
- 0355 Thermosphere: composition and chemistry;
- 0365 Troposphere: composition and chemistry