Measurement of isoprene fluxes at the PROPHET site

As part of the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET), isoprene fluxes were measured in the surface layer immediately above the forest canopy by relaxed eddy accumulation (REA) and eddy covariance (EC). Isoprene profiles obtained from aircraft flights at higher altitudes allowed larger-scale isoprene flux estimates based on a mixed layer gradient modeling technique. Emission results derived from the three methods have been compared and used to generate standard emission factors for use in biogenic emission modeling. A standard emission flux of 11.4 mg m -2 h -1 was determined for the canopy footprint region. The aspen and oak isoprene emitting biomass density in the footprint amounted to approximately 150 g m -2 which, when combined with the standard flux, gives a standard emission rate of 76 μg g -1 h -1 for this northern Michigan forest. We found good agreement between isoprene fluxes determined by REA and EC methods. The general emission pattern is the same for both methods, and in many cases, the REA and EC fluxes were nearly identical. The mixed layer modeling approach gave isoprene fluxes that were consistent with those made at the same time at the canopy scale. The continuous coverage of isoprene fluxes by eddy covariance has provided more detailed insight into emission variability during the daytime period. During the midday period, canopy fluxes often changed significantly from one 30 min period to the next.

[1]  B. Lamb,et al.  Intercomparison of automated methodologies for determination of ambient isoprene during the PROPHET 1998 summer campaign , 2001 .

[2]  B. Lamb,et al.  Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America , 2000 .

[3]  J. Fuentes,et al.  ON THE SEASONALITY OF ISOPRENE EMISSIONS FROM A MIXED TEMPERATE FOREST , 1999 .

[4]  L. Gu,et al.  Seasonal Variations in Isoprene Emissions from a Boreal Aspen Forest , 1999 .

[5]  L. Vierling,et al.  Volatile organic compound emission rates from mixed deciduous and coniferous forests in Northern Wisconsin, USA , 1999 .

[6]  F. Giorgi,et al.  Introduction to special section : Regional climate modeling revisited , 1999 .

[7]  S. Wofsy,et al.  Seasonal course of isoprene emissions from a midlatitude deciduous forest , 1998 .

[8]  A. Guenther,et al.  Eddy covariance measurement of isoprene fluxes , 1998 .

[9]  P. Harley,et al.  Environmental controls over isoprene emission in deciduous oak canopies. , 1997, Tree physiology.

[10]  Terry J. Gillespie,et al.  Ambient biogenic hydrocarbons and isoprene emissions from a mixed deciduous forest , 1996 .

[11]  Dennis D. Baldocchi,et al.  Isoprene fluxes measured by enclosure, relaxed eddy accumulation, surface layer gradient, mixed layer gradient, and mixed layer mass balance techniques , 1996 .

[12]  John Moncrieff,et al.  The propagation of errors in long‐term measurements of land‐atmosphere fluxes of carbon and water , 1996 .

[13]  J. William Munger,et al.  Measurements of carbon sequestration by long‐term eddy covariance: methods and a critical evaluation of accuracy , 1996 .

[14]  D. Baldocchi,et al.  Energy and CO(2) flux densities above and below a temperate broad-leaved forest and a boreal pine forest. , 1996, Tree physiology.

[15]  P. Harley,et al.  Effects of light, temperature and canopy position on net photosynthesis and isoprene emission from sweetgum (Liquidambar styraciflua) leaves. , 1996, Tree physiology.

[16]  C. N. Hewitt,et al.  A global model of natural volatile organic compound emissions , 1995 .

[17]  Dennis D. Baldocchi,et al.  The fluxes and air chem istry of isoprene above a deciduous hardwood forest , 1995, Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences.

[18]  B. Lamb,et al.  Evaluation of forest canopy models for estimating isoprene emissions. Interim report, July 1992-1994 , 1996 .

[19]  Thomas E. Pierce,et al.  An improved model for estimating emissions of volatile organic compounds from forests in the eastern United States , 1994 .

[20]  Patrick R. Zimmerman,et al.  Natural volatile organic compound emission rate estimates for U.S. woodland landscapes , 1994 .

[21]  G. Grell,et al.  A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5) , 1994 .

[22]  R. Desjardins,et al.  Accuracy of the relaxed eddy-accumulation technique, evaluated using CO2 flux measurements , 1993 .

[23]  F. Fehsenfeld,et al.  Peroxy radicals as measured in ROSE and estimated from photostationary state deviations , 1993 .

[24]  T. W. Horst,et al.  Verification of flux measurement using relaxed eddy accumulation , 1993 .

[25]  R. Monson,et al.  Isoprene and monoterpene emission rate variability: Model evaluations and sensitivity analyses , 1993 .

[26]  C. N. Hewitt,et al.  Emissions of volatile organic compounds from vegetation and the implications for atmospheric chemistry , 1992 .

[27]  J. Wyngaard,et al.  Parameterizing turbulent diffusion through the joint probability density , 1992 .

[28]  Tilden P. Meyers,et al.  An open path, fast response infrared absorption gas analyzer for H2O and CO2 , 1992 .

[29]  Randal S. Martin,et al.  Measurement of isoprene and its atmospheric oxidation products in a central Pennsylvania deciduous forest , 1991 .

[30]  P. Zimmerman,et al.  Isoprene measurement by ozone-induced chemiluminescence , 1990 .

[31]  Joost A. Businger,et al.  Flux measurement with conditional sampling , 1990 .

[32]  R. Monson,et al.  Isoprene emission from aspen leaves : influence of environment and relation to photosynthesis and photorespiration. , 1989, Plant physiology.

[33]  T. Meyers,et al.  Measuring Biosphere‐Atmosphere Exchanges of Biologically Related Gases with Micrometeorological Methods , 1988 .

[34]  R. McMillen,et al.  An eddy correlation technique with extended applicability to non-simple terrain , 1988 .

[35]  Stuart A. McKeen,et al.  Impact of natural hydrocarbons on hydroxyl and peroxy radicals at a remote site , 1987 .

[36]  E. K. Webb,et al.  Correction of flux measurements for density effects due to heat and water vapour transfer , 1980 .