Details:

Journal Title:
Agricultural and Forest Meteorology
Personal Author:
Moon, Zachary ; Fuentes, Jose D. ; Staebler, Ralf M.
Moon, Zachary ; Fuentes, Jose D. ; Staebler, Ralf M. Less -
NOAA Program & Office:
Education and outreach
Description:
Although photolysis frequencies are wavelength-dependent and the dependence varies among chemical species, previous canopy radiative transfer models did not consider more than three broad bands (ultraviolet, photosynthetically active radiation (PAR), and near-infrared). In this study, high spectral resolution and wavelength-dependent idealized leaf optical properties allow us to determine the disposition of the light spectrum within a mixed deciduous forest canopy. Four radiative transfer approaches of varying complexity are applied to obtain vertical profiles of spectral actinic flux. Broad-band radiation measurements made above and below a mixed deciduous forest provide the necessary information to verify the fidelity of each radiative transfer approach. Model comparison results indicate that the Beer–Lambert scheme gives less total actinic flux, while the other three schemes give similar actinic flux profiles. Spectral actinic flux profiles are used to calculate in-canopy photolysis for different chemical species and to assess the importance of in-canopy photochemistry in modifying biogenic volatile organic compounds transported to the overlying atmospheric boundary layer. We find that, depending on the time of day and chemical species, percent errors in photolysis frequencies incurred by using a common in-canopy approximation based on weighting by relative PAR profiles can be as high as ± 50% in lower regions of the canopy, or 10–20% in daily canopy integrated photolysis frequency. Results obtained using a one-dimensional photochemical model suggest that choice of canopy radiative transfer scheme can have substantial impacts on in-canopy chemical reactions and concentrations in the overlying atmospheric boundary layer air. Such effects caused in-canopy gas concentration differences ranging from 8% for ozone and 35% for hydroxyl radical to 77% for nitrate radical.
Keywords:
[+]
Agronomy And Crop Science Atmospheric Science Forestry Global And Planetary Change
Source:
Agricultural and Forest Meteorology, 291, 108012
DOI:
https://doi.org/10.1016/j.agrformet.2020.108012
ISSN:
0168-1923
Format:
PDF
Publisher:
Elsevier BV
Document Type:
Journal Article
Funding:
Grant no. NA16SEC4810006
Rights Information:
Accepted Manuscript
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:b425f167196f191f07a5814e4ff4c94e8567d10e7cf8c96250eef7ecb61298ce
Download URL:
https://repository.library.noaa.gov/view/noaa/57388/noaa_57388_DS1.pdf
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