Budgets of reactive nitrogen, hydrocarbons, and ozone over the Amazon forest during the wet season
- Harvard Univ., Cambridge, MA (USA)
The atmospheric composition over the Amazon forest during the wet season is simulated with a one-dimensional photochemical model for the planetary boundary layer (PBL) extending from the ground to 2,000-m altitude. The model is constrained and evaluated using observations from the ABLE 2B field expedition. Results indicate that only {approx} 20% of NO{sub x} emitted by soils is exported to the atmosphere above the forest canopy. The balance is deposited to vegetation before leaving the canopy layer. The small NO{sub x} flux that escapes from the canopy is nevertheless sufficient to account for the low NO concentrations observed in the PBL. Decomposition of peroxyacetylnitrate (PAN) supplied from aloft provides only a minor source of NO{sub x} in the PBL, although it could provide the major source of NO{sub x} at higher altitudes. Soil emission can account for only a portion of NO{sub y} observed over the forest. Organic nitrates of nonbiogenic origin likely account for the balance of NO{sub y}. Enhancements of CO observed in the PBL cannot be explained by oxidation of biogenic hydrocarbons, and appear to reflect direct emission of CO by the forest ecosystem. Concentrations of O{sub 3} in the PBL are regulated largely by transport from aloft and deposition to the canopy, with little net influence from photochemistry. Ozone is photochemically produced immediately above the forest where NO concentrations are relatively high, but is photochemically consumed in the upper portion of the PBL.
- OSTI ID:
- 6061078
- Journal Information:
- Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 95:D10; ISSN 0148-0227; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
540220 -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION
AMAZON RIVER
ATMOSPHERIC CHEMISTRY
BIOSPHERE
BOUNDARY LAYERS
BRAZIL
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMISTRY
DEGASSING
DEVELOPING COUNTRIES
EARTH ATMOSPHERE
ECOSYSTEMS
ENVIRONMENT
ENVIRONMENTAL TRANSPORT
ESTERS
FORESTS
LATIN AMERICA
LAYERS
MASS TRANSFER
NITRATES
NITRIC ACID ESTERS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
ONE-DIMENSIONAL CALCULATIONS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
OZONE
PEROXYACETYL NITRATE
POLLUTION
POLLUTION SOURCES
RIVERS
SEASONAL VARIATIONS
SIMULATION
SOILS
SOUTH AMERICA
STREAMS
SURFACE WATERS
TROPOSPHERE
VARIATIONS