Origin of tropospheric NO{sub x} over subarctic eastern Canada in summer
Abstract
The origin of NO{sub x} in the summertime troposphere over subarctic eastern Canada is investigated by photochemical modeling of aircraft and ground-based measurements from the Arctic Boundary Layer Expedition (ABLE 3B). It is found that decomposition of peroxyacetyl nitrate (PAN) can account for most of the NO{sub x} observed between the surface and 6.2 km altitude (aircraft ceiling). Forest fires represent the principal source of PAN in the region, implying the same origin for NO{sub x}. There is, however, evidence for an unidentified source of NO{sub x} in occasional air masses subsiding from the upper troposphere. Isoprene emissions from boreal forests maintain high NO{sub x} concentrations in the continental boundary layer over eastern Canada by scavenging OH and NO{sub 3}, thus slowing down conversion of NO{sub x} to HNO{sub 3}, both in the daytime and at night. This effect is partly compensated by the production of CH{sub 3}CO{sub 3} radicals during isoprene oxidation, which slows down the decomposition of PAN subsiding from the free troposphere. The peroxy radical concentrations estimated from concurrent measurements of NO and NO{sub 2} concentrations during ABLE 3B are consistent with values computed from our photochemical model below 4 km, but model values are low atmore »
- Authors:
-
- Harvard Univ., Cambridge, MA (United States)
- Georgia Institute of Technology, Atlanta, GA (United States)
- Univ. of California, Irvine, CA (United States)
- NASA Ames Research Center, Moffett Field, CA (United States)
- Univ. of New Hampshire, Durham, NH (United States)
- NASA Langley Research Center, Hampton, VA (United States)
- Publication Date:
- OSTI Identifier:
- 98852
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Geophysical Research
- Additional Journal Information:
- Journal Volume: 99; Journal Issue: D8; Other Information: PBD: 20 Aug 1994
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; CANADA; AEROSOL MONITORING; NITROUS OXIDE; TROPOSPHERE; ATMOSPHERIC CHEMISTRY; PHOTOCHEMISTRY; GREENHOUSE GASES; ORIGIN; POLLUTANTS; OXIDATION
Citation Formats
Fan, S M, Jacob, D J, Mauzerall, D L, Bradshaw, J D, Sandholm, S T, Blake, D R, Singh, H B, Talbot, R W, Gregory, G L, and Sachse, G W. Origin of tropospheric NO{sub x} over subarctic eastern Canada in summer. United States: N. p., 1994.
Web. doi:10.1029/94JD01122.
Fan, S M, Jacob, D J, Mauzerall, D L, Bradshaw, J D, Sandholm, S T, Blake, D R, Singh, H B, Talbot, R W, Gregory, G L, & Sachse, G W. Origin of tropospheric NO{sub x} over subarctic eastern Canada in summer. United States. https://doi.org/10.1029/94JD01122
Fan, S M, Jacob, D J, Mauzerall, D L, Bradshaw, J D, Sandholm, S T, Blake, D R, Singh, H B, Talbot, R W, Gregory, G L, and Sachse, G W. 1994.
"Origin of tropospheric NO{sub x} over subarctic eastern Canada in summer". United States. https://doi.org/10.1029/94JD01122.
@article{osti_98852,
title = {Origin of tropospheric NO{sub x} over subarctic eastern Canada in summer},
author = {Fan, S M and Jacob, D J and Mauzerall, D L and Bradshaw, J D and Sandholm, S T and Blake, D R and Singh, H B and Talbot, R W and Gregory, G L and Sachse, G W},
abstractNote = {The origin of NO{sub x} in the summertime troposphere over subarctic eastern Canada is investigated by photochemical modeling of aircraft and ground-based measurements from the Arctic Boundary Layer Expedition (ABLE 3B). It is found that decomposition of peroxyacetyl nitrate (PAN) can account for most of the NO{sub x} observed between the surface and 6.2 km altitude (aircraft ceiling). Forest fires represent the principal source of PAN in the region, implying the same origin for NO{sub x}. There is, however, evidence for an unidentified source of NO{sub x} in occasional air masses subsiding from the upper troposphere. Isoprene emissions from boreal forests maintain high NO{sub x} concentrations in the continental boundary layer over eastern Canada by scavenging OH and NO{sub 3}, thus slowing down conversion of NO{sub x} to HNO{sub 3}, both in the daytime and at night. This effect is partly compensated by the production of CH{sub 3}CO{sub 3} radicals during isoprene oxidation, which slows down the decomposition of PAN subsiding from the free troposphere. The peroxy radical concentrations estimated from concurrent measurements of NO and NO{sub 2} concentrations during ABLE 3B are consistent with values computed from our photochemical model below 4 km, but model values are low at higher altitudes. The discrepancy may reflect either a missing radical source in the model or interferences in the NO{sub 2} measurement. 63 refs., 10 figs., 1 tab.},
doi = {10.1029/94JD01122},
url = {https://www.osti.gov/biblio/98852},
journal = {Journal of Geophysical Research},
number = D8,
volume = 99,
place = {United States},
year = {Sat Aug 20 00:00:00 EDT 1994},
month = {Sat Aug 20 00:00:00 EDT 1994}
}