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Title: 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 » 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.« less

Authors:
; ;  [1]; ;  [2];  [3];  [4];  [5]; ;  [6]
  1. Harvard Univ., Cambridge, MA (United States)
  2. Georgia Institute of Technology, Atlanta, GA (United States)
  3. Univ. of California, Irvine, CA (United States)
  4. NASA Ames Research Center, Moffett Field, CA (United States)
  5. Univ. of New Hampshire, Durham, NH (United States)
  6. 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}
}