Chemical NO/sub x/ budget in the upper troposphere over the tropical South Pacific. Schultz, M., G., Jacob, D., J., Bradshaw, J., D., Sandholm, S., T., Dibb, J., E., Talbot, R., W., & Singh, H., B. Journal of Geophysical Research, 105(D5):6669-6679, 2000.
abstract   bibtex   
The chemical NO/sub x/ budget in the upper troposphere over the tropical South Pacific is analyzed using aircraft measurements made at 6-12 km altitude in September 1996 during the Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM) Tropics A campaign. Chemical loss and production rates of NO/sub x/ along the aircraft flight tracks are calculated with a photochemical model constrained by observations. Calculations using a standard chemical mechanism show a large missing source for NO/sub x/; chemical loss exceeds chemical production by a factor of 2.4 on average. Similar or greater NO/sub x/ budget imbalances have been reported in analyses of data from previous field studies. Ammonium aerosol concentrations in PEM-Tropics A generally exceeded sulfate on a charge equivalent basis, and relative humidities were low (median 25% relative to ice). This implies that the aerosol could be dry in which case N/sub 2/O/sub 5/ hydrolysis would be suppressed as a sink for NO/sub x/. Suppression of N/sub 2/O/sub 5/ hydrolysis and adoption of new measurements of the reaction rate constants for NO/sub 2/+OH+M and HNO/sub 3/+OH reduces the median chemical imbalance in the NO/sub x/ budget for PEM-Tropics A from 2.4 to 1.9. The remaining imbalance cannot be easily explained from known chemistry or long-range transport of primary NO/sub x/ and may imply a major gap in our understanding of the chemical cycling of NO/sub x/ in the free troposphere.
@article{
 title = {Chemical NO/sub x/ budget in the upper troposphere over the tropical South Pacific},
 type = {article},
 year = {2000},
 keywords = {6 to 12 km,Aerosol,Air pollution,Atmosphere,Atmospheric chemistry,Atmospheric composition,Budget,Chemical composition,Chemical cycling,Chemical mechanism,Chemistry,Global Tropospheric Experiment,HNO/sub 2/,HNO/sub 3/,HO/sub 2/NO/sub 2/,Imbalance,Loss,N/sub 2/O/sub 5/,NO/sub 2/,NO/sub 3/,NO/sub x/,Nitrogen compounds,Pacific Exploratory Mission,Photochemical model,Production rate,Source,South Pacific,Tropical atmosphere,Tropics A campaign,Troposphere,ad 1996,gte,no,pem},
 pages = {6669-6679},
 volume = {105},
 id = {17227e2b-0c8c-3678-89a0-477ff632248d},
 created = {2015-02-12T14:35:17.000Z},
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 last_modified = {2015-02-12T20:25:07.000Z},
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 source_type = {Journal Article},
 notes = {<m:note>Article<m:linebreak/>American Geophys. Union</m:note>},
 abstract = {The chemical NO/sub x/ budget in the upper troposphere over the tropical South Pacific is analyzed using aircraft measurements made at 6-12 km altitude in September 1996 during the Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM) Tropics A campaign. Chemical loss and production rates of NO/sub x/ along the aircraft flight tracks are calculated with a photochemical model constrained by observations. Calculations using a standard chemical mechanism show a large missing source for NO/sub x/; chemical loss exceeds chemical production by a factor of 2.4 on average. Similar or greater NO/sub x/ budget imbalances have been reported in analyses of data from previous field studies. Ammonium aerosol concentrations in PEM-Tropics A generally exceeded sulfate on a charge equivalent basis, and relative humidities were low (median 25% relative to ice). This implies that the aerosol could be dry in which case N/sub 2/O/sub 5/ hydrolysis would be suppressed as a sink for NO/sub x/. Suppression of N/sub 2/O/sub 5/ hydrolysis and adoption of new measurements of the reaction rate constants for NO/sub 2/+OH+M and HNO/sub 3/+OH reduces the median chemical imbalance in the NO/sub x/ budget for PEM-Tropics A from 2.4 to 1.9. The remaining imbalance cannot be easily explained from known chemistry or long-range transport of primary NO/sub x/ and may imply a major gap in our understanding of the chemical cycling of NO/sub x/ in the free troposphere.},
 bibtype = {article},
 author = {Schultz, M G and Jacob, D J and Bradshaw, J D and Sandholm, S T and Dibb, J E and Talbot, R W and Singh, H B},
 journal = {Journal of Geophysical Research},
 number = {D5}
}

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