A useful application of the hydrocarbon measurements collected during the Pacific Exploratory Mission (PEM-West A) is as markers or indices of atmospheric processing. Traditionally, ratios of particular hydrocarbons have been interpreted as photochemical indices, since much of the effect due to atmospheric transport is assumed to cancel by using ratios. However, an ever increasing body of observatonial and theoretical evidence suggests that turbulent mixing associated with atmospheric transport influences certain hydrocarbon ratios significantly. In this study a three-dimensional mesoscale photochemical model is used to study the interaction of photochemistry and atmospheric mixing on select hydrocarbons. In terms of correlations and functional relationships between various alkanes the model results and PEM-West A hydrocarbon observations share many similar characteristics as well as explainable differences. When the three-dimensional model is applied to inert tracers, hydrocarbon ratios and other relationships exactly follow those expected by simple dilution with model-imposed ''background air,'' and the three-dimensional results for reactive hydrocarbons are quite consistent with a combined influence of photochemistry and simple dilution. Analogous to these model results, relationships between various hydrocarbons collected during the PEM-West A experiment appear to be consistent with this simplified picture of photochemistry and dilution affecting individual air masses, When hydrocarbons are chosen that have negligeble contributions to clean background air, unambiguous determinations of the relative contributions to photochemistry and dilution can be estimated from the hydrocarbon samples, Both the three-dimensional model results and the observations imply an average characteristic lifetime for dilution with background air roughly equivalent to the photochemical lifetime of butane for the western Pacific lower troposphere. Moreover, the dominance of OR as the primary photochemical oxidant downwind of anthropogenic source regions can be inferred from correlations between the highly reactive alkane ratios, By incorporating back-trajectory information within the three-dimensional model analysis, a correspondence between time and a particular hydrocarbon or hydrocarbon ratio can be determined, and the influence of atmospheric mixing or photochemistry can be quantified, Results of the three-dimensional model study are compared and applied to the PEM-West A hydrocarbon dataset, yielding a practical methodology for determining average OH concentrations and atmospheric mixing rates from the hydrocarbon measurements. Aircraft data taken below 2 km during wall flights east of Japan imply a diurnal average OH concentration of similar to 3 x 10(6) cm(-3). The characteristic time for dilution with background air is estimated to be similar to 2.5 days for the two study areas examined in this work.
%0 Journal Article
%1 McKeen1996
%A McKeen, S. A.
%A Liu, S. C.
%A Hsie, E. Y.
%A Lin, X.
%A Bradshaw, J. D.
%A Smyth, S.
%A Gregory, G. L.
%A Blake, D. R.
%D 1996
%I Amer Geophysical Union
%J Journal of Geophysical Research-Atmospheres
%K PACIFICAIRMASSES;ATMOSPHERICCONCENTRATIONS;PHOTOCHEMICALHISTORIES;TROPOSPHERICCHEMISTRY;RADICALCONCENTRATIONS;RURALTROPOSPHERE;POINT-ARENA;NOX;CALIFORNIA;EMISSIONS
%N D1
%P 2087--2109
%T Hydrocarbon ratios during PEM-WEST A: A model perspective
%V 101
%X A useful application of the hydrocarbon measurements collected during the Pacific Exploratory Mission (PEM-West A) is as markers or indices of atmospheric processing. Traditionally, ratios of particular hydrocarbons have been interpreted as photochemical indices, since much of the effect due to atmospheric transport is assumed to cancel by using ratios. However, an ever increasing body of observatonial and theoretical evidence suggests that turbulent mixing associated with atmospheric transport influences certain hydrocarbon ratios significantly. In this study a three-dimensional mesoscale photochemical model is used to study the interaction of photochemistry and atmospheric mixing on select hydrocarbons. In terms of correlations and functional relationships between various alkanes the model results and PEM-West A hydrocarbon observations share many similar characteristics as well as explainable differences. When the three-dimensional model is applied to inert tracers, hydrocarbon ratios and other relationships exactly follow those expected by simple dilution with model-imposed ''background air,'' and the three-dimensional results for reactive hydrocarbons are quite consistent with a combined influence of photochemistry and simple dilution. Analogous to these model results, relationships between various hydrocarbons collected during the PEM-West A experiment appear to be consistent with this simplified picture of photochemistry and dilution affecting individual air masses, When hydrocarbons are chosen that have negligeble contributions to clean background air, unambiguous determinations of the relative contributions to photochemistry and dilution can be estimated from the hydrocarbon samples, Both the three-dimensional model results and the observations imply an average characteristic lifetime for dilution with background air roughly equivalent to the photochemical lifetime of butane for the western Pacific lower troposphere. Moreover, the dominance of OR as the primary photochemical oxidant downwind of anthropogenic source regions can be inferred from correlations between the highly reactive alkane ratios, By incorporating back-trajectory information within the three-dimensional model analysis, a correspondence between time and a particular hydrocarbon or hydrocarbon ratio can be determined, and the influence of atmospheric mixing or photochemistry can be quantified, Results of the three-dimensional model study are compared and applied to the PEM-West A hydrocarbon dataset, yielding a practical methodology for determining average OH concentrations and atmospheric mixing rates from the hydrocarbon measurements. Aircraft data taken below 2 km during wall flights east of Japan imply a diurnal average OH concentration of similar to 3 x 10(6) cm(-3). The characteristic time for dilution with background air is estimated to be similar to 2.5 days for the two study areas examined in this work.
@article{McKeen1996,
abstract = {A useful application of the hydrocarbon measurements collected during the Pacific Exploratory Mission (PEM-West A) is as markers or indices of atmospheric processing. Traditionally, ratios of particular hydrocarbons have been interpreted as photochemical indices, since much of the effect due to atmospheric transport is assumed to cancel by using ratios. However, an ever increasing body of observatonial and theoretical evidence suggests that turbulent mixing associated with atmospheric transport influences certain hydrocarbon ratios significantly. In this study a three-dimensional mesoscale photochemical model is used to study the interaction of photochemistry and atmospheric mixing on select hydrocarbons. In terms of correlations and functional relationships between various alkanes the model results and PEM-West A hydrocarbon observations share many similar characteristics as well as explainable differences. When the three-dimensional model is applied to inert tracers, hydrocarbon ratios and other relationships exactly follow those expected by simple dilution with model-imposed ''background air,'' and the three-dimensional results for reactive hydrocarbons are quite consistent with a combined influence of photochemistry and simple dilution. Analogous to these model results, relationships between various hydrocarbons collected during the PEM-West A experiment appear to be consistent with this simplified picture of photochemistry and dilution affecting individual air masses, When hydrocarbons are chosen that have negligeble contributions to clean background air, unambiguous determinations of the relative contributions to photochemistry and dilution can be estimated from the hydrocarbon samples, Both the three-dimensional model results and the observations imply an average characteristic lifetime for dilution with background air roughly equivalent to the photochemical lifetime of butane for the western Pacific lower troposphere. Moreover, the dominance of OR as the primary photochemical oxidant downwind of anthropogenic source regions can be inferred from correlations between the highly reactive alkane ratios, By incorporating back-trajectory information within the three-dimensional model analysis, a correspondence between time and a particular hydrocarbon or hydrocarbon ratio can be determined, and the influence of atmospheric mixing or photochemistry can be quantified, Results of the three-dimensional model study are compared and applied to the PEM-West A hydrocarbon dataset, yielding a practical methodology for determining average OH concentrations and atmospheric mixing rates from the hydrocarbon measurements. Aircraft data taken below 2 km during wall flights east of Japan imply a diurnal average OH concentration of similar to 3 x 10(6) cm(-3). The characteristic time for dilution with background air is estimated to be similar to 2.5 days for the two study areas examined in this work.},
added-at = {2009-06-08T21:16:24.000+0200},
author = {McKeen, S. A. and Liu, S. C. and Hsie, E. Y. and Lin, X. and Bradshaw, J. D. and Smyth, S. and Gregory, G. L. and Blake, D. R.},
biburl = {https://www.bibsonomy.org/bibtex/220ecfa246c31b66d63fbfbbea085379f/claas},
c1 = {UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717.EOLEOLGEORGIA INST TECHNOL,ATLANTA,GA 30332.EOLEOLNASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665.EOLEOLUNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309.},
citedreferences = {1989, EPA600789012A TECH R ; 1990, WORLD ENERGY STATIST ; 1990, YB ENERGY STATISTICS ; ANTHES RA, 1987, NCARTN282 STR TECH N ; ATKINSON R, 1985, INT J CHEM KINET, V17, P33 ; ATKINSON R, 1990, ATMOS ENVIRON A-GEN, V24, P1 ; BAMBER D, 1984, ATMOS ENVIRON, V18, P1756 ; BLAKE DR, 1986, NATURE, V321, P231 ; BLAKE DR, 1996, J GEOPHYS RES-ATMOS, V101, P1763 ; BLAKE NJ, 1993, J GEOPHYS RES-ATMOSP, V98, P2851 ; BROST RA, 1988, J GEOPHYS RES, V93, P2371 ; BROWELL EV, 1996, J GEOPHYS RES-ATMOS, V101, P1691 ; CALVERT JG, 1976, ENVIRON SCI TECHNOL, V10, P256 ; CRAWFORD J, 1996, J GEOPHYS RES-ATMOS, V101, P2053 ; DEMORE WB, 1992, JPL PUBL, V9220 ; DIGNON J, 1992, ATMOS ENVIRON A-GEN, V26, P1157 ; GREGORY GL, 1996, J GEOPHYS RES-ATMOS, V101, P1727 ; HOELL JM, 1996, J GEOPHYS RES-ATMOS, V101, P1641 ; JOBSON BT, 1994, J GEOPHYS RES-ATMOSP, V99, P1589 ; KATO N, 1992, ATMOS ENVIRON A-GEN, V26, P2997 ; LEVY H, 1971, SCIENCE, V173, P141 ; LIN X, 1994, J GEOPHYS RES, V99, P25615 ; LIU SC, 1996, J GEOPHYS RES-ATMOS, V101, P2073 ; LOGAN JA, 1981, J GEOPHYS RES, V86, P7210 ; LOVELOCK JE, 1961, ANAL CHEM, V33, P162 ; LURMANN FW, 1986, J GEOPHYS RES, V91, P10905 ; MCKEEN SA, 1990, J GEOPHYS RES-ATMOSP, V95, P7493 ; MCKEEN SA, 1991, J GEOPHYS RES-ATMOSP, V96, P10809 ; MCKEEN SA, 1993, GEOPHYS RES LETT, V20, P2363 ; MCKENNA DS, 1995, IN PRESS J GEOPHYS R ; MERRILL JT, 1996, J GEOPHYS RES, V101 ; NELSON PF, 1982, ENVIRON SCI TECHNOL, V16, P650 ; PARRISH DD, 1992, J GEOPHYS RES-ATMOSP, V97, P15883 ; PARRISH DD, 1993, J GEOPHYS RES-ATMOSP, V98, P14995 ; ROBERTS JM, 1984, ATMOS ENVIRON, V18, P2421 ; ROBERTS JM, 1985, ATMOS ENVIRON, V19, P1945 ; RUDOLPH J, 1990, J GEOPHYS RES-ATMOSP, V95, P20583 ; SINGH HB, 1981, ENVIRON SCI TECHNOL, V15, P113 ; SMOLARKIEWICZ PK, 1984, J COMPUT PHYS, V54, P325 ; SMYTH S, 1996, J GEOPHYS RES-ATMOS, V101, P1743 ; TALBOT RW, 1996, J GEOPHYS RES-ATMOS, V101, P1713 ; TRAINER M, 1993, J GEOPHYS RES, V98, P2917},
file = {McKeen1996.pdf:McKeen1996.pdf:PDF},
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intrahash = {20ecfa246c31b66d63fbfbbea085379f},
j9 = {J GEOPHYS RES-ATMOS},
ji = {J. Geophys. Res.-Atmos.},
journal = {Journal of Geophysical Research-Atmospheres},
keywords = {PACIFICAIRMASSES;ATMOSPHERICCONCENTRATIONS;PHOTOCHEMICALHISTORIES;TROPOSPHERICCHEMISTRY;RADICALCONCENTRATIONS;RURALTROPOSPHERE;POINT-ARENA;NOX;CALIFORNIA;EMISSIONS},
la = {English},
month = {#jan#},
nr = {42},
number = {D1},
pa = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009},
pages = {2087--2109},
pg = {23},
pi = {WASHINGTON},
publisher = {Amer Geophysical Union},
rp = {McKeen, SA, NOAA,AERON LAB,325 BROADWAY,R-E-AL4,BOULDER,CO 80303.},
sc = {Meteorology & Atmospheric Sciences},
sn = {0148-0227},
tc = {76},
timestamp = {2009-06-08T21:16:24.000+0200},
title = {Hydrocarbon ratios during PEM-WEST A: A model perspective},
ut = {ISI:A1996TR61600054},
volume = 101,
year = 1996
}