Latitudinal, vertical, and seasonal variations of C1‐C4 alkyl nitrates in the troposphere over the Pacific Ocean during PEM‐Tropics A and B: Oceanic and continental sources

[1] We present concentration distributions of C1-C4 alkyl nitrates observed during the NASA airborne campaigns Pacific Exploratory Mission (PEM) -Tropics A (September–October 1996) and PEM-Tropics B (March–April 1999). The total geographic range for PEM-Tropics A was 45°N–72°S latitude and 153°E–75°W longitude, and for PEM-Tropics B was 40°N–36°S latitude and 149°E–75°W longitude. The maximum altitude for these missions was 12 km. These experiments provide the most extensive set of tropospheric measurements collected to date over the tropical Pacific Ocean. We observed high methyl nitrate (MeONO2, CH3ONO2) mixing ratios (approximately 50 pptv) at low altitudes in a latitude band between 8°N to 13°S stretching across the equatorial Pacific, illustrating the oceanic source of MeONO2. This source may be associated with the high-nutrient, low-chlorophyll character of equatorial Pacific waters. We discuss MeONO2 and ethyl nitrate (EtONO2, C2H5ONO2), whose abundance is dominated by equatorial oceanic sources, 2-Propyl nitrate (2-PrONO2, 2-C3H7ONO2), which has significant oceanic and northern hemispheric (NH) sources associated with urban/industrial hydrocarbon emissions, and 2-butyl nitrate (2-BuONO2 2-C4H8ONO2), which has mostly NH sources. PEM-Tropics A and B resulted in remarkably similar equatorial mixing ratios. The excellent correlations between MeONO2 and the other alkyl nitrates in this region produced comparable correlation slopes between the two expeditions. By contrast, NH air masses influenced by urban/industrial emissions typically exhibited much lower MeONO2:EtONO2, MeONO2:2-PrONO2, and MeONO2:2-BuONO2 ratios. These relationships can be useful as a diagnostic of air mass origin. North of 10°N, the springtime PEM-Tropics B mixing ratios of C2-C4 alkyl nitrates were many-fold higher at low-mid altitudes than for late summer PEM-Tropics A, consistent with strong continental outflow of NMHC precursors during spring.

[1]  Yuanlong Hu,et al.  Mean moist circulation for PEM‐Tropics missions , 2001 .

[2]  D. Blake,et al.  Large-scale latitudinal and vertical distributions of NMHCs and selected halocarbons in the troposphere over the Pacific Ocean during the March-April 1999 Pacific Exploratory Mission (PEM-Tropics B) , 2001 .

[3]  H. Fuelberg,et al.  A meteorological overview of the second Pacific Exploratory Mission in the Tropics , 2001 .

[4]  D. Blake,et al.  Trace gas transport and scavenging in PEM‐Tropics B South Pacific Convergence Zone convection , 2001 .

[5]  D. Blake,et al.  Chemical transport across the ITCZ in the central Pacific during an El Niño-Southern Oscillation cold phase event in March-April 1999 , 2001 .

[6]  D. Jacob,et al.  Pacific Exploratory Mission in the Tropical Pacific: PEM-Tropics B, March-April 1999 , 2001 .

[7]  D. Blake,et al.  Seasonal differences in the photochemistry of the South Pacific: A comparison of observations and model results from PEM-Tropics A and B , 2001 .

[8]  D. Blake,et al.  Factors controlling tropospheric O3, OH, NO x and SO2 over the tropical Pacific during PEM-Tropics B , 2001 .

[9]  D. Blake,et al.  Description of the analysis of a wide range of volatile organic compounds in whole air samples collected during PEM-tropics A and B. , 2001, Analytical chemistry.

[10]  Isobel J. Simpson,et al.  Aircraft Measurements of Dimethyl Sulfide (DMS) Using a Whole Air Sampling Technique , 2001 .

[11]  D. Blake,et al.  Tropospheric reactive odd nitrogen over the South Pacific in austral springtime , 2000 .

[12]  Nicola J. Blake,et al.  Reactive nitrogen budget during the NASA SONEX Mission , 1999 .

[13]  D. Blake,et al.  Aircraft measurements of the latitudinal, vertical, and seasonal variations of NMHCs, methyl nitrate, methyl halides, and DMS during the First Aerosol Characterization Experiment (ACE 1) , 1999 .

[14]  W. Sturges,et al.  Oxidized nitrogen chemistry and speciation in the Antarctic troposphere , 1999 .

[15]  D. Blake,et al.  Influence of southern hemispheric biomass burning on midtropospheric distributions of nonmethane hydrocarbons and selected halocarbons over the remote South Pacific. , 1999 .

[16]  Nicola J. Blake,et al.  On the origin of tropospheric ozone and NOx over the tropical South Pacific , 1999 .

[17]  James M. Hoell,et al.  Pacific Exploratory Mission in the tropical Pacific: PEM-Tropics A, August-September 1996 , 1999 .

[18]  B. Jobson,et al.  Measurement of alkyl nitrates at Chebogue Point, Nova Scotia during the 1993 North Atlantic Regional Experiment (NARE) intensive , 1998 .

[19]  D. Blake,et al.  during PEM-West A and PEM-West B , 1997 .

[20]  P. Hess,et al.  Aircraft measurements made during the spring maximum of ozone over Hawaii: Peroxides, CO, O3, NOy, condensation nuclei, selected hydrocarbons, halocarbons, and alkyl nitrates between 0.5 and 9 km altitude , 1997 .

[21]  F. Chai,et al.  Iron and grazing constraints on primary production in the central equatorial Pacific: An EqPac synthesis , 1997 .

[22]  Y. Yokouchi,et al.  Distribution of methyl iodide, ethyl iodide, bromoform, and dibromomethane over the ocean (east and southeast Asian seas and the western Pacific) , 1997 .

[23]  K. Clemitshaw,et al.  Gas-phase ultraviolet absorption cross-sections and atmospheric lifetimes of several C2C5 alkyl nitrates , 1997 .

[24]  F. Fehsenfeld,et al.  Episodic removal of NOy species from the marine boundary layer over the North Atlantic , 1996 .

[25]  Raphael Kudela,et al.  A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean , 1996, Nature.

[26]  E. Atlas,et al.  The Mauna Loa Observatory Photochemistry Experiment: Introduction , 1996 .

[27]  D. Blake,et al.  Measurements of PAN, alkyl nitrates, ozone, and hydrocarbons during spring in interior Alaska , 1996 .

[28]  P. Shepson,et al.  Measurements of alkyl and multifunctional organic nitrates at a rural site in Ontario , 1995 .

[29]  A. Bandy,et al.  Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry , 1993 .

[30]  E. Atlas,et al.  Alkyl nitrates, nonmethane hydrocarbons, and halocarbon gases over the equatorial Pacific Ocean during Saga 3 , 1993 .

[31]  P. Shepson,et al.  Alkyl nitrates and their contribution to reactive nitrogen at a rural site in Ontario , 1993 .

[32]  S. Madronich,et al.  Observations of peroxyacetyl nitrate, peroxypropionyl nitrate, methyl nitrate and ozone during the Mauna Loa Observatory photochemistry experiment , 1992 .

[33]  E. Atlas,et al.  Alkyl nitrate and selected halocarbon measurements at Mauna Loa Observatory, Hawaii , 1992 .

[34]  E. Robinson,et al.  The Mauna Loa Observatory photochemistry experiment , 1992 .

[35]  J. Cullen.  Hypotheses to explain high-nutrient conditions in the open sea , 1991 .

[36]  Thomas M. Powell,et al.  Ecological dynamics in the subarctic Pacific, a possibly iron-limited ecosystem , 1991 .

[37]  S. Madronich,et al.  Correction to ``The behavior of some organic nitrates at Boulder and Niwot Ridge, Colorado,'' , 1990 .

[38]  F. Fehsenfeld,et al.  Contribution of organic nitrates to the total reactive nitrogen budget at a rural eastern U.S. site , 1990 .

[39]  C. Atherton,et al.  Organic nitrates in remote marine environments: Evidence for long range transport , 1989 .

[40]  M. Uematsu.  Study of continental material transported through the atmosphere to the oeean , 1987 .

[41]  W. Carter,et al.  Alkyl nitrate formation from the NO/sub x/-air photooxidations of C/sub 2/-C/sub 8/ n-alkanes , 1982 .

[42]  M. Joseph.  Eolian transport to the world ocean , 1981 .

[43]  O. Zafiriou,et al.  Nitric oxide from nitrite photolysis in the central equatorial Pacific , 1981 .

[44]  W. Carter,et al.  Importance of RO2 + nitric oxide in alkyl nitrate formation from C4-C6 alkane photooxidations under simulated atmospheric conditions , 1976 .

[45]  D. Kley,et al.  Measurements of alkyl nitrates in rural and polluted air masses , 1991 .

[46]  J. Roberts,et al.  The atmospheric chemistry of organic nitrates , 1990 .