Airborne lidar observations of long-range transport in the free troposphere

Shipley, S. T.; Browell, Edward V.; McDougal, D. S.; Orndorff, Brian L.; Haagenson, Philip L.

doi:10.1021/es00128a006

Cited by 14 publications

(5 citation statements)

References 11 publications

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“…The convective cloud layer extends from the top of the mixed layer to the trade wind inversion separating the PBL from the free tropo-sphere. Mixed layer heights varied from about 500 m (early morning) to 1.5 km (early afternoon), while the free troposphere began around 3.5-4 km [Gregory et al, this issue].Although mixing within the ML is considered to be fast, mixing across the transition layer separating the ML from the CCL is only rapid in the vicinity of convective clouds where their pumping action transports air in both upward and downward directions[Gidel, 1983;Chatfield and Crutzen, 1984;Shipley et al, 1984;Dickerson et al, 1987].…”

mentioning

confidence: 99%

Tropospheric nitric oxide measurements over the Amazon Basin

Torres¹,

Buchan²

1988

J. Geophys. Res.

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Horizontal and vertical distributions of nitric oxide (NO) were measured over the Amazon Basin during NASA's Global Tropospheric Experiment (GTE) Amazon Boundary Layer Experiment (ABLE 2A) mission in July-August 1985. During transit flights between the Virginia coast and Manaus, Brazil, NO mixing ratios were 12-15 parts per trillion by volume (pptv) at 5 km altitude. Values up to 200 pptv were observed in electrically active clouds. During longitudinal surveys over the Amazon region, NO mixing ratios in the lower planetary boundary layer decreased from 25-60 pptv over the central basin to 10-12 pptv in coastal regions. In the convective cloud layer or free troposphere, NO mixing ratios averaged 13 pptv in regions not influenced by biomass burning. No longitudinal trend above the mixed layer could be detected. A steep negative gradient with increasing altitude was noted within the mixed layer before midday. Mixing ratios decreased from 60 pptv at 0.2 km to about 15 pptv at the top of the mixed layer (1 km). No further change in mixing ratio with altitude through the convective cloud layer and lower edge of the free troposphere could be detected at this time. By midday, growth of the mixed layer height and enhanced mixing reduced the gradient, and evidence for mixing of NO into the convective cloud layer was noted. INTRODUCTION Tropical forests, soils, and wetland environments within the Amazon Basin ecosystem represent significant natural emission sources of many species important to atmospheric chemistry [Mayer et al., 1982; Crutzen and Gidel, 1983; Keller et al., 1986; Logan, 1983; Zimmerman et al., this issue; Kaplan et al., this issue; Bartlett et al., this issue; Rasmussen and Khalil, this issue]. In addition to natural sources, there are large anthropogenic emissions produced by biomass burning for agricultural purposes [Delany et al., 1985; Crutzen et al., 1985; Greenberg et al., 1984; Andreae et al., this issue]. The Amazon Boundary Layer Experiment (ABLE 2A) was an investigation of tropospheric chemistry over the Amazon Basin and of how this chemistry is affected by biosphere-atmosphere interactions [Harriss et al., this issue]. We present in this paper results of atmospheric nitric oxide (NO) measurements made during the ABLE 2A experiment. Intense solar flux and high concentrations of hydrocarbons and moisture in regions such as the Amazon Basin result in complex photochemical processes involving many species. These processes are often important sources or sinks for these species and, consequently, control their abundances and distributions [Logan et al., 1981; National Research Council, 1984]. This is especially true for ozone [Logan, 1985; Delany et al., 1985; Fishman et al., 1986, 1987; Jacob and Wofsy, this issue], one of the most important of the trace gases because of its role in hydroxyl radical production [Levy, 1972; 1973]. Photochemical production of ozone depends critically on the amount of nitric oxide that is present [Chameides, 1978; Fishman and Crutzen, 1978; Crutzen, 1979; Fishman et al.,

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confidence: 99%

Tropospheric nitric oxide measurements over the Amazon Basin

Torres¹,

Buchan²

1988

J. Geophys. Res.

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“…The long-range transport of ozone between urban areas has become increasingly evident (4)(5)(6)(7)(8). As a result, model development programs to address the regional-scale 03 issue began about 10 years ago and continue today.…”

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Modeling ozone concentrations

Schere¹

1988

Environ. Sci. Technol.

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“…CN concentrations and relative humidity occasionally show a positive relationship in the free troposphere. Other studies [Shipley et al, 1984] have shown that transport within the free troposphere is often in layers, under relatively stable conditions. Transport of CN and higher moisture within the same layer during WATOX-86 explains this rough correlation.…”

Section: As Asp Mass In the Marine Boundary Layer Exhibits Nomentioning

confidence: 90%

Aerosol and ozone distributions over the western North Atlantic during WATOX‐86

Bridgman¹,

Schnell²,

Bodhaine³

et al. 1988

Global Biogeochemical Cycles

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On January 4, 6, 8, and 9, 1986, a series of National Oceanic and Atmospheric Administration WP‐3D research flights was conducted over the western Atlantic Ocean 200‐300 km off the coast of North America from Nova Scotia to Georgia as part of the Western Atlantic Ocean Experiment (WATOX). Rights were made perpendicular to NW airflow to establish the flux of gas and aerosol emissions off the North American continent to the ocean. Representative condensation nucleus (CN) concentrations averaged 150‐250 cm−3 in the free troposphere in clean conditions, but in atmospheric layers containing anthropogenic air pollution transported from long distances, CN concentrations reached 6500 cm−3. In the marine boundary layer, CN concentrations averaged 500 to 750 cm−3 under relatively clean conditions, and 1500 to 3000 cm−3 in polluted air. Aerosol scattering extinction (bsp) ranged from 70 × 10−6 m−1 in the marine boundary layer to 20 × 10−6 m−1 in the free troposphere. Aerosol bsp was not as responsive to changes in atmospheric structure as CN although factor‐of‐2 changes across the marine boundary layer were observed. Aerosol size spectra in the marine boundary layer were an order of magnitude greater than those in the free troposphere. Consistent peaks in the volume spectra between 8 and 10 μm diameter established the importance of sea salt as a major aerosol component. Ozone profiles in the free troposphere, normally in the 30‐40 ppb range, exhibited laminae of enhanced concentrations (up to 70 ppb) at moisture boundaries, suggesting that active ozone production was occurring at these levels. Ozone concentrations within the marine boundary layer were generally lower than in the free troposphere.

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Airborne lidar observations of long-range transport in the free troposphere

Cited by 14 publications

References 11 publications

Tropospheric nitric oxide measurements over the Amazon Basin

Tropospheric nitric oxide measurements over the Amazon Basin

Modeling ozone concentrations

Aerosol and ozone distributions over the western North Atlantic during WATOX‐86

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