Title: Tall Tower Vertical Profiles and Diurnal Trends of Ammonia in the Colorado Front Range: Tall Tower Vertical Profiles of Ammonia

Abstract

Ammonia (NH ₃) mixing ratios were measured between the surface and 280 m aboveground level from a moveable carriage at the Boulder Atmospheric Observatory tower in summer 2014 as part of the Front Range Air Pollution and Photochemistry Éxperiment. The campaign median mixing ratio was 3.3 ppb, ranging from below detection limits to 192 ppb. Median vertical profiles show an overall increase in NH ₃ mixing ratios toward the surface of 6.7 ppb (89%) during the day and 3.9 ppb (141%) at night. In contrast to the overall increasing trend, some individual profiles show decreasing NH ₃ in the lowest 10 m. This suggests that the local surface is capable of acting as either a source or a sink, depending on the relative amounts of NH ₃ at the surface, and in advected air parcels. We further use this data set to investigate the variation in diurnal patterns of NH ₃ as a function of height above the surface. At higher altitudes (100 ± 5 and 280 ± 5 m), NH ₃ mixing ratios reach a gradual maximum during the day between 9:00 and 16:00 local time, likely driven by changes in source region. At lower altitudes (10 ± 5more » m), the daytime maximum begins earlier at about 7:00 local time, followed by a sharper increase at 9:00 local time. At this height we also observe a peak in NH3 mixing ratios during the night, likely driven by the trapping of emitted NH ₃ within the shallower nocturnal boundary layer.« less

Authors:

Tevlin, A. G.  ^[1];

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Li, Y.  ^[2];

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Collett, J. L. ^[3]; McDuffie, E. E.  ^[4];

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Fischer, E. V.  ^[3];

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Murphy, J. G.  ^[1]

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+ Show Author Affiliations

1. Univ. of Toronto, ON (Canada)
2. Arizona Department of Environmental Quality, Phoenix, AZ (United States)
3. Colorado State Univ., Fort Collins, CO (United States)
4. Univ. of Colorado, Boulder, CO (United States); National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.

Publication Date:

2017-11-03

Research Org.:

Aerodyne Research, Inc., Billerica, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1537316

Alternate Identifier(s):

OSTI ID: 1410352

Grant/Contract Number:  

SC0006193; DESC0006193

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research: Atmospheres

Additional Journal Information:

Journal Volume: 122; Journal Issue: 22; Journal ID: ISSN 2169-897X

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Meteorology & Atmospheric Sciences