TY - JOUR
T1 - Urban emissions of water vapor in winter
AU - Salmon, Olivia E.
AU - Shepson, Paul B.
AU - Ren, Xinrong
AU - Marquardt Collow, Allison B.
AU - Miller, Mark A.
AU - Carlton, Annmarie G.
AU - Cambaliza, Maria O.L.
AU - Heimburger, Alexie
AU - Morgan, Kristan L.
AU - Fuentes, Jose D.
AU - Stirm, Brian H.
AU - Grundman, Robert
AU - Dickerson, Russell R.
N1 - Funding Information:
We thank Joel A. Thornton and Steven S. Brown for organizing and inviting us to take part in the WINTER campaign. We are grateful for help with the design, installation, and maintenance of the ALAR instrument package we received from Purdue University’s Jonathan Amy Facility for Chemical Instrumentation. We thank Daniel P. Sarmiento for read ing and suggesting improvements to this manuscript. We acknowledge sup port for this research from James Whetstone and the National Institute of Standards and Technology (NIST), for which we are grateful. We also thank three anonymous reviewers for valuable input on this manuscript. The UMD and Purdue flight experiments and analysis were supported by NIST award 70NANB14H333 and 70NANB14H332, respectively. The radiative transfer modeling was supported by the National Aeronautics and Space Administration’s Earth Science Research Program. All airborne data collected during the WINTER campaign by the Purdue and UMD aircraft are available on the WINTER Data Archive at EOL: http://data.eol.ucar.edu/master_list/? project=WINTER. Purdue University air- borne data collected in Indianapolis as part of the INFLUX campaign are avail able at http://sites.psu.edu/influx/data/. The authors declare no competing financial interest.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/9/16
Y1 - 2017/9/16
N2 - Elevated water vapor (H2Ov) mole fractions were occasionally observed downwind of Indianapolis, IN, and the Washington, D.C.-Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2Ov excess signal was observed, H2Ov emission estimates range between 1.6 × 104 and 1.7 × 105 kg s−1 and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2Ov from the urban study sites. Estimates of H2Ov emissions from combustion sources and electricity generation facility cooling towers are 1–2 orders of magnitude smaller than the urban H2Ov emission rates estimated from observations. Instances of urban H2Ov enhancement could be a result of differences in snowmelt and evaporation rates within the urban area, due in part to larger wintertime anthropogenic heat flux and land cover differences, relative to surrounding rural areas. More study is needed to understand why the urban H2Ov excess signal is observed on some days, and not others. Radiative transfer modeling indicates that the observed urban enhancements in H2Ov and other greenhouse gas mole fractions contribute only 0.1°C d−1 to the urban heat island at the surface. This integrated warming through the boundary layer is offset by longwave cooling by H2Ov at the top of the boundary layer. While the radiative impacts of urban H2Ov emissions do not meaningfully influence urban heat island intensity, urban H2Ov emissions may have the potential to alter downwind aerosol and cloud properties.
AB - Elevated water vapor (H2Ov) mole fractions were occasionally observed downwind of Indianapolis, IN, and the Washington, D.C.-Baltimore, MD, area during airborne mass balance experiments conducted during winter months between 2012 and 2015. On days when an urban H2Ov excess signal was observed, H2Ov emission estimates range between 1.6 × 104 and 1.7 × 105 kg s−1 and account for up to 8.4% of the total (background + urban excess) advected flow of atmospheric boundary layer H2Ov from the urban study sites. Estimates of H2Ov emissions from combustion sources and electricity generation facility cooling towers are 1–2 orders of magnitude smaller than the urban H2Ov emission rates estimated from observations. Instances of urban H2Ov enhancement could be a result of differences in snowmelt and evaporation rates within the urban area, due in part to larger wintertime anthropogenic heat flux and land cover differences, relative to surrounding rural areas. More study is needed to understand why the urban H2Ov excess signal is observed on some days, and not others. Radiative transfer modeling indicates that the observed urban enhancements in H2Ov and other greenhouse gas mole fractions contribute only 0.1°C d−1 to the urban heat island at the surface. This integrated warming through the boundary layer is offset by longwave cooling by H2Ov at the top of the boundary layer. While the radiative impacts of urban H2Ov emissions do not meaningfully influence urban heat island intensity, urban H2Ov emissions may have the potential to alter downwind aerosol and cloud properties.
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U2 - 10.1002/2016JD026074
DO - 10.1002/2016JD026074
M3 - Article
C2 - 29308343
AN - SCOPUS:85030098280
SN - 2169-897X
VL - 122
SP - 9467
EP - 9484
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
IS - 17
ER -