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  • Author or Editor: Russell L. Scott x
  • Bulletin of the American Meteorological Society x
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Kenneth E. Kunkel
,
Thomas R. Karl
,
Harold Brooks
,
James Kossin
,
Jay H. Lawrimore
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Derek Arndt
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Lance Bosart
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David Changnon
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Susan L. Cutter
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Nolan Doesken
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Kerry Emanuel
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Pavel Ya. Groisman
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Richard W. Katz
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Thomas Knutson
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James O'Brien
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Christopher J. Paciorek
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Thomas C. Peterson
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Kelly Redmond
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David Robinson
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Jeff Trapp
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Russell Vose
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Scott Weaver
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Michael Wehner
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Klaus Wolter
, and
Donald Wuebbles

The state of knowledge regarding trends and an understanding of their causes is presented for a specific subset of extreme weather and climate types. For severe convective storms (tornadoes, hailstorms, and severe thunderstorms), differences in time and space of practices of collecting reports of events make using the reporting database to detect trends extremely difficult. Overall, changes in the frequency of environments favorable for severe thunderstorms have not been statistically significant. For extreme precipitation, there is strong evidence for a nationally averaged upward trend in the frequency and intensity of events. The causes of the observed trends have not been determined with certainty, although there is evidence that increasing atmospheric water vapor may be one factor. For hurricanes and typhoons, robust detection of trends in Atlantic and western North Pacific tropical cyclone (TC) activity is significantly constrained by data heterogeneity and deficient quantification of internal variability. Attribution of past TC changes is further challenged by a lack of consensus on the physical link- ages between climate forcing and TC activity. As a result, attribution of trends to anthropogenic forcing remains controversial. For severe snowstorms and ice storms, the number of severe regional snowstorms that occurred since 1960 was more than twice that of the preceding 60 years. There are no significant multidecadal trends in the areal percentage of the contiguous United States impacted by extreme seasonal snowfall amounts since 1900. There is no distinguishable trend in the frequency of ice storms for the United States as a whole since 1950.

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Russell S. Vose
,
Scott Applequist
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Mark A. Bourassa
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Sara C. Pryor
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Rebecca J. Barthelmie
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Brian Blanton
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Peter D. Bromirski
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Harold E. Brooks
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Arthur T. DeGaetano
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Randall M. Dole
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David R. Easterling
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Robert E. Jensen
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Thomas R. Karl
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Richard W. Katz
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Katherine Klink
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Michael C. Kruk
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Kenneth E. Kunkel
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Michael C. MacCracken
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Thomas C. Peterson
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Karsten Shein
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Bridget R. Thomas
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John E. Walsh
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Xiaolan L. Wang
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Michael F. Wehner
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Donald J. Wuebbles
, and
Robert S. Young

This scientific assessment examines changes in three climate extremes—extratropical storms, winds, and waves—with an emphasis on U.S. coastal regions during the cold season. There is moderate evidence of an increase in both extratropical storm frequency and intensity during the cold season in the Northern Hemisphere since 1950, with suggestive evidence of geographic shifts resulting in slight upward trends in offshore/coastal regions. There is also suggestive evidence of an increase in extreme winds (at least annually) over parts of the ocean since the early to mid-1980s, but the evidence over the U.S. land surface is inconclusive. Finally, there is moderate evidence of an increase in extreme waves in winter along the Pacific coast since the 1950s, but along other U.S. shorelines any tendencies are of modest magnitude compared with historical variability. The data for extratropical cyclones are considered to be of relatively high quality for trend detection, whereas the data for extreme winds and waves are judged to be of intermediate quality. In terms of physical causes leading to multidecadal changes, the level of understanding for both extratropical storms and extreme winds is considered to be relatively low, while that for extreme waves is judged to be intermediate. Since the ability to measure these changes with some confidence is relatively recent, understanding is expected to improve in the future for a variety of reasons, including increased periods of record and the development of “climate reanalysis” projects.

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Charles O. Stanier
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R. Bradley Pierce
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Maryam Abdi-Oskouei
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Zachariah E. Adelman
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Jay Al-Saadi
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Hariprasad D. Alwe
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Timothy H. Bertram
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Gregory R. Carmichael
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Megan B. Christiansen
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Patricia A. Cleary
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Alan C. Czarnetzki
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Angela F. Dickens
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Marta A. Fuoco
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Dagen D. Hughes
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Joseph P. Hupy
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Scott J. Janz
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Laura M. Judd
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Donna Kenski
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Matthew G. Kowalewski
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Russell W. Long
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Dylan B. Millet
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Gordon Novak
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Behrooz Roozitalab
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Stephanie L. Shaw
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Elizabeth A. Stone
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James Szykman
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Lukas Valin
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Michael Vermeuel
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Timothy J. Wagner
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Andrew R. Whitehill
, and
David J. Williams

Abstract

The Lake Michigan Ozone Study 2017 (LMOS 2017) was a collaborative multiagency field study targeting ozone chemistry, meteorology, and air quality observations in the southern Lake Michigan area. The primary objective of LMOS 2017 was to provide measurements to improve air quality modeling of the complex meteorological and chemical environment in the region. LMOS 2017 science questions included spatiotemporal assessment of nitrogen oxides (NO x = NO + NO2) and volatile organic compounds (VOC) emission sources and their influence on ozone episodes; the role of lake breezes; contribution of new remote sensing tools such as GeoTASO, Pandora, and TEMPO to air quality management; and evaluation of photochemical grid models. The observing strategy included GeoTASO on board the NASA UC-12 aircraft capturing NO2 and formaldehyde columns, an in situ profiling aircraft, two ground-based coastal enhanced monitoring locations, continuous NO2 columns from coastal Pandora instruments, and an instrumented research vessel. Local photochemical ozone production was observed on 2 June, 9–12 June, and 14–16 June, providing insights on the processes relevant to state and federal air quality management. The LMOS 2017 aircraft mapped significant spatial and temporal variation of NO2 emissions as well as polluted layers with rapid ozone formation occurring in a shallow layer near the Lake Michigan surface. Meteorological characteristics of the lake breeze were observed in detail and measurements of ozone, NOx, nitric acid, hydrogen peroxide, VOC, oxygenated VOC (OVOC), and fine particulate matter (PM2.5) composition were conducted. This article summarizes the study design, directs readers to the campaign data repository, and presents a summary of findings.

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