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L. O. Myrup
,
D. L. Morgan
, and
R. L. Boomer

Abstract

An observational study of the three-dimensional structure of the wind field over Sacramento, California, is reported. The observations were made with a double-theodolite network during the summer period. Although the topography is relatively uniform, the analysis revealed a complex, three-dimensional structure in the wind field, including wind reversals with height and substantial horizontal variability. Spatial correlation functions showed that correlation increased with altitude and decreased with separation distance for the westerly and northerly components. It is suggested that the distance at which 50% of the variance is accounted for by the correlations might be an appropriate criterion for determining upper air grid spacing in air quality models. In the Sacramento data, this figure would be of the order of 10 km. Horizontal divergence and vertical velocities were calculated and revealed substantial subsidence over Sacramento during the study period. The diurnal variation of these quantities resembled that of the Los Angeles basin. The calculated subsidence was of the order of −5 cm s−1 and it is suggested that subsidence is a factor which should not be routinely ignored in air quality models.

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L. O. Myrup
,
D. L. Morgan
, and
R. Boomer

Abstract

An analytical study of transport phenomena during the evening transition period in the vicinity of Sacramento, California is presented. The study is based on a network of double-theodolite wind stations, aircraft soundings and micrometeorological measurements made in the city. The transition period could be described in terms of three stability regimes: 1) moderately unstable (h/L = −4.19), 2) moderately stable (h/L = 1.06) and, later in the evening 3) very stable (h/L = 295). During the analysis period, the boundary layer depth first increased in the late afternoon unstable period, reaching a maximum depth of about 1 km, then dropped discontinuously to about 200 m in the early evening (moderately stable period). During the remainder of the evening, the boundary-layer depth increased steadily, extending to over 700 m after midnight. Comparison of aircraft soundings made up- and downwind of the city of Sacramento indicated that the city had the effect of increasing the boundary layer depth by an average of 165 m. During the stability transition, the temperature profile rapidly developed a strong, low level inversion, capping an extremely shallow (< = 100 m) unstable layer, presumably associated with the urban heat island. The most prominent feature of the soundings was the rapid development, during the period of moderate stability, of low-level transient jets in the wind field. The jet was associated with low-level maxima in the horizontal transport of moisture and sensible heat.

The boundary layer water vapor budget was evaluated for the entire analysis period. All three stability regimes displayed approximate equilibrium. For each period, the depth-integrated balance was between vertical diffusion, as a source, and horizontal and vertical advection, as sinks. It is noteworthy that subsiding dry air was found to be important throughout the entire period.

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D. L. Morgan
,
W. O. Pruitt
, and
F. J. Lourence

Abstract

Various methods of estimating atmospheric radiation including the use of radiation charts and six empirical formulas are examined, using micrometeorological data collected at Davis, Calif. The Bolz method for adjusting the clear-sky estimates of atmospheric radiation from empirical formulas for cloudy, conditions is studied using observed cloud conditions and measured atmospheric radiation. This method works well for overcast low-cloud conditions. However, in high-cloud conditions with less than complete sky coverage, it is less satisfactory, perhaps due to problems in analytically representing the cloud conditions.

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Peter J. Walton
,
Morgan B. Yarker
,
Michel D. S. Mesquita
, and
Friederike E. L. Otto

Abstract

Globally, decision-makers are increasingly using high-resolution climate models to support policy and planning; however, many of these users do not have the knowledge needed to use them appropriately. This problem is compounded by not having access to quality learning opportunities to better understand how to apply the models and interpret results. This paper discusses and proposes an educational framework based on two independent online courses on regional climate modeling, which addresses the accessibility issue and provides guidance to climate science professors, researchers, and institutions who want to create their own online courses.

The role of e-learning as an educational tool is well documented, highlighting the benefits of improved personal efficiency through “anywhere, anytime” learning with the flexibility to support professional development across different sectors. In addition, improved global Internet means increased accessibility. However, e-learning’s function as a tool to support understanding of atmospheric physics and high-resolution climate modeling has not been widely discussed. To date, few courses, if any, support understanding that takes full advantage of e-learning best practices.

There is a growing need for climate literacy to help inform decision-making on a range of scales, from individual households to corporate CEOs. And while there is a plethora of climate information online, educational theory suggests that people need to be guided in how to convert this information into applicable knowledge.

Here, we present how the experience of the courses we designed and ran independent of each other, both engaging learners with better understanding benefits and limitations of regional climate modeling, lead to a framework of designing e-learning for climate modeling.

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D. T. HILLEARY
,
E. L. HEACOCK
,
W. A. MORGAN
,
R. H. MOORE
,
E. C. MANGOLD
, and
S. D. SOULES

Abstract

Three spectrometers and associated experiments are described. The work reviewed comprises the early experimental phases of a program to develop a satellite infrared spectrometer capable of making radiometric measurements in the 15-micron carbon dioxide band needed for deduction of atmospheric temperature profiles. Initially, a simplified, breadboard spectrometer with four spectral channels was used to determine the temperature profile of the lower atmosphere from the ground. Next, a commercial spectrophotometer was modified and another determination of the atmospheric temperature profile was made using more spectral intervals. Instrument specifications for a balloon flight model spectrometer were derived from these experiments. Following the model*s fabrication, testing, and calibration, two high-altitude balloon flights were conducted to demonstrate that the atmospheric temperature profile could be ascertained from above the atmosphere.

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Fuqing Zhang
,
Rebecca E. Morss
,
J. A. Sippel
,
T. K. Beckman
,
N. C. Clements
,
N. L. Hampshire
,
J. N. Harvey
,
J. M. Hernandez
,
Z. C. Morgan
,
R. M. Mosier
,
S. Wang
, and
S. D. Winkley

Abstract

Hurricane Rita made landfall near the Texas–Louisiana border in September 2005, causing major damage and disruption. As Rita approached the Gulf Coast, uncertainties in the storm’s track and intensity forecasts, combined with the aftermath of Hurricane Katrina, led to major evacuations along the Texas coast and significant traffic jams in the broader Houston area. This study investigates the societal impacts of Hurricane Rita and its forecasts through a face-to-face survey with 120 Texas Gulf Coast residents. The survey explored respondents’ evacuation decisions prior to Hurricane Rita, their perceptions of hurricane risk, and their use of and opinions on Hurricane Rita forecasts. The vast majority of respondents evacuated from Hurricane Rita, and more than half stated that Hurricane Katrina affected their evacuation decision. Although some respondents said that their primary reason for evacuating was local officials’ evacuation order, many reported using information about the hurricane to evaluate the risk it posed to them and their families. Despite the major traffic jams and the minor damage in many evacuated regions, most evacuees interviewed do not regret their decision to evacuate. The majority of respondents stated that they intend to evacuate for a future category 3 hurricane, but the majority would stay for a category 2 hurricane. Most respondents obtained forecasts from multiple sources and reported checking forecasts frequently. Despite the forecast uncertainties, the respondents had high confidence in and satisfaction with the forecasts of Rita provided by the National Hurricane Center.

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Melanie Wetzel
,
David Dempsey
,
Sandra Nilsson
,
Mohan Ramamurthy
,
Steve Koch
,
Jennie Moody
,
David Knight
,
Charles Murphy
,
David Fulker
,
Mary Marlino
,
Michael Morgan
,
Doug Yarger
,
Dan Vietor
, and
Greg Cox

An education-oriented workshop for college faculty in the atmospheric and related sciences was held in Boulder, Colorado, during June 1997 by three programs of the University Corporation for Atmospheric Research. The objective of this workshop was to provide faculty with hands-on training in the use of Web-based instructional methods for specific application to the teaching of satellite remote sensing in their subject areas. More than 150 faculty and associated scientists participated, and postworkshop evaluation showed it to have been a very successful integration of information and activities related to computer-based instruction, educational principles, and scientific lectures.

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V. Masson-Delmotte
,
S. Hou
,
A. Ekaykin
,
J. Jouzel
,
A. Aristarain
,
R. T. Bernardo
,
D. Bromwich
,
O. Cattani
,
M. Delmotte
,
S. Falourd
,
M. Frezzotti
,
H. Gallée
,
L. Genoni
,
E. Isaksson
,
A. Landais
,
M. M. Helsen
,
G. Hoffmann
,
J. Lopez
,
V. Morgan
,
H. Motoyama
,
D. Noone
,
H. Oerter
,
J. R. Petit
,
A. Royer
,
R. Uemura
,
G. A. Schmidt
,
E. Schlosser
,
J. C. Simões
,
E. J. Steig
,
B. Stenni
,
M. Stievenard
,
M. R. van den Broeke
,
R. S. W. van de Wal
,
W. J. van de Berg
,
F. Vimeux
, and
J. W. C. White

Abstract

A database of surface Antarctic snow isotopic composition is constructed using available measurements, with an estimate of data quality and local variability. Although more than 1000 locations are documented, the spatial coverage remains uneven with a majority of sites located in specific areas of East Antarctica. The database is used to analyze the spatial variations in snow isotopic composition with respect to geographical characteristics (elevation, distance to the coast) and climatic features (temperature, accumulation) and with a focus on deuterium excess. The capacity of theoretical isotopic, regional, and general circulation atmospheric models (including “isotopic” models) to reproduce the observed features and assess the role of moisture advection in spatial deuterium excess fluctuations is analyzed.

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Britton B. Stephens
,
Matthew C. Long
,
Ralph F. Keeling
,
Eric A. Kort
,
Colm Sweeney
,
Eric C. Apel
,
Elliot L. Atlas
,
Stuart Beaton
,
Jonathan D. Bent
,
Nicola J. Blake
,
James F. Bresch
,
Joanna Casey
,
Bruce C. Daube
,
Minghui Diao
,
Ernesto Diaz
,
Heidi Dierssen
,
Valeria Donets
,
Bo-Cai Gao
,
Michelle Gierach
,
Robert Green
,
Justin Haag
,
Matthew Hayman
,
Alan J. Hills
,
Martín S. Hoecker-Martínez
,
Shawn B. Honomichl
,
Rebecca S. Hornbrook
,
Jorgen B. Jensen
,
Rong-Rong Li
,
Ian McCubbin
,
Kathryn McKain
,
Eric J. Morgan
,
Scott Nolte
,
Jordan G. Powers
,
Bryan Rainwater
,
Kaylan Randolph
,
Mike Reeves
,
Sue M. Schauffler
,
Katherine Smith
,
Mackenzie Smith
,
Jeff Stith
,
Gregory Stossmeister
,
Darin W. Toohey
, and
Andrew S. Watt

Abstract

The Southern Ocean plays a critical role in the global climate system by mediating atmosphere–ocean partitioning of heat and carbon dioxide. However, Earth system models are demonstrably deficient in the Southern Ocean, leading to large uncertainties in future air–sea CO2 flux projections under climate warming and incomplete interpretations of natural variability on interannual to geologic time scales. Here, we describe a recent aircraft observational campaign, the O2/N2 Ratio and CO2 Airborne Southern Ocean (ORCAS) study, which collected measurements over the Southern Ocean during January and February 2016. The primary research objective of the ORCAS campaign was to improve observational constraints on the seasonal exchange of atmospheric carbon dioxide and oxygen with the Southern Ocean. The campaign also included measurements of anthropogenic and marine biogenic reactive gases; high-resolution, hyperspectral ocean color imaging of the ocean surface; and microphysical data relevant for understanding and modeling cloud processes. In each of these components of the ORCAS project, the campaign has significantly expanded the amount of observational data available for this remote region. Ongoing research based on these observations will contribute to advancing our understanding of this climatically important system across a range of topics including carbon cycling, atmospheric chemistry and transport, and cloud physics. This article presents an overview of the scientific and methodological aspects of the ORCAS project and highlights early findings.

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Chelsea R. Thompson
,
Steven C. Wofsy
,
Michael J. Prather
,
Paul A. Newman
,
Thomas F. Hanisco
,
Thomas B. Ryerson
,
David W. Fahey
,
Eric C. Apel
,
Charles A. Brock
,
William H. Brune
,
Karl Froyd
,
Joseph M. Katich
,
Julie M. Nicely
,
Jeff Peischl
,
Eric Ray
,
Patrick R. Veres
,
Siyuan Wang
,
Hannah M. Allen
,
Elizabeth Asher
,
Huisheng Bian
,
Donald Blake
,
Ilann Bourgeois
,
John Budney
,
T. Paul Bui
,
Amy Butler
,
Pedro Campuzano-Jost
,
Cecilia Chang
,
Mian Chin
,
Róisín Commane
,
Gus Correa
,
John D. Crounse
,
Bruce Daube
,
Jack E. Dibb
,
Joshua P. DiGangi
,
Glenn S. Diskin
,
Maximilian Dollner
,
James W. Elkins
,
Arlene M. Fiore
,
Clare M. Flynn
,
Hao Guo
,
Samuel R. Hall
,
Reem A. Hannun
,
Alan Hills
,
Eric J. Hintsa
,
Alma Hodzic
,
Rebecca S. Hornbrook
,
L. Greg Huey
,
Jose L. Jimenez
,
Ralph F. Keeling
,
Michelle J. Kim
,
Agnieszka Kupc
,
Forrest Lacey
,
Leslie R. Lait
,
Jean-Francois Lamarque
,
Junhua Liu
,
Kathryn McKain
,
Simone Meinardi
,
David O. Miller
,
Stephen A. Montzka
,
Fred L. Moore
,
Eric J. Morgan
,
Daniel M. Murphy
,
Lee T. Murray
,
Benjamin A. Nault
,
J. Andrew Neuman
,
Louis Nguyen
,
Yenny Gonzalez
,
Andrew Rollins
,
Karen Rosenlof
,
Maryann Sargent
,
Gregory Schill
,
Joshua P. Schwarz
,
Jason M. St. Clair
,
Stephen D. Steenrod
,
Britton B. Stephens
,
Susan E. Strahan
,
Sarah A. Strode
,
Colm Sweeney
,
Alexander B. Thames
,
Kirk Ullmann
,
Nicholas Wagner
,
Rodney Weber
,
Bernadett Weinzierl
,
Paul O. Wennberg
,
Christina J. Williamson
,
Glenn M. Wolfe
, and
Linghan Zeng

Abstract

This article provides an overview of the NASA Atmospheric Tomography (ATom) mission and a summary of selected scientific findings to date. ATom was an airborne measurements and modeling campaign aimed at characterizing the composition and chemistry of the troposphere over the most remote regions of the Pacific, Southern, Atlantic, and Arctic Oceans, and examining the impact of anthropogenic and natural emissions on a global scale. These remote regions dominate global chemical reactivity and are exceptionally important for global air quality and climate. ATom data provide the in situ measurements needed to understand the range of chemical species and their reactions, and to test satellite remote sensing observations and global models over large regions of the remote atmosphere. Lack of data in these regions, particularly over the oceans, has limited our understanding of how atmospheric composition is changing in response to shifting anthropogenic emissions and physical climate change. ATom was designed as a global-scale tomographic sampling mission with extensive geographic and seasonal coverage, tropospheric vertical profiling, and detailed speciation of reactive compounds and pollution tracers. ATom flew the NASA DC-8 research aircraft over four seasons to collect a comprehensive suite of measurements of gases, aerosols, and radical species from the remote troposphere and lower stratosphere on four global circuits from 2016 to 2018. Flights maintained near-continuous vertical profiling of 0.15–13-km altitudes on long meridional transects of the Pacific and Atlantic Ocean basins. Analysis and modeling of ATom data have led to the significant early findings highlighted here.

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