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B. B. Hicks
and
J. D. Shannon

Abstract

Radioactive fallout data suggest that the concentration of pollutants in rainfall, while highly variable, might be described on the average by about an inverse half-power dependence on the amount of precipitation. Recent measurements of sulfur concentrations in summer rainfall collected at Argonne National Laboratory tend to support this contention, as do preliminary results derived from operations of the DOE precipitation chemistry network. The concept is extended to develop a bulk removal rate for airborne total sulfur by precipitation for use in regional dispersion modeling.

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Jennifer K. Fletcher
,
Shannon Mason
, and
Christian Jakob

Abstract

A climatology of clouds within marine cold air outbreaks, primarily using long-term satellite observations, is presented. Cloud properties between cold air outbreaks in different regions in both hemispheres are compared. In all regions marine cold air outbreak clouds tend to be low level with high cloud fraction and low-to-moderate optical thickness. Stronger cold air outbreaks have clouds that are optically thicker, but not geometrically thicker, than those in weaker cold air outbreaks. There is some evidence that clouds deepen and break up over the course of a cold air outbreak event. The top-of-the-atmosphere longwave cloud radiative effect in cold air outbreaks is small because the clouds have low tops. However, their surface longwave cloud radiative effect is considerably larger. The rarity of cold air outbreaks in summer limits their shortwave cloud radiative effect. They do not contribute substantially to global shortwave cloud radiative effect and are, therefore, unlikely to be a major source of shortwave cloud radiative effect errors in climate models.

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W. J. Emery
,
K. Cherkauer
,
B. Shannon
, and
R. W. Reynolds

Abstract

The design and deployment of an inexpensive hull temperature sensor and data logger system was undertaken for the purpose of improving the measurement of sea surface temperature (SST) by ship-of-opportunity merchant vessels. The resulting hull sensors and data logger systems were installed on four merchant vessels and one research vessel. A variety of installations tested the effects of placement and insulation on the temperature sensors themselves. The resulting hull SST data were compared with monthly SST analyses using optimal interpolation (OI) as well as with data from the thermosalinograph (TSG) on board the research vessel. The data collected from the hull sensor systems, while being slightly offset from the TSG data (likely due to a TSG calibration problem), were found to be in excellent agreement with the monthly OI data.

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Evan M. Oswald
,
Richard B. Rood
,
Kai Zhang
,
Carina J. Gronlund
,
Marie S. O’Neill
,
Jalonne L. White-Newsome
,
Shannon J. Brines
, and
Daniel G. Brown

Abstract

On an annual basis, heat is the chief cause of weather-related deaths in the United States. Therefore, understanding the temperature structure where people live is important for reducing the health burden imposed by hot weather. This study focused on the air temperatures in the Detroit, Michigan, metropolitan region during the summer of 2009. An observational network was established that included 1) monitors sited in the backyards of residential participants, 2) National Weather Service standard observations, and 3) a network of monitors operated by the State of Michigan. Daily high and low temperatures were analyzed for spatial pattern, magnitude of spatial variability, and relationships with weather conditions. The existence of spatial variability was confirmed specifically during weather that was considered to be dangerous to public health. The relationships between temperature observations and distance to water, distance to city center, and local percent of impervious surface were investigated. The spatial variability during the daily low was typically stronger in magnitude and the spatial pattern was more consistent than were those during the daily high. The largest correlation with land-cover and location attributes was between values of percent of impervious surface and daily low temperatures. Daily high temperatures were most correlated with distance to water. Consistent with previous studies on spatial variability in urban environments, the results suggest a need for sensitivity to the spatially variable nature of exposure to heat events in both public health and urban planning. For example, these results showed that the downtown area experienced elevated temperatures during nights and that the eastern portions of Detroit experienced decreased temperatures during afternoons.

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Marcin J. Kurowski
,
Joao Teixeira
,
Chi Ao
,
Shannon Brown
,
Anthony B. Davis
,
Linda Forster
,
Kuo-Nung Wang
,
Matthew Lebsock
,
Mary Morris
,
Vivienne Payne
,
Mark T. Richardson
,
Richard Roy
,
David R. Thompson
, and
Robert C. Wilson

Abstract

To address critical gaps identified by the National Academies of Sciences, Engineering, and Medicine in the current Earth system observation strategy, the 2017–27 Decadal Survey for Earth Science and Applications from Space recommended incubating concepts for future targeted observables including the atmospheric planetary boundary layer (PBL). A subsequent NASA PBL Incubation Study Team Report identified measurement requirements and activities for advancing the maturity of the technologies applicable to the PBL targeted observables and their associated science and applications priorities. While the PBL is the critical layer where humans live and surface energy, moisture, and mass exchanges drive the Earth system, it is also the farthest and most inaccessible layer for spaceborne instruments. Here we document a PBL retrieval observing system simulation experiment (OSSE) framework suitable for assessing existing and new measurement techniques and determining their accuracy and improvements needed for addressing the elevated Decadal Survey requirements. In particular, the benefits of large-eddy simulation (LES) are emphasized as a key source of high-resolution synthetic observations for key PBL regimes: from the tropics, through subtropics and midlatitudes, to subpolar and polar regions. The potential of LES-based PBL retrieval OSSEs is explored using six instrument simulators: Global Navigation Satellite System–Radio Occultation, differential absorption radar, visible to shortwave infrared spectrometer, infrared sounder, Multi-angle Imaging SpectroRadiometer, and microwave sounder. The crucial role of LES in PBL retrieval OSSEs and some perspectives for instrument developments are discussed.

Open access
Shannon M. McNeeley
,
Sarah A. Tessendorf
,
Heather Lazrus
,
Tanya Heikkila
,
Ian M. Ferguson
,
Jennifer S. Arrigo
,
Shahzeen Z. Attari
,
Christina M. Cianfrani
,
Lisa Dilling
,
Jason J. Gurdak
,
Stephanie K. Kampf
,
Derek Kauneckis
,
Christine J. Kirchhoff
,
Juneseok Lee
,
Benjamin R. Lintner
,
Kelly M. Mahoney
,
Sarah Opitz-Stapleton
,
Pallav Ray
,
Andy B. South
,
Andrew P. Stubblefield
, and
Julie Brugger
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J. C. Doran
,
S. Abbott
,
J. Archuleta
,
X. Bian
,
J. Chow
,
R. L. Coulter
,
S. F. J. de Wekker
,
S. Edgerton
,
S. Elliott
,
A. Fernandez
,
J. D. Fast
,
J. M. Hubbe
,
C. King
,
D. Langley
,
J. Leach
,
J. T. Lee
,
T. J. Martin
,
D. Martinez
,
J. L. Martinez
,
G. Mercado
,
V. Mora
,
M. Mulhearn
,
J. L. Pena
,
R. Petty
,
W. Porch
,
C. Russell
,
R. Salas
,
J. D. Shannon
,
W. J. Shaw
,
G. Sosa
,
L. Tellier
,
B. Templeman
,
J. G. Watson
,
R. White
,
C. D. Whiteman
, and
D. Wolfe

A boundary layer field experiment in the Mexico City basin during the period 24 February–22 March 1997 is described. A total of six sites were instrumented. At four of the sites, 915-MHz radar wind profilers were deployed and radiosondes were released five times per day. Two of these sites also had sodars collocated with the profilers. Radiosondes were released twice per day at a fifth site to the south of the basin, and rawinsondes were flown from another location to the northeast of the city three times per day. Mixed layers grew to depths of 2500–3500 m, with a rapid period of growth beginning shortly before noon and lasting for several hours. Significant differences between the mixed-layer temperatures in the basin and outside the basin were observed. Three thermally and topographically driven flow patterns were observed that are consistent with previously hypothesized topographical and thermal forcing mechanisms. Despite these features, the circulation patterns in the basin important for the transport and diffusion of air pollutants show less day-to-day regularity than had been anticipated on the basis of Mexico City's tropical location, high altitude and strong insolation, and topographical setting.

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