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  • Author or Editor: W. L. Smith x
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Steven A. Ackerman
,
Ed W. Eloranta
,
Chris J. Grund
,
Robert O. Knuteson
,
Henry E. Revercomb
,
William L. Smith
, and
Donald P. Wylie

During the period of 26 October 1989 through 6 December 1989 a unique complement of measurements was made at the University of Wisconsin—Madison to study the radiative properties of cirrus clouds. Simultaneous observations were obtained from a scanning lidar, two interferometers, a high spectral resolution lidar, geostationary and polar orbiting satellites, radiosonde launches, and a whole-sky imager. This paper describes the experiment, the instruments deployed, and, as an example, the data collected during one day of the experiment.

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J. A. Curry
,
A. Bentamy
,
M. A. Bourassa
,
D. Bourras
,
E. F. Bradley
,
M. Brunke
,
S. Castro
,
S. H. Chou
,
C. A. Clayson
,
W. J. Emery
,
L. Eymard
,
C. W. Fairall
,
M. Kubota
,
B. Lin
,
W. Perrie
,
R. A. Reeder
,
I. A. Renfrew
,
W. B. Rossow
,
J. Schulz
,
S. R. Smith
,
P. J. Webster
,
G. A. Wick
, and
X. Zeng

High-resolution surface fluxes over the global ocean are needed to evaluate coupled atmosphere–ocean models and weather forecasting models, provide surface forcing for ocean models, understand the regional and temporal variations of the exchange of heat between the atmosphere and ocean, and provide a large-scale context for field experiments. Under the auspices of the World Climate Research Programme (WCRP) Global Energy and Water Cycle Experiment (GEWEX) Radiation Panel, the SEAFLUX Project has been initiated to investigate producing a high-resolution satellite-based dataset of surface turbulent fluxes over the global oceans to complement the existing products for surface radiation fluxes and precipitation. The SEAFLUX Project includes the following elements: a library of in situ data, with collocated satellite data to be used in the evaluation and improvement of global flux products; organized intercomparison projects, to evaluate and improve bulk flux models and determination from the satellite of the input parameters; and coordinated evaluation of the flux products in the context of applications, such as forcing ocean models and evaluation of coupled atmosphere–ocean models. The objective of this paper is to present an overview of the status of global ocean surface flux products, the methodology being used by SEAFLUX, and the prospects for improvement of satellite-derived flux products.

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Sarah J. Doherty
,
Stephan Bojinski
,
Ann Henderson-Sellers
,
Kevin Noone
,
David Goodrich
,
Nathaniel L. Bindoff
,
John A. Church
,
Kathy A. Hibbard
,
Thomas R. Karl
,
Lucka Kajfez-Bogataj
,
Amanda H. Lynch
,
David E. Parker
,
I. Colin Prentice
,
Venkatachalam Ramaswamy
,
Roger W. Saunders
,
Mark Stafford Smith
,
Konrad Steffen
,
Thomas F. Stocker
,
Peter W. Thorne
,
Kevin E. Trenberth
,
Michel M. Verstraete
, and
Francis W. Zwiers

The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming is “unequivocal” and that most of the observed increase since the mid-twentieth century is very likely due to the increase in anthropogenic greenhouse gas concentrations, with discernible human influences on ocean warming, continental-average temperatures, temperature extremes, wind patterns, and other physical and biological indicators, impacting both socioeconomic and ecological systems. It is now clear that we are committed to some level of global climate change, and it is imperative that this be considered when planning future climate research and observational strategies. The Global Climate Observing System program (GCOS), the World Climate Research Programme (WCRP), and the International Geosphere-Biosphere Programme (IGBP) therefore initiated a process to summarize the lessons learned through AR4 Working Groups I and II and to identify a set of high-priority modeling and observational needs. Two classes of recommendations emerged. First is the need to improve climate models, observational and climate monitoring systems, and our understanding of key processes. Second, the framework for climate research and observations must be extended to document impacts and to guide adaptation and mitigation efforts. Research and observational strategies specifically aimed at improving our ability to predict and understand impacts, adaptive capacity, and societal and ecosystem vulnerabilities will serve both purposes and are the subject of the specific recommendations made in this paper.

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D. Durnford
,
V. Fortin
,
G. C. Smith
,
B. Archambault
,
D. Deacu
,
F. Dupont
,
S. Dyck
,
Y. Martinez
,
E. Klyszejko
,
M. MacKay
,
L. Liu
,
P. Pellerin
,
A. Pietroniro
,
F. Roy
,
V. Vu
,
B. Winter
,
W. Yu
,
C. Spence
,
J. Bruxer
, and
J. Dickhout

Abstract

In this time of a changing climate, it is important to know whether lake levels will rise, potentially causing flooding, or river flows will dry up during abnormally dry weather. The Great Lakes region is the largest freshwater lake system in the world. Moreover, agriculture, industry, commerce, and shipping are active in this densely populated region. Environment and Climate Change Canada (ECCC) recently implemented the Water Cycle Prediction System (WCPS) over the Great Lakes and St. Lawrence River watershed (WCPS-GLS version 1.0) following a decade of research and development. WCPS, a network of linked models, simulates the complete water cycle, following water as it moves from the atmosphere to the surface, through the river network and into lakes, and back to the atmosphere. Information concerning the water cycle is passed between the models. WCPS is the first short-to-medium-range prediction system of the complete water cycle to be run on an operational basis anywhere. It currently produces two forecasts per day for the next three days. WCPS generally provides reliable results throughout the length of the forecast. The transmission of errors between the component models is reduced by data assimilation. Interactions between the environmental compartments are active. This ongoing intercommunication is valuable for extreme events such as rapid ice freeze-up and flooding or drought caused by abnormal amounts of precipitation. Products include precipitation; evaporation; lake water levels, temperatures, and currents; ice cover; and river flows. These products are of interest to a wide variety of governmental, commercial, and industrial groups, as well as the public.

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J. P. Taylor
,
W. L Smith
,
V. Cuomo
,
A. M. Larar
,
D. K. Zhou
,
C. Serio
,
T. Maestri
,
R. Rizzi
,
S. Newman
,
P. Antonelli
,
S. Mango
,
P. Di Girolamo
,
F. Esposito
,
G. Grieco
,
D. Summa
,
R. Restieri
,
G. Masiello
,
F. Romano
,
G. Pappalardo
,
G. Pavese
,
L. Mona
,
A. Amodeo
, and
G. Pisani

The international experiment called the European Aqua Thermodynamic Experiment (EAQUATE) was held in September 2004 in Italy and the United Kingdom to validate Aqua satellite Atmospheric Infrared Sounder (AIRS) radiance measurements and derived products with certain groundbased and airborne systems useful for validating hyperspectral satellite sounding observations. A range of flights over land and marine surfaces were conducted to coincide with overpasses of the AIRS instrument on the Earth Observing System Aqua platform. Direct radiance evaluation of AIRS using National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) and the Scanning High-Resolution Infrared Sounder has shown excellent agreement. Comparisons of level-2 retrievals of temperature and water vapor from AIRS and NAST-I validated against high-quality lidar and dropsonde data show that the 1-K/l-km and 10%/1-km requirements for temperature and water vapor (respectively) are generally being met. The EAQUATE campaign has proven the need for synergistic measurements from a range of observing systems for satellite calibration/validation and has paved the way for future calibration/validation activities in support of the Infrared Atmospheric Sounding Interferometer on the European Meteorological Operational platform and Cross-Track Infrared Sounder on the U.S. NPOESS Prepatory Project platform.

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Bruce A. Wielicki
,
D. F. Young
,
M. G. Mlynczak
,
K. J. Thome
,
S. Leroy
,
J. Corliss
,
J. G. Anderson
,
C. O. Ao
,
R. Bantges
,
F. Best
,
K. Bowman
,
H. Brindley
,
J. J. Butler
,
W. Collins
,
J. A. Dykema
,
D. R. Doelling
,
D. R. Feldman
,
N. Fox
,
X. Huang
,
R. Holz
,
Y. Huang
,
Z. Jin
,
D. Jennings
,
D. G. Johnson
,
K. Jucks
,
S. Kato
,
D. B. Kirk-Davidoff
,
R. Knuteson
,
G. Kopp
,
D. P. Kratz
,
X. Liu
,
C. Lukashin
,
A. J. Mannucci
,
N. Phojanamongkolkij
,
P. Pilewskie
,
V. Ramaswamy
,
H. Revercomb
,
J. Rice
,
Y. Roberts
,
C. M. Roithmayr
,
F. Rose
,
S. Sandford
,
E. L. Shirley
,
Sr. W. L. Smith
,
B. Soden
,
P. W. Speth
,
W. Sun
,
P. C. Taylor
,
D. Tobin
, and
X. Xiong

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a “NIST [National Institute of Standards and Technology] in orbit.” CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

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AIRS

Improving Weather Forecasting and Providing New Data on Greenhouse Gases

MOUSTAFA T. CHAHINE
,
THOMAS S. PAGANO
,
HARTMUT H. AUMANN
,
ROBERT ATLAS
,
CHRISTOPHER BARNET
,
JOHN BLAISDELL
,
LUKE CHEN
,
MURTY DIVAKARLA
,
ERIC J. FETZER
,
MITCH GOLDBERG
,
CATHERINE GAUTIER
,
STEPHANIE GRANGER
,
SCOTT HANNON
,
FREDRICK W. IRION
,
RAMESH KAKAR
,
EUGENIA KALNAY
,
BJORN H. LAMBRIGTSEN
,
SUNG-YUNG LEE
,
JOHN Le MARSHALL
,
W. WALLACE MCMILLAN
,
LARRY MCMILLIN
,
EDWARD T. OLSEN
,
HENRY REVERCOMB
,
PHILIP ROSENKRANZ
,
WILLIAM L. SMITH
,
DAVID STAELIN
,
L. LARRABEE STROW
,
JOEL SUSSKIND
,
DAVID TOBIN
,
WALTER WOLF
, and
LIHANG ZHOU

The Atmospheric Infrared Sounder (AIRS) and its two companion microwave sounders, AMSU and HSB were launched into polar orbit onboard the NASA Aqua Satellite in May 2002. NASA required the sounding system to provide high-quality research data for climate studies and to meet NOAA's requirements for improving operational weather forecasting. The NOAA requirement translated into global retrieval of temperature and humidity profiles with accuracies approaching those of radiosondes. AIRS also provides new measurements of several greenhouse gases, such as CO2, CO, CH4, O3, SO2, and aerosols.

The assimilation of AIRS data into operational weather forecasting has already demonstrated significant improvements in global forecast skill. At NOAA/NCEP, the improvement in the forecast skill achieved at 6 days is equivalent to gaining an extension of forecast capability of six hours. This improvement is quite significant when compared to other forecast improvements over the last decade. In addition to NCEP, ECMWF and the Met Office have also reported positive forecast impacts due AIRS.

AIRS is a hyperspectral sounder with 2,378 infrared channels between 3.7 and 15.4 μm. NOAA/NESDIS routinely distributes AIRS data within 3 hours to NWP centers around the world. The AIRS design represents a breakthrough in infrared space instrumentation with measurement stability and accuracies far surpassing any current research or operational sounder..The results we describe in this paper are “work in progress,” and although significant accomplishments have already been made much more work remains in order to realize the full potential of this suite of instruments.

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Howard B. Bluestein
,
Robert M. Rauber
,
Donald W. Burgess
,
Bruce Albrecht
,
Scott M. Ellis
,
Yvette P. Richardson
,
David P. Jorgensen
,
Stephen J. Frasier
,
Phillip Chilson
,
Robert D. Palmer
,
Sandra E. Yuter
,
Wen-Chau Lee
,
David C. Dowell
,
Paul L. Smith
,
Paul M. Markowski
,
Katja Friedrich
, and
Tammy M. Weckwerth

To assist the National Science Foundation in meeting the needs of the community of scientists by providing them with the instrumentation and platforms necessary to conduct their research successfully, a meeting was held in late November 2012 with the purpose of defining the problems of the next generation that will require radar technologies and determining the suite of radars best suited to help solve these problems. This paper summarizes the outcome of the meeting: (i) Radars currently in use in the atmospheric sciences and in related research are reviewed. (ii) New and emerging radar technologies are described. (iii) Future needs and opportunities for radar support of high-priority research are discussed. The current radar technologies considered critical to answering the key and emerging scientific questions are examined. The emerging radar technologies that will be most helpful in answering the key scientific questions are identified. Finally, gaps in existing radar observing technologies are listed.

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I. A. Renfrew
,
R. S. Pickart
,
K. Våge
,
G. W. K. Moore
,
T. J. Bracegirdle
,
A. D. Elvidge
,
E. Jeansson
,
T. Lachlan-Cope
,
L. T. McRaven
,
L. Papritz
,
J. Reuder
,
H. Sodemann
,
A. Terpstra
,
S. Waterman
,
H. Valdimarsson
,
A. Weiss
,
M. Almansi
,
F. Bahr
,
A. Brakstad
,
C. Barrell
,
J. K. Brooke
,
B. J. Brooks
,
I. M. Brooks
,
M. E. Brooks
,
E. M. Bruvik
,
C. Duscha
,
I. Fer
,
H. M. Golid
,
M. Hallerstig
,
I. Hessevik
,
J. Huang
,
L. Houghton
,
S. Jónsson
,
M. Jonassen
,
K. Jackson
,
K. Kvalsund
,
E. W. Kolstad
,
K. Konstali
,
J. Kristiansen
,
R. Ladkin
,
P. Lin
,
A. Macrander
,
A. Mitchell
,
H. Olafsson
,
A. Pacini
,
C. Payne
,
B. Palmason
,
M. D. Pérez-Hernández
,
A. K. Peterson
,
G. N. Petersen
,
M. N. Pisareva
,
J. O. Pope
,
A. Seidl
,
S. Semper
,
D. Sergeev
,
S. Skjelsvik
,
H. Søiland
,
D. Smith
,
M. A. Spall
,
T. Spengler
,
A. Touzeau
,
G. Tupper
,
Y. Weng
,
K. D. Williams
,
X. Yang
, and
S. Zhou

Abstract

The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere–ocean research program investigating climate processes in the source region of the densest waters of the Atlantic meridional overturning circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region, including a research vessel, a research aircraft, moorings, sea gliders, floats, and a meteorological buoy. A remarkable feature of the field campaign was the highly coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean, and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the life cycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere–ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modeling activities underway.

Open access
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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