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K.-M. Lau
,
V. Ramanathan
,
G.-X. Wu
,
Z. Li
,
S. C. Tsay
,
C. Hsu
,
R. Sikka
,
B. Holben
,
D. Lu
,
G. Tartari
,
M. Chin
,
P. Koudelova
,
H. Chen
,
Y. Ma
,
J. Huang
,
K. Taniguchi
, and
R. Zhang

Aerosol- and moonsoon-related droughts and floods are two of the most serious environmental hazards confronting more than 60% of the population of the world living in the Asian monsoon countries. In recent years, thanks to improved satellite and in situ observations, and better models, great strides have been made in aerosol and monsoon research, respectively. There is now a growing body of evidence suggesting that interaction of aerosol forcing with monsoon dynamics may alter the redistribution of energy in the atmosphere and at the Earth s surface, thereby influencing monsoon water cycle and climate. In this article, the authors describe the scientific rationale and challenges for an integrated approach to study the interactions between aerosol and monsoon water cycle dynamics. A Joint Aerosol-Monsoon Experiment (JAMEX) is proposed for 2007–11, with enhanced observations of the physical and chemical properties, sources and sinks, and long-range transport of aerosols, in conjunction with meteorological and oceanographic observations in the Indo-Pacific continental and oceanic regions. JAMEX will leverage on coordination among many ongoing and planned national research programs on aerosols and monsoons in China, India, Japan, Nepal, Italy, and the United States, as well as international research programs of the World Climate Research Program (WCRP) and the World Meteorological Organization (WMO).

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Sonia Lasher-Trapp
,
David C. Leon
,
Paul J. DeMott
,
Cecille M. Villanueva-Birriel
,
Alexandria V. Johnson
,
Daniel H. Moser
,
Colin S. Tully
, and
Wei Wu

Abstract

Three flights from the Ice in Clouds Experiment–Tropical (ICE-T) field campaign examined the onset of ice near the ascending cloud tops of tropical maritime cumuli as they cooled from 0° to −14°C. Careful quantitative analysis of ice number concentrations included manual scrutiny of particle images and corrections for possible particle-shattering artifacts. The novel use of the Wyoming Cloud Radar documented the stage of cloud development and tops relative to the aircraft sampling, complemented the manual estimates of graupel concentrations, and provided new clear evidence of graupel movement through the rime-splintering zone. Measurements of ice-nucleating particles (INPs) provided an estimate of primary initiated ice.

The data portray a dynamically complex picture of hydrometeor transport contributing to, and likely resulting from, the rime-splintering process. Hundreds per liter of supercooled raindrops ascended within the updrafts as the cloud tops reached 0°C and contributed in part to the 0.1 L−1 graupel detected soon after the cloud tops cooled to −5°C. Rime splintering could thus be initiated upon first ascent of the cloud top through that zone and arguably contributed to the 1 L−1 or more graupel observed above it. Graupel ascending/descending into, or balanced within, the rime-splintering zone were found. In wider, less isolated clouds with dying updrafts and tops near −14°C, ice particle concentrations sometimes reached 100 L−1. Future 3D numerical modeling will be required to evaluate if rime splintering alone can explain the difference of three to four orders of magnitude in the observed INPs and the graupel observed at −5°C and colder.

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Yongkang Xue
,
Jinjun Ji
,
Shufen Sun
,
Guoxiong Wu
,
K-M. Lau
,
Isabelle Poccard
,
Hyun-Suk Kang
,
Renhe Zhang
,
John C. Schaake
,
Jian Yun Zhang
, and
Yanjun Jiao

Abstract

This is an exploratory study to investigate the spatial and temporal characteristics of east China’s (EC) river runoff and their relationship with precipitation and sea surface temperature (SST) at the continental scale. Monthly mean data from 72 runoff stations and 160 precipitation stations in EC, covering a period between 1951 and 1983, are used for this study. The station river runoff data have been spatially interpolated onto 1° grid boxes as runoff depth based on an extracted drainage network. Comparing runoff depth with precipitation shows that seasonal variation in runoff is consistent with the development of the summer monsoon, including the delayed response of runoff in several subregions. The dominant spatial scales and temporal patterns of summer runoff and precipitation are studied with empirical orthogonal function (EOF) analysis and wavelet analyses. The analyses show interannual, biennial, and longer-term variations in the EOF modes. South–north dipole anomaly patterns for the first two runoff EOF’s spatial distributions have been identified. The first/second runoff principal components (PCs) are highly correlated with the second/first precipitation PCs, respectively. The summer runoff’s EOF PCs also show significant correlations with the multivariate El Niño–Southern Oscillation index (MEI) of the summer and winter months, while the summer precipitation PCs do not. Statistic analysis shows that EOF1 of runoff and EOF2 of precipitation are related to El Niño, while EOF2 of runoff and EOF1 of precipitation are related to a dipole SST anomaly over the northwestern Pacific. The interdecadal relationship between summer runoff, precipitation, and SST variability is further studied by singular value decomposition (SVD) analysis. Pronounced warming (SST) and drying (runoff) trends in first SVD PCs have been identified. These SVDs are used to reconstruct a decadal anomaly pattern, which produces flooding in part of the Chang Jiang River basin and dryness in the northern EC, consistent with observations.

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F. Vitart
,
C. Ardilouze
,
A. Bonet
,
A. Brookshaw
,
M. Chen
,
C. Codorean
,
M. Déqué
,
L. Ferranti
,
E. Fucile
,
M. Fuentes
,
H. Hendon
,
J. Hodgson
,
H.-S. Kang
,
A. Kumar
,
H. Lin
,
G. Liu
,
X. Liu
,
P. Malguzzi
,
I. Mallas
,
M. Manoussakis
,
D. Mastrangelo
,
C. MacLachlan
,
P. McLean
,
A. Minami
,
R. Mladek
,
T. Nakazawa
,
S. Najm
,
Y. Nie
,
M. Rixen
,
A. W. Robertson
,
P. Ruti
,
C. Sun
,
Y. Takaya
,
M. Tolstykh
,
F. Venuti
,
D. Waliser
,
S. Woolnough
,
T. Wu
,
D.-J. Won
,
H. Xiao
,
R. Zaripov
, and
L. Zhang

Abstract

Demands are growing rapidly in the operational prediction and applications communities for forecasts that fill the gap between medium-range weather and long-range or seasonal forecasts. Based on the potential for improved forecast skill at the subseasonal to seasonal time range, the Subseasonal to Seasonal (S2S) Prediction research project has been established by the World Weather Research Programme/World Climate Research Programme. A main deliverable of this project is the establishment of an extensive database containing subseasonal (up to 60 days) forecasts, 3 weeks behind real time, and reforecasts from 11 operational centers, modeled in part on the The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) database for medium-range forecasts (up to 15 days).

The S2S database, available to the research community since May 2015, represents an important tool to advance our understanding of the subseasonal to seasonal time range that has been considered for a long time as a “desert of predictability.” In particular, this database will help identify common successes and shortcomings in the model simulation and prediction of sources of subseasonal to seasonal predictability. For instance, a preliminary study suggests that the S2S models significantly underestimate the amplitude of the Madden–Julian oscillation (MJO) teleconnections over the Euro-Atlantic sector. The S2S database also represents an important tool for case studies of extreme events. For instance, a multimodel combination of S2S models displays higher probability of a landfall over the islands of Vanuatu 2–3 weeks before Tropical Cyclone Pam devastated the islands in March 2015.

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Jason C. Knievel
,
Yubao Liu
,
Thomas M. Hopson
,
Justin S. Shaw
,
Scott F. Halvorson
,
Henry H. Fisher
,
Gregory Roux
,
Rong-Shyang Sheu
,
Linlin Pan
,
Wanli Wu
,
Joshua P. Hacker
,
Erik Vernon
,
Frank W. Gallagher III
, and
John C. Pace

Abstract

Since 2007, meteorologists of the U.S. Army Test and Evaluation Command (ATEC) at Dugway Proving Ground (DPG), Utah, have relied on a mesoscale ensemble prediction system (EPS) known as the Ensemble Four-Dimensional Weather System (E-4DWX). This article describes E-4DWX and the innovative way in which it is calibrated, how it performs, why it was developed, and how meteorologists at DPG use it. E-4DWX has 30 operational members, each configured to produce forecasts of 48 h every 6 h on a 272-processor high performance computer (HPC) at DPG. The ensemble’s members differ from one another in initial-, lateral-, and lower-boundary conditions; in methods of data assimilation; and in physical parameterizations. The predictive core of all members is the Advanced Research core of the Weather Research and Forecasting (WRF) Model. Numerical predictions of the most useful near-surface variables are dynamically calibrated through algorithms that combine logistic regression and quantile regression, generating statistically realistic probabilistic depictions of the atmosphere’s future state at DPG’s observing sites. Army meteorologists view E-4DWX’s output via customized figures posted to a restricted website. Some of these figures summarize collective results—for example, through means, standard deviations, or fractions of the ensemble exceeding thresholds. Other figures show each forecast, individually or grouped—for example, through spaghetti diagrams and time series. This article presents examples of each type of figure.

Open access
M. Goldberg
,
G. Ohring
,
J. Butler
,
C. Cao
,
R. Datla
,
D. Doelling
,
V. Gärtner
,
T. Hewison
,
B. Iacovazzi
,
D. Kim
,
T. Kurino
,
J. Lafeuille
,
P. Minnis
,
D. Renaut
,
J. Schmetz
,
D. Tobin
,
L. Wang
,
F. Weng
,
X. Wu
,
F. Yu
,
P. Zhang
, and
T. Zhu

The Global Space-based Inter-Calibration System (GSICS) is a new international program to assure the comparability of satellite measurements taken at different times and locations by different instruments operated by different satellite agencies. Sponsored by the World Meteorological Organization and the Coordination Group for Meteorological Satellites, GSICS will intercalibrate the instruments of the international constellation of operational low-earth-orbiting (LEO) and geostationary earth-orbiting (GEO) environmental satellites and tie these to common reference standards. The intercomparability of the observations will result in more accurate measurements for assimilation in numerical weather prediction models, construction of more reliable climate data records, and progress toward achieving the societal goals of the Global Earth Observation System of Systems. GSICS includes globally coordinated activities for prelaunch instrument characterization, onboard routine calibration, sensor intercomparison of near-simultaneous observations of individual scenes or overlapping time series, vicarious calibration using Earth-based or celestial references, and field campaigns. An initial strategy uses high-accuracy satellite instruments, such as the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and Atmospheric Infrared Sounder (AIRS) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT)'s Centre National d'Études Spatiales (CNES) Infrared Atmospheric Sounding Interferometer (IASI), as space-based reference standards for intercalibrating the operational satellite sensors. Examples of initial intercalibration results and future plans are presented. Agencies participating in the program include the Centre National d'Études Spatiales, China Meteorological Administration, EUMETSAT, Japan Meteorological Agency, Korea Meteorological Administration, NASA, National Institute of Standards and Technology, and NOAA.

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Xin-Zhong Liang
,
Drew Gower
,
Jennifer A. Kennedy
,
Melissa Kenney
,
Michael C. Maddox
,
Michael Gerst
,
Guillermo Balboa
,
Talon Becker
,
Ximing Cai
,
Roger Elmore
,
Wei Gao
,
Yufeng He
,
Kang Liang
,
Shane Lotton
,
Leena Malayil
,
Megan L. Matthews
,
Alison M. Meadow
,
Christopher M. U. Neale
,
Greg Newman
,
Amy Rebecca Sapkota
,
Sanghoon Shin
,
Jonathan Straube
,
Chao Sun
,
You Wu
,
Yun Yang
, and
Xuesong Zhang

Abstract

Climate change presents huge challenges to the already-complex decisions faced by U.S. agricultural producers, as seasonal weather patterns increasingly deviate from historical tendencies. Under USDA funding, a transdisciplinary team of researchers, extension experts, educators, and stakeholders is developing a climate decision support Dashboard for Agricultural Water use and Nutrient management (DAWN) to provide Corn Belt farmers with better predictive information. DAWN’s goal is to provide credible, usable information to support decisions by creating infrastructure to make subseasonal-to-seasonal forecasts accessible. DAWN uses an integrated approach to 1) engage stakeholders to coproduce a decision support and information delivery system; 2) build a coupled modeling system to represent and transfer holistic systems knowledge into effective tools; 3) produce reliable forecasts to help stakeholders optimize crop productivity and environmental quality; and 4) integrate research and extension into experiential, transdisciplinary education. This article presents DAWN’s framework for integrating climate–agriculture research, extension, and education to bridge science and service. We also present key challenges to the creation and delivery of decision support, specifically in infrastructure development, coproduction and trust building with stakeholders, product design, effective communication, and moving tools toward use.

Open access
J. W. Waters
,
W. G. Read
,
L. Froidevaux
,
R. F. Jarnot
,
R. E. Cofield
,
D. A. Flower
,
G. K. Lau
,
H. M. Pickett
,
M. L. Santee
,
D. L. Wu
,
M. A. Boyles
,
J. R. Burke
,
R. R. Lay
,
M. S. Loo
,
N. J. Livesey
,
T. A. Lungu
,
G. L. Manney
,
L. L. Nakamura
,
V. S. Perun
,
B. P. Ridenoure
,
Z. Shippony
,
P. H. Siegel
,
R. P. Thurstans
,
R. S. Harwood
,
H. C. Pumphrey
, and
M. J. Filipiak

Abstract

The Microwave Limb Sounder (MLS) experiments obtain measurements of atmospheric composition, temperature, and pressure by observations of millimeter- and submillimeter-wavelength thermal emission as the instrument field of view is scanned through the atmospheric limb. Features of the measurement technique include the ability to measure many atmospheric gases as well as temperature and pressure, to obtain measurements even in the presence of dense aerosol and cirrus, and to provide near-global coverage on a daily basis at all times of day and night from an orbiting platform. The composition measurements are relatively insensitive to uncertainties in atmospheric temperature. An accurate spectroscopic database is available, and the instrument calibration is also very accurate and stable. The first MLS experiment in space, launched on the (NASA) Upper Atmosphere Research Satellite (UARS) in September 1991, was designed primarily to measure stratospheric profiles of ClO, O3, H2O, and atmospheric pressure as a vertical reference. Global measurement of ClO, the predominant radical in chlorine destruction of ozone, was an especially important objective of UARS MLS. All objectives of UARS MLS have been accomplished and additional geophysical products beyond those for which the experiment was designed have been obtained, including measurement of upper-tropospheric water vapor, which is important for climate change studies. A follow-on MLS experiment is being developed for NASA’s Earth Observing System (EOS) and is scheduled to be launched on the EOS CHEMISTRY platform in late 2002. EOS MLS is designed for many stratospheric measurements, including HO x radicals, which could not be measured by UARS because adequate technology was not available, and better and more extensive upper-tropospheric and lower-stratospheric measurements.

Full access
C. P. Weaver
,
X.-Z. Liang
,
J. Zhu
,
P. J. Adams
,
P. Amar
,
J. Avise
,
M. Caughey
,
J. Chen
,
R. C. Cohen
,
E. Cooter
,
J. P. Dawson
,
R. Gilliam
,
A. Gilliland
,
A. H. Goldstein
,
A. Grambsch
,
D. Grano
,
A. Guenther
,
W. I. Gustafson
,
R. A. Harley
,
S. He
,
B. Hemming
,
C. Hogrefe
,
H.-C. Huang
,
S. W. Hunt
,
D.J. Jacob
,
P. L. Kinney
,
K. Kunkel
,
J.-F. Lamarque
,
B. Lamb
,
N. K. Larkin
,
L. R. Leung
,
K.-J. Liao
,
J.-T. Lin
,
B. H. Lynn
,
K. Manomaiphiboon
,
C. Mass
,
D. McKenzie
,
L. J. Mickley
,
S. M. O'neill
,
C. Nolte
,
S. N. Pandis
,
P. N. Racherla
,
C. Rosenzweig
,
A. G. Russell
,
E. Salathé
,
A. L. Steiner
,
E. Tagaris
,
Z. Tao
,
S. Tonse
,
C. Wiedinmyer
,
A. Williams
,
D. A. Winner
,
J.-H. Woo
,
S. WU
, and
D. J. Wuebbles

This paper provides a synthesis of results that have emerged from recent modeling studies of the potential sensitivity of U.S. regional ozone (O3) concentrations to global climate change (ca. 2050). This research has been carried out under the auspices of an ongoing U.S. Environmental Protection Agency (EPA) assessment effort to increase scientific understanding of the multiple complex interactions among climate, emissions, atmospheric chemistry, and air quality. The ultimate goal is to enhance the ability of air quality managers to consider global change in their decisions through improved characterization of the potential effects of global change on air quality, including O3 The results discussed here are interim, representing the first phase of the EPA assessment. The aim in this first phase was to consider the effects of climate change alone on air quality, without accompanying changes in anthropogenic emissions of precursor pollutants. Across all of the modeling experiments carried out by the different groups, simulated global climate change causes increases of a few to several parts per billion (ppb) in summertime mean maximum daily 8-h average O3 concentrations over substantial regions of the country. The different modeling experiments in general do not, however, simulate the same regional patterns of change. These differences seem to result largely from variations in the simulated patterns of changes in key meteorological drivers, such as temperature and surface insolation. How isoprene nitrate chemistry is represented in the different modeling systems is an additional critical factor in the simulated O3 response to climate change.

Full access
S. Pawson
,
K. Kodera
,
K. Hamilton
,
T. G. Shepherd
,
S. R. Beagley
,
B. A. Boville
,
J. D. Farrara
,
T. D. A. Fairlie
,
A. Kitoh
,
W. A. Lahoz
,
U. Langematz
,
E. Manzini
,
D. H. Rind
,
A. A. Scaife
,
K. Shibata
,
P. Simon
,
R. Swinbank
,
L. Takacs
,
R. J. Wilson
,
J. A. Al-Saadi
,
M. Amodei
,
M. Chiba
,
L. Coy
,
J. de Grandpré
,
R. S. Eckman
,
M. Fiorino
,
W. L. Grose
,
H. Koide
,
J. N. Koshyk
,
D. Li
,
J. Lerner
,
J. D. Mahlman
,
N. A. McFarlane
,
C. R. Mechoso
,
A. Molod
,
A. O'Neill
,
R. B. Pierce
,
W. J. Randel
,
R. B. Rood
, and
F. Wu

To investigate the effects of the middle atmosphere on climate, the World Climate Research Programme is supporting the project “Stratospheric Processes and their Role in Climate” (SPARC). A central theme of SPARC, to examine model simulations of the coupled troposphere–middle atmosphere system, is being performed through the initiative called GRIPS (GCM-Reality Intercomparison Project for SPARC). In this paper, an overview of the objectives of GRIPS is given. Initial activities include an assessment of the performance of middle atmosphere climate models, and preliminary results from this evaluation are presented here. It is shown that although all 13 models evaluated represent most major features of the mean atmospheric state, there are deficiencies in the magnitude and location of the features, which cannot easily be traced to the formulation (resolution or the parameterizations included) of the models. Most models show a cold bias in all locations, apart from the tropical tropopause region where they can be either too warm or too cold. The strengths and locations of the major jets are often misrepresented in the models. Looking at three-dimensional fields reveals, for some models, more severe deficiencies in the magnitude and positioning of the dominant structures (such as the Aleutian high in the stratosphere), although undersampling might explain some of these differences from observations. All the models have shortcomings in their simulations of the present-day climate, which might limit the accuracy of predictions of the climate response to ozone change and other anomalous forcing.

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