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Annarita Mariotti
,
Siegfried Schubert
,
Kingtse Mo
,
Christa Peters-Lidard
,
Andy Wood
,
Roger Pulwarty
,
Jin Huang
, and
Dan Barrie

diverse methodologies including ensemble hydrologic prediction approaches. Broad NIDIS-inspired progress is influencing the development of a Global Drought Information System (GDIS) under the auspices of the World Climate Research Program. NOAA DROUGHT TASK FORCE MEETING W hat : Over 40 participants, including Drought Task Force scientists from multiple academic and federal institutions and invitees from drought service and operational organizations, met to discuss the latest drought research advances

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Robert Wood
,
Michael P. Jensen
,
Jian Wang
,
Christopher S. Bretherton
,
Susannah M. Burrows
,
Anthony D. Del Genio
,
Ann M. Fridlind
,
Steven J. Ghan
,
Virendra P. Ghate
,
Pavlos Kollias
,
Steven K. Krueger
,
Robert L. McGraw
,
Mark A. Miller
,
David Painemal
,
Lynn M. Russell
,
Sandra E. Yuter
, and
Paquita Zuidema

radiation resulting in a net cooling of the climate. The representation of marine low clouds in climate models is one of the largest uncertainties in the estimation of climate sensitivity (e.g., Bony and Dufresne 2005 ), and marine low clouds are critical mediators of global aerosol radiative forcing ( Zelinka et al. 2014 ). Despite the importance of these cloud systems to Earth’s climate, their parameterization continues to be challenging because of an incomplete understanding of key processes that

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M. Zhang
,
A. Mariotti
,
Z. Lin
,
V. Ramasmamy
,
J. Lamarque
,
Z. Xie
, and
J. Zhu

the eastern oceans in the subtropics is one of the most conspicuous features of any daily global satellite image, with large areas of bright clouds in the visible channels but low-contrast clouds in the infrared channels that are barely distinguishable from SSTs. These clouds owe their existence to the large-scale conditions of cold SSTs, subsidence in the free troposphere, and advective forcing of cold and dry air in the trade winds. Despite concentrated efforts in recent years, models still have

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Neil J. Holbrook
,
Jianping Li
,
Matthew Collins
,
Emanuele Di Lorenzo
,
Fei-Fei Jin
,
Thomas Knutson
,
Mojib Latif
,
Chongyin Li
,
Scott B. Power
,
Rhonghui Huang
, and
Guoxiong Wu

exhibit strong variance in the low frequency and decadal band, they are not characterized by a preferred time scale of oscillation. The EOF time series spectrum of these climate modes is consistent with a red noise process. Overall, stochastic atmospheric forcing appears to be the most important driving mechanism for the interdecadal variability (e.g., Liu 2012 ). The IPO and PDO are not independent in space and time. The tropics make important contributions to both the IPO and PDO through the ENSO

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Jonathan Pleim
,
Rohit Mathur
,
S. T. Rao
,
Jerome Fast
, and
Alexander Baklanov

the following: improved numerical weather prediction by including the effects of aerosols and gases on radiation and cloud microphysics as well as improving satellite retrievals and data assimilation for NWP operations by providing more accurate profiles of aerosols and radiatively active gases; regional climate–chemistry modeling, including direct and indirect radiative forcing from short-lived climate forcers (SLCF); improved air quality modeling due to closer coupling of dynamical and chemical

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Dragana Bojovic
,
Roberto Bilbao
,
Leandro B. Díaz
,
Markus Donat
,
Pablo Ortega
,
Yohan Ruprich-Robert
,
Balakrishnan Solaraju-Murali
,
Marta Terrado
,
Deborah Verfaillie
, and
Francisco Doblas-Reyes

, at decadal time scale, the shortness of the observational records by comparison to the time scale of interest strongly limits our ability to evaluate model performance. Knowing how much variability is externally or internally driven is key to understand the sources and limits of climate predictability. At regional scale particularly, simulations from CGCMs fed with historical external forcing show large differences, highlighting model uncertainties and the importance of internal variability. Due

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P. O. Canziani
,
A. O'Neill
,
R. Schofield
,
M. Raphael
,
G. J. Marshall
, and
G. Redaelli

idealized atmospheric models to climate models with interactive chemistry) indicate that the ozone hole is the primary cause of the observed changes, which lie outside the range of SH extratropical summer climate natural variability. Ozone loss and GHG increases have both driven the recent positive trend in the SAM during austral summer. Ozone recovery over the next decades will impose a negative forcing on the SAM, thus dampening the positive influence of a continuing rise in GHG concentrations

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Scott Sandgathe
,
Barbara Brown
,
Brian Etherton
, and
Edward Tollerud

relative scientific merits and drawbacks of the multimodel approach versus an approach based on a single-model framework that incorporates stochastic forcing? Given the merits and drawbacks of the two approaches, how can current ensemble systems advance to enable appropriate representation of model uncertainty? Given the answers to questions 1 and 2, how should current multimodel ensemble systems appropriately quantify model uncertainty? How should design aspects such as number of members, forecast

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Jianping Li
,
Richard Swinbank
,
Ruiqiang Ding
, and
Wansuo Duan

and its coupling to the interior flow is a key process that needs to be adequately represented in numerical models to improve the forecast accuracy of secondary eyewall formation, including the timing and preferred region of formation. Asymmetric inflow forcing induced by outer rainbands drives the sustained convection outside the primary eyewall during the early phase of secondary eyewall formation, and it too needs to be better understood. The poleward movement of TCs often leads to a reduction

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J. Li
,
J. Steppeler
,
F. Fang
,
C. C. Pain
,
J. Zhu
,
X. Peng
,
L. Dong
,
Y. Li
,
L. Tao
,
W. Leng
,
Y. Wang
, and
J. Zheng

elaborate Coriolis force scheme). In numerical modeling of flows around the pole, the time step can be enlarged to a practical value. Due to the pole problem and inefficiency of massively parallel computing for a latitude–longitude grid, the quasi-uniform grids—such as the Yin-Yang (GRAPES_YY), the icosahedral (ICON), and centroidal Voronoi (MPAS) grids—are becoming attractive. Peng (Chinese Academy of Meteorological Sciences) demonstrated that the Yin-Yang grid is capable of avoiding the strict

Open access