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  • Author or Editor: Lindsey N. Long x
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Rongqing Han
,
Hui Wang
,
Zeng-Zhen Hu
,
Arun Kumar
,
Weijing Li
,
Lindsey N. Long
,
Jae-Kyung E. Schemm
,
Peitao Peng
,
Wanqiu Wang
,
Dong Si
,
Xiaolong Jia
,
Ming Zhao
,
Gabriel A. Vecchi
,
Timothy E. LaRow
,
Young-Kwon Lim
,
Siegfried D. Schubert
,
Suzana J. Camargo
,
Naomi Henderson
,
Jeffrey A. Jonas
, and
Kevin J. E. Walsh

Abstract

An assessment of simulations of the interannual variability of tropical cyclones (TCs) over the western North Pacific (WNP) and its association with El Niño–Southern Oscillation (ENSO), as well as a subsequent diagnosis for possible causes of model biases generated from simulated large-scale climate conditions, are documented in the paper. The model experiments are carried out by the Hurricane Work Group under the U.S. Climate Variability and Predictability Research Program (CLIVAR) using five global climate models (GCMs) with a total of 16 ensemble members forced by the observed sea surface temperature and spanning the 28-yr period from 1982 to 2009. The results show GISS and GFDL model ensemble means best simulate the interannual variability of TCs, and the multimodel ensemble mean (MME) follows. Also, the MME has the closest climate mean annual number of WNP TCs and the smallest root-mean-square error to the observation.

Most GCMs can simulate the interannual variability of WNP TCs well, with stronger TC activities during two types of El Niño—namely, eastern Pacific (EP) and central Pacific (CP) El Niño—and weaker activity during La Niña. However, none of the models capture the differences in TC activity between EP and CP El Niño as are shown in observations. The inability of models to distinguish the differences in TC activities between the two types of El Niño events may be due to the bias of the models in response to the shift of tropical heating associated with CP El Niño.

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Eric D. Maloney
,
Suzana J. Camargo
,
Edmund Chang
,
Brian Colle
,
Rong Fu
,
Kerrie L. Geil
,
Qi Hu
,
Xianan Jiang
,
Nathaniel Johnson
,
Kristopher B. Karnauskas
,
James Kinter
,
Benjamin Kirtman
,
Sanjiv Kumar
,
Baird Langenbrunner
,
Kelly Lombardo
,
Lindsey N. Long
,
Annarita Mariotti
,
Joyce E. Meyerson
,
Kingtse C. Mo
,
J. David Neelin
,
Zaitao Pan
,
Richard Seager
,
Yolande Serra
,
Anji Seth
,
Justin Sheffield
,
Julienne Stroeve
,
Jeanne Thibeault
,
Shang-Ping Xie
,
Chunzai Wang
,
Bruce Wyman
, and
Ming Zhao

Abstract

In part III of a three-part study on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) models, the authors examine projections of twenty-first-century climate in the representative concentration pathway 8.5 (RCP8.5) emission experiments. This paper summarizes and synthesizes results from several coordinated studies by the authors. Aspects of North American climate change that are examined include changes in continental-scale temperature and the hydrologic cycle, extremes events, and storm tracks, as well as regional manifestations of these climate variables. The authors also examine changes in the eastern North Pacific and North Atlantic tropical cyclone activity and North American intraseasonal to decadal variability, including changes in teleconnections to other regions of the globe. Projected changes are generally consistent with those previously published for CMIP3, although CMIP5 model projections differ importantly from those of CMIP3 in some aspects, including CMIP5 model agreement on increased central California precipitation. The paper also highlights uncertainties and limitations based on current results as priorities for further research. Although many projected changes in North American climate are consistent across CMIP5 models, substantial intermodel disagreement exists in other aspects. Areas of disagreement include projections of changes in snow water equivalent on a regional basis, summer Arctic sea ice extent, the magnitude and sign of regional precipitation changes, extreme heat events across the northern United States, and Atlantic and east Pacific tropical cyclone activity.

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Justin Sheffield
,
Andrew P. Barrett
,
Brian Colle
,
D. Nelun Fernando
,
Rong Fu
,
Kerrie L. Geil
,
Qi Hu
,
Jim Kinter
,
Sanjiv Kumar
,
Baird Langenbrunner
,
Kelly Lombardo
,
Lindsey N. Long
,
Eric Maloney
,
Annarita Mariotti
,
Joyce E. Meyerson
,
Kingtse C. Mo
,
J. David Neelin
,
Sumant Nigam
,
Zaitao Pan
,
Tong Ren
,
Alfredo Ruiz-Barradas
,
Yolande L. Serra
,
Anji Seth
,
Jeanne M. Thibeault
,
Julienne C. Stroeve
,
Ze Yang
, and
Lei Yin

Abstract

This is the first part of a three-part paper on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that evaluates the historical simulations of continental and regional climatology with a focus on a core set of 17 models. The authors evaluate the models for a set of basic surface climate and hydrological variables and their extremes for the continent. This is supplemented by evaluations for selected regional climate processes relevant to North American climate, including cool season western Atlantic cyclones, the North American monsoon, the U.S. Great Plains low-level jet, and Arctic sea ice. In general, the multimodel ensemble mean represents the observed spatial patterns of basic climate and hydrological variables but with large variability across models and regions in the magnitude and sign of errors. No single model stands out as being particularly better or worse across all analyses, although some models consistently outperform the others for certain variables across most regions and seasons and higher-resolution models tend to perform better for regional processes. The CMIP5 multimodel ensemble shows a slight improvement relative to CMIP3 models in representing basic climate variables, in terms of the mean and spread, although performance has decreased for some models. Improvements in CMIP5 model performance are noticeable for some regional climate processes analyzed, such as the timing of the North American monsoon. The results of this paper have implications for the robustness of future projections of climate and its associated impacts, which are examined in the third part of the paper.

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