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X. Gao, J. Li, and S. Sorooshian

1. Introduction This study investigated the capacity of a regional climate model (RCM) to reproduce the major elements of the 2004 North American monsoon (NAM) system. The modeling time period is from 0000 UTC 1 June to 0000 UTC 1 September, which overlaps with the North American Monsoon Experiment (NAME) 2004 Enhanced Observation Period. The NAME project aims to determine the sources and limits of predictability of warm-season precipitation over North America, and has proposed to achieve its

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Emily J. Becker, Ernesto Hugo Berbery, and R. Wayne Higgins

North America (e.g., Ropelewski and Halpert 1986 , 1996 ; Kiladis and Diaz 1989 ; Mo and Higgins 1998 ), also affects the character of daily precipitation. According to Schubert et al. (2005) , La Niña years tend to produce considerably fewer extreme storms than El Niño years along the Gulf and East Coasts. Higgins et al. (2007) found that during winter the Southwest averages up to 15% more days with measurable (>1 mm) precipitation per season during El Niño phases, compared to La Niña. On

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Mekonnen Gebremichael, Enrique R. Vivoni, Christopher J. Watts, and Julio C. Rodríguez

1. Introduction The North American monsoon (also referred to as the southwest, Mexican, or Arizona monsoon) is a subcontinental-scale climate feature that produces a significant increase in rainfall during the summer months in northwestern Mexico and the southwestern United States ( Douglas et al. 1993 ; Adams and Comrie 1997 ; Fuller and Stensrud 2000 ). It is the most important source of water in the region, as it accounts for 50%–70% of the annual precipitation. The monsoon impacts

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Sally Langford, Samantha Stevenson, and David Noone

1. Introduction Southwestern North America is projected to undergo drying in the twenty-first century ( Seager et al. 2007 ; Cayan et al. 2010 ; Christensen and Lettenmaier 2007 ), potentially increasing the frequency of occurrence and duration of drought-like conditions in the region. Climate records derived from tree core measurements (e.g., Stahle et al. 2007 ; Cook et al. 2004 ; Woodhouse et al. 2006 ) or vegetation growth in lake beds (e.g., Stine 1994 ) from the past millennia

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Celine Herweijer, Richard Seager, Edward R. Cook, and Julien Emile-Geay

1. Introduction Modern-day North America, especially the water-thirsty West, needs little reminder of the cost of drought: “water shortages” and “wildfires” are familiar midsummer season headlines, and tales of devastation from the 1930s Dust Bowl and 1950s Southwestern droughts are far from forgotten. As recently as 1998, widespread drought conditions returned to the American West and Plains, and another multiyear drought event commenced, persisting in the Northern Plains and western Canda

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Stefan Sobolowski, Gavin Gong, and Mingfang Ting

Northern Hemisphere from mid- to high latitudes. Because of this spatiotemporal variation and the striking geographical differences between the North American and Eurasian landmasses, the influence of snow on climate and the physical pathways through which this influence is expressed is still an area of ongoing research. In particular, questions regarding large-scale dynamic responses and their corresponding mechanisms abound. Evidence for physically based snow climate teleconnections is more abundant

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Richard Seager and Martin Hoerling

years an increasing amount of this research effort has focused on whether, where, and when droughts in the United States will become more common or severe due to climate change caused by rising greenhouse gases. Despite years of study, progress in understanding the causes of North American droughts only made serious headway in the last decade or so. By then the computational resources were widespread enough to make possible large ensembles of long simulations with atmosphere models forced by

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Benjamin I. Cook, Jason E. Smerdon, Richard Seager, and Edward R. Cook

and van den Dool 2004 ). Base period for the standardization was 1948–2012. Analyzed drought regions in this study are outlined by the black dashed lines. The regions are defined as the southwest (SW; 32°–40°N, 125°–105°W), central plains (CP; 34°–46°N, 102°–92°W), northwest (NW; 42°–50°N, 125°–110°W), and southeast (SE; 30°–39°N, 92°–75°W). Drought is a common and recurrent feature of North American climate (e.g., Cook et al. 2007 ; McCabe et al. 2004 ; Nigam et al. 2011 ; Schubert et al

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D. S. Gutzler, L. N. Long, J. Schemm, S. Baidya Roy, M. Bosilovich, J. C. Collier, M. Kanamitsu, P. Kelly, D. Lawrence, M.-I. Lee, R. Lobato Sánchez, B. Mapes, K. Mo, A. Nunes, E. A. Ritchie, J. Roads, S. Schubert, H. Wei, and G. J. Zhang

1. Introduction The North American Monsoon Experiment (NAME) (n.b., a table of acronyms is included as an appendix ) was organized as an international effort to improve observations, modeling, and prediction of the warm season circulation regime across southwestern North America ( NAME Science Working Group 2004 ). NAME activities centered on an intensive field observation campaign in summer 2004. In support of this field-oriented process study, a suite of modeling activities has taken place

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Melissa S. Bukovsky, David J. Gochis, and Linda O. Mearns

1. Introduction Many climate models are challenged by the complexity of the North American monsoon (NAM) system ( Gutzler et al. 2005 ). While several existing studies that employ RCMs (e.g., Anderson and Roads 2002 ; Saleeby and Cotton 2004 ; Xu et al. 2004 ; Castro et al. 2007a , b ; Cerezo-Mota et al. 2011 ; Chan and Misra 2011 ; Gao et al. 2012 ) have individually demonstrated simulation fidelity, a more systematic analysis of multiple models running under a common comparison

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