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Richard Seager and Martin Hoerling

.S. Conclusions are offered in section 9 . 2. Observed data and models used The observed precipitation is the latest version of the Mitchell and Jones (2005) University of East Anglia (UEA) Climatic Research Unit data at 1° resolution (CRU TS3.1). SST data in the observational analysis come from the Hadley Centre ( Kennedy et al. 2011a , b ). The soil moisture data come from the Climate Prediction Center (CPC) and are an estimate of 1.6-m depth soil moisture in which a leaky bucket model is driven with

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Siegfried D. Schubert, Hailan Wang, Randal D. Koster, Max J. Suarez, and Pavel Ya. Groisman

, tend to be associated with multiple years of drought ( Borisenkov and Pasetsky 1988 ). An interesting and telling aspect of the literature addressing droughts in northern Eurasia is the lack therein of a clear distinction between drought and heat waves. To some extent, this is because summer dryness in this region has two different manifestations: agricultural drought (i.e., soil moisture deficits) and “fire weather” (in the forested areas of northern Eurasia, a prolonged period of hot weather with

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Omar V. Müller, Ernesto Hugo Berbery, Domingo Alcaraz-Segura, and Michael B. Ek

the tropical and subtropical regions, but little is found on land surface effects for southern South America. Nevertheless, Lee and Berbery (2012) showed that the regional climate over the La Plata basin is sensitive to idealized changes in land cover. Entekhabi et al. (1992) argued that land surface memory due to soil moisture storage could result in enhancing and prolonging both floods and droughts. Along this reasoning, Hong and Kalnay (2002) showed that, while the 1998 Oklahoma

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Mathew Barlow, Benjamin Zaitchik, Shlomit Paz, Emily Black, Jason Evans, and Andrew Hoell

Turkey. The waters of the Tigris and Euphrates support extensive irrigation developments in all riparian states and feed the marshlands of southern Iraq, both of which have been found to affect the local climate through their influence on evaporation ( Evans and Zaitchik 2008 ; Marcella and Eltahir 2012b ). There has not been much study of soil moisture in the region, but winter and spring precipitation and temperature have a strong influence on soil moisture in the Euphrates plain ( Zaitchik et al

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Siegfried D. Schubert, Ronald E. Stewart, Hailan Wang, Mathew Barlow, Ernesto H. Berbery, Wenju Cai, Martin P. Hoerling, Krishna K. Kanikicharla, Randal D. Koster, Bradfield Lyon, Annarita Mariotti, Carlos R. Mechoso, Omar V. Müller, Belen Rodriguez-Fonseca, Richard Seager, Sonia I. Seneviratne, Lixia Zhang, and Tianjun Zhou

meteorological drought propagates to agricultural or hydrological droughts, or how soil moisture feedbacks, temperature changes, or human water use act to maintain or even amplify the different types of drought, although these issues are addressed to varying degrees in the articles of the GDIS collection. Such a focus does not come without limitations; for example, the impact of long-term evapotranspiration changes induced by temperature and radiation changes (e.g., from climate change) may turn out to be as

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Belen Rodríguez-Fonseca, Elsa Mohino, Carlos R. Mechoso, Cyril Caminade, Michela Biasutti, Marco Gaetani, J. Garcia-Serrano, Edward K. Vizy, Kerry Cook, Yongkang Xue, Irene Polo, Teresa Losada, Leonard Druyan, Bernard Fontaine, Juergen Bader, Francisco J. Doblas-Reyes, Lisa Goddard, Serge Janicot, Alberto Arribas, William Lau, Andrew Colman, M. Vellinga, David P. Rowell, Fred Kucharski, and Aurore Voldoire

–September (JAS)] in the Sahel. Enhanced precipitation is associated with the seasonal northward migration of the intertropical convergence zone (ITCZ), where the northeasterly harmattan winds converge with the moisture-laden flow from the colder eastern equatorial Atlantic Ocean. Nicholson (2013) recently conducted an extensive review of rainfall variability over the Sahel and documented novel features of the region’s storm circulations. Figure 1 (from Huffman et al. 2007 ) shows a latitude–time plot

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Bradfield Lyon

for (b) MAM, (c) JJA, and (c) OND. Data are from GPCC. Monthly averaged values of various atmospheric variables contained in the National Centers for Environmental Prediction (NCEP) Reanalysis 1 product (R1; Kalnay et al. 1996 ) were employed. The gridded R1 data cover the period 1948–2013 and are at 2.5° latitude–longitude resolution. Vertically integrated (850–500 hPa) moisture flux anomalies were computed using R1, the anomalous flux being separated into three terms: where the subscripts m

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Lixia Zhang and Tianjun Zhou

meteorological drought index used widely throughout the world and provides a good reflection of soil moisture deficit or surplus ( Palmer 1965 ; Dai et al. 1998 , 2004 ). To date, PDSI has mostly been used in drought assessment, comparisons, and assessments of spatial and temporal changes of drought. Because of the complicated topography of East Asia, the determination and computation of empirical parameters in PDSI is difficult. It is hard to use PDSI for drought monitoring and application in East Asia

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Wenju Cai, Ariaan Purich, Tim Cowan, Peter van Rensch, and Evan Weller

Australian rainfall, and its influence on drought, rather than on other drought indicators such as soil moisture content (e.g., Ummenhofer et al. 2011 ). To investigate factors responsible for such rainfall trends, we use monthly observations and CMIP5 climate model data, averaged over the four austral seasons defined in this study: autumn [April–May (AM)], winter [June–August (JJA)], spring [September–November (SON)], and summer [December–March (DJFM)]. For Australia, March is a transition month during

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