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Feng Hu, Tim Li, Jianyun Gao, and Lisheng Hao

envelope and MJO-scale moisture was assumed ( Thual et al. 2014 ; Thual and Majda 2015 , 2016 ). Yang and Ingersoll (2013 , 2014 ) put forward a gravity wave theory. The essence of this theory is the interference of westward and eastward inertia–gravity waves whose dispersion relations are not symmetric due to the beta effect. This theory, however, requires further observational validation. One school of recent studies emphasized the important role of perturbation moisture in MJO propagation

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Bart van den Hurk, Janneke Ettema, and Pedro Viterbo

1. Introduction Root zone soil moisture is a crucial variable in the climate system. Initial conditions in numerical weather prediction models of soil moisture for the upper meter of the soil are a crucial element in the forecast performance in midlatitudes spring/summer (e.g., Beljaars et al. 1996 ) and might extend predictability over land in the monthly to seasonal range ( Koster et al. 2004 ). Root zone soil moisture affects transpiration, strongly influencing the partitioning of available

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Aihui Wang, Dennis P. Lettenmaier, and Justin Sheffield

combination of precipitation and/or temperature anomalies, hydrological anomalies (e.g., low soil moisture or groundwater from previous seasons or years), terrestrial ecosystem conditions, and/or human activities ( Woodhouse and Overpeck 1998 ; Understanding drought characteristics, including their duration, areal extent, and possible causes, is critical to understanding the nature of future droughts and eventually for forecasting of droughts, a science that is currently in its infancy ( Svoboda et al

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Nicole J. Schiffer and Stephen W. Nesbitt

days. Despite the long-held belief that surges are associated with enhanced regional mean NAM precipitation, recent work by Ladwig and Stensrud (2009) showed that surge events might redistribute NAM precipitation within the domain rather than enhance it. Several studies examine the structure and evolution of surges using case studies (e.g., Hales 1972 ; Brenner 1974 ; Rogers and Johnson 2007 ) as well as wind, temperature, pressure, and meridional moisture flux composites of several surges (e

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Peter J. Lamb, Diane H. Portis, and Abraham Zangvil

1. Introduction Central to atmospheric behavior on a range of space and time scales is the relative importance of horizontal water vapor advection versus the vertical moisture flux from the earth’s land and ocean surfaces. At the small-scale extreme, the interaction of these moisture sources and their associated thermodynamic and dynamic processes contributes to the development of shallow cumulus clouds (e.g., Krishnamurti et al. 1980 ; Rabin et al. 1990 ; Chen and Avissar 1994 ; Berg and

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T. N. Krishnamurti, S. Pattnaik, and D. V. Bhaskar Rao

through the temperature and moisture tendencies as control variables. Similar analysis has been provided by JMA and BMRC in published ( Davidson and Weber 2000 ) and unrefereed reports ( Tada 2002 ; Tauchi et al. 2003 ). The inclusion of initial rains, based on Newtonian relaxation or using variational data assimilation, has only seen limited application for very high resolution mesoscale models ( Ishikawa 2002 ; Koizumi et al. 2005 ; Macpherson 2001 ; Jones and Macpherson 1997 ). From the

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M. Tugrul Yilmaz and Wade T. Crow

et al. 2011 ; Anderson et al. 2012 ; Yilmaz et al. 2012 ; Yilmaz and Crow 2013 ; Zwieback et al. 2013 ; Draper et al. 2013 ). The majority of TCA land surface applications have focused on quantifying errors in satellite-based surface soil moisture products retrieved from instruments like the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) sensor aboard the National Aeronautics and Space Administration’s (NASA) Aqua satellite. In addition, ongoing Soil Moisture

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Samson Hagos, L. Ruby Leung, and Jimy Dudhia

(2005) , Lau and Waliser (2005) , and the references therein. One of the earliest theories proposed to explain large-scale intraseasonal variability is a mechanism often referred to as wave conditional instability of the second kind (wave-CISK; Lindzen 1974 ; Lau and Peng 1987 ). In this theory, convective heating and moisture convergence interact to create unstable modes. This theory has been refined to account for inconsistencies with observations such as the fact that the smallest wavelength

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Jinling Piao, Wen Chen, Qiong Zhang, and Peng Hu

; Yoon and Yeh 2010 ; Li et al. 2014 ). Lee et al. (2005) found that the summer rainfall over Northeast Asia is associated with ENSO and the Eurasian wave pattern. Liu and Yanai (2002) suggested that the Eurasian snow cover in the spring can exert a great impact on summer rainfall in northern Mongolia through a Rossby wave train–like response. The Northern Hemisphere circumglobal teleconnection can also contribute to the precipitation anomalies over northern China via modulating moisture

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Edward I. Tollerud, Fernando Caracena, Steven E. Koch, Brian D. Jamison, R. Michael Hardesty, Brandi J. McCarty, Christoph Kiemle, Randall S. Collander, Diana L. Bartels, Steven Albers, Brent Shaw, Daniel L. Birkenheuer, and W. Alan Brewer

1. Introduction Previous studies of the low-level jet (LLJ) have helped to establish its role as the major conveyor of low-level moisture from the Gulf of Mexico into the central United States ( Stensrud 1996 ; Higgins et al. 1996 ). Higgins et al. (1997) estimate that the contribution of the LLJ to low-level moisture transport over the central plains is almost 50% above average non-LLJ values. A major factor in the LLJ contribution to central plains precipitation is the relationship between

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