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J. Li, S. Sorooshian, W. Higgins, X. Gao, B. Imam, and K. Hsu

1. Introduction The North American monsoon (NAM) accounts for approximately 40%–80% of the annual rainfall in the southwestern United States and Mexico ( Douglas et al. 1993 ; Stensrud et al. 1995 ). As a consequence, it has a tremendous influence on the summer weather, climate, and water resources of this region. The NAM is characterized by numerous multiscale interactions, both in space and time. The climatological and synoptic features of the NAM have been studied systematically at the

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Donald Wylie

summaries of global cloud cover and is broken into the opposite seasons of boreal summer (June–August) and boreal winter (December–February). Clouds are most frequent in the tropics especially over South America and Africa. This is the intertropical convergence zone (ITCZ), which moves north and south with the seasons. Clouds are less frequent north and south of the ITCZ, which is where the subtropical deserts occur over land and the subtropical high pressure centers occur over oceans. Frequent cloud

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Munehisa K. Yamamoto, Fumie A. Furuzawa, Atsushi Higuchi, and Kenji Nakamura

compared with that for PR and TMI. Focusing on specific regions, the peak time differences show different distributions. There is little time lag between PR and TMI over tropical Africa ( Fig. 3c ), but VIRS frequently lags behind PR and TMI by more than 5 h. In contrast, time differences between PR and TMI over the Tibetan Plateau and western North America ( Figs. 3d,e , respectively) are prominent. The time shifts for TMI − PR and for VIRS − PR (TMI) over the Tibetan Plateau is more outstanding at 1

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Alex C. Ruane and John O. Roads

with the earth system to excite other time scales, leading to many possible regimes in the water cycle’s behavior. Examinations of the water cycle have been conducted on seasonal (e.g., Roads and Betts 2000 ; Roads et al. 2002 ) and diurnal (e.g., Anderson and Kanamaru 2005 ; Lee et al. 2007 ) time scales. Ruane and Roads (2007a , hereafter RR07a ) examined the atmospheric water cycle’s diurnal phase and amplitude over North America as part of an investigation into the water and energy cycles

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Song Yang and Eric A. Smith

and autumn periods lead to this double-peak structure. In the case of continental rainfall, the maximum amplitudes are located in the Northern Hemisphere (NH) during spring and summer (mainly due to the Asian monsoon), shifting to the Southern Hemisphere (SH) during autumn and winter partly due to the onsets of the rainy seasons in South Africa and South America. The unrealistically large rainfall features exhibited by 2a12 north of 20°N during winter and spring draw attention to the fact that

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R. Cifelli, S. W. Nesbitt, S. A. Rutledge, W. A. Petersen, and S. Yuter

mean SSTs generally above 27°C (see Fig. 1 of CNR07 ). However, the EPIC region is located more centrally to the warm pool; TEPPS is situated along the fringe at the western end, in closer proximity to the equatorial cold tongue. Satellite-observed outgoing longwave radiation (OLR) brightness temperatures are generally lower at the eastern end of the warm pool, closer to the Central America landmass where the EPIC campaign was conducted. These results are consistent with field campaign data

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R. E. Carbone and J. D. Tuttle

Ahijevych 2007 ; Levizzani et al. 2006 ; Jiang at al. 2006 ; Janowiak et al. 2007 ; Keenan and Carbone 2008 ; Laing et al. 2008 ) have extended our understanding of phenomena that underlie the diurnal cycle of warm-season rainfall. Among recent findings, it has been determined that several continents and countries (e.g., China, Africa, South America, Europe, Australia, and India) are frequented by the diurnal excitation of propagating convection. With few exceptions these regions are located in the

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Song Yang, Kwo-Sen Kuo, and Eric A. Smith

, North America, and Asia. These more detailed diurnal features suggest that either different mechanisms are at work or singular mechanisms dominate but are dispersive in their timing of the maxima within different environments. Similar analyses at lower spatial resolution confirms that the underlying spatial distribution patterns of primary and secondary modes, as seen in Fig. 8 , are not greatly affected by the use of a high-resolution scale. The higher-order harmonic modes conform to semidiurnal

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T. N. Krishnamurti, C. Gnanaseelan, A. K. Mishra, and A. Chakraborty

Sanjay 2003 ). It is possible to use these weights and construct a single forecast model that uses a weighted average (based on these weights) for a unified model. Such a unified model was shown to carry a skill higher than those of the member models and their ensemble mean but lower than a multimodel superensemble. These results are shown in Figs. 1 and 2 for days 1 and 2 of rainfall forecasts over the global tropics, North America, and the Asian monsoon domain. In a related study, Chakraborty

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Tianjun Zhou, Rucong Yu, Haoming Chen, Aiguo Dai, and Yang Pan

regional studies of the diurnal cycle over the United States (e.g., Wallace 1975 ; Dai et al. 1999 ), the coastal and island regions in Asia (e.g., Oki and Musiake, 1994 ; Yang and Slingo 2001 ), tropical Americas ( Kousky 1980 ), and West Africa ( Shinoda et al. 1999 ; Pinker et al. 2006 ). Partly because of a lack of high-resolution data, precipitation frequency, intensity, and their diurnal variations over China have not been well documented. Previous studies of diurnal variations of

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