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Kingtse C. Mo, Eric Rogers, Wesley Ebisuzaki, R. Wayne Higgins, J. Woollen, and M. L. Carrera

mean square difference and the variance of CDASw for any given variable F ( Fig. 4 ). The ratio is defined as where Var is the daily variance of F averaged over the EOP period for CDASw. Equation (1) can also be applied to CDASwtmex. The mean differences [CDASw − CDASwt] and [CDASw − CDASwtmex] averaged over the EOP period (1 July–15 August 2004) are similar ( Fig. 3 ). The differences in 500-hPa height and 200-hPa winds are located in the Tropics with larger values over Central America. In

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Richard H. Johnson, Paul E. Ciesielski, Brian D. McNoldy, Peter J. Rogers, and Richard K. Taft

.g., Gallus and Johnson 1991 ) where relatively dry conditions (compared to the Tropics) in the lower troposphere contribute to enhanced precipitation evaporation. This effect can also be seen in the Q 2 profiles ( Figs. 18 and 19 ) where moistening is observed in the lower troposphere. While these results are consistent with past studies over land, they must be regarded as tentative and awaiting further analysis using additional sounding data. Determination of the vertical profile of heating in the

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Katrina Grantz, Balaji Rajagopalan, Martyn Clark, and Edith Zagona

the northern Pacific region (same as in Fig. 9 ) and negative correlations (between −0.3 and −0.4) to the southeast of this region extending down to the Tropics. That is, warmer northern Pacific SSTs and cooler tropical Pacific SSTs during winter–spring are related to increased monsoon rainfall during July. We hypothesize that these SST conditions result in decreased winter–spring precipitation over the southwest United States (e.g., Ropelewski and Halpert 1986 ), increasing the land

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Alberto M. Mestas-Nuñez, David B. Enfield, and Chidong Zhang

east of the Bahamas Islands ( Figs. 7a and 7b ). At low latitudes during boreal winter, an ENSO signal is identified in the correlation of the flows from east, to west, and from south with the Niño-3 and -3.4 indices ( Table 2 ) and in the SST patterns associated with these fluxes ( Figs. 6a , 6c and 6d ), which are similar to the canonical ENSO SST pattern (e.g., Mestas-Nuñez and Enfield 2001 ). In the Tropics, the precipitation patterns associated with the flow from east ( Fig. 5a ) to west

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John E. Janowiak, Valery J. Dagostaro, Vernon E. Kousky, and Robert J. Joyce

States, precipitation data are not generally available at the temporal resolution that is sufficient to diagnose important subdaily variations such as the diurnal cycle. Diurnal variations in precipitation, in particular, dominate the variability at all other time scales over much of the Tropics and warm season extratropics, including the Americas and particularly over the NAME tier-1 domain. Therefore, it is important not only to document the variations on diurnal time scales, but also to know the

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Christopher R. Williams, Allen B. White, Kenneth S. Gage, and F. Martin Ralph

, C. R. , W. L. Ecklund , and K. S. Gage , 1995 : An algorithm for classifying rain in the Tropics using 915-MHz wind profilers. J. Atmos. Oceanic Technol. , 12 , 996 – 1012 . Williams , C. R. , W. L. Ecklund , P. E. Johnston , and K. S. Gage , 2000 : Cluster analysis techniques to separate air motion and hydrometeors in vertical incident profiler observations. J. Atmos. Oceanic Technol. , 17 , 949 – 962 . Williams , C. R. , K. S. Gage , W. Clark , and P

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

overestimates rainfall over the extratropical oceanic region. Because tropical rainfall can influence NAM system development significantly ( Yu and Wallace 2000 ; Higgins and Shi 2001 ), this study uses the Eta PBL scheme in domain 1 (which includes a portion of the Tropics) and the MRF scheme in domain 2, with one-way communication between these domains. 3. Precipitation observation data Three precipitation observation datasets are used to evaluate the model’s precipitation output. National Centers for

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J. Craig Collier and Guang J. Zhang

, e.g., Hack et al. 2006a , b ; Rasch et al. 2006 ). Focused efforts on the analysis of the regional aspects of the model simulation such as the North American monsoon are yet to come. Recently, a modified version of the Zhang and McFarlane (1995) parameterization for rainfall simulation ( Zhang 2002 ) was tested. It was shown that the modifications produce favorable results for simulation in the Tropics ( Zhang and Mu 2005a , b ). However, in the domain of this study, the modifications

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Timothy J. Lang, David A. Ahijevych, Stephen W. Nesbitt, Richard E. Carbone, Steven A. Rutledge, and Robert Cifelli

derived from passive microwave and geosynchronous infrared data. J. Climate , 6 , 2144 – 2161 . Nesbitt , S. W. , E. J. Zipser , and D. J. Cecil , 2000 : A census of precipitation features in the Tropics using TRMM: Radar, ice scattering, and lightning observations. J. Climate , 13 , 4087 – 4106 . Nesbitt , S. W. , R. Cifelli , and S. A. Rutledge , 2006 : Storm morphology and rainfall characteristics of TRMM precipitation features. Mon. Wea. Rev. , 134 , 2702 – 2721

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Myong-In Lee, Siegfried D. Schubert, Max J. Suarez, Isaac M. Held, Arun Kumar, Thomas L. Bell, Jae-Kyung E. Schemm, Ngar-Cheung Lau, Jeffrey J. Ploshay, Hyun-Kyung Kim, and Soo-Hyun Yoo

: Diurnal cycle of summertime deep convection over North America: A satellite perspective. J. Geophys. Res. , 110 . D08108, doi:10.1029/2004JD005275 . Wallace , J. M. , 1975 : Diurnal variations in precipitation and thunderstorm frequency over the conterminous United States. Mon. Wea. Rev. , 103 , 406 – 419 . Yang , G. Y. , and J. Slingo , 2001 : The diurnal cycle in the Tropics. Mon. Wea. Rev. , 129 , 784 – 801 . Zhang , G. J. , 2003 : Roles of tropospheric and boundary layer

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