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Enrique R. Vivoni, Hugo A. Gutiérrez-Jurado, Carlos A. Aragón, Luis A. Méndez-Barroso, Alex J. Rinehart, Robert L. Wyckoff, Julio C. Rodríguez, Christopher J. Watts, John D. Bolten, Venkataraman Lakshmi, and Thomas J. Jackson

properties, in particular soil moisture and vegetation, have received much less attention. Theoretically, soil wetness and plant cover can influence the surface energy balance through changes to the albedo, temperature, and partitioning into sensible and latent heat fluxes. Eltahir (1998) hypothesized that variations in surface conditions caused by soil moisture and vegetation dynamics can have a direct impact on the moist static energy in the boundary layer with subsequent effects on rainfall

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Paquita Zuidema, Chris Fairall, Leslie M. Hartten, Jeffrey E. Hare, and Daniel Wolfe

1. Introduction Monsoons are fundamentally driven by land–sea heating asymmetries. While the North American Monsoon Experiment (NAME) was well instrumented on land, for logistical reasons observations of the coincident conditions at sea were far fewer. One of the participating research vessels was the Mexican Navy’s R/V Altair , which positioned itself close to the mouth of the gulf intermediate between Mazatlan and La Paz from 7 July until 12 August. 1 The shipboard measurements contributed

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

European Centre for Medium-Range Weather Forecasts (ECMWF) 15-yr global reanalysis (ERA15, Gibson et al. 1997 ). They examine uncertainties arising from choices of area boundaries, calculation algorithms, spatial and temporal resolutions, as well as a combination of these effects. Their main conclusion is that these uncertainties are smaller than the large annual and interannual variabilities in moisture flux divergence estimated from the NCEP–NCAR reanalysis. The implication is that the NCEP

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J. Craig Collier and Guang J. Zhang

quasi-equilibrium theory of Arakawa and Shubert (1974) in which destabilization of the atmosphere due to large-scale processes is approximately balanced by stabilization due to convection. The amount of convective rainfall is a function of the cloud-base mass flux, which itself is modulated by the change of CAPE. As for its boundary layer parameterization, for unstable or convective conditions, transport of heat, water vapor, or passive scalars by convective turbulence is related to the nonlocal

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Wayne Higgins and David Gochis

drier-than-normal conditions in Arizona and northern Sonora. On interannual time scales the dominance of a particular transient regime can also influence summer rainfall patterns (Douglas and Englehart). Furthermore, Mestas-Nunez et al. show that variability in the transport from the key moisture source region of the intra-America Seas is linked to changes in summertime precipitation patterns over the central and eastern United States. Since the initiation of monsoon convection is often aided by

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

the southwestern United States and northern Mexico, the 2004 NAM results are examined in diagnoses 3–5 above. It is well known that the results of a regional climate model can be affected by many factors, including the selection of the modeling configurations, boundary forcing, initialization data, and methods. One decision that must be made for modeling the 2004 NAM is how frequently the model run should be adjusted (by reinitialization or nudging methods) using observation data assimilations to

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Andrea J. Ray, Gregg M. Garfin, Margaret Wilder, Marcela Vásquez-León, Melanie Lenart, and Andrew C. Comrie

respond to slowly varying oceanic and continental surface boundary conditions (tier III) ( NAME 2004 ; Fig. 2 ). The region can also be defined in human terms, including large urban complexes, irrigated agricultural valleys, ranches, forests, deserts, protected areas, and national parks in monsoon-influenced areas of several states in Mexico and the United States ( Fig. 2 ). The variability of climate and the monsoon itself is embedded in the culture of the region ( Meyer 1996 ), for example

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Chunmei Zhu and Dennis P. Lettenmaier

of calibrated parameters and the Nash–Sutcliffe model efficiency (Ef) and bias for each basin on a monthly time step. The model parameters vary widely between different basins. Seemingly, there are some empirical relationships among the estimated parameters and climate conditions, with two humid regions (Poza Rica and Las Perlas) having much higher B i than other semiarid and dry subhumid basins. Among the 14 basins, there are 11 with Ef exceeding 0.5. Three semiarid basins (Casas Grandes

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

, and five additional sounding sites established along the GoC (Puerto Peñasco, Bahia Kino, Los Mochis, Loreto, and the R/V Altair ). In the EBA, up to six soundings per day were obtained during IOPs in order to study the diurnal cycle of the flow and convection in the vicinity of the SMO both when significant weather events were occurring and during undisturbed conditions. The launch frequencies for these sites during the interval encompassing nine IOPs, 1 July–15 August, are indicated in Fig. 1

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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

boundary forcing (i.e., orography and land–sea contrast) in global climate models that are typically run at a horizontal resolution of several hundred kilometers, as well as limitations in the parameterization of moist convection ( Dai et al. 1999 ; Zhang 2003 ; Liang et al. 2004 ; Lee et al. 2007 ). While the diurnal cycle of atmospheric convection over the continents is largely controlled by the direct thermodynamic response to insolation and surface heating, there are nevertheless large

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