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Kerry H. Cook and Edward K. Vizy

1989 ), and the unified Noah land surface model (LSM; Chen and Dudhia 2001 ). An ensemble simulation approach is used. Two ensembles, each with six members, are generated. The first represents the average late twentieth-century conditions for 1981–2000 and is referred to as 20C. Initial, lateral, and surface boundary conditions for each ensemble member are derived from the 1981–2000 monthly climatology in the National Centers for Environmental Prediction reanalysis 2 (NCEP2; Kanamitsu et al. 2002

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Gang Zhang, Kerry H. Cook, and Edward K. Vizy

time scales. Regional climate modeling provides an efficient alternative. RCMs use the same set of governing equations as GCMs and lateral boundary conditions from GCMs, but the use of a limited domain makes high-resolution simulation practical, and the constraint of requiring hydrostatic balance used in GCMs can be relaxed. In addition, the focus on a particular region can produce more accurate simulations when surface features such as topography are more accurately represented, and physical

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M. Issa Lélé, Lance M. Leslie, and Peter J. Lamb

position, tropical Atlantic sea surface temperature anomalies, the El Niño–Southern Oscillation (ENSO) phenomenon, and regional-scale atmospheric features—to account for the observed variations in rainfall. An overview is provided by Nicholson (2013) . Given the proximity of the extent of monsoon layer, the ITF latitude, and the rain belt over West Africa (WA), the concept of an interaction between the three has an intuitive appeal since the northern boundary of the moisture flux position determines

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Rosalind Cornforth, Douglas J. Parker, Mariane Diop-Kane, Andreas H. Fink, Jean-Philippe Lafore, Arlene Laing, Ernest Afiesimama, Jim Caughey, Aida Diongue-Niang, Abdou Kassimou, Peter Lamb, Benjamin Lamptey, Zilore Mumba, Ifeanyi Nnodu, Jerome Omotosho, Steve Palmer, Patrick Parrish, Leon-Guy Razafindrakoto, Wassila Thiaw, Chris Thorncroft, and Adrian Tompkins

for the forecaster. The chapter brings new research from AMMA into forecasting, such as the dependence of measures of daily maximum/minimum temperatures on soil moisture and new observations of wind shear in the lower boundary layer. Topics discussed include gravity waves, inertial oscillations, land–sea breezes and related cloudiness, winds and convective initiation related to land surface characteristics, surface energy fluxes, low-level shear, and fog. A critical forecasting element influencing

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

Cloud and Land Surface Interaction Campaign (CLASIC) conducted over the SGP ( Fig. 1 ) during 7–30 June 2007 by the Atmospheric Radiation Measurement (ARM) Program of the U.S. Department of Energy. The primary goal of CLASIC was “to improve understanding of the physics of the early stages of cumulus cloud convection as it relates to land surface conditions, and to translate this new understanding into improved representations in GCMs and regional climate models” ( Miller et al. 2007a , p. 2

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Zewdu T. Segele, Michael B. Richman, Lance M. Leslie, and Peter J. Lamb

being governed by slowly varying surface boundary conditions, such as SSTs, land surface albedo, and soil moisture. For Africa, the role of basin- and global-scale SST anomalies for such rainfall variability received considerable attention over the last 35 years (e.g., Lamb 1978a , b ; Folland et al. 1986 , 1991 ; Lamb and Peppler 1992 ; Barnston et al. 1996 ; Ward 1998 ; Mutai and Ward 2000 ; Camberlin et al. 2001 ; Giannini et al. 2003 ; Segele et al. 2009a ; Part I ; Ndiaye et al

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Mimi Stith, Alessandra Giannini, John del Corral, Susana Adamo, and Alex de Sherbinin

institutional responses to late-twentieth-century drought The Sahel reached its current prominence in the study of human–environment interactions because of the well-documented environmental crisis that occurred with the abrupt onset and persistence of multiyear drought in the late 1960s ( Glantz 1977 ). Persistent drought led to widespread food insecurity into the 1970s and 1980s, with acute episodes during 1968–73 and 1982–84 causing significant human loss. The climatic shift from wet conditions in the

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Lisa Hannak, Peter Knippertz, Andreas H. Fink, Anke Kniffka, and Gregor Pante

). Here we use 20-yr climate simulations covering the period 1991–2010. All models use weekly SSTs and sea ice concentrations based on the NOAA Optimum Interpolation V2 product ( Reynolds et al. 2002 ) as lower boundary conditions and prescribed aerosols. Despite different native resolutions, output was archived every 6 h on a standard horizontal (2.5° × 2.5°) grid with 22 vertical pressure levels (nine below 700 hPa). Unfortunately only eight of the YoTC models provide all the output necessary for

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John G. Dwyer, Michela Biasutti, and Adam H. Sobel

relative importance of SST and insolation at forcing precipitation. We also confirm that this is the case by running aquaplanet simulations, which have no land—only an ocean with an imposed seasonally varying SST—and no zonal asymmetries in the boundary conditions. As expected, in the aquaplanet simulations the direct effects are still present: delayed and amplified SST yields delayed and amplified precipitation, respectively. However, the cross-effects are smaller and no longer statistically

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