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Huw C. Davies

cloud diabatic effects will serve to highlight a significant difference between balanced and unbalanced flows. Diabatic effects are customarily incorporated into the QG omega equation by including an additional forcing term so that Eq. (1) becomes where is a measure of the diabatic heating rate with a unit of corresponding to approximately 3.0 × 10 −2 degrees heating per day. The equation remains self-contained provided can be specified externally or in terms of geostrophic flow variables

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Robert Wood

subtropics. The hemispheric asymmetry in seasonality is caused by greater orographic forcing from the elevated continent to the east for the southern sheets ( Richter and Mechoso 2004 , 2006 ). Fig . 6. (a) Seasonal amplitude (maximum − minimum coverage), and (b) month of maximum stratocumulus cover. Locations with no reports, or where the seasonal amplitude of stratocumulus cover is less than 2.5% are not shown. Data are from the combined land–ocean cloud atlas database ( Hahn and Warren 2007 ). There

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John Molinari and Michael Dudek

results for the fully explicit approach As noted above, the fully explicit approach is mostlikely to succeed when grid-scale forcing is large andinstability is relatively small. Large forcing ensures thatvertical motions will be sufficient to minimize the delays in precipitation onset caused by the need for gridscale saturation and spinup of cloud and rainwater.Modest convective instability suggests the vertical eddyfluxes are sufficiently small to minimize errors in thevertical distribution of

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Robert A. Houze Jr.

force acting on the radial inflow). Outward-directed Coriolis and centrifugal forces acting on the supergradient tangential wind in turn slow the boundary layer inflow. Convergence in region A, resulting in part from this effect, feeds the eyewall cloud with higher- θ e air than would be supplied from directly beneath the eyewall as in Emanuel’s (1986) model. But the rising supergradient flow turns radially outward in a layer atop the inflow layer as it seeks gradient balance. This low

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David M. Schultz and Philip N. Schumacher

of where MSI might be present. Therefore, since forcing for ascent need not be surface based, but can exist above the boundary layer, the absence of analyzed surface fronts is not adequate for eliminating the possibility of frontogenetical forcing for ascent. Further examples of climatologies of banded clouds and precipitation include Bennetts and Hoskins (1979) , Bennetts and Sharp (1982) , and Byrd (1989) . Bennetts and Hoskins (1979 , section 5) examine 36 cases of satellite and radar

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Dayton G. Vincent

Pacific convergence zone (SPCZ) contains one of the earth's most expansive and persistentconvective cloud bands, and is recognized as playing asignificant role in global-scale circulation patterns. Although first depicted in the surface analyses of Bergeron (1930), the vast extent of the SPCZ, both spatiallyand temporally, was not fully appreciated until satelliteimagery became available in the early 1960s (e.g., Hubert 1961). Since that time, numerous studies have beenconducted of this rather

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Tammy M. Weckwerth and David B. Parsons

. Previous studies have also shown the degree of moisture variability associated with horizontal roll circulations (e.g., LeMone and Pennell 1976 ; Reinking et al. 1981 ). The roll updraft branches force moist, near-surface air upward into the boundary layer while the roll downdraft branches bring downward dry air from near the inversion level (e.g., Weckwerth et al. 1996 ). Since clouds and thunderstorms form atop roll updraft branches, it is essential that this updraft air be sampled to obtain an

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Paul M. Markowski

understood. b. Formation Fujita (1958a) originally attributed hook echo formation to the advection of precipitation from the rear of the main echo around the region of rotation associated with the tornado cyclone and updraft. Browning (1964, 1965b) also documented hook echoes and attributed their evolution ( Fig. 6 ) to essentially the same process described by Fujita (1958a) . Fujita (1965) later attributed hook echo formation to the Magnus force. He explained that this force pulled the spiraling

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Markus Gross, Hui Wan, Philip J. Rasch, Peter M. Caldwell, David L. Williamson, Daniel Klocke, Christiane Jablonowski, Diana R. Thatcher, Nigel Wood, Mike Cullen, Bob Beare, Martin Willett, Florian Lemarié, Eric Blayo, Sylvie Malardel, Piet Termonia, Almut Gassmann, Peter H. Lauritzen, Hans Johansen, Colin M. Zarzycki, Koichi Sakaguchi, and Ruby Leung

convection scheme then delayed the onset of the parameterized convection toward the evening. The CAPE accumulated such that in a region with weak orographic forcing of moist air in a low-shear environment, an explicit convective cloud is permitted at a single grid point before the convection scheme is triggered. In the IFS, such single-gridpoint structures are then pathologically amplified by the semi-Lagrangian advection scheme of the IFS dynamics ( Malardel and Ricard 2015 ). The resulting unrealistic

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Roland A. Madden and Paul R. Julian

sponsored bythe National Science Foundation. Corresponding author address: Dr. Roland A. Madden, NCAR/Climate Analysis Section, P.O. Box 3000, Boulder, CO 80307-3000.describe what we judge to be some of the most important findings from studies of these and of other data. The discussion concentrates on eastward-movingcloud complexes that are associated with the oscillation, the northward-propagating cloud zones related tothe break and active phases during the northern summermonsoon, some possible

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