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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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Kuo-Nan Liou

numerical models. - The physical fundamentals and parameterizationfor the formation of cirrus clouds need to be developedin conjunction with large-scale weather and climatemodels. In addition, the manner in which the ice content is generated in the model should be connected tothe radiative transfer calculations. The aforementionedcloud and cloud radiative data may then be used toverify and tune the cirrus cloud model developed. Acknowledgments. This research was supported bythe Air Force

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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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Graeme L. Stephens

. J. Atmos. Sci., 33, 806-809.~, 1978a and b: Radiative properties of extended water clouds. Parts I and IL J. Atmos. Sci., 35, 21ll-2132.--., 1980: Radiative properties of cirrus clouds in the infrared region. J. Atmos. Sci., 37, 435-446.~, G. W. Paltridge and C. M. R. Platt, 1978: Radiative profiles of extended water clouds. IIl: Observations. J. Atmos. Sci., 35, 2133-2141.--., and P. J. Webster, 1979: Sensitivity of radiative forcing to variable cloud and moisture. J, Atmos. Sci., 36

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William M. Frank

from thethree-dimensional mass convergence in the sub-cloudlayer [including subsidence in clear air (3~r) and inconvective downdrafis (Ma)l: Mc = 3~ - Ma - 3~. (2)By allowing subsiding mass at cloud base to contribute to the forcing of updrafts, it is hoped that thescheme will provide a more realistic time evolutionof the convection and reduce the dependence onscale. A related closure hypothesis is the specification ofthe net latent heating as a function of the

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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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