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M. Segal, J. R. Garratt, G. Kallos, and R. A. Pielke

temperature as a result of synoptic scale weather perturbationsat a given location are anticipated to cause a modification in the magnitude of the daytime surface sensibleheat flux. Assuming a midlatitude region, the impactof a synoptic cold front passage, or arctic air penetrationduring the winter, may be involved with a significant * Present affiliation: CSIRO Division of Atmospheric Research,Private Bag No. 1, Mordialloc, Victoria, 3195, Australia. t Present affiliation: Department of Applied

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Morris Tepper

FEBRUARY 1950MORRIS TEPPER21A PROPOSED MECHANISM OF SQUALL LINES: THE PRESSURE JUMP LINE By Morris TepperUnited States Weather Bureau'(Manuscript received 22 July 1949) ABSTRACTThe squall line of 16 May 1948 in the area of the Cloud Physics Project, U. S. Weather Bureau micrometeorological network of weather recording stations near Wilmington, Ohio, is analyzed by means of oneminute synoptic maps, %--t diagrams and isochrone maps. The relative behavior of the pressure jump, windshift

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Y. C. Sud, Winston C. Chao, and G. K. Walker

-radiation interaction.3. Simulation experiments In order to alleviate the problem of very large initialconvective rainfall (also referred to as the spinup problem) as well as excessive subsequent rainfall and evaporation, four different modifications were made to thecumulus parameterization of the GLA GCM. Some ofthese modifications were beneficial for the model simulated circulation and rainfall fields. We summarizethe model modifications and the accompanying experiments in Table 1

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A. Wiin-Nielsen

2040 JOURNAL OF THE ATMOSPHERIC SCIENCES VOLUME36On Normal Mode Linear Initialization on the Sphere A. WIIN-NIELSENEuropean Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading, Berkshire, England(Manuscript received 26 March 1979, in final form 21 June 1979). ABSTRACT The normal mode initialization procedure is investigated. It is shown that a

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Kenneth C. Young

. Mee, 1963: The effect of dry-ice pellet velocity on the generation of ice crystals. J. Appl. Meteor., 2, 260-265.Elliott~ R. D., and E. L. Hovind, 1964: The water balance of orographic clouds. J. Appl. Meteor., 3, 235-239.Fukuta, N., 1963: Ice nucleation by metaldehyde. Nature, 199, 475--476.Grant, L. O., Ed., 1969: An operational adaptation program of weather modification for the Colorado River basin. Interim report to Bureau of Reclamation, Colorado State University, 98 pp.Hobbs, P

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Michael Oczkowski, Istvan Szunyogh, and D. J. Patil

system, such as a realistic dynamical model of the atmosphere, computation of the Lyapunov dimension is not feasible. Thus, quantifying the dimensionality of atmospheric dynamics requires a different approach. A dimension definition that was specifically designed for large degree-of-freedom, spatiotemporally chaotic dynamical systems, such as the weather prediction models, is the Bred Vector Dimension (BV dimension) introduced by Patil et al. (2001) . This measure estimates the dimensionality

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David E. Stevens, Andrew S. Ackerman, and Christopher S. Bretherton

the full range of length scales from that of entraining eddies to the mesoscale are ideal for designing and testing cloud parameterizations for large-scale models. Prior LES simulations have often used domains a few kilometers wide. The larger domain size considered here is comparable to the grid resolution of a typical current mesoscale model (a similar resolution will soon be achieved in some global weather forecast models), and can better represent the potential horizontal variability

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Roger K. Smith

. L., 1971: A circularly symmetric primitive-equa tion model' of tropical cyclones and its response to artificial enhancement of th.e convective heating functions. Mort. Wea. Rev., 99, 414-426.---, 1974: Computer simulation of hurricane development and structure. Weather and Climate Modification, W. N. Hess, Ed., Wiley, 522-551.Rossby, C. G., 1937: On the mutual adjustment of pressure and velocity distributions in certain simple current systems. J. Mar. Res., 1, 15-28.Sheets, R. C

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Robert J. Beare and Michael J. P. Cullen

1. Introduction The response of large-scale convective circulations to the sea surface temperature (SST) is a key component of tropical dynamics. In weather and climate models, the interaction between the physical parameterizations and the large-scale dynamics is critical in the tropics. Improving such interactions presents an important frontier in future model development. Although the boundary layer mediates between the horizontally varying SST and the spatially uniform weak temperature

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Gary M. Lackmann and Richard M. Yablonsky

hypothesized that inclusion of the mass sink mechanism in numerical models will produce lower central pressure, stronger cyclonic wind speeds, and enhanced precipitation. Although modern numerical weather prediction (NWP) models include water substance continuity, most do not explicitly account for the precipitation mass sink effect in the pressure-tendency or full-continuity equations 2 ( Gu and Qian 1991 ; Qiu et al. 1991 , 1993 ; Davies et al. 2002 ). Even sophisticated mesoscale models such as the

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