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Bjørn Røsting and Jón Egill Kristjánsson

: Piecewise potential vorticity inversion . J. Atmos. Sci. , 49 , 1397 – 1411 . Davis , C. A. , and K. A. Emanuel , 1991 : Potential vorticity diagnostics of cyclogenesis . Mon. Wea. Rev. , 119 , 1929 – 1953 . Demirtas , M. , and A. J. Thorpe , 1999 : Sensitivity of short range weather forecasts to local potential vorticity modifications . Mon. Wea. Rev. , 127 , 922 – 939 . Eady , E. T. , 1949 : Long waves and cyclone waves . Tellus , 1 , 33 – 52 . Egger , J. , 2008

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Richard A. Craig, Chester W. Newton, R. Robert Rapp, and Robert O. Reid

September.) 2. Similarly, papers which describe a proposed or existing measuring program (without principal em phasis on analysis of the measurements) should ordi narily be sent to JAM, unless of very clear interest to the MWR audience, but in any case not to JAS. 3. JAM should publish weather-modification papers, including those on cloud seeding. More fundamental papers on cloud microphysics ordinarily go to JAS. 4. MWR, as well as JAS, is a suitable outlet for articles on cloud structure, circulation

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Don G. Friedman

region bounded by 30"N, 60"N, 65"W and125 "R' are approximated by a linear combination of Tschebyscheff orthogonal polynomials. The coefficients of the polynomials are used as circulation indices and are related to the weather through the use ofa linear operator. The usefulness of this new method is illustrated by the comparison of a classification oftemperature and precipitation data for January 1948 to 1952 at a number of localities with a classificationof the same data based on previous methods

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S. Gathman and Eva Mae Trent

stratification. As a consequence, wave generation forces may be completely dissipated. These studiesemphasize the need for inclusion of some measure ofstratification just above the air-sea interface when aninvestigation of the environment on either side of thisinterface is made. REFERENCESBellaire, F. R., 1965: The modification of warm air moving over cold water. Pro*. 8th Conf. Great Lakes Re*., Univ. of Michigan, Great Lakes Res. Div., Publ. No. 13, 249-256.Brown, P. R., 1953: Wave data for

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Yi-Ping Hsieh

smaller than the originally existing absolutevorticity, while the change of the density of the air inthe vortex as a mean would be about 1 per cent or less,as indicated by the 'change of the surface pressure.Furthermore, we are interested only in the sign of theintegral, which is entirely dependent on d(f + )/atin this case.Our weather services take observations at 12-hrintervals. Strictly speaking, both the changes of pressure and vorticity should refer to instantaneous valuesat certain times. The

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Piero Malguzzi

number, which can be accomplished by taking a domain with large meridional extension. In the following, for the sake of simplicity,only the first case is worked out formally, although onecan easily convince oneself that the same results hold,with minor modifications, in the second case as well. At the lowest order, Eq. (3b) admits a class of verysimple solutions, namely Rossby waves. A Galileantransformation to the reference frame moving with thephase speed of a particular Rossby wave does not

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Irving I. Gringorten

DECEMBER 1959Am =IRVING I. GRINGORTENa11 0.. a lm* aki , (1),aa1 ffam)663PROBABILITY ESTIMATES OF THE WEATHER IN RELATION TO OPERATIONAL DECISIONS By Irving I. Gringorten Geophysics Research Directorate, Air Force Cambridge Research Center(Original manuscript received 13 August 1958; revised manuscript received 25 May 1959)ABSTRACTIf an operation is influenced by the weather, each course of action should result in a profit, cost, or lossdepending upon the subsequent

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Mu Mu and Zhina Jiang

1. Introduction Atmospheric blocking is a typical large-scale circulation with a characteristic time scale larger than that of synoptic motions, which has long been recognized to have a profound effect upon regional weather and climate ( Rex 1950 ). Furthermore, weather forecasts during periods when the atmospheric flow changes from a strong zonal flow to blocking or vice versa frequently suffer a rapid loss in accuracy predictability ( Tibaldi and Molteni 1990 ; Kimoto et al. 1992

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Irving I. Gringorten

388JOURNAL OF METEOROLOGYVOLUME IFORECASTING BY STATISTICAL INFERENCES By Irving I. GringortenAir Force Cambridge Research Laboratories(Manuscript received 27 July 1950)ABSTRACTIn recognition of the fact that a weather forecast is rarely 100 per cent accurate, this paper considers thevalue of figures for the probability of a meteorological event in meeting specified operational requirements.An objective method is presented for deciding between alternative meteorological predictors. It is

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Christopher P. Weaver

Kang and Davis, in their paper “The Effects of Mesoscale Surface Heterogeneity on the Fair-Weather Convective Atmospheric Boundary Layer,” ( Kang and Davis 2008 , hereafter KD08 ) use large-eddy simulation (LES) to investigate the response of the convective atmospheric boundary layer (ABL) to surface heat flux heterogeneity. The authors make a number of good points. They rightly question the performance, for certain regimes, of turbulence parameterizations typically used in mesoscale models

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