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T. N. Krishnamurti

: 0 O-~ Ku = (Kv. Ku) - Ox (6) 0 0-~ Kv = (e. Kv) - (Ko. Ku) - Dv (7) 0 0~ e = -(e' Ko) + G - De. (8)where Ku, Ko and P denote the zonal, meridional kinetic and available potential energy respectively, overthe entire mass of the atmosphere and Dx, Dy and Dedenote dissipation of the three aforementioned energyquantities. In a system that is either exhibiting an increase

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David M. Schultz and Philip N. Schumacher

and Aktary 1993 , 1995 ). Although we do not deny the likely existence of slantwise convection or the possible involvement of MSI in some precipitating systems in the atmosphere, it is our contention that CSI is frequently misused and overused as a diagnostic tool, a point also noted by Wiesmueller and Zubrick (1998 , p. 86). We believe the following four reasons are responsible, in part, for the present situation. 1) The theory of CSI has certain limitations and caveats that are discussed

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Clifford Mass and Brigid Dotson

disappeared, and as suggested later, this may be due to the destabilization of the atmosphere as cooler air moved in aloft. By 0600 UTC, the strongest winds with the bent-back front were poised to make landfall as the low center began crossing central Vancouver Island ( Fig. 12c ). Finally, at 0900 UTC, the extraordinary pressure gradient and winds with the bent-back trough had moved over western Washington ( Fig. 12d ). At the same time, the low center was moving to the north over the British Columbia

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Dayton G. Vincent

ClimateResearch Programme/Tropical Oceans and Global Atmosphere (WCRP/TOGA) archive II European Centrefor Medium-Range Weather Forecasts (ECMWF) analyses. In January, the most prominent feature is thetrough of low pressure that extends eastward from themonsoonal low centered over northern Australia acrossthe Pacific to a location near the equator and 130-W.The western part of this trough is commensurate withthe zonal portion of the SPCZ. Also shown is the troughassociated with the diagonal portion of the SPCZ

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Daniel Keyser and M. A. Shapiro

operator on an isen tropic surfacegradient operator in (y, p) plane [defined following (2.4)1REFERENCESAnthes, R. A., 1983: Regional models of the atmosphere in middle latitudes. Mon. Wea. Rev., 111, 1306-1335.~, Y.-H. Kuo, S. G. Benjamin and Y.-F. Li, 1982: The evolution of the mesoscale environment of severe local storms: Preliminary modeling results. Mon. Wea. Rev., 110, 1187-1213.Berggren, R., 1952: The distribution of temperature and wind con nected with active tropical air in the higher

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Huw C. Davies

refined Sutcliffe formulation [Eq. (2b) ] this equates to a value of less than 0.05 m s −1 . 2) More refined configurations The contribution of a localized region of (say) negative forcing to the net forcing could be countered or indeed negated by a region of strong positive forcing located in the near vicinity. This is noteworthy because the atmosphere’s pattern of forcing often exhibits dipole-like structures. Schematics of two such common configurations are shown in the left panels of Fig. 2

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Volkmar Wirth, Michael Riemer, Edmund K. M. Chang, and Olivia Martius

: Interaction of North Atlantic baroclinic wave packets and the Mediterranean storm track . Quart. J. Roy. Meteor. Soc. , 140 , 754 – 765 , . 10.1002/qj.2171 Aiyyer , A. , 2015 : Recurving western North Pacific tropical cyclones and midlatitude predictability . Geophys. Res. Lett. , 42 , 7799 – 7807 , . 10.1002/2015GL065082 Andrews , D. G. , J. R. Holton , and C. B. Leovy , 1987 : Middle Atmosphere Dynamics. Academic

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Loïk Berre and Gérald Desroziers

illustrated in the middle panel of Fig. 10 , where values have been averaged over a radius of 500 km for each observation point. In this case, some large-scale contrasts can be identified more clearly, such as relatively large values over the central Pacific compared to relatively small values over the southern Atlantic. This filtered innovation-based variance map was also compared to an ensemble-based variance map. For this purpose, the background field of each ensemble member was projected to

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John Molinari and Michael Dudek

of NCAR, forproviding the NCAR MM4 model and related documentation. Numerical simulations were carded out atthe National Center for Atmospheric Research, whichis supported by the National Science Foundation. Thiswork was supported by National Science FoundationGrant ATM8902487. REFERENCESAlbrecht, B. A., 1983: A cumulus parameterization for climate studies of the tropical atmosphere. Part I: Model formulation and sen sitivity tests. J. Atmos. $ci., 40, 2166-2182.Anthes, R. A., 1977

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Robert A. Houze Jr.

add more vorticity to the MCV. During the middle life cycle state in Fig. 2b , the MCS contains vorticity structures both in the form of convective-scale VHTs and in the form of the wider stratiform-region MCV. In the late stages of the MCS life cycle, the hot towers cease forming, but the stratiform cloud region containing MCV vorticity remains for some hours ( Fig. 2c ). b. Example of a vortical hot tower An example of vortical hot tower has been documented with airborne Doppler radar by Houze

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