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Mark J. Rodwell and Brian J. Hoskins

paper is used to investigate the mechanisms that sustain thelow-level East African jet. The East African Highlands and a land/sea contrast in surface friction are shown tobe essential for the existence and concentration of cross-equatorial flow. The question of inertial instability asair crosses the equator is addressed from a potential vorticity (PV) perspective. Surface friction and local diabaticheating provide mechanisms for material modification of PV and both are important for the maintenance

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Roscoe R. Braham Jr.

hissincere appreciatim~ to Mr. Paul Spyers-Duran whofor several.years carried out the CCN measurementsfor the Chicago Cloud .Physics Group; to Dr. W. A,Hoppel for providing spectral parameters for the NRLdata, and to members of the Chicago Cloud PhysicsGroup for assistance in obtaining and analyzing ourCCN data. This research was performed under NSFGrant 33373 as part of the research on METROMEX,sponsored by the Weather Modification Program,Research Applications Directorate, National ScienceFoundation

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H. Wexler

temperature, TI during the coolingperiod instead of remaining constant as Brunt assumed.Assuming that R is a linear function of T, then theobservations of the outgoing radiation published bythe writer in the Monthly Weather Rewiew SupplementNo. 46 afford an opportunity of investigating thevalue of dR/dT. By applying least squares formulaefor all clear-weather observations (less than 2/10cloudiness) for Fairbanks, Alaska, and Fargo, NorthDakota, we note from figs. 1 and 2 of SupplementNO. 46 an apparent

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Glenn W. Brier and Isadore Enger

JUNE 1955CORRESPONDENCECORRESBQNDENCE285Comments on "Relation between geomagnetic activity and pressure variations aloft"By GLENN W. BRIER and ISADORE ENGERScientijc Services Division, U. S. Weather Bureau, Washington 25, D. C. 19 March 1953In a recent article in the JOURNAL, Kaciak andLangwell' examined the relationship between geomagnetic activity and pressure aloft at a number ofdifferent locations and levels. They applied certainstatistical tests of significance to the

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Ralph C. Foster and Gad Levy

and momentum balance. Nonetheless, the PBL is generally baroclinic and is predominantly near-neutral over the global oceans ( United States Weather Bureau 1965 ). Our analyses indicate that the normally neglected roll effect is significant. The baroclinic and thermal stratification modifications often work in concert, further amplifying this effect. Therefore the baroclinic effect should be properly parameterized in PBL models. We have no climatology of PBL rolls; however, the current research

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Peter M. Kuhn

Atmospheric and Biological Sciences, and by theBOMEX project. The Panel on Weather and Climate Modification(1966) discussed two possible effects of supersonic transport aircraft on the stratosphere---the possibility of asignificant increase of stratospheric water vapor, andan increase in persistent cirriform cloud producingcontrails. Both could affect the radiation budget and asa result possibly the general circulation. The Panelconcluded that the addition of water vapor would notappreciably alter the

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Edwin K. Schneider and Meizhu Fan

.74), whereas ψ g does not fit as well (correlation = −0.66). In the spirit of Eqs. (3) and (4) , ψ d is related to the weather noise wind stress forcing, taken to be proportional to Δ F noise , with constant of proportionality f d and delay time t m : A lag regression analysis gives the estimates t m /2 = 3 yr and f d = 0.081 Sv (W m −2 ) −1 . A modification of the simple model is required to take into account the distinction between the dynamics represented by the difference gyre and the

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Paul A. O’Gorman and Tapio Schneider

1. Introduction It is possible that on gas giant planets, baroclinic eddies occur in a weather layer above a barotropic deep layer ( Williams 2003a , b ; Ingersoll et al. 2004 ; Vasavada and Showman 2005 ). This is in contrast to the much studied case of Earth’s troposphere, in which baroclinic eddies are active immediately above the planetary surface. Current theories may be inadequate to describe the equilibration of baroclinic eddies in a weather layer. Theories and simulations based on

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B. Vonnegut, C. B. Moore, and C. K. Harris

812JOURNAL OF METEOROLOGYVOLUME 18AGRIMETER FOR MEASUREMENT OF ATMOSPHERIC ELECTRICAL POTENTIAL GRADIENTB. Vonnegut, C. B. Moore and C. K. HarrisArthur D. Little, Inc., Cambridge, Mass.(Manuscript received 2 February 1961)1. Intfoductionpassive device for ineasureiiient of the potential gradient that will operate continuously in all weather conditions. The agrimeter [I] is a simple device wellsuited to this purpose, for it supplies a direct voltageIn studies of atmospheric electricity during

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A. I. Weinstein

appropriate applications of models of this typethat have been used are as follows: 1) In sensitivity analyses "...to isolate the role played by each complicated phenomenon [-in cumulus clouds3, [-in order to~ decide which should be modeled in detail and to determine the neces sary field data needed for comparative studies.''2 2) In conjunction with weather modification field projects "...as a help in selecting test clouds for which the dynamics effect [-of seeding~ is expected to be

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