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SIDNEY TEWELES

Abstract

The anomalous stratospheric warming of January and February 1957 is studied in detail by means of constant pressure charts, time sections, and cross sections. The warming occurred as the meandering Arctic stratospheric jet stream of wave number two developed into a pair of vortices extending to above the 10-mb. surface. It is concluded that development of stratospheric waves in the Northern Hemisphere is facilitated by autumnal growth of a forced perturbation locked in place by a warm ridge over the Aleutian area. The baroclinicity and rate of development were in agreement with Fleagle's criteria for the growth of disturbances. Interaction between the tropospheric jet stream and Arctic stratospheric jet stream during the period of development is believed responsible for the great intensity of the 1957 warming.

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SIDNEY TEWELES

Abstract

Contour and isotherm patterns of 100-, 50-, and 30-mb. charts have been subjected to harmonic analysis after the manner of Saltzman and Fleisher. The resulting wave-number statistics permit a detailed examination of the sudden warming and circulation breakdown that occurred in the Northern Hemisphere stratosphere in January–February 1958.

The stratospheric warming epoch of January 1958 was preceded by a marked expansion in the ring of tropospheric westerlies. Thereafter in the stratosphere the kinetic energy of wave number 1 increased by nearly the same amount transferred to it by the zonal flow and the other waves. However a subsequent great increase in the kinetic energy of wave number 2 occurred simultaneously with a large transfer of kinetic energy from that wave to both the zonal flow and the other waves. This development of wave number 2 thus appears to have been baroclinic in nature. Correlation of daily spectral statistics for the stratosphere and troposphere show a number of significant interlevel relationships in the growth and decay of the longer cyclone waves.

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Sidney Teweles

In dealing with differences in upper-air relative humidity over short distances and during small time intervals, investigators have noted a tendency for low values to be reported by U.S. radiosondes, particularly those sent aloft in daytime. This paper summarizes the proceedings of a colloquium of experts who described the nature of the spurious diurnal variation and recommended the manner in which the radiosonde should be modified and in which archived data might be corrected.

The billiard sharp whom anyone catches,

His doom's extremely hard—

He's made to dwell in a dungeon cell

On a spot that's always barred.

And there he plays extravagant matches

In fitless finger stalls

On a cloth untrue, with a twisted cue

And elliptical billiard balls!

The Mikado, Act II.

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SIDNEY TEWELES

Abstract

Winds and temperatures to above 80 km. measured during the International Geophysical Year by grenade, sphere accelerometer, and Pitot-static tube experiments at Churchill, Manitoba are combined with radiosonde data in time sections. The resulting analyses are discussed in reference to 10-mb. constant pressure charts showing the horizontal circulation near the 30-km. level. Periods in July, August, and December 1957 and January–February 1958 are covered.

The nature of the circulation in successive layers of the stratosphere and mesosphere is suggested by this investigation. In summer, irregular wind flow that is predominantly from the east appears in the middle and upper stratosphere. Strong easterlies in the lower and middle mesosphere are bounded in the upper mesosphere above 75 km. by a sharp vertical wind shear layer with highly variable west winds above, suggesting the existence of rapidly moving, intense cellular circulations near the mesopause. In winter when the boundary of the polar night is close to Churchill, such circulations seem to extend into lower layers until in January they occupy the entire mesosphere.

Strong west winds develop in the mid-stratosphere of wintertime, and a temperature minimum appears near the 30-km. level. During January 1958 the strong westerlies and the temperature minimum as well were disrupted by sudden warming of the entire stratosphere. The vertical structure of this warming effect, as it moved westward across the Atlantic and first appeared at the 40-km. level aver Churchill, is shown by means of a cross section.

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Sidney Teweles

For reasons of economy, it is necessary to minimize the size and scope of the data set to be collected for global analysis and prognostication of macroscale weather phenomena. For this purpose, it is generally agreed that a 12-hr observational frequency and a 500-km upper-air network spacing are adequate and consistent with each other. However, inasmuch as the observations may be influenced by mesoscale activity, may contain errors, or may not survive transmission, some redundancy is desirable. The requirement for covering the globe with a complete network of stations, based in large part on ships, buoys, and inhospitable land sites that are expensive to maintain, has been greatly alleviated by the success of satellite-borne indirect sounding systems. However, numerical weather prediction specialists are now faced with the problem of developing a four-dimensional data assimilation procedure to cope with the continuous influx of asynoptic reports from satellites, aircraft, balloons, and other moving platforms along with the reports from conventional stations. Studies to date have brought out one factor of special interest to the designers of a global observing system; that is, the data requirements for successful NWP may be substantially less stringent than is generally believed with respect to synopticity, errors, and variables to be reported.

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Sidney Teweles

The atmospheric layers from 60 to 200 km above the Earth's surface can be sounded only by expensive rocket-launched experiments, problematical indirect methods, or satellites in rapid orbital decay. Measurements of large-scale phenomena are masked by large amplitude perturbations, both aperiodic and tidal. Still the needs of the rapidly increasing traffic of aerospace vehicles through this region must be served. There is a growing requirement for meteorologists to apply their special skills to the analysis of the costly data now accumulating in substantial amounts from the mesosphere and lower thermosphere.

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Sidney Teweles
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SIDNEY TEWELES JR.

Abstract

No Abstract Available.

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Sidney Teweles Jr.

Abstract

No Abstract Available

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SIDNEY TEWELES and MIRCO SNIDERO

Abstract

A method of numerical objective analysis, developed by Cressman, is adapted for application to stratospheric constant pressure surfaces by giving greater weight to wind observations, correcting heights for radiation error, and building up the pressure pattern statistically over ocean areas. The temperature pattern is analyzed by a similar method.

Specimens of regression and temperature correction diagrams are shown, and the array of wind, temperature, and height errors engendered by a radiosonde pressure error is discussed.

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