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Sidney Teweles and Frederick G. Finger

Abstract

Because temperature and height data reported by different types of radiosondes at constant-pressure surfaces high in the synoptic stratosphere are often incompatible, an empirical study has been made of diurnal changes computed from successive radiosonde observations taken in daylight and darkness and the variation of these changes with solar elevation angle. An attempt has been made to evaluate the spurious portion of these changes for principal types of instruments used by weather agencies of the United States during the International Geophysical Year. Graphs are presented giving temperature and height corrections that may be applied to the reported data to improve compatibility between stations, even across the line separating daylight from darkness. The method by which data were examined should prove useful in arriving at a similar system of corrections for any particular type of radiosonde.

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Frederick G. Finger and Raymond M. McInturff

Abstract

An attempt is made to determine empirically the diurnal temperature range between 24 and 36 km, by using means of 12-hr temperature differences obtained from successive rawinsonde observations over North America. With a technique for isolating effects of solar radiation on the radiosonde instrument, it has become possible to construct a model of the middle stratospheric daily temperature variation. According to this model, the temperature reaches a maximum near sunset and a minimum near sunrise. The amplitude of the oscillation is found to increase with altitude between the 30- and 5-mb levels and to depend on latitude. A seasonal effect is strongly suggested.

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Frederick G. Finger and Francis J. Schmidlin

The tremendous interest in upper-air measurement quality by the meteorological community brought together experts from many agencies at a Workshop on Upper-Air Measurements and Instruments. The workshop was held at NASA's Wallops Island facility on 14–15 November 1989. The purpose of the workshop was to establish a forum for the interchange of information to discuss mutual problems and to provide a basis for future work. A major recommendation of the workshop was for the development of a reference radiosonde instrument. A description of the workshop highlights are presented.

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Frederick G. Finger and Harold M. Woolf

Abstract

Fourteen HASP and two ARCAS rockets, carrying WOX-1A and Arcasonde 1A instrumentation, respectively, were launched at Wallops Island during a 39-hr period in September 1965 to gain information regarding 1) the daily variation of temperature and wind within the 30- to 50-km layer, and 2) the compatibility between temperatures measured nearly simultaneously by the rocketsondes and by supporting balloon-borne radiosondes. Analysis of the observed rocketsonde temperatures indicates a diurnal variation ranging from about 3C at 30 km to 9C at 48 km. Marked differences in the temperatures measured by rocketsondes launched prior and subsequent to sunrise and sunset suggest that a portion of the variation may not be real, but is possibly a, function of instrumental error. Support for this inference is provided by computations utilizing the rocketsonde winds as an independent means of determining the diurnal temperature wave. The results yield an amplitude about half that of the observed variation in the 35- to 45-km layer.

Temperatures obtained from several rockets launched within a short time interval disclose that the HASP (WOX-1A) system is capable of reproducing a given temperature profile with relatively small random error. In addition, ARCAS (Arcasonde 1A) measurements appear compatible with those of the HASP. However, a definite discrepancy was found to exist between rocketsonde temperatures and these reported by the supporting rawinsonde observations. Additional experiments are suggested as a means of determining the errors inherent in measurement of temperature by the various systems.

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Frederick G. Finger and Harold M. Woolf

Abstract

Meteorological data from the NASA Mobile Launch Expedition aboard USNS Croatan are utilized to investigate the early autumn stratospheric circulation of the Southern Hemisphere. Time-height and cross-section analyses indicate the vertical and areal extent of the developing wintertime polar vortex. A comparison is made between this cyclone and that of the Northern Hemisphere at a similar stage of development. Additional sets of analyses illustrate segments of the circulation patterns in both hemispheres along the 78th meridian at the time period of the Croatan observations.

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FREDERICK G. FINGER, RALPH B. MASON, and HAROLD A. CORZINE

Abstract

A recently published set of 10-mb. charts, analyzed six times monthly, is used as a basis for the discussion of circulation and temperature patterns during the year from July 1958 through June 1959. Comparison with events that transpired at that level throughout the previous year is made, and the most pronounced differences are investigated.

The transition of the extremely stable summertime easterlies to the more intense wintertime circulation of predominantly westerlies is found to be orderly and closely related to radiation cooling in northern latitudes. In contrast, the timing of the highly complex springtime reversal can vary considerably from year to year, appearing to be influenced by the timing of wintertime developments such as “explosive warmings” and accompanying circulation changes.

During the winter of 1959, data coverage over the Caribbean area was sufficient to allow delineation of low-latitude disturbances. A 10-mb. shear line system, moving northward through the area during January, is briefly discussed.

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MILES F. HARRIS, FREDERICK G. FINGER, and SIDNEY TEWELES

Abstract

The frictional and thermal contributions to S 2 2,2 (p), the dominant wave type in the progressive solar semidiurnal pressure wave, are evaluated from upper air observations at nine rawinsonde stations. The theoretical basis for the investigation follows from the approximation of friction as a potential force in the tidal equations. The model parameters and boundary conditions are those adopted by Siebert. Surface friction is evaluated semi-empirically, by the use of a friction model which is essentially an adaptation, to the semidiurnal motions, of the Ekman theory of the boundary layer. The assumption of a constant coefficient of the vertical transfer of momentum leads to uncertainties in the magnitude of the frictional contribution to the wave.

Further uncertainties arise from a systematic error in the observed temperatures, caused by radiation effects on the radiosonde instrument. The latter error, however, is believed to be negligible in the lower troposphere, where an unexpectedly large temperature variation is apparently caused by eddy transfer of heat from the earth's surface.

The results of the study must be considered in the light of the probable errors arising from data sampling, from the diurnal bias in the radiosonde observations, and from the restrictive assumptions of the theory. Considered in this light, the results suggest that the semidiurnal oscillation may be explained by three processes, of approximately equal importance: (1) eddy transfer of heat from the earth's surface; (2) direct absorption of solar radiation by water vapor and ozone, as computed by Siebert; and (3) surface friction, or eddy transfer of momentum. Surface friction apparently delays the surface pressure oscillation by about one hour.

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FREDERICK G. FINGER, HAROLD M. WOOLF, and CALVIN E. ANDERSON

Abstract

Rocket data from the Meteorological Rocket Network and other sources, in addition to high-level rawinsonde observations, are being employed to analyze a series of 5-, 2-, and 0.4-mb. charts. The broadscale analyses are being constructed for each week of the International Years of the Quiet Sun period, and primarily cover the North American and adjacent ocean areas. Methods employed for processing the various types of data as well as the analysis procedure are described.

Analyses completed thus far confirm the existence of large-scale systems, such as the wintertime polar cyclone, and the Aleutian anticyclone, to at least the level of the stratopause. In addition there is evidence of large-scale periodic oscillations in the heights of upper-stratospheric constant-pressure surfaces during autumn and early winter. Furthermore, a significant tidal component is apparent in summertime rocketsonde winds, for which adjustment must be made in order to obtain consistent quasi-synoptic patterns.

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Miles F. Harris, Frederick G. Finger, and Sidney Teweles

Abstract

The diurnal and semidiurnal variations of wind, pressure, and temperature at Lajes Field, Terceira, Azores, were computed for each month of the year for 30 levels between the surface and 10 mb. The semidiurnal variations were found to agree fairly closely with those at Washington, D.C., where data for the troposphere during the summer months are available for comparison. However, the diurnal variations of pressure and wind at the two stations are quite dissimilar. In order to check the consistency of the wind and pressure variations at Lajes Field, the diurnal and semidiurnal height variations were computed from the wind variation at each isobaric surface by the use of a model based on a linearized form of the equations of motion, frictionless flow, and the assumption that the oscillations are simple progressive waves. Results of the analysis indicate that the radiosonde observations contain diurnal, and smaller semidiurnal, temperature errors which superimpose fictitious pressure variations on the true pressure oscillations in the stratosphere, causing the phase of the latter to be moved toward noon. These results are supported by a similar analysis of rawinsonde data for Ft. Worth, Texas. The diurnal and semidiurnal temperature variations implied by the wind-derived height changes in the stratosphere are in general agreement with the results of determinations based on radiation theory. The diurnal error of the radiosonde temperature observations (observed minus computed temperature change) shows a maximum near noon at levels between 12 and 27 km, the diurnal range increasing from about 1C at the lower to about 2.5C at the upper level.

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Frederick G. Finger, Melvyn E. Gelman, Francis J. Schmidlin, Robert Leviton, and Bruce W. Kennedy

Abstract

Under the auspices of the Commission for Instruments and Methods of Observation of the World Meteorological Organization, meteorological rocketsonde intercomparisons took place at Wallops Island in March 1972 and at the Guiana Space Center, French Guiana, in September 1973. France, Japan and the United States participated in the Wallops tests, and France, the United Kingdom, the Union of Soviet Socialist Republics and the United States participated in the Guiana tests. Measurements were made during the day as well as at night.

Comparisons ire presented of temperature and wind data obtained by the different rocketsonde systems over the. altitude region from 25 to 80 km. Results indicate generally good compatibility among temperatures obtained below approximately 50 km. Above that level, biases increasing with height are evident. Temperature adjustments are derived, which, when applied to operational rocketsonde data, would in the mean achieve compatibility for synoptic analyses and other uses. Comparisons among wind observations indicate generally good agreement below approximately 60 km. However, some significant problem areas are pointed out and discussed.

The Guiana series of observations also provided valuable information on the diurnal temperature change at stratospheric and mesospheric levels. An evaluation of this aspect is presented, and results are compared with those predicted by tidal theory.

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