Frederick G. Finger

A METHOD FOR OBJECTIVE ANALYSIS OF STRATOSPHERIC CONSTANT-PRESSURE CHARTS

Abstract A method of numerical objective analysis has been developed for application to stratospheric constant-pressure data at the 100-, 50-, 30-, and 10-mb. levels (approximately 16, 20, 24, and 31 km., respectively). This system evolved from successive modifications of the programs employed for operational objective analysis of lower-level charts at the National Meteorological Center. For use with stratospheric data, the Automatic Data Processing portion of these programs was expanded to correct for the errors in high-level rawinsonde temperatures and heights caused by short and long-wave radiational effects on the temperature sensor. In addition, procedures for vertical extrapolation of rawinsonde reports and merging of off-time data were incorporated to compensate for the scarcity of reports at a given observation time. General degradation of stratospheric data with increasing height necessitated more stringent data rejection criteria within the entire system. It was also essential that increased emp...

Diurnal Variation of Wind, Pressure, and Temperature in the Troposphere and Stratosphere over the Azores

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 t...

Compatibility of meteorological rocketsonde data as indicated by international comparison tests

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. Com...

REDUCTION OF DIURNAL VARIATION IN THE REPORTED TEMPERATURES AND HEIGHTS OF STRATOSPHERIC CONSTANT-PRESSURE SURFACES

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.

SYNOPTIC ANALYSES OF THE 5-, 2-, AND 0.4-MILLIBAR SURFACES FOR THE IQSY PERIOD

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.

The Diurnal Temperature Range of the Middle Stratosphere

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.

FRICTIONAL AND THERMAL INFLUENCES IN THE SOLAR SEMIDIURNAL TIDE

Abstract The frictional and thermal contributions to S22,2 (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 tempe...

Southern Hemisphere Stratospheric Circulation as Indicated by Shipboard Meteorological Rocket Observations

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.

Diurnal Variation of Temperature in the Upper Stratosphere as Indicated by a Meteorological Rocket Experiment

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 3...

DIURNAL VARIATION IN STRATOSPHERIC TEMPERATURES AND HEIGHTS REPORTED BY THE U.S. WEATHER BUREAU OUTRIGGER RADIOSONDE

Abstract The diurnal change in temperature and height measured by the new U.S. Weather Bureau outrigger radiosonde at and above 100 mb. has been determined from pairs of successive radiosonde observations taking place in daylight and darkness. Analyzed graphs of the change as a function of solar elevation angle are presented. For a given solar angle, the observed diurnal variations are found to be larger with afternoon daylight than with morning daylight. Furthermore, values computed for Plateau stations with afternoon daylight are particularly large. Use of the white 50-mil rod thermistor with outrigger mounting has radically improved the compatibility of reported temperatures and heights at adjacent stations, primarily because the radiational temperature error has been reduced by a factor of about two to four. The observed diurnal variations measured by this new instrument are comparable with those of the military outrigger radiosonde, allowing for the slightly smaller thermistor of the latter.