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N. J. Beyers, B. T. Miers, and R. J. Reed

Abstract

Wind and temperature soundings from a series of 16 meteorological rocket firings over a period of 51 hours between 30 June and 2 July 1965 are presented. Harmonic analysis revealed large diurnal oscillations in the zonal and meridional winds. Both components displayed amplitudes of about 12 m sec−1 near the stratopause (52–56 km) with the phase of the meridional (v) component leading the zonal (u) component by about 5–7 hours at that level. The v component was generally more uniform in both phase and amplitude over the two-day period. Harmonic analysis of the temperatures also revealed a diurnal oscillation with an amplitude of 8.2C at 52 km with the maximum occurring near 1330 hours local time. An attempt to arrive at an independent estimate of the temperature cycle, based essentially on a generalized thermal wind equation, yielded inconclusive results. When this series was combined with previous data, it was concluded that an unmistakable, dominant, diurnal tidal oscillation exists in the stratopause region over White Sands Missile Range (32N) during most or all seasons, particularly in the meridional component.

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Mark D. Albright, Donald R. Mock, Ernest E. Recker, and Richard J. Reed

Abstract

Heat and moisture budgets are used to compute net condensation rates in the GATE B-scale network for four hours of the day: 0000, 0600, 1200 and 1800 GMT. Budgets are presented for all phases combined, for selected periods of enhanced convection and for selected periods of suppressed convection. Computations are based on fitted values of the meteorological sounding data for the center of the B-scale ship array, on surface heat flux and evaporation measurements for seven ships in the array and on Cox and Griffith's (1979) radiation measurements for Phase III. Results are also presented for the diurnal variation of the basic variables.

Main findings are as follows:

  1. 1) Temperature variations are small, of the order of a few tenths of a degree, with a daytime maximum and nighttime minimum. There is evidence of possible radiation error above 400 mb where the amplitude is largest.
  2. 2) The atmosphere appears to be relatively dry during the day, when convection is most active, and relatively moist at night. It is suggested that this behavior may be caused by instrumental error.
  3. 3) The divergence and vertical velocity undergo characteristic cycles that were repeated in all three phases. It is hypothesized from their behavior that the convection evolves in three distinct stages: a stage of shallow convection during the early night, a stage of vigorously growing, primarily moderate-depth convection in the late night and morning and a stage of predominantly deep convection in the afternoon.
  4. 4) The vertical advection terms dominated both budgets. Variations of heat and moisture storage and of radiation were also important. Surface evaporation and sensible heat flux were essentially constant throughout the day.
  5. 5) Rainfall diagnosed from the heat budget was less than the observed precipitation and rainfall diagnosed from the moisture budget was greater than the observed precipitation in all three phases.
  6. 6) Maximum diagnosed condensation preceded maximum observed precipitation by ∼6 h. Differences between condensation and precipitation rates are attributed in part to storage of condensed water, though errors of measurement undoubtedly contributed to them as well.
  7. 7) The diurnal cycles of precipitation and low-level vertical motion were much larger in the disturbed (trough) region of easterly waves than in the suppressed (ridge) region. During highly suppressed periods the precipitation was uniformly distributed throughout the day while the vertical motion still appeared to show a variation.

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Anita Menhofer, Roger K. Smith, Michael J. Reeder, and Douglas R. Christie

Abstract

Results of a field experiment carried out in 1991 to gather upper-air data on the morning-glory environment are presented. The data include daily early morning radiosonde soundings from Burketown in north Queensland, Australia, for a 28-day period during the late dry season, together with pressure, wind, temperature, and humidity data from a number of surface stations in the region. During the experiment, 16 morning glories were recorded. On all but one day, radiosonde soundings were carried out in the pre-morning-glory environment. On 7 days, additional soundings were carried out within an hour or two of the passage of a morning glory.

Soundings made on days on which morning glories were generated over Cape York Peninsula but failed to reach Burketown are compared with those on days when morning glories were recorded at Burketown. The comparison shows that the depth and strength of the surface-based inversion did not differ significantly and that the stratification of the almost neutral layer above the stable layer was similar on days with and without morning glories. An examination of the wind profiles is unrevealing and leads the authors to reject the hypothesis that the trapping of wave energy is the key factor that determines the longevity of the disturbances. That the leakiness of the wave-guide is not the only factor in the ability of disturbances to cover large distances from their place of origin is consistent with a numerical study by Noonan and Smith, which suggests that the morning-glory bore-wave system is formed and maintained by mesoscale circulations associated with the sea breezes over Cape York Peninsula.

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Guenter Warnecke, Edith I. Reed, Walter B. Fowler, Earl R. Kreins, Lewis J. Allison, and Jaques E. Blamont

Abstract

The presence or absence of clouds, their characteristics, and variations of surface albedo have been correlated with observations made at several different wavelengths in the visible spectrum. These were made at high and low nighttime light levels by an airglow photometer aboard the OGO-4 satellite during August 1967 through January 1968. The wavelength regions studied were approximately 50 Å bands centered at 3914, 5577, 5893, 6225 and 6300 Å, in the energy range of 10−7 to 10−3 erg cm−2 sec−1−1 ster−1 with a field of view of ˜10 degrees. It was found that at the longer wavelengths (6225 and 6300 Å) the observations were strongly influenced by the variations of surface albedo. At the shorter wavelengths, the surface albedo variations were partly masked by the light returned through Rayleigh and Mie scattering. Preliminary analysis is made of surface and clouds by study of reflective radiance under moonlight and other nocturnal illuminations. Possibilities of further analysis are examined including methods of deducing cloud height information.

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