摘要:

The analysis of an extensive series of zenith attenuation measurements of the atmosphere on both sides of the oxygen absorption spectrum (48–72 GHz) elucidates the absorption characteristics of the 4‐ to 6‐mm wavelength band. With the sun as a source, zenith attenuation measurements were made and used as a function of the precipitable water content of the atmosphere to determine the zenith attenuation coefficients of precipitable water. From these coefficients and measurements of the total precipitable water in the atmosphere the oxygen components of the zenith attenuations were determined. The zenith oxygen attenuations as a function of frequency and altitude are used to compare the theories for collision‐broadened spectral lines and to develop a new expression for pressure‐broadened spectral lines. The Gross and the Lorentz theories and the newly derived two‐piece linear expression for collision‐broadened spectral lines of atmospheric oxygen provide a theoretical fit to the measured data of 8.3%; the Van Vleck‐Weisskopf theory for the shape of collision‐broadened lines provid

ISSN:0148-0227    

DOI:10.1029/JC077i021p03831

年代:1972

数据来源: WILEY

摘要:

The dominant features of the half‐yearly wave in the stratospheric temperature above the 50‐mb level are an amplitude peak in equatorial latitudes, the maximums being in the transition seasons, and amplitude peaks at higher latitudes of either hemisphere, the maximums being in the extreme seasons. The low‐ and high‐latitude peaks are separated by a circumpolar belt of low values in the subtropics where the phase changes rapidly. The half‐yearly wave in the zonal thermal wind, at least as high as 5 mb, reaches a peak in the subtropics where the phase in the temperature wave reverses, and the half‐yearly wave in the geostrophic and the observed zonal wind above 50 mb accordingly increases poleward to latitudes of 30°–35° from a minimum a few degrees north of the equator and upward. The wave in the zonal wind reaches another, but weaker, peak in th

ISSN:0148-0227    

DOI:10.1029/JC077i021p03846

年代:1972

数据来源: WILEY

摘要:

A significant change in prevailing winds at the 75‐ to 105‐km level at College, Alaska, was observed during the midwinter stratospheric warmings of 1967–1968 and 1970–1971. Neutral wind values for the upper mesosphere and lower thermosphere were derived from radar measurements of the drift of meteor trails. The normal prevailing wind at College in the winter is eastward and usually poleward. During stratospheric warming events for two winters, both the meridional and the zonal prevailing flow reversed for a period of 10–15 days. The winds above 100 km, however, did not appear to be as strongly affected during the warming event of 1970–1971. The change in the wind pattern in the 75‐ to 105‐km level occurs about the time that the circulation breakdown begins at

ISSN:0148-0227    

DOI:10.1029/JC077i021p03856

年代:1972

数据来源: WILEY

摘要:

Measurements of electric charge on cloud droplets and drizzle drops were performed in clouds along the Mauna Loa‐Mauna Kea saddle road on the Island of Hawaii. Positively charged cloud droplets were found to predominate in the upper part of these warm clouds, whereas negatively charged cloud droplets predominated in the lower part. More than 80% of the drizzle drops were observed to be electrified negatively. It is proposed that in warm clouds, cloud droplets are electrified negatively when they are formed at the cloud base, that drizzle drops accumulate negative electric charge through the diffusion process, and that the positive ions are carried upward and attach to the cloud droplets at the upper part of the cloud

ISSN:0148-0227    

DOI:10.1029/JC077i021p03869

年代:1972

数据来源: WILEY

摘要:

A simple numerical model is used to study internal gravity waves ducted on a stable layer with wind shear. In strong but stable shear, ducted modes are confined to propagation cones nearly normal to the shear vector. If the surrounding medium is also stable, ducted modes have a long‐wavelength cutoff. If the duct has a saturated wave spectrum, the spectrum peak should occur near the cutof

ISSN:0148-0227    

DOI:10.1029/JC077i021p03879

年代:1972

数据来源: WILEY

摘要:

Wind velocity and temperature fluctuations have been recorded over a large, flat, snow covered ice floe in the Gulf of St. Lawrence using sonic anemometer‐thermometers. Reynolds stresses and heat fluxes have been computed digitally by the eddy correlation method. The average drag coefficient, C10= 0.0014, is the same as that of the sea surface and about half that of moderately rough ice. Spectra and cospectra of velocity and temperature fluctuations are expressed in dimensionless forms, and coherence cospectra of the fluctuations at various lateral separations are examine

ISSN:0148-0227    

DOI:10.1029/JC077i021p03886

年代:1972

数据来源: WILEY

摘要:

Wave spectra calculated from 204 observations in the Atlantic trade‐wind region east of Barbados, each observation with average duration of 11 minutes, were analyzed for the slope of the equilibrium region of the spectrum and the dispersion relation. Anomalous dispersion relations were correlated to shallow slopes of the equilibrium range, indicating that waves steeper than third‐order Stokes waves may have contributed to the spec

ISSN:0148-0227    

DOI:10.1029/JC077i021p03902

年代:1972

数据来源: WILEY

摘要:

Quartz has been isolated from deep‐sea cores from the Pacific Ocean. Grain sizes range up to 40 μm, the mode in the distribution being around 5–10 μm. Oxygen isotope ratios in each core sample vary systematically from +16 to +19‰ (relative to SMOW) from coarsest to finest quartz fractions of the North Pacific cores. For a given grain size the isotopic composition is remarkably uniform from core to core. The isotopic abundances are incompatible with either a volcanic or an authigenic origin. The fact that the size distribution and isotopic composition of quartz from the north‐central Pacific Ocean are identical with those quartz from surface soils in the Hawaiian Islands suggests that both are derived from the northern hemisphere continents by eolian transport. This conclusion is supported by measurements on quartz from tropospheric dusts collected in Japan and the Caribbean. Quartz isolated from South Pacific cores is consistently lower in18O than that isolated from the North Pacific but coincides in composition with quartz in eolian deposits in Australia and New Zealand, consistent with aerial transport. The unusual isotopic composition of the quartz may indicate a reservoir of quartz in the arid areas of continents, consisting of quartz derived from igneous and metamorphic rocks mixed with that of low‐temperature origin, su

ISSN:0148-0227    

DOI:10.1029/JC077i021p03907

年代:1972

数据来源: WILEY

摘要:

Although the concentration of particles in the stratosphere above the sulfate layer has been found to be typically 2–8 cm−3STP, on three occasions over the United States and four over Australia, concentrations greater by at least two orders of magnitude have been encountered. The particles have modal diameters of about 0.05 μm but are often joined together to form chains. In appearance and size distribution they closely resemble the particles obtained on some rocket flights at levels above 60 km. Phenomena that may be related and have been observed to occur at the same time of year are stratospheric aerosol layers, which appear optically dense when they are viewed horizontally looking toward the sun, and some twilight striations. The origin of the particles has not been determ

ISSN:0148-0227    

DOI:10.1029/JC077i021p03916

年代:1972

数据来源: WILEY

摘要:

According to Arnold and Pierce (1964) the pause time distributions in a stepped leader may under suitable conditions have a pronounced effect on the VLF spectra radiated. Experimental evidence in support of this finding is presented.

ISSN:0148-0227    

DOI:10.1029/JC077i021p03924

年代:1972

数据来源: WILEY