摘要:

Winds determined from chemical release trails in the 90‐ to 120‐km region (primarily from the early and middle fall season) are analyzed by a method that is an extension of the method used by Hines for the determination of the diurnal tide. This method is designed to reveal the prevailing, diurnal, and semidiurnal components. A diurnal tide is computed that has a vertical wavelength (19 ± 1 km) in agreement with the measurements of Hines and with tidal theory predictions for the (1, 3) mode. The observed height variation of the prevailing wind can most easily be explained in terms of a wave whose vertical wavelength is 27 ± 5 km. The small observed magnitude of the semidiurnal tide indicates that there is considerable seasonal variation of this component, since a large semidiurnal tide has previously been observed during periods near the summer and winter solstices. Observed phase differences between the northward and eastward components of the prevailing and tidal winds are discussed. Some suggestions for improvements in the tidal extraction analysis method are also

ISSN:0148-0227    

DOI:10.1029/JB073i002p00467

年代:1968

数据来源: WILEY

摘要:

Simultaneous soundings of ozone and submicron dust over north and Central America are reported. The results show considerably more dust in the equatorial stratosphere than in the higher‐latitude stratosphere. An increase in the dust concentration is observed near the level of the tropical tropopause and as far north as 60°. The occasional secondary dust maximum and dust layers between the local tropopause and the altitude of the tropical tropopause is attributed to a form of transport other than eddy diffusion. There appears to be a large positive correlation of dust and ozone in the region of the secondary dust maximum. The possibilities of the dust source's being meteoric, volcanic, or stratospheric are discuss

ISSN:0148-0227    

DOI:10.1029/JB073i002p00479

年代:1968

数据来源: WILEY

摘要:

A study of weather radar data on 117 cyclones occurring in the vicinity of Tanegashima weather station, Japan, during the period January 1960 to December 1964 has been made. In 82% of the cyclones observed, one or more line echoes were detected in the warm sector. A detailed description of one of these cyclones (A‐type) is given, demonstrating that the line echoes represent prefrontal squall lines similar to those found in the central United States. The observations on these subtropical oceanic cyclones are contrasted with the Bjerknes cyclone mode

ISSN:0148-0227    

DOI:10.1029/JB073i002p00487

年代:1968

数据来源: WILEY

摘要:

A rocket‐borne ozonesonde that utilizes the chemiluminescent principle for the measurement of ozone concentration in the upper atmosphere has been developed. The sonde is deployed in the mesosphere by a small meteorological rocket (Arcas), and ozone concentration is measured as the instrument descends on a drag parachute. This instrument was flown during and before the total solar eclipse of November 12, 1966, at Tartagal (22°32′S, 63°50′W), Argentina, with the cooperation of scientists from that country. Ozone was monitored as the sonde passed through the total eclipse shadow beween 60 and 54 km and registered a higher concentration than the sounding made a day earlier at about the same time. A decrease in the ozone concentration was noticed as the sonde emerged from the shadow of the total eclipse. Ozone concentration at 57 km during total solar eclipse was measured to be 3.7 × 10−3cm km−1as compared with 1.4 × 10−3cm km−1measured a day earlier at the same altitude. No marked effect on the ozone concentration in the upper stratosphere was noted during the partial eclipse conditions under which that re

ISSN:0148-0227    

DOI:10.1029/JB073i002p00493

年代:1968

数据来源: WILEY

摘要:

The temperature decay of a lightning channel during the interstroke period is determined theoretically. It is shown that, in the absence of input energy to the channel, the channel temperature will decay sufficiently slowly so that conditions conducive to the initiation and propagation of a dart leader will exist in the channel after a typical interstroke period of 40 msec. Thus, it would appear unnecessary to invoke the special mechanisms suggested by Brook et al. and by Loeb to explain the ‘long’ interstroke period. The calculations indicate that the lightning channel radius during the latter stages of a lightning stroke is of the order of centimeters. A mechanism is suggested to explain the phenomenon of bead lightning and to account for the observed long‐lasting luminosity occurring at certain points on the normal discharge ch

ISSN:0148-0227    

DOI:10.1029/JB073i002p00497

年代:1968

数据来源: WILEY

摘要:

In the past few years a number of observations have been made at sea of the wind speed gradient and the turbulent Reynolds stress. It is of considerable interest to make some estimates of the effect of buoy motion on the measurements, particularly since the measurements from buoys and fixed masts show marked differences. The calculations are quite simple if we use fairly simple motions to approximate the behavior of the buoy. Provided that some damping is done of the vertical motion and provided that the amplitude of the oscillating tilt is smaller than 10°–20°, the effects are fairly small. The error arising from the correlation between the turbulent velocity components and the components produced by the buoy motion is probably 10–20%. It is shown, however, that it is extremely important to keep the mean tilt very

ISSN:0148-0227    

DOI:10.1029/JB073i002p00507

年代:1968

数据来源: WILEY

摘要:

A method based on the equation of radiative transfer has been developed for predicting the two‐dimensional wind wave spectrum in the North Atlantic Ocean. The model takes account of wave generation by both resonance and instability mechanisms. A simple representation for wave breaking is also included, as are the effects of nonlinear wave interactions. This combination of energy transfer mechanisms is used to compute wave spectra that are in reasonable accord with observations. The results question the concept of a ‘fully developed’ spectrum. The work also points up a lack of understanding of the particulars of various energy transfer mechanisms, as well as the shortcomings of the basic predictive input

ISSN:0148-0227    

DOI:10.1029/JB073i002p00513

年代:1968

数据来源: WILEY

摘要:

An eddy was observed disrupting the subtropical convergence in the vicinity of the Schmidt‐Ott Bank during a cruise ofAfricanaII in March 1964. The subtropical convergence is therefore not necessarily continuous past South Africa, exact conditions probably depending on the seasonal variation in strength of the Agulhas Current. Subantarctic water moved northward both by sinking at the convergence and by mixing along the edge of the eddy. Some effects were observed as deep as the Antarctic Intermediate Wate

ISSN:0148-0227    

DOI:10.1029/JB073i002p00531

年代:1968

数据来源: WILEY

摘要:

In the Gulf of Alaska, the winter profiles of temperature and salinity against depth show considerable fine structure, the features of which are most pronounced in the pycnocline. Regarding the observed profiles as consisting of a mean profile and a perturbation profile, we can compute the wave number spectrum of the perturbations. The temperature spectrum shows a single significant peak at 17 cycles per kilometer. The salinity spectrum has a peak at 20 cycles per kilometer and differs from the temperature spectrum at high wave numbers. Temperature and salinity perturbations are directly related to each other in a narrow band of wave numbers centered around 20 cycles per kilometer; elsewhere, they are unrelated. The dominant wavelength of the temperature perturbations is 60 meters and of salinity perturbations, 50 meters. The Vaisala frequency is a very complicated function of depth and has a maximum, 0.016 sec−1, in the halocline. It is a useful measure of the stability oscillations only if the vertical displacements are less than about a mete

ISSN:0148-0227    

DOI:10.1029/JB073i002p00535

年代:1968

数据来源: WILEY

摘要:

It is widely stated in wind erosion studies that the boundary layer flow of surfaces of sand is aerodynamically rough at the inception of particle motion. At comparable roughness Reynolds numbers in water, however, the roughness state is considered as transitional. Clarification of the matter is important if the nature of fluid force acting on the surface particles is to be understood. In this study the boundary layer velocity profiles of published wind tunnel results are reanalyzed in terms of the relation between the roughness lengthz0and the roughness Reynolds number. For aerodynamically rough flow, the ratioz0/kis expected to be constant as the Reynolds number (V*k/ν) varies. Most of the evidence indicates that the boundary flow is transitional rather than rough. Furthermore, the results do not follow the classical work of Nikuradse for uniform sand roughness. This may be due to the uncertainties in defining the reference datum (z= 0) and the effective roughness element lengthk. It is concluded that there is insufficient experimental evidence for the assertion of fully developed roughness

ISSN:0148-0227    

DOI:10.1029/JB073i002p00541

年代:1968

数据来源: WILEY