摘要:

Data from 5 years of continuous surface ozone measurements made at 16 European and African stations, located on a meridional chain between 69.5°N and 34°S, are presented. The analysis of monthly averages exhibits an annual sinusoidal variation with mean, amplitude, and phase characteristic for each latitude. Thirty‐four meridional cross‐sections of ozone in the high troposphere were measured aboard commercial jetliners. Both ground‐based and aircraft measurements indicate enhanced stratospheric‐tropospheric ozone injection at about 30°, 45°, and 65°N. The average ozone injection fluxes vary between 3×1010mol/cm2s at the equator and 10×1010mol/cm2s at the main inje

ISSN:0148-0227    

DOI:10.1029/JC082i015p02063

年代:1977

数据来源: WILEY

摘要:

A comparison of several measurements of the size distribution for tropospheric aerosols in which soil‐derived aerosols are significant shows that these aerosol size distributions appear to be characterized by a common mode structure, with the optically important soil particles having radii between 0.5 and 10.0 μm. These measurements suggest that under conditions of low dust loading a reasonable characterization of the size distribution for soil‐derived aerosols is a log normal distribution with a surface mean radius of 1.5 μm and a geometric standard deviation o

ISSN:0148-0227    

DOI:10.1029/JC082i015p02074

年代:1977

数据来源: WILEY

摘要:

Microwave brightness temperature data from the Nimbus 5 satellite have been analyzed by using threshold brightness temperatures to yield tropical oceanic precipitation frequencies for several classes of rainfall rates during the season December 1972 through February 1973. Data taken near local noon and near local midnight were analyzed. The overall results are consistent with both climatological precipitation frequency and with concurrent satellite‐derived frequency of highly reflective clouds. The difference between the local noon and the local midnight frequency is small, but the heavier rainfall rates tend to occur more frequently near local noon. The ratios of the frequencies of light, moderate, and heavy rain were observed to be relatively constant over the tropical oceans. Passive microwave measurements from space seem to be an important step toward accurate measurement of oceanic precipitatio

ISSN:0148-0227    

DOI:10.1029/JC082i015p02083

年代:1977

数据来源: WILEY

摘要:

Hydrographic and current observations of the Norwegian Current (Horn and Schott, 1976) show a considerable amount of low‐frequency variability; in particular, many of the current spectra are broadly peaked at around 2–3 days. In this paper we consider a number of simple barotropic and baroclinic instability models of the mean flow in an attempt to explain these fluctuations. The theoretical results suggest that the current fluctuations are most likely due to baroclinic instability of the mean f

ISSN:0148-0227    

DOI:10.1029/JC082i015p02087

年代:1977

数据来源: WILEY

摘要:

The diffusion and transport of particles suspended in turbulent flows depend on the interaction between the particles and the turbulence. To investigate a possible particle‐turbulence interaction, we observed particle trajectories in a rotating fluid with a solid body velocity profile, as might occur in the core of a vortex or an eddy. The experiments were conducted with a series of single small spheres (with low particle Reynolds numbers) sinking or rising in a horizontal cylinder rotating about its central axis at a constant speed. Each sphere was found to follow a nearly circular orbit in a vertical plane perpendicular to the cylinder axis. The orbit center lay very near the horizontal plane through the axis of the cylinder and was at the point in the fluid where the velocity of the fluid was equal and opposite to the terminal velocity of the particle. The particle trajectories also evolved slowly, spiraling either inward or outward. A theoretical description of the particle motion shows that the two principal forces on the particle, fluid drag and gravity‐buoyancy, account for the circular motion. A force due to particle inertia (a centrifugal force from the center of its orbit), a small position‐dependent wall effect on drag, a very small force (also affected by the walls), and a very small centrifugal buoyancy force account for the long‐term inward or outward spirals. This kind of systematic interaction in which particles seek and remain in fluid closely opposing their own motion could have a role in the suspension of small particles in some turbulen

ISSN:0148-0227    

DOI:10.1029/JC082i015p02096

年代:1977

数据来源: WILEY

摘要:

For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300‐m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil‐type discrimination based on identification of type‐specific spectral signatures. Therefore remote sensing, conducted in the 0.4‐ to 1.0‐μm wavelength region of the solar spectrum, would seem to be much more suited to identifying crop and soil types than to estimating of soil wat

ISSN:0148-0227    

DOI:10.1029/JC082i015p02101

年代:1977

数据来源: WILEY

摘要:

Periods and structures of gravitational free oscillations in Lake Huron, Saginaw Bay, Georgian Bay, and the North Channel are determined from theoretical calculations. The calculations take into account the bathymetry and shape of the Huron system and also the effect of the earth's rotation. Time series analyses are performed on water level data from 13 stations around the lake. The power and coherence spectra exhibit peaks corresponding to diurnal and semidiurnal forcing and various modes of free oscillation of the lake. Both theory and observations show that Saginaw Bay, Georgian Bay, and the North Channel each have a fundamental frequency of oscillation lower than the frequency of Lake Huron's first longitudinal oscillation. There is reasonable agreement between theoretical and observed characteristics for several of the free modes of the Lake Huron system.

ISSN:0148-0227    

DOI:10.1029/JC082i015p02105

年代:1977

数据来源: WILEY

摘要:

Present theories of nonlinear interactions within a random internal wave field depend upon the assumption of quasi‐Gaussian statistics; i.e., the nonlinearities are assumed to be perturbations on a Gaussian base state. Examination of horizontal current, temperature, and vertical displacement data has been ambiguous as to the correctness of this assumption. This report describes the time variability of the probability distribution of the east and north velocity components and the up (vertical displacement) variable of the internal wave experiment (IWEX ); the goal is to test for the Gaussianity of internal waves. In order to use the classical chi‐square and the two‐tailed Kolmogorov‐Smirnov goodness‐of‐fit tests the correlation or spectral structure of the data must be considered. Starting with artificially generated Gaussian random time series that are white in frequency space, the Gentleman and Sande (1966) method is used to incorporate desired spectral shapes into the series, which are then used to find, for the two goodness‐of‐fit tests, new confidence levels that recognize the presence of an internal wavelike correlation structure in the data. The degree of Gaussianity of the east, north, and up variables throughout IWEX is discussed in this light and compared with results of previous investigations. It is concluded from the IWEX data that temperature and displacement are more likely to be Gaussian than are current data, that small kurtosis is characteristically associated with non‐Gaussian current data, that negative skewness contributes to non‐Gaussian temperature/displacement data, and that bursts of high variance may precede times of non‐Gaussian behavior. No consideration was given to the frequency domain behavior of the data other than to the overall spectral shape for use in generating the artificial data. In this sense, then, this report is a preliminary study only, because the temporal evolution of the statistics of the various frequency bands in the internal wave field is the underlying q

ISSN:0148-0227    

DOI:10.1029/JC082i015p02117

年代:1977

数据来源: WILEY