摘要:

The generation of internal waves by advecting wind stress and air pressure fields is considered. For the open ocean, wind stress values of 1 dyn/cm2and pressure changes of 10 mbar can generate internal displacement of the order of meters during resonance, but stringent limits are placed on the variation of the advection velocity of the atmospheric field. Also, random atmospheric turbulence is shown to be an ineffective energy source. Wind stress forcing excites higher‐order internal wave modes comparable in amplitude to the lowest mode, while for air pressure forcing, only the lower modes are significant. The presence of one lateral boundary alters the dynamics of the response to advecting fields. A low‐frequency (ω<ƒ) Kelvin wave can propagate along the boundary, and an additional resonance point can occur when the component of advection velocity along the boundary equals the phase velocity of an internal wave in the linear portion of the dispersion curve. Low‐frequency oscillations in moored temperature data taken during the passage of hurricane Inez through the Tongue of the Ocean, Bahamas, are in qualitative agreement with predictions of wind stress generation in the presence of a b

ISSN:0148-0227    

DOI:10.1029/JC082i012p01711

年代:1977

数据来源: WILEY

摘要:

Ship drift data are utilized in studying the velocity field associated with the Gulf Stream system by computing three quantities suggested by the theory of turbulence: the mean kinetic energy, the eddy energy, and the energy exchange between the mean and fluctuating portions of the flow field (calleddE/dt). Contours of the mean kinetic energy demonstrate that the mean velocity field is well defined and contains the major accelerations and decelerations described in the literature. Eddy energy contours show a smaller range of variance in comparison with the mean kinetic energy and a minimum situated along the center of the flow axis. The distribution of thedE/dtquantity is somewhat puzzling, although it is certainly contourable and nonrandom. It is suggested that downstream, cross‐stream, and vertical components all may play important roles in its composition, whereas previous authors have made the assumption that only the cross‐stream component is signific

ISSN:0148-0227    

DOI:10.1029/JC082i012p01718

年代:1977

数据来源: WILEY

摘要:

The structure of larger‐scale motions in Lake Ontario, which are under the influence of the earth's rotation, is analyzed by the application of (1) rotary spectrum analysis, (2) ‘constant phase’ shape or ‘harmonic lock’ representation, and (3) bispectrum analysis. A set of continuous wind, current, and temperature data at several depths was extracted from the records of the International Field Year for the Great Lakes network. The results indicate that apart from the well‐known primary spectral peak near the inertial period there exists a significant secondary peak at half this period. A shift of the primary peak beyond the limiting inertial period is observed near the steepest vertical temperature gradient at stations closer to shore. It is suggested that the secondary peak is due to resonant interaction of spectral components near the inertial frequency and that the observed frequency shift below the inertial frequency is due to interaction between the low‐frequency waves of the Kelvin type and the Poincaré type waves near the iner

ISSN:0148-0227    

DOI:10.1029/JC082i012p01725

年代:1977

数据来源: WILEY

摘要:

An understanding of the mechanics of nonuniform flow is important in a variety of ecological and geophysical fluid mechanical problems. Moreover, the ability to predict local boundary shear stress on an uneven bed is essential in erosion and sediment transport problems. In order to elucidate the important fluid mechanical phenomena active over natural quasi‐two‐dimensional bed forms a series of detailed flow measurements were made above 60‐ to 100‐m‐long 1‐ to 3‐m‐high dunes in the Columbia River. In this paper, velocity profiles obtained by averaging these flow data along lines of constant distance above the riverbed are examined, and it is shown that they can be constructed from well‐known uniform flow results used in conjunction with a hypothesis about the structure of internal boundary layers. This approach permits skin friction as well as total boundary shear stress, averaged over one wavelength of the bed form, to be determined from spatially averaged velocity profiles and, conversely, provides a mechanism whereby zero‐order velocity profiles can be constructed for two‐dimensional nonuniform channel flows. Corrections for changes in the bottom roughness parameter caused by bed load transport and for flow stratification induced by suspended load transport are derived and applied in order to make the results consistent with the measured spatially averag

ISSN:0148-0227    

DOI:10.1029/JC082i012p01735

年代:1977

数据来源: WILEY

摘要:

A study is made of the two‐dimensional buoyant surface discharge into an ambient body of water. The numerical study is based on an initial boundary value problem using the full Navier‐Stokes and diffusion equations. A turbulence model using the Munk‐Anderson parameterization formula for density stratification effect is also incorporated. The results show the establishment of a surface density current with strong surface convergence and downwelling near the front. Comparison is made with the field experiments of Garvine and Monk on a small‐scale oceanic front in Long Island Sound. Excellent agreement is o

ISSN:0148-0227    

DOI:10.1029/JC082i012p01747

年代:1977

数据来源: WILEY

摘要:

From measurements made in the stratosphere and upper troposphere, atmospheric inventories of CCl3F, CCl4, and SF6are calculated for April and July 1975. Mean Northern Hemispheric altitude profiles Of CCl3F and CCl4in April 1975 show reasonable agreement with predictions of one‐dimensional diffusion models. From the distribution of these trace gases in the stratosphere, including comparisons with a few85Kr and tritium measurements, we deduce a stratospheric circulation pattern consistent with patterns of a number of radioactive substances which have been injected into the stratosphere. The observed stratospheric and tropospheric inventories Of CCl3F and SF6are consistent with an atmospheric residence time of 26 years and discount the existence of an important tropospheric sin

ISSN:0148-0227    

DOI:10.1029/JC082i012p01753

年代:1977

数据来源: WILEY

摘要:

The important variables in the problem of ozone reduction by nitrogen fertilizers are regarded to be as follows: τ, the atmospheric residence time of nitrous oxide; β, the fraction of nitrogen fertilizer that is denitrified within a few decades; and α, the fraction of denitrified gases that is nitrous oxide. With these three parameters, plus the results of the Climatic Impact Assessment Program, the time and the degree of ozone reduction can be estimated by ultrasimple equations which give about the same results as more elaborate model calculations. At the present state of uncertainty concerning the global nitrogen balance this simple approach may be useful in framing working hypotheses for solution of the full probl

ISSN:0148-0227    

DOI:10.1029/JC082i012p01767

年代:1977

数据来源: WILEY

摘要:

An analysis of atmospheric radio noise originally appearing in the literature to describe the VLF structure of atmospherics is repeated here, keeping a term discarded in the previous work and extending the results to include all frequencies and some simple effects of amplitude variations. It is shown that at high frequencies, atmospheric radiation appears to be the result of incoherent sources, whereas at low frequencies the sferics appear to originate from coherent sources. These conclusions are valid with only weak restrictions, regardless of the actual statistical model assumed for the process. An implication of these results is that at high frequencies the magnitude of the spectrum of the received signal can be related to the spectrum of the source current, a means for the study of lightning current wave forms thus possibly being provided.

ISSN:0148-0227    

DOI:10.1029/JC082i012p01773

年代:1977

数据来源: WILEY

摘要:

A data set from Bermuda of 10 particle size distribution measurements of the marine aerosol, by five‐stage cascade impactor and X ray analysis, has been used in a two‐component model to resolve tropospheric from sea surface derived trace elements. Assuming a sea surface origin for largest‐particle S and Cl and a tropospheric origin for Fe in all particle size ranges, the ratios to Fe of the tropospheric components S, K, and Zn decrease with increasing particle size, but Ca/Fe increases. The net sea surface component for the largest particles exhibits a ratio of Cl/S = 5.7, apparently differing from the seawater ratio of 21.4 because of S enrichment and Cl depletion, relative to the sea surface components of K or Ca which are found approximately in seawater propor

ISSN:0148-0227    

DOI:10.1029/JC082i012p01778

年代:1977

数据来源: WILEY

摘要:

Methods are described for estimating the quantity and dispersion on a global scale of the material injected into the stratosphere by a violent volcanic eruption by using a combination of lidar measurements of stratospheric aerosols and a previously described two‐dimensional atmospheric dispersion model with the initial volcanic cloud as the ‘source function’ (Cadle et al., 1976). The technique involves comparing the lidar data with model predictions normalized by using data of various kinds obtained after the Gunung Agung eruption in Bali in 1963. In this paper we show that the estimates for the Fuego eruption of 1974 can be made equally well by comparing model and lidar measurements of peak stratospheric concentrations or the total masses within a range of altitudes in a column above the place where the lidar measurements were made. The lidar data previously reported have been extended to several months following the eruption of Augustine volcano in Alaska during January and February 1976. The results indicate that the Augustine eruption must have injected no more than one fiftieth of the amount of material into the stratosphere that was injected by Agung and confirm the previous finding (Cadle et al., 1976) that Fuego injected one fifth of the amount injected by

ISSN:0148-0227    

DOI:10.1029/JC082i012p01783

年代:1977

数据来源: WILEY