摘要:

The ozone distribution in the earth's atmosphere is estimated from measurements of the absorption spectra of the 60,6–61,5rotation line of ozone at 110.836 GHz by using the maximum likelihood method. Only a single observation is required with the radio technique, whereas multiple observations are necessary with the IR and UV techniques. The resulting estimate of the ozone distribution is more stable and less dependent on a priori assumptions than the estimates using IR and UV measurement

ISSN:0148-0227    

DOI:10.1029/JC080i021p02957

年代:1975

数据来源: WILEY

摘要:

Infrared in situ radiance measurements in the 9.5‐ through 11.5‐μm spectral region resulted in a direct determination of the IR volume extinction coefficient. Aerosols were collected for an analysis of size distributions and chemical composition. Mie calculations based on these data show that at 10‐μm wavelength more than 95% of the IR extinction is caused by absorption. A comparison of the calculated with the measured aerosol absorptivity resulted in values for the imaginary part of the IR refractive index of 0.47 and 0.19 for the urban and rural aerosols, respe

ISSN:0148-0227    

DOI:10.1029/JC080i021p02960

年代:1975

数据来源: WILEY

摘要:

Fume was collected at Kilauea Volcano with equipment patterned after that used in industrial pollution studies. Particulates arid some of the gases present were separated. The fume analyzed was collected from Halemaumau crater in a noneruptive state, from Mauna Ulu lava lake with mild lava fountaining, and from vigorous but short‐lived fountaining from fissures across the floor of Kilauea caldera. The chief components were SO2, SO4, Cl, Na, Ca, K, F, Mg, and Fe in about that order of decreasing concentration. Content and order of abundance varied depending on the state of activity of the volcanic sources of the fume. Sulfur compounds were preponderan

ISSN:0148-0227    

DOI:10.1029/JC080i021p02963

年代:1975

数据来源: WILEY

摘要:

Records from microbarograph arrays at Boulder, Colorado, and Washington, D. C., for December 1971 through March 1972 and at Boulder for June 1972 through August 1972 are analyzed for gravity wave events. Rawinsonde soundings from Denver, Colorado, and Dulles International Airport near Washington, D. C., are examined for corresponding times to determine the existence of dynamically unstable (defined by small Richardson number) wind shear layers in the atmosphere. Comparison of these two sets of data indicates that at least one half of the 280 gravity wave events detected and analyzed are shear‐induced. Further, the ratio of the average wavelength of a shear‐induced gravity wave to shear layer thickness is found to be close to theoretical estimates based on linear perturbation theory. It is also indicated that shear layers may be likely to generate gravity waves because the layer has an almost dry adiabatic lapse rate (small Brunt‐Väisälä frequency) rather than because it has a large wind shear. Finally, further study is desirable on the question of why the wind shear mechanism is not responsible for a larger number of the gravity waves that are seen on the microb

ISSN:0148-0227    

DOI:10.1029/JC080i021p02967

年代:1975

数据来源: WILEY

摘要:

The electromagnetic field generated by a progressive ocean wave in a horizontally stratified ocean is a sum of a transverse electric type field, a transverse magnetic type field, and an electrostatic type field. Seawater velocity components in a vertical plane containing the direction of wave propagation generate the transverse electric part of the field, and the velocity component normal to the plane generates the transverse magnetic part of the field, which vanishes above an ocean surface. The electrostatic part of the field results from surface charges that halt vertical electric currents at an ocean surface. Gradients of magnetic fields generated at the surface by both surface and internal waves provide sensible signals for recently developed magnetic gradiometers based on the Josephson effect, provided surface speeds exceed 1 cm/s or so. Vertically spaced measurements of noise spectra of magnetic field gradients above an ocean surface offer a unique and promising means of obtaining a measure of surface and internal wave spectra for three reasons: (1) magnetic field strengths above the surface are proportional to a weighted average of seawater speed over an ocean depth, which provides a response depending on the mode structure of internal waves; (2) field strengths decrease exponentially with height above the surface ase−kh, wherekdenotes wave number, which provides means of wave number discrimination and, together with frequency discrimination, offers means of resolving internal wave spectra mode by mode; and (3) noise spectra of magnetic field gradients are effectively cross spectra and so provide directional information on wave spectra from an effective point measuremen

ISSN:0148-0227    

DOI:10.1029/JC080i021p02977

年代:1975

数据来源: WILEY

摘要:

As ocean waves shoal and approach the shoreline, they peak and finally break, usually as either plunging or spilling breaker types. This study applies the theory of wave propagation in water of gradually varying depth, as developed by Biesel (1952), to determine the dependence of breaker type on the beach slope tangent s and on the deep water wave steepnessH∞/L∞, the ratio of the deep water wave heightH∞to the deep water wave lengthL∞. By representing the fluid motion at the surface in Lagrangian coordinates, a graph (Figure 7) is developed for the breaker type on the basis of 21 combinations of s andH∞/L∞. A comparison with laboratory wave tank data on breaker types shows good agreement with this graph based entirely on theory. The steepening of the shoaling wave profile on the shoreward wave face leads to the occurrence of a vertical surface. The first appearance of such a vertical surface provides a natural breaking criterion compatible with experimental usage. On the basis of this breaking criterion the dimensionless ratiosHb/H∞andHb/hb, whereHbis the breaker height andhbthe depth at breaking, are theoretically evaluated. The well‐known dependence ofHb/H∞onH∞/L∞is also correctly demonstrated by the

ISSN:0148-0227    

DOI:10.1029/JC080i021p02991

年代:1975

数据来源: WILEY

摘要:

Genetically, beach cusps are of at least two types: those linked with incident waves which are surging and mostly reflected (reflective systems) and those generated on beaches where wave breaking and nearshore circulation cells are important (dissipative systems). The spacings of some cusps formed under reflective wave conditions both in the laboratory and in certain selected natural situations are shown to be consistent with models hypothesizing formation by either (1) subharmonic edge waves (period twice that of the incident waves) of zero mode number or (2) synchronous (period equal to that of incident waves) edge waves of low mode. Experiments show that visible subharmonic edge wave generation occurs on nonerodable plane laboratory beaches only when the incident waves are strongly reflected at the beach, and this observation is quantified. Edge wave resonance theory and experiments suggest that synchronous potential edge wave generation can also occur on reflective beaches and is a higher‐order, weaker resonance than the subharmonic type. In dissipative systems, modes of longshore periodic motion other than potential edge waves may be important in controlling the longshore scale of circulation cells and beach morphologies. On reflective plane laboratory beaches, initially large subharmonic edge waves rear‐rage sand tracers into shapes which resemble natural beach cusps, but the edge wave amplitudes decrease as the cusps grow. Cusp growth is thus limited by negative feedback from the cusps to the edge wave excitation process. Small edge waves can form longshore periodic morphologies by providing destabilizing perturbations on a berm properly located in the swash zone. In this case the retreating incident wave surge is channelized into breeches in the berm caused by the edge waves, and there is an initially positive feedback from the topography to longshore periodic perturbati

ISSN:0148-0227    

DOI:10.1029/JC080i021p02997

年代:1975

数据来源: WILEY

摘要:

A model for interstitial silica concentrations is derived, incorporating biological mixing of sediments. This model predicts concentrations and gradients and can account for the observed geographical variations in interstitial silica on the basis of a dynamic balance between solution of silica particles and diffusion from the sediments. The flux of particulate biogenous silica into the sediments is confirmed as an important parameter controlling interstitial silica concentrations. Biological mixing of sea floor sediments also has an important influence on interstitial composition by modifyirig the depth at which dissolving particles react. Faster mixing raises the interstitial concentration. The rate at which siliceous particles dissolve also plays a role; the slower they dissolve, the greater the interstitial silica concentration. Measurements on near‐bottom waters of the Atlantic show no consistent gradients in dissolved silica, but antarctic bottom water seems significantly more variable in the benthic boundary layer than in the water mass above or in the benthic zone of North Atlantic deep wate

ISSN:0148-0227    

DOI:10.1029/JC080i021p03013

年代:1975

数据来源: WILEY

摘要:

Biological mixing in deep‐sea sediments is described in terms of a time‐dependent eddy diffusion model where mixing takes place to a depthLat constant eddy diffusivityD. The differential equation that describes this model has been solved for an impulse source of tracer delivered to the plane surface that forms the top of the mixed layer. The solution then serves as a Green's function, which can be used to determine the distribution of tracer in depth and in time for a surface input of tracer specified as any arbitrary function of time. The characteristic properties of the solution are dependent on the dimensionless parameterD/Lυ, where υ is the sedimentation rate. IfD/Lυ is greater than 10, the surface layer becomes homogeneous, and the model is identical to the homogeneous layer model proposed by Berger and Heath (1968). IfD/Lυ is less than 0.1, little mixing can take place before the sediments are buried, and so the surface concentration propagates downward into the sediments with little dispersion. For all values ofD/Lυ the weighted mean depth of the concentration distribution is the depth at which an impulse source would be found in the sediment if no mixing had taken place. The microtektite data of Glass (1969, 1972) and Glass et al. (1973) indicate that abyssal sediments are mixed from the surface to a maximum mixing depth that ranges between 17 and 40 cm below the surface. Mixing occurs at rates between 1 and 100 cm2kyr−1. Higher mixing rates may occur nearer the surface, but microtektite distributions cannot be used to estimate these rates in the presence of the deeper, slower mixing. Estimates forDbased on dimensional analysis of sediment reworking rates for nearshore organisms (103–106cm2kyr−1) are used to predict abyssal mixing rates between 1 and 103cm2kyr−1by invoking the assumption that mixing is proportional to biomass. Plutonium distributions in deep‐sea sediments (Noshkin and Bowen, 1973) indicate abyssal mixing rates ranging from 1

ISSN:0148-0227    

DOI:10.1029/JC080i021p03032

年代:1975

数据来源: WILEY

摘要:

Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day‐night periods. They were also found to be linear functions of the daily maximum value of the surface soil‐air temperature differential. Tests on three additional soils ranging from sandy loam to clay indicated that the relations determined for Avondale loam could not be accurately applied to these other soil types. When the moisture characteristic curves of each soil were used to transform water contents into pressure potentials, however, it was found that soil water pressure potential could be determined without prior knowledge of soil type, and thus its value as a potential soil water status survey tool was significantly enhan

ISSN:0148-0227    

DOI:10.1029/JC080i021p03044

年代:1975

数据来源: WILEY