摘要:

Reanalysis of the data from the 1966 Great Lakes–Illinois River Basin Project (GLIRBP) of the Federal Water Pollution Control. Administration (FWPCA) reveals some of the large‐scale persistent summertime circulation patterns in Lake Huron. The greatest density of data from the original 45 current meter moorings covers June–August 1966, when some 21 stations returned synoptically significant data from current meters at depths of 10 and 15m. From this somewhat sparse sample it is deduced that at 10‐m depth a counterclockwise circulation dominates the northern two thirds of the lake. The shallower southern portion shows a more complex pattern, with generally southward flow along the shorelines on both sides and a return flow northward near the center line of the southern basin. This latter pattern may decay later in the summer, but the data become too patchy for definite analysis. The data set from 15‐m depth indicates similar circulations. Spectral analysis of currents at individual stations reveals a strong inertial rotation of the current vector at open lake sites. Only the data from the Straits of Mackinac lack the inertial component and are dominated by the lunar semidiurnal tide and the seiches of Lake

ISSN:0148-0227    

DOI:10.1029/JC081i018p03069

年代:1976

数据来源: WILEY

摘要:

For a long breakwater on a slowly varying bottom as asymptotic theory is given which accounts for the combined effects of refraction and Fresnel diffraction of water waves. Numerical examples are given for two cases: an offshore breakwater and an isolated jetty.

ISSN:0148-0227    

DOI:10.1029/JC081i018p03079

年代:1976

数据来源: WILEY

摘要:

A semiempirical theory of breaking‐induced mean currents on a beach is developed here to study the combined effects of refraction and diffraction. With the omission of convective inertia and lateral turbulent diffusion the resulting averaged equations are solved by finite differences. The case of an offshore breakwater is studied in detail, and the predicted current pattern is consistent with laboratory observations and the known tendency of tombolo formation near sandy beaches. Numerical results for an isolated breakwater extending from the shore are also presented, and observational evidences cite

ISSN:0148-0227    

DOI:10.1029/JC081i018p03085

年代:1976

数据来源: WILEY

摘要:

Aircraft observations of the microwave emission from the Bering Sea show that the spectral character of brightness temperature variation with wind speed in a fully developed sea is due to a combination of surface roughness and a surface layer with varying dielectric constant over a physical depth of a few millimeters. The varying dielectric layer is identified with cusps formed by the bubbles associated with thin foam streaks. Computations of the radiative transfer through such a layer show that the change in microwave emissivity due to the presence of that layer decreases as microwave wavelength increases. Since foam streak coverage on the ocean surface increases with surface wind speed, the increase in microwave brightness temperature with increasing wind speed will be less at longer wavelengths, a characteristic that is observed in the experimental results presented. In addition, it has been observed that in fetch‐limited situations the microwave brightness temperature depends in the same way on surface wind speed but is essentially independent of varying foam coverage, the implication being that the surface wave structure becomes more important in determining the microwave brightness temperatures as fetch approaches zero. It appears that microwave brightness temperatures are directly related to ocean surface wind speeds, regardless of fetc

ISSN:0148-0227    

DOI:10.1029/JC081i018p03095

年代:1976

数据来源: WILEY

摘要:

Coastal sea elevations measured at tide gages in the northern North Pacific when adjusted for the atmospheric pressure show a seasonal high in winter (November–February). This high is well out of phase with the midocean response of geopotential anomaly (steric height) to the heating and cooling cycle, which produces highest steric elevations in July–October. We attempt to show that steric height near the coast varies seasonally in phase with the measurements at the tide gages and that the high elevations in winter are a consequence of the circulation of the subarctic cyclonic gyre of the North Pacific Ocean. The flow of the coastal limb of this gyre (along the eastern, northern, and western boundary of the ocean) is intensified in winter, and in geostrophic balance the sea surface slopes upward toward the coast, accounting for the winter rise. Sea elevation along the eastern boundary as determined from steric height does not slope uniformly downward from the equator toward higher latitudes but has several maxima and minima. These appear to be the consequence of the sea surface slopes associated with the quasi‐geostrophically balanced system of cyclonic and anticyclonic gyres in middle and high latitudes and zonal flows near the eq

ISSN:0148-0227    

DOI:10.1029/JC081i018p03100

年代:1976

数据来源: WILEY

摘要:

We describe results of a self‐consistent one‐dimensional coupled flow calculation for Ox, NOx, HOx, ClX, H2O, H2, CH4, H2O2, and N2O densities between 10 and 120 km. Our results agree well with observations for the normal mid‐latitude atmosphere over this altitude range. We have varied ClX, NOx, and H2O independently in our model. We show that the effect of depletion of ozone by ClX is to remove ozone preferentially above 30 km and to lower the altitude of maximum ozone density. This leads to enhanced solar heating of the lower stratosphere and tropopause and suggests the possibility of an increased flux of water into the stratosphere. We show that increasing water vapor in the stratosphere greatly enhances the rate of destruction of O3by ClX and also causes an increase in the rate of destruction of O3in the NOx‐perturbed atm

ISSN:0148-0227    

DOI:10.1029/JC081i018p03111

年代:1976

数据来源: WILEY

摘要:

More insight on rare earth element pathways from land to ocean comes from analyses of suspended matter in four major world rivers (Amazon, Congo, Ganges, Mekong), while their geochemical behavior at the river‐ocean boundary has been studied in the Gironde estuary (France). The Gironde data indicate that soluble rare earth elements are removed from solution in the estuarine zone; this observation invalidates any rare earth element balance to the ocean which would not take into account the river‐ocean boundary processes. Data on rare earth element concentrations in soluble and detrital river loads show that solid discharge represents the major part of rare earth elements supplied by rivers to the ocean. A rare earth material balance to the ocean is discussed on the basis of the results presented in this pa

ISSN:0148-0227    

DOI:10.1029/JC081i018p03119

年代:1976

数据来源: WILEY

摘要:

A two‐dimensional dynamic model developed by Louis and Danielsen to study the global scale transport of tracers applied to the investigation of the global scale dispersion of the eruption clouds of Volcán de Fuego (October 1974), Gunung Agung (March 1973), and Bezymianny (March 1956). The strength and chemical composition of source functions were adjusted so that the concentrations and concentration distributions agreed in general with actual measurements, published and unpublished. The resulting agreement with lidar measurements of the stratospheric aerosols is especially encouraging. The results indicate that the Fuego eruption injected no more than one fifth of the mass of material into the stratosphere that was injected by the Agung eruption. Furthermore, an eruption of the size of that of Agung may inject into the stratosphere much greater amounts of chlorine in the form of hydrogen chloride than presently reaches the stratosphere annually as chlorofluoromethanes. As the model is applied to additional eruptions, the adjustments that must be made to the strength and Chemical composition of the eruption cloud so that the model predictions agree with measurements of atmospheric trace constituents resulting from the eruption will furnish important information concerning the very early stages of the eruption cloud that to date has been very difficult to obta

ISSN:0148-0227    

DOI:10.1029/JC081i018p03125

年代:1976

数据来源: WILEY

摘要:

We performed an experiment to test the suggestion that the infrasound radiated by certain severe storms is caused by lightning. During the 1972 storm season we recorded at Boulder, Colorado, the rate and arrival direction of both VLF atmospherics and infrasound from severe thunderstorms in the midwestern United States. If infrasound were caused by lightning, we should have observed a good agreement in direction and time between the radio and acoustic emissions of lightning, within observational uncertainty. Fewer than half of the infrasound events showed such agreement with electromagnetic emissions. Those agreements can be attributed to noncausal coincidence. We argue that the correlation should be much higher if the infrasound emissions were caused by lightning. Some detailed case studies illustrate the differing phenomenologies of the emissions; for example, they show that the infrasound is probably emitted during an earlier stage of storm growth than that usually associated with lightning.

ISSN:0148-0227    

DOI:10.1029/JC081i018p03133

年代:1976

数据来源: WILEY

摘要:

Geological and paleooceanographic data are now sufficiently good that detailed theories of climatic change can be tested. The data Include faunal studies, refined oxygen isotope fractionation studies, and improved analyses of time series in deep‐sea cores. In one theory, Weyl (1968) specifies the role of the oceans in modulating climatic change in great detail. The available evidence largely agrees with the major features of equilibrium glacial circulation suggested by Weyl. The North Atlantic was cold, with a low‐salinity surface layer and cyclonic subarctic gyres. Atlantic Bottom Water probably was warmer than it is at present, most likely due to disruption of the northern formation of Atlantic Deep Water and the resulting inhibition of Antarctic Bottom Water formation. In addition, glacial Pacific Intermediate Water seems to have expanded at the expense of Pacific Deep Water. However, the data indicate that Weyl's model for the inception or the termination of a Glacial Epoch is inadequate. This test shows that patterns of climatic change can be resolved with increasingly greater detail but that ‘first causes’ of climatic change remain

ISSN:0148-0227    

DOI:10.1029/JC081i018p03141

年代:1976

数据来源: WILEY