摘要:

Cosmic‐ray‐produced Be7, P32, P33, and S35radioactivities have been measured in aircraft filter collections made at 20 km over the central United States during 1961 and 1962. Fission products Ba140and Sr90have been measured in the same samples. Observed concentrations of the natural radionuclides were close to the predicted equilibrium levels before the resumption of nuclear weapons tests by the Soviet Union in 1961. Strong evidence of artificial production of P32and S35during the 1961 Soviet tests was found. These nuclides were also produced during the 1962 United States tests, and there is also evidence for the production of Be7and P33during the latter test series. The artificial production can be satisfactorily explained by a consideration of possible target materials in the weapons and of the radiations present in nuclear explosi

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01457

年代:1964

数据来源: WILEY

摘要:

A meteorological analysis of the storm which occurred on February 7, 1962, at Santa Barbara, California, was made in conjunction with radiochemical analysis of precipitation collected continuously at altitudes of sea level, 600 m, and 1200 m. The sampling period included the approach toward the coast and passage of one wave and the approach of a second wave. The three altitudes exhibited similar Sr90deposition patterns. Concentrations ranged from over 100 dpm/l to less than 1 dpm/l, with several changes of more than a factor of 10 within hourly periods. The large variations of Sr00 concentration in the precipitation at the three altitudes may be linked to atmospheric changes during the storm. Such effects as saturation of the lower layers of air, overturning of the marine layer, approaches of the frontal and upper trough zones, vertical growth of the cloud system up to the tropopause, and incursions of high‐level layers of dry air may explain the observed changes in fallout rate during the stor

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01469

年代:1964

数据来源: WILEY

摘要:

The large and rapid changes in kinetic energy and in total potential energy of the lower stratosphere (100 to 25 mb) during the warming of mid‐January to mid‐February, 1957, have been investigated in terms of energy transport and generation processes. These processes are represented by the corresponding terms in the balance equations for kinetic and total potential energy. The terms were evaluated using the 100‐, 50‐, and 25‐mb values of geopotential, temperature, the geostrophic wind components, and adiabatic vertical motion at each point of a grid covering most of the North American continent and the adjacent North Atlantic. A limited atmospheric region was considered, which exchanged energy with the surrounding atmosphere through the vertical boundaries as well as through the upper and lower boundary pressure surfaces. Terms in the kinetic energy budget explicitly involving existing kinetic energy were found to be negligible in comparison with the other terms. Conversion of energy was from kinetic to potential energy throughout most of the period. The contributions to energy changes due to generation of kinetic energy at the upper and lower boundaries and net vertical flux of enthalpy are shown to be qu

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01481

年代:1964

数据来源: WILEY

摘要:

Radar echoes can be converted to digital form by means of a sequence of (x, y) coordinates obtained around the periphery of the echo. Procedures for computing echo areas and centroids from the (x, y) coordinates are presented. Computations are made by a high‐speed computer. Other radar echo characteristics can also be computed and summarize

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01497

年代:1964

数据来源: WILEY

摘要:

The topography along latitude circles for each 5° between the poles has been subjected to harmonic analysis. The amplitude and phase of the first 15 harmonics are presented in tabular form. The first four harmonics are represented on Mercator charts

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01501

年代:1964

数据来源: WILEY

摘要:

A Lower Greensand outcrop forms a ridge of highly variable elevation between Ely and Leighton Buzzard in east‐central England. In an investigation to determine whether measurements of soil shearing resistance could be rationalized sufficiently to partly explain differences in ‘geomorphic resistance,’ the influence of six independent parameters (median grain size, range of grain sizes, percentage of silt and clay sizes, moisture content, dry soil density, and unit dry root weight) on shearing resistance was treated by multiple regression analysis with an electronic computer. Although some interesting reinforcements appeared from combinations of these variables, the six together could account for only 53.2 per cent of the total variation of shearing resistance. Consequently, the influence of other factors must be investigated in order to account for the major topographic variations within this form

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01507

年代:1964

数据来源: WILEY

摘要:

The development of sediment ripples on an initially flat bed in a closed rectangular conduit is analyzed as a stability problem by examining the kinematics of sediment motion. The central steps in the analysis are the use of the potential flow over a moving bed having a sinusoidal form and a time‐varying amplitude to predict the velocity distribution and the introduction of a sediment transport relation in which the local transport rate at any point is proportional to a power of the local velocity a distance δ upstream. The analysis is extended to sediment ripples formed by wind‐driven sand in arid regions by allowing the conduit depth to tend to infinity. Formulas are developed for the length, velocity of movement, and height of sediment ripples. Calculated and measured values of the ripple index are found to agree satisfactorily. The mathematical model suggests an explanation for the flat, rippleless surface that occurs at higher velocities; it also forms the basis for a hypothesis that ripples result from a systematic perturbation of the bed load movement, whereas dunes are initiated by a perturbation of the suspended sediment

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01517

年代:1964

数据来源: WILEY

摘要:

The problem of the water table in equilibrium with the rainfall on sloping land is analyzed by solving Boussinesq's equation. It is assumed that the hillside is drained by parallel ditches which are founded in the impermeable layer. A nomogram is presented for calculating the ditch spacing as a function of rate of replenishment, soil hydraulic conductivity, and maximum height of the water table above the impermeable layer.

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01525

年代:1964

数据来源: WILEY

摘要:

The buildup and decay of a laminar or turbulent flow over a sloping plane is treated by the kinematic‐wave method, neglecting the slope of the water surface relative to the slope of the plane. The relationships developed show certain distinct differences from those postulated in the unit hydrograph method. However, a comparison of the results of calculations with published experimental measurements shows quite good agreement. The problem is extended to include the case of groundwater flow through a porous medium overlying a sloping impermeable stratum, where water is supplied by infiltration from the ground surface above. Here the depth of water may be appreciable, so that the actual slope of the water surface influences the gravity flow significantly, leading to a nonlinear diffusion problem. Solutions of this problem for the buildup and decay phases are compared with those obtained by the kinematic‐wave method, and significant differences are noted for the latter phase. Further, the physical boundary condition at the upper edge of the slope changes at a critical precipitation rate, the depth of water being either finite or zero there depending upon whether the rate is greater than or less than the critical va

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01531

年代:1964

数据来源: WILEY

摘要:

A nonlinear mathematical model, starting with the integral of an infiltration capacity function, is developed to analytically equate the difference between rainfall and runoff to hydrologie variables. Only the three independent variables—storm rainfall, duration, and soil moisture—are used, and an equation is evolved in which the identity of the coefficients is kept intact and unusually good statistical control is maintained. The coefficients of the equation appear to be stable over a range of watershed sizes and conditions. The equation strongly indicates that runoff usually originates from a small, but relatively consistent, part of the watershed. The function can be manipulated to show a ‘function of apparent watershed infiltration capacity’ This function characterizes the infiltration capacity of that portion contributing to runoff, on the average, and should prove to be a useful infiltration capacity index with which watersheds can be compared. The equation itself provides insight into why in situ measurements of infiltration capacity seldom agree with the capacity determined from rainfall‐runoff data. It also indicates why storm runoff frequently is not linear with respect to causativ

ISSN:0148-0227    

DOI:10.1029/JZ069i008p01541

年代:1964

数据来源: WILEY