摘要:

The stratosphere above McMurdo Station, Antarctica (77°53′S, 166°44′E), as determined from the first systematic meteorological rocket probes on that continent, is described briefly. These probes were made with Areas rockets equipped with modified AN/AMT‐4 transmitters and associated temperature‐sensing and calibration instrumentation. Winds were determined by a triangulation procedure in which two ground meteorological detector systems were used. The data, taken from early winter through early summer, 1962, demonstrate the slow, then rapid, buildup of the wintertime westerlies, their subsequent destruction, and the accompanying stratospheric warming. A strong reversal of the meridional winds is evident at the time of the warming, and the wintertime westerlies are replaced by weak and erratic easterlies. These easterlies appear to begin at the top and descend through the stratosphere. There is no indication that the wintertime circulation is disrupted by a period of stormy, erratic winds, as occurs in the northern h

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00749

年代:1965

数据来源: WILEY

摘要:

Investigation of planetary‐scale pressure fields in mid‐troposphere before, during, and after the occurrence of four midwinter polar stratospheric warmings has been made. Similar investigation has been made in four winters during which no such warming occurred. Wide‐spread high‐latitude height rises of the 500‐mb surface were found during the course of the warming. Winters without such stratospheric events were not always free of such height increases at high latitudes, but these were restricted to narrow longitude bands and did not persist through the period of interest. Zonal kinetic energies from 40°N to 80°N at 500 mb were calculated. In winters when warming events occurred, the stratospheric meridional temperature gradient reversed sense in early February. At that time, consistently less mid‐tropospheric zonal kinetic energy was present than in winters when no stratospheric warming occurred. Before the onset of the period when stratospheric warmings tend to occur, the parameter distinguishing the two sets of winters was the phase velocity of wave number 1 in high latitudes. During the initial phases of the warmings, the movement of this wave number changed from an eastward to a westward direction in all four winters. The results, although solely statistical, suggest that the troposphere is participating in the energetics of the stratosph

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00757

年代:1965

数据来源: WILEY

摘要:

The Lagrangian eddy frictional force for mean motion in the atmosphere is defined and evaluated. The average magnitude of the Lagrangian eddy frictional force is found to be at least as significant as the magnitude of the average acceleration term. Analyses of the eddy frictional force following balloon trajectories in planetary waves in the upper troposphere show that a predominantly cyclonic rotation of the force occurs in all parts of waves of various amplitudes and phase speeds. It is found that this force seems to resist the motion of the balloon in the vicinity of the ridge line regardless of the balloon's position with respect to the jet stream core. As the balloon moves from the ridge toward the trough, it rotates cyclonically from the upstream direction. By the time the balloon reaches the inflection point of the wave, the force vector rotates to a direction predominantly normal to the direction of motion and toward lower pressure. It is also found that the tangential component of the Lagrangian eddy frictional force is of the same order of magnitude as the tangential component of the pressure force.

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00769

年代:1965

数据来源: WILEY

摘要:

The correlation between polar conductivity and the concentration of atmospheric small ions with mobilities higher than 10−4m2v−1sec−1has been investigated by means of a Gerdien conductivity meter. The apparatus has been operated in Socorro at an elevation of 4620 ft and at 10,640 ft on a nearby mountaintop at the Langmuir Laboratory. The correlation coefficient between conductivity and concentration is higher than 0.97 for positive as well as for negative ions at both locations. A least‐squares analysis of the results of measurement furthermore shows that the conductivity is proportional to the concentration of small ions. The over‐all average mobility has been found to be 1.6×10−4m2v−1sec−1for small positive ions and 2.0×10−4m2v−1sec−1for small negative ions. The average fair‐weather negative and positive conductivities on the campus and the negative conductivity at the Langmuir Laboratory are essentially the same, having a value of 1.4×10−14(ohm‐m)−1. The average positive conductivity at the mountain site is 3.2 times the other values. This is attributed to the higher atmospheric electric field, wit

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00779

年代:1965

数据来源: WILEY

摘要:

Both estimated and measured values of net radiation over several different surfaces established the retention of approximately two‐thirds of the sunlight as net radiation for stations at low elevations in Hawaii. This high retention of sunlight was a consequence of both low reflectance and a very low heating coefficient (change of long‐wave net radiation with change in total net radiation). The persistent high elevation of the sun and the efficient convective heat sink formed by the maritime air helped to account for this large retention of sunlight as net radiation. The mineralogic composition of the soil and the leaf habit of the vegetative cover contributed to the low reflectance from these surfaces. Since this net radiation can be used to heat the soil, plants, and air, and to evaporate water, the heat and moisture budgets of a surface in the maritime tropics may differ markedly from those of a surface in the temperate latitudes under similar solar radiat

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00785

年代:1965

数据来源: WILEY

摘要:

Temperate latitudinal expressions such as the Dalton and Penman formulations predict class A pan evaporation though certain of the constants seemed unique for the tropics. Air temperature alone was not a sensitive index of evaporation. The winter rate of pan evaporation supports the contention that a large fraction of sunlight is converted to net radiation. The seasonal shift in the fraction of sunlight used for pan evaporation responded to the seasonal shift in net radiation, but also included was the effect of strong positive advection of heat from the surroundings, particularly in the summer. Pineapple planted upwind from the pan served as a dry fetch. Evaporation measured by atmometer followed conventional patterns, with the black Bellani plate as the best index of sunlight and pan evaporation.

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00795

年代:1965

数据来源: WILEY

摘要:

The relation between present weather and concurrent daily 700‐mb circulation is studied for the winter season in the United States. All weather data are averaged within 40 climatologically homogeneous circles and expressed as a numerical index giving the proportion of precipitation or cloudiness within each circle at map time. The synoptic climatology of the resulting weather index is analyzed, and schematic models are constructed showing preferred parts of the 700‐mb contour pattern for general precipitation or clear skies in different parts of the country. By means of the screening method of multiple regression, specification equations are derived for each circle, giving the weather index as a linear function of selected 700‐mb heights located over North America or adjacent oceans. On the average, about 36% of the variance of the weather index is explained by five heights, but there is considerable geographical variation. Similar equations are derived to specify the occurrence or nonoccurrence of precipitation within a 24‐hour period. Both sets of equations are tested by applying them to 36‐hour baroclinic prognostic heights prepared in the National Meteorological Center during the past two winters. The resulting objective forecasts of weather and precipitation are consistently better than persistence, but they are not quite as good as predictions made by experienced fo

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00801

年代:1965

数据来源: WILEY

摘要:

The phenomenon of blocking in stratified inviscid flows over an obstacle is characterized by the occurrence of stagnant zones separated from the flow region by lines of velocity discontinuity. The stagnant zone occurs in front of and is caused by the obstacle. In this paper, it is shown that the mathematical solution for flows with a stagnant layer involves the solution of a free streamline problem, the free streamline being the line of velocity discontinuity. An inverse method is used to obtain an exact solution to the problem. The parameter governing the flow is a modified Froude number. It is found that at low Froude number, the height of the stagnant zone is the same as the height of the obstacle, but as the Froude number increases, the stagnant zones have been found to decrease for wedge‐shaped obstacles. Large‐amplitude lee waves behind the obtacle are also found, as well as downstream edd

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00815

年代:1965

数据来源: WILEY

摘要:

The anomalous groundwater mound and resulting flow regime associated with the Aardvark underground nuclear explosion have been examined. The initial anomalous groundwater mound was estimated to be about 200 m high and 250 m in radius with a central depression. The major mechanism for mound development was probably compaction of nearly saturated rock surrounding the explosion. Results of the calculations indicate that water first flowed into the collapsed zone, then radially outward with early velocities approximately 200 times preshot flow velocities. After about 400 days the magnitude of the anomalous flow had declined to or below the magnitude of the preshot groundwater flow rates. Ideally ‘traced tagged’ water particles initially near the edge of the collapsed zone are estimated to have moved outward about 6.2 m during the first 100 days after the explosion. It is shown that the anomalous mound does not significantly increase the migration of radionuclides from this explosion environm

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00823

年代:1965

数据来源: WILEY

摘要:

The drainage of deep anisotropic soil layers is investigated by an approximate method, similar to that adopted previously for isotropic soils. The main approximation of the flow system is the linearization of the boundary condition on the free surface. The problem is transferred from the anisotropic medium to an isotropic one. In the transformation the drain shape becomes elliptic. The potential distribution and the movement of the free surface caused by recharge are determined by conformal mapping. The mathematical problem is reduced to the solution of a Volterra integral equation of the first kind, which is evaluated numerically. The results are presented in tables and graphs.

ISSN:0148-0227    

DOI:10.1029/JZ070i004p00837

年代:1965

数据来源: WILEY