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- Author or Editor: GLENN W. BRIER x
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Abstract
Recent investigations indicate that the quasi-biennial oscillation (QBO) in stratospheric winds may be related to variations in the tropospheric circulation in middle and high latitudes. Although the QBO was noticed years ago in a number of worldwide atmospheric phenomena, it is still not well understood. A logical question arises as to whether the oscillation might be a result of the annual forcing by the solar heating, since it is well known that in some nonlinear systems subharmonic oscillations can be produced of order one-half the frequency of the exciting force. A conceptual model is presented to show how a two-year oscillation could be produced by a negative feedback process acting on a two-state system, i.e., winter and summer states. Even for a relatively weak biennial oscillation with stochastic elements involved, the results show that rather strong links must exist in the chain or feedback loop, indicating potential predictability for periods of six months or more. Support for the concept is provided by the analysis of monthly mean observations of the 50 mb zonal winds at Balboa (9°N, 80°W) f man September 1950 to October 1976. It is clear that the transitions from an easterly to westerly mode (and vice versa) and the duration of a particular mode are closely related to the annual cycle.
Abstract
Recent investigations indicate that the quasi-biennial oscillation (QBO) in stratospheric winds may be related to variations in the tropospheric circulation in middle and high latitudes. Although the QBO was noticed years ago in a number of worldwide atmospheric phenomena, it is still not well understood. A logical question arises as to whether the oscillation might be a result of the annual forcing by the solar heating, since it is well known that in some nonlinear systems subharmonic oscillations can be produced of order one-half the frequency of the exciting force. A conceptual model is presented to show how a two-year oscillation could be produced by a negative feedback process acting on a two-state system, i.e., winter and summer states. Even for a relatively weak biennial oscillation with stochastic elements involved, the results show that rather strong links must exist in the chain or feedback loop, indicating potential predictability for periods of six months or more. Support for the concept is provided by the analysis of monthly mean observations of the 50 mb zonal winds at Balboa (9°N, 80°W) f man September 1950 to October 1976. It is clear that the transitions from an easterly to westerly mode (and vice versa) and the duration of a particular mode are closely related to the annual cycle.
Abstract
The tendency for the recurrence of weather events on or near the same calendar date has been the subject of controversy for many years. The statistical evidence has been far from conclusive, and no generally acceptable physical explanation of such phenomena, if real, is available. Dr. E. G. Bowen has advanced the meteoritic-dust hypothesis to explain singularities in the number of ice nuclei and in world rainfall amounts. This paper describes a statistical test comparing three independent series of daily rainfall: (1) world rainfall amounts determined from several hundred stations assembled by Bowen for the period 1880 to 1950; (2) average daily precipitation amounts during the period 1952 to 1957 for a network of approximately 150 stations distributed over the United States; and (3) average daily precipitation amounts for the same United States network during the year 1958. A non-parametric test, made possible through, use of an electronic computer, shows a highly significant association among these series. These results lead to the conclusion that there has been a strong tendency for precipitation anomalies (both high and low) to occur on specific calendar dates.
Abstract
The tendency for the recurrence of weather events on or near the same calendar date has been the subject of controversy for many years. The statistical evidence has been far from conclusive, and no generally acceptable physical explanation of such phenomena, if real, is available. Dr. E. G. Bowen has advanced the meteoritic-dust hypothesis to explain singularities in the number of ice nuclei and in world rainfall amounts. This paper describes a statistical test comparing three independent series of daily rainfall: (1) world rainfall amounts determined from several hundred stations assembled by Bowen for the period 1880 to 1950; (2) average daily precipitation amounts during the period 1952 to 1957 for a network of approximately 150 stations distributed over the United States; and (3) average daily precipitation amounts for the same United States network during the year 1958. A non-parametric test, made possible through, use of an electronic computer, shows a highly significant association among these series. These results lead to the conclusion that there has been a strong tendency for precipitation anomalies (both high and low) to occur on specific calendar dates.
Abstract
Recently published data on the average hourly rates of visual meteors for each night of the year have been compared with the average daily precipitation of a number of stations for a 50-year period. No significant relation was found between meteor showers and precipitation although there was a very slight suggestion of a maximum in precipitation around 30 days after peak meteor activity.
Abstract
Recently published data on the average hourly rates of visual meteors for each night of the year have been compared with the average daily precipitation of a number of stations for a 50-year period. No significant relation was found between meteor showers and precipitation although there was a very slight suggestion of a maximum in precipitation around 30 days after peak meteor activity.
Abstract
Developments in the statistical theory of turbulence during the past thirty years have been used by a number of investigators studying the problem of eddy diffusion. Taylor has derived a formula for the diffusion of particles from a point source. This formula and its extension by Sutton make use of a Lagrangian correlation coefficient Rξ defined as the correlation between the velocity of a fluid particle at any instant and that of the same particle after a time interval ξ. A more general formula that takes account of the initial distance between the particles is presented here and it is shown that the Taylor formula can be derived as a special case of this formula.
An experiment is described where modern radar equipment was used to measure the scatter of a cluster of balloons released simultaneously in the free atmosphere. Questions are raised as to the usefulness of balloon data in obtaining estimates of the rate of diffusion, due to such factors as variable ascension rates of balloons, the change of wind speed and direction with height, and the failure of large balloons to respond to smaller-scale eddies that might contribute considerably to the diffusion of small particles such as smoke.
Abstract
Developments in the statistical theory of turbulence during the past thirty years have been used by a number of investigators studying the problem of eddy diffusion. Taylor has derived a formula for the diffusion of particles from a point source. This formula and its extension by Sutton make use of a Lagrangian correlation coefficient Rξ defined as the correlation between the velocity of a fluid particle at any instant and that of the same particle after a time interval ξ. A more general formula that takes account of the initial distance between the particles is presented here and it is shown that the Taylor formula can be derived as a special case of this formula.
An experiment is described where modern radar equipment was used to measure the scatter of a cluster of balloons released simultaneously in the free atmosphere. Questions are raised as to the usefulness of balloon data in obtaining estimates of the rate of diffusion, due to such factors as variable ascension rates of balloons, the change of wind speed and direction with height, and the failure of large balloons to respond to smaller-scale eddies that might contribute considerably to the diffusion of small particles such as smoke.
Abstract
Evidence is presented that precipitation variations in the United States are related to the solar and lunar tidal forces. The results of the statistical investigation are consistent with a mathematical model that shows how a small periodic influence can be of possible importance for the timing of an event such as the initiation of precipitation.
Abstract
Evidence is presented that precipitation variations in the United States are related to the solar and lunar tidal forces. The results of the statistical investigation are consistent with a mathematical model that shows how a small periodic influence can be of possible importance for the timing of an event such as the initiation of precipitation.
Abstract
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Abstract
Superposed epoch analyses, based on solar sector boundary crossings as key times and the Vorticity Area Index as the response variable, are tested for significance using both parametric and randomization techniques. We conclude from a comparison of these techniques that the randomization procedure leads to markedly different results from those obtained from parametric tests. In particular, the results are strongly affected by the modest skewness of the Vorticity Area Index distribution.
Abstract
Superposed epoch analyses, based on solar sector boundary crossings as key times and the Vorticity Area Index as the response variable, are tested for significance using both parametric and randomization techniques. We conclude from a comparison of these techniques that the randomization procedure leads to markedly different results from those obtained from parametric tests. In particular, the results are strongly affected by the modest skewness of the Vorticity Area Index distribution.
Abstract
Plans are underway to attempt to reduce the destructive force of hurricanes by artificially modifying their structure by means of cloud seeding. Since the natural variability of meteorological elements observed in hurricanes is high, the success of the project depends upon establishing a cause and effect relationship between the seeding and the hurricane's response. The small sample of mature hurricanes coupled with rigorous selection criteria make a randomized experiment impractical. Therefore, an evaluation technique based on the concept of randomization in time is developed.
Abstract
Plans are underway to attempt to reduce the destructive force of hurricanes by artificially modifying their structure by means of cloud seeding. Since the natural variability of meteorological elements observed in hurricanes is high, the success of the project depends upon establishing a cause and effect relationship between the seeding and the hurricane's response. The small sample of mature hurricanes coupled with rigorous selection criteria make a randomized experiment impractical. Therefore, an evaluation technique based on the concept of randomization in time is developed.
Abstract
A cycle of 14.765 days, one-half of the lunar synodic month, can be demonstrated in the precipitation data for the United States for the period 1871–1961. Numerous rigorous statistical tests show that association is real and an estimate is obtained of the magnitude of the lunar effect. Geographical, seasonal and other sources of variation in the effect are suggested by the data. No other periodicity with comparable amplitude was found by the statistical analysis, but there is evidence that the lunar synodic cycle interacts with the nodical cycle.
Abstract
A cycle of 14.765 days, one-half of the lunar synodic month, can be demonstrated in the precipitation data for the United States for the period 1871–1961. Numerous rigorous statistical tests show that association is real and an estimate is obtained of the magnitude of the lunar effect. Geographical, seasonal and other sources of variation in the effect are suggested by the data. No other periodicity with comparable amplitude was found by the statistical analysis, but there is evidence that the lunar synodic cycle interacts with the nodical cycle.
