Showing papers on "Precipitation published in 1969"
TL;DR: In this paper, the conservation and distribution of water substance in atmospheric circulations are considered within a frame of continuity principles, model air flows, and models of microphysical processes, where the simplest considerations of precipitation involve its vertical distribution in an updraft column, where condensate appears immediately as precipitation with uniform terminal fallspeed.
Abstract: The conservation and distribution of water substance in atmospheric circulations is considered within a frame of continuity principles, model air flows, and models of microphysical processes. The simplest considerations of precipitation involve its vertical distribution in an updraft column, where condensate appears immediately as precipitation with uniform terminal fallspeed. The study also treats steady two-dimensional air circulations in which time-dependent distributions of water vapor, cloud and precipitation respond to model microphysical processes.
1,572 citations
216 citations
TL;DR: In this article, the residence time of the fluoride ion in sea water is calculated from its sedimentation rate to be a few million years, similar to that of calcium, and it is shown that calcium carbonate precipitation dominates the removal of dissolved fluoride from sea water, with incorporation into calcium phosphates apparently the next most important removal mechanism.
140 citations
TL;DR: In this article, the effects of precipitation on a model of cumulus cloud initiation and development over mountains are studied by numerically integrating the equations of motion, equations of conservation of water substance, and the thermodynamic energy equation.
Abstract: The effects of precipitation on a model of cumulus cloud initiation and development over mountains are studied by numerically integrating the equations of motion, equations of conservation of water substance, and the thermodynamic energy equation. The model is two-space dimensional with a vertical wind shear in a stable, incompressible atmosphere. Heating and evaporation at the valley and mountain interact with the initial ambient flow to initiate clouds which produce shadows on the surface and cut down both heating and evaporation. The model is restricted vertically to 3.5 km and horizontally to 7.0 km. Several precipitation parameters are studied in this model. One, the critical water content determines when cloud water converts to rainwater. A second, the autoconversion rate, determines how rapidly the cloud water converts to rainwater. The third parameter determines how quickly the precipitation evaporates beneath the cloud. The rainwater first forms by autoconversion and is then increased by...
127 citations
TL;DR: In this article, the authors used statistical correlation methods to define sampling requirements for precipitation measurement networks and found that a minimum acceptance of 75% explained variance between sampling points is needed for 1-min rain rates compared with 7.5 mi for total storm rainfall in summer storms.
Abstract: One approach to defining sampling requirements for precipitation measurement networks is through statistical correlation methods. Data from three dense raingage networks in Illinois were used with this method on rainfall measurements ranging from 1-min rates to total storm, monthly and seasonal amounts. Effects of rain type, synoptic storm type, and other factors on spatial correlations were studied. Correlation decay with distance, used to indicate sampling requirements, was greatest in thunderstorms, rainshowers and air mass storms. Conversely, minimum decay occurred with steady rain and the passage of low pressure centers. Seasonally, the decay rate is much greater in May–September storms than in cold season precipitation. Sampling requirements are extreme in measuring rainfall rates; thus, assuming a minimum acceptance of 75% explained variance between sampling points, a gage spacing of 0.3 mi is needed for 1-min rain rates compared with 7.5 mi for total storm rainfall in summer storms.
102 citations
TL;DR: In this article, the frequency of occurrence of freezing precipitation was used to obtain a simple index of this hazard and the statistical distributions of the estimated annual extremes of ice-storm accretion and of contingent strong winds were examined, but the results are somewhat speculative because of the short duration of the period of analysis and the lack of confirming observations.
Abstract: Ice storms are a major hazard which must be considered in structural design in all parts of Canada. The frequencies of occurrence of freezing precipitation are used to obtain a simple index of this hazard. To obtain more quantitative estimates, the total amounts of freezing precipitation in each storm are considered. Since recording gages rarely operate during these storms, the amounts are estimated from hourly weather reports and 6-hr precipitation measurements. The statistical distributions of the estimated annual extremes of ice-storm accretion and of contingent strong winds are examined, but the results are somewhat speculative because of the short duration of the period of analysis and the lack of confirming observations.
69 citations
TL;DR: In this article, the isotopic exchange between ice and water is found to take place in temperate glaciers and the exchange causes homogenization of deuterium in snow during summer thaw, together with a general increase in deutetium concentration.
58 citations
TL;DR: Low energy electron precipitation data at northern high latitudes obtained from satellite low altitude polar orbit was used in this article to estimate the amount of precipitation at high altitude in northern high latitude regions.
Abstract: Low energy electron precipitation data at northern high latitudes obtained from satellite low altitude polar orbit
58 citations
TL;DR: A review of recent research in the United States concerning urban effects on precipitation has revealed that relatively few studies have been performed as discussed by the authors, and the difficulties associated with separating orographic, maritime, and gage-exposure effects are the primary reasons for so little research.
Abstract: A review of recent research in the United States concerning urban effects on precipitation has revealed that relatively few studies have been performed. The lack of densely spaced precipitation stations with good historical records, inadequate instruments for airborne measurements of the mechanisms that affect precipitation systems, and the difficulties associated with separating orographic, maritime, and gage-exposure effects are the primary reasons for so little research. However, certain climatological studies of four variously sized cities in the midwest and two large cities in the east have shown apparent urban-produced increases ranging from 5 to 16% in annual precipitation and rain days, with 7 to 20% increases in summer thunderstorm days. Substantially greater increases in precipitation, thunderstorms, and hailfalls, 31 to 246%, have been shown in a recent study of an area downwind from a major steel mill complex. The available results show little evidence of urban effects on the occurrence of exc...
53 citations
TL;DR: In this paper, a simple theoretical analysis of the effect of the wind in and near the melting layer was presented, and it was shown that the perturbations propagate with the velocity of the precipitation generators and their magnitude increases with the precipitation rate.
Abstract: Doppler radar observations during widespread frontal precipitation in England on 20 February 1967 show significant perturbations of the wind in and near the melting layer. The analysis suggests the following hypotheses: (i) Mesoscale oscillations of the wind near the melting layer are produced by pressure perturbations due to horizontal variations in cooling by melting snow associated with the precipitation pattern. A simple theoretical analysis of the effect is presented. In simple patterns, the perturbed wind has a maximum on the low pressure side of the rainfall. The perturbations propagate with the velocity of the precipitation generators and their magnitude increases with the precipitation rate. This hypothesis is in accord with the finding that the oscillation in the tangential wind across hurricane rain bands is generally a maximum on the low pressure side of the bands. (ii) Smaller scale wind perturbations were also observed in the melting layer with scale of a few kilometers comparable to those reported by Harrold and Browning (1967). However, unlike their observations, these perturbations did not appear to move with the melting layer winds. A tentative suggestion is made that these may represent wave motions.
53 citations
TL;DR: The effect of the Chicago industrial complex on precipitation, reported by Changnon, showed itself mainly in changes in other variables, but was apparently evident also in total precipitation readings as discussed by the authors.
Abstract: Port Kembla steelworks, on the New South Wales coast, produced 3.6 million tons of steel in 1967. Relative to background, its output of freezing nuclei (at −15.8C) is probably negligible, but its output of condensation nuclei is high, and the outputs of heat and water vapor are appreciable. There are about 90 rainfall stations within 100 km of the plant which were operating 15 years before steelmaking began. When other extraneous effects are allowed for, their records show probably no influence of the steelworks greater than 5% on total rainfall, summer rain (when onshore winds predominate), or light rain. The effect of the Chicago industrial complex on precipitation, reported by Changnon, showed itself mainly in changes in other variables, but was apparently evident also in changes in total precipitation readings. It is shown that the dates and nature of the changes in this variable make the industrial effect an unlikely explanation.
TL;DR: In this article, a study has been made of the climatological characteristics of storm precipitation on a point and areal basis through the use of two sets of data, one is from a 12-year operation of a dense raingage network on 400 mi2 in central Illinois, and the other is the long-term point rainfall records of daily precipitation from U. S. Weather Bureau climatic stations throughout the state.
Abstract: A study has been made of the climatological characteristics of storm precipitation on a point and areal basis through the use of two sets of data. One is from a 12-year operation of a dense raingage network on 400 mi2 in central Illinois, and the other is the long-term point rainfall records of daily precipitation from U. S. Weather Bureau climatic stations throughout the state. The detailed network data were used to investigate effects of storm intensity and duration, precipitation type, synoptic weather type, wet and dry periods, and other factors upon storm distribution characteristics. Frequency distributions of both rainfall depth and number of storms were determined for various classifications, and these distributions were evaluated with respect to implications in weather modification during the critical growing season (May-September) and the water-supply replenishment period (October-April). Nomograms were developed from the climatological distributions to facilitate the evaluations. By re...
TL;DR: The importance of determining a relationship between deposited fallout, airborne concentration and rainfall is discussed in this paper, where the methods of collection are described, and the relationship between deposited fallout and rainfall at Pretoria is examined.
TL;DR: In this article, Li et al. showed that high moisture stress during the spring is shown by the low ratios of actual evapotranspiration ( ET ) to potential evapOTranspiration( PE ), together with low preseasonal soil moisture storage, is responsible for spring drought.
TL;DR: Coherence and partial coherence between cyclic components of hydrologic time series show strong correlations among annual oscillations in precipitation and runoff for stations located in the Pacific Coast region of the United States as discussed by the authors.
Abstract: Coherence and partial coherence between cyclic components of hydrologic time series show strong correlations among annual oscillations in precipitation and runoff for stations located in the Pacific Coast region of the United States. To distances of 1000 km the annual cycle of precipitation can be considered practically the same for all stations. Similar relations exist between records of streamflow, but the coherence is less because of variable watershed characteristics, evaporation, storage, and other factors influencing runoff.
31 Dec 1969
TL;DR: In this article, a detailed reconstruction of the flooding of a low-relief delta system can be made, with emphasis on the global warming after the glacial event Mi1a.
Abstract: Lower Miocene strata from boreholes and, in particular, at outcrops in the Lillebaelt and Limfjorden areas of Jylland provide a natural laboratory for studying the drowning of a major delta system during a period of global warming. Detailed studies of sedimentary structures, fossil algae, spores and pollen give information about depositional environments, local temperatures and precipitation. By comparing with the global climatic record from the same period, a detailed reconstruction of the flooding of a low-relief delta system can be made, with emphasis on the global warming after the glacial event Mi1a. The local temperature increase following the Mi1a event is estimated to be c. 5°C.
TL;DR: In this paper, an account of precipitation measurements on small, flat, cultivated areas carried out between 1957 and 1960 by means of very dense networks of precipitation stations was given, where precipitation distributions on single rainfalls were found to vary within large ranges.
Abstract: An account is given of precipitation measurements on small, flat, cultivated areas carried out between 1957 and 1960 by means of very dense networks of precipitation stations. The precipitation distributions on single rainfalls were found to vary within large ranges. Clear distribution patterns appeared in the precipitation not only when the precipitation fell from convective clouds but also after frontal precipitation with almost no convection. The results from occasions with almost no convection indicated a close connection between the direction of the wind and the precipitation distribution. Within the investigation area the precipitation increased along the direction of the wind. When considering accumulated precipitation amounts the percentage variations were considerably lower than those which might occur on single rainfalls. DOI: 10.1111/j.2153-3490.1969.tb00475.x
01 Sep 1969
TL;DR: In this article, the atmospheric water balance and precipitation regime of a moving cyclone are described and a technique based on the conservation of equivalent potential temperature is described to determine the flow of mass and moisture within the storm system.
Abstract: The atmospheric water balance and precipitation regime of a moving cyclone are described. The coordinate system chosen is one that moves with the traveling storm system. The computation of the atmospheric water balance is done to yield the parameter precipitation minus evaporation as a residual. Good agreement is found between the water balance result and gauge data for three twelve-hour periods. A technique, based on the conservation of equivalent potential temperature, to determine the flow of mass and moisture within the storm system is described. The results show that the cyclone studied changed in structure from a statically unstable to a stable system over 36 hours. The distribution of rate of condensation as a function of cloud temperature is determined and a distinct change in character of this parameter is noted as the storm structure is altered.
01 Jan 1969
TL;DR: In this paper, the authors used time distribution models of Storm Rainfall to compare point and areal Storm Durations and concluded that the results showed that the distribution of storm rainfall varied with the type of rain and storm type.
Abstract: 2 INTRODUCTION 3 Data Used in Studies 3 Approach to Problem 4 Representativeness of 29-Storm Sample 7 PART I. TIME DISTRIBUTION STUDIES TIME DISTRIBUTION MODELS OF STORM RAINFALL 12 Previous Research 12 Rainfall Rate Distributions 13 Time Distribution Models 13 Conclusions 20 SEQUENTIAL VARIABILITY 22 Approach to Problem 22 Results of Analyses 23 Effects of Rain and Storm Type 28 Summary and Conclusions 29 LAG CORRELATION ANALYSES 30 Analytical Results 30 Conclusions 35 STORM RAINFALL DISTRIBUTION RELATIONS 35 Relation Between Mean Rainfall Rate and Total Storm Rainfall 35 Percentage Distribution of Storm Rainfall 37 Comparison of Point and Areal Storm Durations 41 PART II. SPACE DISTRIBUTION STUDIES ONE-MINUTE RAINFALL RATE SPATIAL CORRELATIONS 44 Analytical Procedures 44 Analytical Results 44 Conclusions 51
TL;DR: The authors found that 8-inch standard rain gages consistently catch more precipitation in summer and less in winter than adjacent digital punch gages although average annual totals were almost identical in northern Ohio.
Abstract: In northern Ohio 8-inch standard rain gages consistently caught more precipitation in summer and less in winter than adjacent digital punch gages although average annual totals were almost identical. A similar seasonal pattern was found in a comparison of precipitation catch by weighing lysimeters and adjacent weighing type recording rain gages in Ohio and in a comparison of standard and recording rain gage catch in Nebraska. Some reasons for the differences in their implications are discussed.
01 Jan 1969
01 Mar 1969
TL;DR: In this article, it was shown that for convective storms, a properly instrumented 10 cm radar can provide more accurate measurements of rainfall over an area than can a network of gauges, and that a wave length as short as 3 cm is unsatisfactory for measuring precipitation because of attenuation.
Abstract: : The report contains two major sections. In the first, consideration is given to the accuracy and practicality of measuring surface precipitation by radar. The second summarizes studies which have been made regarding mesoscale precipitation patterns and their relation to larger-scale circulations. It is concluded that for convective storms a properly instrumented 10-cm radar can provide more accurate measurements of rainfall over an area than can a network of gauges. A wave length as short as 3 cm is shown to be unsatisfactory for measuring precipitation because of attenuation. In widespread storms appreciable errors, occasionally a factor of two or three, may result from differences between the precipitation in the volume sampled by the radar and that reaching the surface. Observations of such effects are presented and discussed. Advantages and liabilities both of the radar and of a network of gauges for measuring precipitation over an area are illustrated by experiments in which simultaneous measurements by the two methods are compared. The second section of this report presents detailed descriptions of the structure and behavior of mesoscale precipitation areas and convective cells both in extratropical cyclones and in thunderstorm complexes. These descriptions will serve as a basis for physical and numerical studies of mesoscale phenomena.
TL;DR: In this paper, the authors investigated the potential of various meteorological factors for representing the more variable insolation reductions in the tropical atmosphere, and developed curves and formulas for those relationships which appeared to be effective.
Abstract: The goals of this study were to investigate the potential of various meteorological factors for representing the more variable insolation reductions in the tropical atmosphere, and to develop curves and formulas for those relationships which appeared to be effective. Emphasis was placed on developing approaches that depend on simple meteorological entries. The following were studied in relation to the average daily atmospheric transmission ratio (insolation recorded at the earth's surface divided by the computed insolation on a horizontal surface at the top of theatmosphere) on a monthly basis using four years of Canton Island data and considering only hours between sunrise and sunset: average total opaque sky cover, average total sky cover, average daily duration (in minutes) of precipitation, average daily amount (in inches) of precipitation and fraction of days with precipitation. Also, the average daily amount of precipitation and fraction of days with precipitation were studied on an annual ...