scispace - formally typeset
Search or ask a question

Showing papers on "Precipitation published in 1978"


Journal ArticleDOI
TL;DR: In this article, a model for nonconvective condensation processes is developed, which allows condensation to begin before relative humidity reaches 100% and the liquid water content of clouds is a prognostic variable of the model.
Abstract: A model for non-convective condensation processes has been developed. The model allows condensation to begin before relative humidity reaches 100%. The liquid water content of clouds is a prognostic variable of the model. The rate of condensation is a function of relative humidity and moisture flux convergence. The micro-physical processes involved in the formation of clouds and precipitation are parameterized by assuming that the rate of precipitation formation is a function of the amount of cloud water. Evaporation from falling rain is taken into account. Quantitative tests with the model indicated that it yields reasonable evolution times and water content of clouds, and gives reasonable precipitation amounts.

505 citations


Journal ArticleDOI
TL;DR: In this paper, the cumulative distribution function for normalized annual precipitation is derived in terms of two parameters of the storm sequence, the mean number of storms per year and the order of the gamma distribution.
Abstract: Point precipitation is represented by Poisson arrivals of rectangular intensity pulses that have random depth and duration. By assuming the storm depths to be independent and identically gamma distributed, the cumulative distribution function for normalized annual precipitation is derived in terms of two parameters of the storm sequence, the mean number of storms per year and the order of the gamma distribution. In comparison with long-term observations in a subhumid and an arid climate it is demonstrated that when working with only 5 years of storm observations this method tends to improve the estimate of the variance of the distribution of the normalized annual values over that obtained by conventional hydrologic methods which utilize only the observed annual totals.

354 citations


Journal ArticleDOI
TL;DR: In this article, dry deposition and removal in precipitation of SO2 and of paniculate sulphate are considered in turn, and a simplified model suggests that about a half of the SO2 emitted to the atmosphere is removed by dry deposition, the remainder is oxidised to sulphate and removed in precipitation and the atmospheric residence time is about 5 days for sulphur.

238 citations


Journal ArticleDOI
01 Feb 1978-Tellus A
TL;DR: In this paper, the authors present results of experiments on the collection efficiency of collectors, preservation of samples, monthly variation of wet and dry deposition, sample storage, length of sampling period, choice of collector location and sources of variability in precipitation data.
Abstract: This paper is one of a series of publications on the collection and chemical analysis of precipitation. While the first paper presented the results from an intercalibration of 10 different designs of precipitation collectors (Galloway and Likens, 1976), this paper presents results of experiments on the collection efficiency of collectors, preservation of samples, monthly variation of wet and dry deposition, sample storage, length of sampling period, choice of collector location and sources of variability in precipitation data. The primary conclusions are that dry fallout should usually be excluded from rain and snow samples, sampling should be on an event basis, all biocides tested have some detrimental effect on sample composition, and that the major sources of variability in precipitation data are due to sampling errors and choice of collector location. DOI: 10.1111/j.2153-3490.1978.tb00819.x

188 citations


Journal ArticleDOI
TL;DR: Paleoecological and paleogeographical evidence is used to mold a framework from which the basic parameters of the late Quaternary glacial-age climate of tropical Australasia can be inferred.

184 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the current understanding of the organization and structure of clouds and precipitation in extra-tropical cyclonic storms and classified them into five types: warm-frontal, warm-sector, coldfrontal (wide and narrow), prefrontal cold-surge, and postfrontal bands.
Abstract: Our current understanding of the organization and structure of clouds and precipitation in extra-tropical cyclonic storms is reviewed. The regions of relatively heavy precipitation are organized into large mesoscale (∼ 10³–104 km²) rainbands which are classified into five types: warm-frontal, warm-sector, cold-frontal (wide and narrow), prefrontal cold-surge, and postfrontal bands. The rainbands themselves are composed of smaller mesoscale areas (∼ 10–10² km²) or ‘cores’ of precipitation. In some of the rainbands the precipitation cores often originate in higher-level generating cells, probably produced by the lifting of potentially unstable air. The generating cells provide ‘seed’ ice crystals, which grow by aggregation and riming as they fall through lower cloud layers produced by large mesoscale or synoptic scale lifting of the air. In these cases the rainbands move with the velocity of the upper-level winds at the levels of the generating cells and therefore tend to move through the cyclonic storm. Other rainbands have their origins in lower-level convection. For example, narrow cold-frontal bands are fed by moisture from a low-level, southerly jet of air which the cold front progressively overtakes. The narrow cold-frontal band is therefore anchored to the cold front. Appreciable precipitation on the mesoscale in cyclonic storms is invariably associated with high concentrations (∼ 1–100 1−1) of ice particles. Small hills may play an important role in triggering or enhancing mesoscale rainbands in cyclonic storms in regions where the air is unstable. The precipitation over and downwind of large mountain barriers, on the other hand, may be disrupted because the orography interferes with the low-level, southerly flow of air which provides the front with its principal source of moisture.

167 citations


Journal ArticleDOI
TL;DR: In this article, a water balance model for climate-soil-vegetation systems is proposed to express the natural water balance in terms of the average annual values of precipitation, evapotranspiration, surface runoff, and groundwater runoff.
Abstract: Mass conservation is employed to express the natural water balance of climate-soil-vegetation systems in terms of the average annual values of precipitation, evapotranspiration, surface runoff, and groundwater runoff as derived from the probability distributions of storm properties and from the physics of the appropriate storm and interstorm soil moisture fluxes. The resulting conservation equation is used to define the dimensionless parameters governing the dynamic similarity of the annual water balance. An asymptotic analysis of this water balance equation yields a set of rational criteria for the classification of climate-soil-vegetation systems. Sensitivity with respect to the primary climate, soil, and vegetal parameters demonstrates that qualitative changes in water balance behavior are primarily dependent upon the exfiltration effectiveness of the soil. A natural selection hypothesis is presented which specifies the stable vegetation density and the plant coefficient for a given climate-soil system in which water and not nutrition or light is limiting.

140 citations


Journal ArticleDOI
TL;DR: In this paper, the sulfate concentration of precipitation is predicted to be directly proportional to sulfate concentrations of the air ingested into the cloud and inversely proportional to cloud water concentration, and the removal of airborne sulfate by precipitation is strongly dependent upon the mechanism of precipitation formation.
Abstract: The concentration of sulfate in precipitation is predicted to be directly proportional to the sulfate concentration of the air ingested into the cloud and inversely proportional to cloud water concentration. In addition, for light to moderate precipitation rates, the removal of airborne sulfate by precipitation is forecast to be strongly dependent upon the mechanism of precipitation formation. If the precipitation is in the form of snow or originated as snow in the upper portions of the clouds, then the surface sulfate concentration of precipitation is proportional to R−0.3, where R is the precipitation rate. Should the precipitation form without the benefit of an initial ice growth stage, then the sulfate concentrations in precipitation water can increase by a factor of 2 to 10 or more over the ice-dependent predictions. Limited surface observations give support to these predictions. The analyses leading to the prediction of washout ratios are also used to forecast the mean oxidation rate of SO2...

113 citations


Journal ArticleDOI
TL;DR: In this article, the phase and normalized amplitude of the diurnal variations in convective activity and precipitation during phases II and III of GATE were determined using harmonic analysis, and the longterm representativeness of the results for the land areas was judged by comparing them with the results obtained from analysis of data presented by Burpee (1976) on the frequencies of occurrence of thunder, moderate to heavy precipitation and light precipitation during the period June-September 1966-69.
Abstract: Harmonic analysis is used to determine the phase and normalized amplitude of the diurnal variations in convective activity and precipitation during phases II and III of GATE. Satellite results are based on the percent coverage of squares, 3° of latitude and longitude in dimensions, by convective clouds, as estimated subjectively from SMS-1 infrared images. Rainfall results are based on hourly precipitation records for 33 land stations and hourly or 3-hourly rainfall amounts from 13 ships in the A/B-scale networks. The rainfall data for the land stations were combined into four geographically distinct groups and the ship data into a single group before making the harmonic analyses. The long-term representativeness of the results for the land areas is judged by comparing them with the results obtained from analysis of data presented by Burpee (1976) on the frequencies of occurrence of thunder, moderate to heavy precipitation and light precipitation during the period June-September 1966–69. The main...

101 citations


Journal ArticleDOI
TL;DR: In this article, the mesoscale organization and structure of precipitation in a cyclonic storm have been studied using satellite, radar, airborne and ground measurements, and it is shown that the precipitation cores in warm frontal bands originated in generating cells aloft which provided seed ice crystals which grew by collection as they fell through lower cloud layers.
Abstract: The mesoscale organization and structure of precipitation in a cyclonic storm have been studied using satellite, radar, airborne and ground measurements. The large mesoscale regions, which were mainly in the form of rainbands, contained within them smaller mesoscale regions (preciptation cores) which were characterized by higher rainfall rates. It is shown that the precipitation cores in warm frontal bands originated in generating cells aloft which provided “seed” ice crystals which grew by collection as they fell through lower cloud layers. The generating cells were probably produced by the lifting of shallow layers of potentially unstable air which were situated above warm fronts. There is also some evidence that the precipitation cores within cold frontal bands originated within layers of potentially unstable air.

97 citations


Journal ArticleDOI
TL;DR: In this article, a detailed discussion of the relationship between sulfur concentration and amount of precipitation is presented, and the results from a large number of additional sampling sites around and between the regular network sampling sites are most helpful in this regard.

Journal ArticleDOI
TL;DR: In this paper, the average annual soil moisture balance, as derived from the mechanics of storm and interstorm soil moisture movement and from the statistics of the climatic variables, is used to define the average annually soil moisture.
Abstract: The average annual soil moisture balance, as derived from the mechanics of storm and interstorm soil moisture movement and from the statistics of the climatic variables, is used to define the average annual soil moisture. This soil moisture is used in the equation for average annual yield to give a first-order approximation of the annual precipitation yield function. This function is used to transform the cumulative distribution function (cdf) of annual precipitation into the cdf of annual yield, and application is made in a subhumid and in an arid climate. The derived yield frequency function is seen to be sensitive to the soil and vegetal properties. Proper selection of these parameters brings close agreement with observed streamflow-frequency and suggests the model's utility for parameterizing drainage basins with respect to effective average soil and vegetal properties.

Book ChapterDOI
01 Jan 1978
TL;DR: In this article, a brief description of the main microstructural features of clouds is given, focusing primarily on the sizes, number concentrations, and geometry of the particles comprising the visible cloud.
Abstract: Before discussing the microphysical mechanisms of cloud particle formation, we shall give a brief description of the main microstructural features of clouds. Here we shall be concerned primarily with the sizes, number concentrations, and geometry of the particles comprising the visible cloud.

Journal ArticleDOI
TL;DR: In this article, the dominant ions contributing to the acidity of precipitation are usually SO4−2, NO3− and NH4+ after allowance for sea salts, and the role of NH3 is straightforward acid neutralisation but the relationship between NO3 and SO42− is more difficult to define.

Journal ArticleDOI
01 Sep 1978
TL;DR: In this article, Latitude-time cross-sections of precipitation across the West African region indicate that a strong relation exists between the May-September cycle of precipitation in the Sahel and the January-December cycle in the moist Southern sector.
Abstract: Latitude-time cross-sections of precipitation across the West African region indicate that a strong relation exists between the May–September cycle of precipitation in the Sahel and the January–December cycle in the moist Southern sector. It is demonstrated that while the promiment precipitation band moves with the Inter-tropical discontinuity (ITD) in its South-North annual course, another important atmospheric mechanism, the Walker circulation (WC) influences the precipitation in the South where the ITD control breaks down. The effects, on the Sahel region's precipitation, of these atmospheric mechanisms, along with albedo variation are associated with a bio-physical feed-back mechanism forced, in the main, by ocean-atmosphere interaction.

Journal ArticleDOI
TL;DR: In this article, the emissivity of sea ice and atmospheric precipitation was investigated using the data from the Electrically Scanning Microwave Radiometers (ESMR's) on the Nimbus-5 and Nimbus6 satellites operating at wavelengths of 1.55 cm and 8mm, respectively.
Abstract: The emissivity of sea ice and atmospheric precipitation was investigated. Using the above physics, the data from the Electrically Scanning Microwave Radiometers (ESMR's) on the Nimbus-5 and Nimbus-6 satellites operating at wavelengths of 1.55 cm and 8mm, respectively, can be interpreted in terms of rain rate, ice coverage, and first year versus multi-year ice determination. The rain rate data is being used to establish a climatology of rainfall over the oceans. Both ice and rain data sets have been generated for the Global Atmospheric Research Project Data Systems Test.

Journal ArticleDOI
TL;DR: In this article, the frequency distribution of rainfall rates was determined for stations in each of these four climatic zones and a zonal average frequency distribution calculated, showing a progression in the frequency of more intense precipitation from the North Pole to the Equator since all of the data were taken from the Northern Hemisphere.
Abstract: Raingage records from four climatic zones (maritime subtropical, continental temperate, maritime temperate and midlatitude interior) were analyzed to study instantaneous rainfall rates as defined by 1 and 4 min accumulations. The frequency distribution of rainfall rates was determined for stations in each of these climatic zones and a zonal average frequency distribution calculated. A progression in the frequency of more intense precipitation was found from the North Pole to the Equator since all of the data were taken from the Northern Hemisphere. The most intense rainfalls were recorded at stations in the maritime subtropical zones and the least intense rainfalls in the maritime temperate zones.

Journal ArticleDOI
Kikuo Kato1
01 Mar 1978-Nature
TL;DR: In this article, the authors investigated the relationship between the oxygen isotopic composition of fallen snow at the Syowa Station and the transportation process of water vapour to the Antarctic ice sheet.
Abstract: TRANSPORTATION of water vapour to the Antarctic ice sheet is one of the most important factors controlling oxygen isotopic composition of Antarctic snow, firn and ice. In previous studies1–5, the isotopic composition of precipitation was related only to its temperature of formation. In the study reported here, the relationship between the oxygen isotopic composition of fallen snow at the Syowa Station and the transportation process of water vapour to the Antarctic ice sheet has been investigated. It was found that the oxygen isotopic composition of fallen snow is largely controlled by the supply of 18O-rich water vapour resulting from the approach of a cyclone, and is strongly related to the distance from the open sea to the sampling station.

Journal ArticleDOI
TL;DR: In this article, it was shown that long-term trends in the meridional components of the trade wind circulations in both hemisphere over the Pacific are highly correlated with precipitation falling in the intertropical convergence zone (ITCZ) over that region.
Abstract: It is shown that long-term trends in the meridional components of the trade wind circulations in both hemisphere over the Pacific are highly correlated with the precipitation falling in the intertropical convergence zone (ITCZ) over that region. The trends in the trade wind regime, on the one hand, seem to be caused by extratropical sea surface temperature (SST) anomalies in the North Pacific which influence atmospheric meridional temperature and pressure gradients. On the other hand, the release of latent heat in the ITCZ provides a self-enforcing feedback for the trade winds. A study of the recurrence frequency of precipitation surges over the Line Islands suggests the presence of three epoch (1911–28, 1929–62, 1963 to present) during which the Hadley cell circulation and attendant meteorological and oceanographic features showed different characteristics.

Journal ArticleDOI
TL;DR: In this article, a large increase in extent of October 1st snow cover in the Canadian Arctic from 1967-1970 to 1971-1975 is compared to changes in other climate variables over the area of snow-cover expansion.

Journal ArticleDOI
TL;DR: In this article, precipitation phenomena were observed at temporary stations around peaks and ridges of high altitude (5000-5500 m) in Shorong and Khumbu Himal, in addition to the observations made at Lhajung station (4420 m).
Abstract: Through the monsoon period of 1976, precipitation phenomena were observed at temporary stations around peaks and ridges of high altitude (5000-5500 m) in Shorong and Khumbu Himal, in addition to the observations made at Lhajung station (4420 m) in the Khumbu region. Through these observations, it was found that the amounts of precipitation at these two stations is 4 or 5 times larger than that at Lhajung. While day to day convective precipitation contributes the major part of the total amount at Shorong and Glacier EB 050 (E9) stations, a few rainy days of large amount of precipitation account for most of the contribution at Lhajung station. It was also found that the statistical features of precipitation as a function of time of day are systematically different among these three stations. Along the slope to Glacier EB 050 (E9) in Khumbu Himal, the amount of precipitation gradually increases with increase of altitude. However, along the slope to Glacier AX 030 in Shorong Himal, the amount is almost uniformly distributed from 4000 m up to the terminus of the glacier (5200 m).

Journal ArticleDOI
TL;DR: In this paper, the authors present a design for a collector which combines large size with other desirable features, such as height, texture, and composition of the collector surfaces, relation of collector surfaces to natural environmental surfaces, contamination by birds, insects, pollen, and organometallic release from local vegetation, and sample storage.
Abstract: From an analytical viewpoint, total dry and wet precipitation consists of three fractions: (1) dissolved materials in aqueous precipitation, (2) the water-soluble component of dry precipitation, and (3) the water-insoluble component of either wet or dry precipitation. Methods of precipitation collection and processing greatly affect the separation of these components. A literature survey shows that fraction 3 has typically been ignored and that samplers currently in use lead to a highly variable mixture of the three fractions. Major causes of interpretational ambiguity include (1) variable leaching of dry fallout, (2) particle formation and chemical repartitioning in aqueous precipitation, (3) height, texture, and composition of the collector surfaces, (4) relation of collector surfaces to natural environmental surfaces, (5) contamination by birds, insects, pollen, and organometallic release from local vegetation, (6) sample storage, and (7) failure to analyze insoluble particles. A literature survey also shows that most collectors currently in use are of insufficient size to collect samples large enough to support broad-spectrum analysis on a weekly basis. The minimum satisfactory size of collectors is computed from (1) average rain chemistry, (2) sensitivity of standard chemical tests for chemical species of biological interest, and (3) volume required for each analysis. The computations show that collectors should have an area of at least 1200 cm2 in regions of average chemistry and as much as 8300 cm2 in cold climates with minimal aqueous precipitation. A design is given for a collector which combines large size with other desirable features.

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the trends in the recent acidification of rivers and lakes in South Norway, and the evidence for a causal relationship between acid precipitation and acidified surface water is critically examined.

Journal ArticleDOI
TL;DR: In this paper, the results of five years of precipitation measurement from an international network of raingages in Windsor-Detroit were presented, showing that the number of precipitation days and heavy precipitation days were greatest in the southwest urban area and decreased downwind.
Abstract: Most recent research in urban precipitation has suggested that the presence of the city itself causes increased precipitation. The present paper presents the results of five years of precipitation measurement from an international network of raingages in Windsor-Detroit. Increased precipitation downwind appeared to be the case only in summer. The number of precipitation days and the number of heavy precipitation days were greatest in the southwest urban area and decreased downwind.

Journal ArticleDOI
02 Jun 1978-Science
TL;DR: Dendrochronology has provided a new seasonal predictor for air pollution meteorology and a weak tendency for hot summers to follow wet winters explains only a minor part of the ozone-rain relationship in multiple correlations.
Abstract: Insights from dendrochronology have provided a new seasonal predictor for air pollution meteorology. In the San Francisco Bay Area summer ozone excesses over the federal ozone standard are correlated (correlation coefficient r = .87) with precipitation for the two preceding winters, a factor related to tree-ring width in a precipitation-stressed climate. The hypothesis that reactive hydrocarbon emissions from vegetative biomass affects these ozone excesses was supported by a similar correlation between summer hydrocarbon average maximums and the two-winter precipitation factor, reaching r = .88 at suburban stations. A weak tendency for hot summers to follow wet winters (in 16 years of California data) explains only a minor part of the ozone-rain relationship in multiple correlations.

Journal ArticleDOI
TL;DR: In this paper, it was shown that fractional cloudiness and relative humidity decrease with increasing temperature in an intermediate numerical model, in spite of an increase in the evaporation, water transport, condensation, precipitation and cloud water content.
Abstract: It is shown for an intermediate numerical model that fractional cloudiness and relative humidity decrease with increasing temperature. The fractional cloudiness decreases at a rate about 1 per deg K. This occurs in spite of an increase in the evaporation, water transport, condensation, precipitation and cloud water content with increasing temperature. These results are quite similar to those found from models with more highly parameterized clouds, notably the NCAR model. The fractional cloudiness in this model is measured by the fractional coverage of total cloud water and the fractional coverage of positive condensation, in addition to the relative humidity. It is also shown that some of the characteristics of a temperate climate can be simulated in an intermediate numerical model with periodic, antisymmetric and symmetric boundary conditions on an f plane. Intermediate models of this sort may therefore be useful to investigate general questions about the earth's hydrologic cycle on climatic space and time scales

Journal ArticleDOI
TL;DR: In this article, a method suggested by G. B. Tucker of estimating rainfall from present weather observations is tested on 28 coastal stations, and regression formulae are presented to adjust yearly, quarterly, and monthly mean precipitation values for air temperature.
Abstract: A method suggested by G. B. Tucker of estimating rainfall from present weather observations is tested on 28 coastal stations. Tucker's method was developed from a group of stations in Great Britain; at other latitudes, due to air temperature differences, the Tucker estimates may be several times too high or too low. Regression formulae are presented to adjust yearly, quarterly, and monthly mean precipitation values for air temperature. Corrected rainfall maps based upon ocean weather station data reveal a formerly undetected rainfall maximum in western mid-latitudes of the North Pacific and North Atlantic Oceans.

Journal ArticleDOI
TL;DR: In this article, the initial stages of precipitation in uniform updrafts under natural and seeded conditions are examined using a detailed microphysical model of parcel ascent, and the effects of seeding are related to the initiation of precipitation which is considered to be the rate-limiting step in the precipitation process.
Abstract: The initial stages of the formation of precipitation in uniform updrafts under natural and seeded conditions are examined using a detailed microphysical model of parcel ascent The effects of seeding are related to the initiation of precipitation which is considered to be the rate-limiting step in the precipitation process The times required to reach a 20 dBZ radar reflectivity factor are compared between natural and seeded cases Three regions of ice-nucleant seedability are defined on the bases of cloud-base temperature and updraft velocity These are 1) no precipitation under natural or seeded conditions, 2) easy to overseed, and 3) difficult to overseed It is suggested that these regions define a physically valid stratification for the analysis of cloud seeding projects The optimal ice crystal concentration which yields the minimum time to form precipitation is estimated to be between 100 and 1000 crystals per liter Seeding with large drops is shown to produce precipitation more efficient

Journal ArticleDOI
TL;DR: In this article, the problem of rainfall prediction for a tropical storm over the United States is examined from a diagnostic point of view, and a moisture budget is constructed and the differences between the computed and observed precipitation are discussed.
Abstract: The problem of rainfall prediction for a tropical storm over the United States is examined from a diagnostic point of view. A moisture budget is constructed and the differences between the computed and observed precipitation are discussed. Although the areal averages were comparable, the point-by-point agreement was only fair. Stable and convective precipitation are then computed using methods common to many numerical models. The discrepancies between forecast and observed precipitation is assumed to be due to the incomplete formulation of the amount of moisture available for convection. This leads to an expression for the subgrid-scale moisture supply that provides the missing precipitation. Methods are then suggested in which the deficiencies of a parameterization scheme could be corrected during its use in a prognostic model.

Journal ArticleDOI
TL;DR: Run-off, lake level and precipitation are well correlated, indicating that the influence of the catchment is large and rapid, and the lake is covered by ice from late October to the beginning of June.
Abstract: The Lake Ovre Heimdalsvatn is greatly affected by wind. Precipitation, especially heavy rainfall, has probably a good possibility of eroding and leaching material into the lake. The mean annual temperature is −1.2°C, and the estimated mean annual evapo-transpiration is about 200 mm. The lake is covered by ice from late October to the beginning of June. Run-off, lake level and precipitation are well correlated, indicating that the influence of the catchment is large and rapid.