Showing papers in "Journal of Applied Meteorology in 1969"
TL;DR: A relatively simple numerical model of the energy balance of the earth-atmosphere is set up and applied in this paper, where the major conclusions of the analysis are that removing the arctic ice cap would increase annual average polar temperatures by no more than 7C, that a decrease of the solar constant by 2-5% might be sufficient to initiate another ice age, and that man's increasing industrial activities may eventually lead to a global climate much warmer than today.
Abstract: A relatively simple numerical model of the energy balance of the earth-atmosphere is set up and applied. The dependent variable is the average annual sea level temperature in 10° latitude belts. This is expressed basically as a function of the solar constant, the planetary albedo, the transparency of the atmosphere to infrared radiation, and the turbulent exchange coefficients for the atmosphere and the oceans. The major conclusions of the analysis are that removing the arctic ice cap would increase annual average polar temperatures by no more than 7C, that a decrease of the solar constant by 2–5% might be sufficient to initiate another ice age, and that man's increasing industrial activities may eventually lead to a global climate much warmer than today.
996 citations
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TL;DR: In this article, the inadequacy of previous calculations of terminal velocities at other than sea level conditions is discussed, and empirical formulae are presented which fit the data very closely.
Abstract: The inadequacy of previous calculations of terminal velocities at other than sea level conditions is discussed. Attention is called to actual measurements of terminal velocities at different air densities, and empirical formulae are presented which fit the data very closely.
373 citations
TL;DR: In this paper, a general purpose, numerical energy budget model is described and applied to the urban atmosphere to predict the correct order of magnitude of the urban temperature excess, which is found to be the net result of several competing physical processes, such as reduced evaporation in the city center and the thermal properties of the city building and paving materials.
Abstract: The heat island phenomenon is surveyed. Existing theories are criticized as being excessively qualitative. A general purpose, numerical energy budget model is described and applied to the urban atmosphere. Calculations for several special cases as well as a sensitivity analysis are presented. The model is found to predict the correct order of magnitude of the urban temperature excess. The heat island effect is found to be the net result of several competing physical processes. In general, reduced evaporation in the city center and the thermal properties of the city building and paving materials are the dominant parameters. It is suggested that such a model could be used in engineering calculations to improve the climate of existing and future cities.
243 citations
TL;DR: The Line Islands Experiment, conducted on and near Palmyra, Fanning and Christmas Islands during February-April 1967, produced extensive data on disturbances of the equatorial trough zone as discussed by the authors.
Abstract: The Line Islands Experiment, conducted on and near Palmyra, Fanning and Christmas Islands during February-April 1967, produced extensive data on disturbances of the equatorial trough zone. One disturbance which passed through the heart of the data network is analyzed in detail. This disturbance intensified rapidly just east of Fanning Island during the night of 31 March–1 April, but satellite observations show that it dissipated rapidly during the daylight hours of 1 April. The convergence-divergence patterns associated with the growth and decay of the disturbance are most intense in the lowest 500 m. Data from serial rawinsonde releases on the islands, combined with research aircraft data, are presented which demonstrate that highly unsaturated downdrafts are produced, first on the convective scale and the mesoscale, and finally becoming organized over the entire 600-km extent of the system. Cumulus development is effectively suppressed in the downdraft air, only being restored after 6–12 hr by ...
223 citations
TL;DR: In this article, five years of turbidity measurements from a network of stations in the United States are analyzed, and the relationship of these measurements to those of Linke and Angstrom is briefly discussed.
Abstract: Five years of turbidity measurements from a network of stations in the United States are analyzed. Measurements are made with the Volz sunphotometer; the instrumentits calibration, and its use are described. The relationship of these measurements to those of Linke and Angstrom is briefly discussed. Analysis of the data indicates the following: 1) an annual mean pattern of low turbidity (near 0.05) over the western plains and Rocky Mountains and high turbidity (near 0.14) in the east; 2) observed minimum turbidity near 0.02; 3) an annual cycle of low turbidity in winter and high in summer; 4) lowest turbidity in continental polar air masses and highest in maritime tropical; and 5) no noticeable lowering of turbidity following precipitation.
212 citations
TL;DR: An extensive dust devil census taken near Tucson, Ariz., has provided, from two independent areas, quantitative information on the relation of environmental conditions to the spatial distribution, frequency and duration of a particular type of dry atmospheric thermal as mentioned in this paper.
Abstract: An extensive dust devil census taken near Tucson, Ariz., has provided, from two independent areas, quantitative information on the relation of environmental conditions to the spatial distribution, frequency and duration of a particular type of dry atmospheric thermal. The observations indicate that for these two areas, each approximately 100 mi2 in area, dust devils are initially sighted most frequently in the vicinity of dry river beds which lie in the lee of small hills. Once initiated, the visible lifetime of the observed dust devils ranged from a few seconds to approximately 20 rain. These data show that dust devil duration increases with dust devil size. The results indicate that the energy for the dust devil is the warm boundary layer air which is continually being fed into the visible vortex as it moves along with essentially the same speed and direction as the environmental wind. The highest dust devil frequency occurs with the lowest atmospheric stability and not necessarily with the hig...
202 citations
TL;DR: The cumulus cloud populations of the Florida peninsula were photographed periodically and comprehensively on 19 days in August and September 1957, using multiple, high-flying aircraft as mentioned in this paper, and the results revealed that a definite maximum-size class of the cumuli existed in the populations, which increased in size diurnally in a regular fashion, and there was considerable variance, both within single populations and with the time of day, in the relationships of the vertical and horizontal dimensions of the clouds.
Abstract: The cumulus cloud populations of the Florida peninsula were photographed periodically and comprehensively on 19 days in August and September 1957, using multiple, high-flying aircraft. Particular sets of these photographs, called population samples, were selected which showed representative examples of the cumulus populations of customary, widespread occurrence of the various days and hours. These were analyzed to determine the size distribution characteristics of the cumuli and the time trends. The analyses revealed 1) that the number density of the cumuli decreased nearly exponentially with increasing cloud-size, 2) that a definite maximum-size-class of the cumuli existed in the populations, which increased in size diurnally in a regular fashion, 3) that there was considerable variance, both within single populations and with the time of day, in the relationships of the vertical and horizontal dimensions of the clouds, 4) that particular modal classes of the cumuli, of intermediate size, existe...
159 citations
139 citations
TL;DR: In this paper, the Thornthwaite-Holzman equation for turbulent diffusion under adiabatic conditions is used to estimate evapotranspiration from tall grasses and sedges.
Abstract: A new instrument is described which enables integrated values of water and carbon dioxide flux to be obtained under field conditions. The principle of operation is the Thornthwaite-Holzman equation for turbulent diffusion under adiabatic conditions, but a simple adaption would allow automatic correction for nonadiabatic conditions. The instrument is simple and designed for continuous unattended operation under difficult field conditions, where integrated flux values are required over long time intervals. Preliminary tests under such conditions show satisfactory agreement with an independent estimate of evapotranspiration from autumn fields of tall grasses and sedges.
TL;DR: In this paper, the diurnal local winds at the Mauna Loa Observatory showed a 600 m deep upslope flow and 55 m deep down slope flow, and the mass flux of air in the region of the observatory for a mean 24-hr day was analyzed.
Abstract: Measurements, using a captive balloon system, of the diurnal local winds at the Mauna Loa Observatory showed a 600 m deep upslope flow and 55 m deep downslope flow. Using a model, the mass flux of air in the region of the observatory for a mean 24-hr day showed that six times more air is transported by the upslope flow than by the nocturnal downslope flow. The diural periodicity, wind velocity and mass flux of air in the region of the observatory are controlled by the temperature and radiation flux of the lava surface of the mountain, the strength of the free air flow, and the level and strength of the trade wind inversion. A diurnal pressure gradient between the air enveloping the mountain and the free air was detected as a complement to the diurnal wind regime observed.
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.
TL;DR: In this article, it is suggested that helical roll vortices in the atmosphere are responsible for the formation of the longitudinal sand dunes that cover over half of the area of the large deserts of the world.
Abstract: It is suggested that helical roll vortices in the atmosphere are responsible for the formation of the longitudinal sand dunes that cover over half of the area of the large deserts of the world. The dunes are aligned in the direction of the prevailing wind and are spaced ∼2 km apart. Observations in the atmosphere and in the laboratory, and hydrodynamic stability theory, indicate that dominant forms of motion in the boundary layer of the atmosphere are counter-rotating helical roll vortices aligned along the wind and having diameters approximately equal to the thickness of the boundary layer. The necessary conditions for the formation of these roll vortices are fulfilled over large deserts and their spacings agree with the observed spacings of the dunes.
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.
TL;DR: In this article, a series of low-level tracer experiments conducted in metropolitan St. Louis is described, and the results are presented graphically as families of best-fit curves in terms of downwind distance and travel time.
Abstract: A series of low-level tracer experiments conducted in metropolitan St. Louis is described. Values of dispersion parameters, calculated from the tracer data, are related to readily measured or derived meteorological indices of turbulence. The results are presented graphically as families of best-fit curves in terms of downwind distance and travel time. Results are compared with those of previous dispersion experiments conducted over relatively uncomplicated terrain in open country. In terms of the meteorological indices, crosswind dispersion is better described as a function of downwind distance, whereas that in the vertical is about as well described by travel time as by downwind distance. It is concluded that for low-level point sources, the urban area affects crosswind dispersion primarily by enhancing the initial size (i.e., close to the source) of the plume. As the plume becomes much larger than the size of eddies created by the local obstructions, the dispersion closely converges to that ass...
TL;DR: In this paper, the sugar-inversion method (Pallmann method) was used to derive mean temperatures by means of an Arrhenius-type equation, which was tested for precision, accuracy and adaptability to climatological networks.
Abstract: The sugar-inversion method (Pallmann method) of deriving mean temperatures related the reaction velocity of sucrose hydrolysis to temperature by means of an Arrhenius-type equation. The method was tested for precision, accuracy and adaptability to climatological networks. Twenty-milliliter glass ampoules filled with a clear sucrose solution were used as temperature sensors. The sensors were virtually unaffected by shortwave radiation. Precision of the method for half-month periods in forested terrain was ±0.02C. Absolute accuracy of the method was severely affected by the nonlinearity of sensor response; this was circumvented by use of empirical corrections based on the temperature mean and amplitude. At five standard climate stations, arithmetic mean temperatures for half-month periods (1967–1968) were predicted with an average error of 0.37–0.64C in summer (over mean temperatures of 30 to 10C) and 0.86–1.05C in winter (over mean temperatures of 10 to −10C). The Pallmann method of temperature in...
TL;DR: Lidar data obtained at Hamilton AFB, Calif, are analyzed by hand and by electronic computer to explore the operational utility of lidar in determining cloud ceiling and visibility for aircraft landing operations to demonstrate operationally useful information on the ceiling conditions can be represented by digitizing the lidar data and subjecting these data to computer analysis.
Abstract: Lidar (laser radar) data obtained at Hamilton AFB, Calif., under conditions of low ceiling and visibility, are analyzed by hand and by electronic computer to explore the operational utility of lidar in determining cloud ceiling and visibility for aircraft landing operations. Hand analyses of the data show the ability of the lidar to describe the spatial configuration of the low-cloud structure in the direction of the landing-approach path. The problems inherent in evaluating lidar observations are discussed, and initial approaches to quantitative solutions by computer are presented. It is demonstrated that operationally useful information on the ceiling conditions contained in the hand analyses can be represented by digitizing the lidar data and subjecting these data to computer analysis.
TL;DR: In this paper, a program of aerosol measurements made in the fall of 1965 at Cape Blanco and Crater Lake, Ore. was described, where a Royco light-scattering type particle counter and with condensation nuclei counters were used to determine the size distribution of the chloride and sulfur-compound fractions of the aerosol.
Abstract: This paper describes a program of aerosol measurements made in the fall of 1965 at Cape Blanco and Crater Lake, Ore. Aerosol size distributions were determined with a Royco light-scattering type particle counter and with condensation nuclei counters. Size distributions at Crater Lake (2200 m altitude) were found to be well approximated by power law distributions with exponents between 3 and 4. The Cape Blanco data agree well with earlier measurements of sea-spray, aerosol size distributions. A Goetz aerosol centrifuge was used, in conjunction with filter sampling, to determine the size distribution of the chloride- and sulfur-compound fractions of the aerosol. At Crater Lake, sulfur-to-chloride ratios of about 8 were observed and considerable concentrations of other materials could be inferred. The data indicate that significant amounts of sea-spray aerosol did not penetrate upward to altitudes >2000 m. The aerosols identified with these 2000 m tropospheric levels are believed to be aged aerosols...
TL;DR: In this paper, a method is proposed whereby incorrect analyses at two successive times may be optimally adjusted to maintain dynamical consistency with a given prediction model, and it is shown that the mean-square error of the adjusted analyses is half that of the original analyses.
Abstract: A method is proposed whereby incorrect analyses at two successive times may be optimally adjusted to maintain dynamical consistency with a given prediction model. It is shown that, in the ensemble average, the mean-square error of the adjusted analyses is half that of the original analyses.
TL;DR: In this article, the interaction between the urban heat island and the lake circulation is studied using several years of records of daily maximum temperatures from a network of about 23 observing stations, pre-stratifying the data according to the regional wind patterns at the geostrophic level and according to daily sunshine total.
Abstract: Metropolitan Toronto (population of about 2,160,000 and area of 2282 km2) is on the north shore of Lake Ontario (area of 19,400 km2). The interaction between the daytime urban heat island and the lake circulation is studied using several years of records of daily maximum temperatures from a network of about 23 observing stations, pre-stratifying the data according to the regional wind patterns at the geostrophic level and according to the daily sunshine total. The results show that the heat island exists and is detectable during the time of maximum heating in Toronto. Further, the position of the heat island, although a result of urban influence (automobile traffic, industry, home heating units, etc.), is displaced in response to regional and lake breeze wind patterns and the modification of the lake breeze as it moves across the built-up area.
TL;DR: Measurments were taken along the east slopes Mauna Loa, Hawaii, to determine whether the normally present trade wind inversion reaches the mountain and whether its properties there are similar to those over the ocean as discussed by the authors.
Abstract: Measurments were taken along the east slopes Mauna Loa, Hawaii, to determine whether the normally present trade wind inversion reaches the mountain and whether its properties there are similar to those over the ocean Temperature, mixing ratio and condensation nuclei concentration profiles were measured and plotted to study the properties of the air along the slopes, especially at altitudes where the radiosonde observations indicated an inversion This inversion, along with its properties in the free atmosphere, has been detected at the surface of the mountain and is particularly pronounced in the early morning Its properties there correspond closely with those in the free air
TL;DR: In this article, the authors developed and applied objective data reduction and analysis techniques to the wind, temperature and moisture data measured during a selected thunderstorm case and evaluated the sounding system's limitations and reliability for resolving the mesoscale circulations associated with convective processes.
Abstract: Guidelines followed in designing and operating a special mesoscale rawinsonde network are discussed. Objective data reduction and analysis techniques are developed and applied to the wind, temperature and moisture data measured during a selected thunderstorm case. The goal is to appraise the sounding system's limitations and reliability for resolving the mesoscale circulations associated with convective processes. A consistent four-dimensional synoptic portrayal of the variables is achieved by accounting for balloon drift, differing station-to-station and sounding-to-sounding ascent rates, and departures from scheduled release time.Temporal variations in the spatial distributions of computed divergence and kinematic vertical motion are in good qualitative agreement with the location and intensity of thunderstorm radar echoes, after further objective adjustments are applied to compensate for the assumed character of wind measurement and analysis errors. For the purpose of assessing data and analyt...
TL;DR: In this paper, an aspirated psychrometer system using thermopiled copper-constantan sensors is described, and field data are presented showing temperature and humidity profiles obtained over a turf crop by nine self-contained units mounted on a 6 m mast.
Abstract: An aspirated psychrometer system using thermopiled copper-constantan sensors is described. Field data are presented showing temperature and humidity profiles obtained over a turf crop by nine self-contained units mounted on a 6 m mast. Temperature and humidity can be determined with accuracies of 0.025C and 0.15 mm Hg vapor pressure. The units are relatively inexpensive and easy to fabricate. The wet-bulb element, a porous ceramic cup supplied with a continuous column of water from a reservoir, provides more reliable and less critical operation than the conventional cotton-wick elements.
TL;DR: In this article, the authors show that falling rain changes sea surface conditions, because of its different salinity, different temperature, and its momentum, and experimental evidence of the action of these three factors has been gathered using artificial and natural rain falling on a salt water tank.
Abstract: Falling rain changes sea surface conditions, because of its different salinity, different temperature, and its momentum. Experimental evidence of the action of these three factors has been gathered using artificial and natural rain falling on a salt water tank. Big drops cause substantital mixing; smaller ones create a very stable surface layer.
TL;DR: In this paper, the nocturnal cold airflow on a small forested slope was studied in an attempt to relate the volume and velocity of flow to the net radiation balance of the slope.
Abstract: The nocturnal cold airflow on a small forested slope was studied in an attempt to relate the volume and velocity of flow to the net radiation balance of the slope. The hillside, with an approximately 30% grade, was about 400 m long and covered with an uneven-aged spruce-fir stand of about 20 m height. The location was near Fraser, Colo., at an altitude of 3000 m. The vertical profiles of wind speed and air temperature were measured at various points on a transect approximating a streamline segment down the hill for several nights. Net radiation was measured at the base of the transect. Canopy closure and tree heights and diameters were measured on sample plots along the transect. The vertical profiles of potential temperature deficit and wind speed at the various stations show approximate similarity when scaled by the height of the lowest inversion and by the average velocities and potential temperature deficits below that inversion. The latter varies in a nearly linear manner down the slope, and...
TL;DR: In this paper, a large scale crossequatorial flows determined by ATS-1 photographs were determined by a large-scale Crossequential flow determined by large scale anticyclones over eastern Pacific.
Abstract: Equatorial anticyclones over eastern Pacific caused by large scale crossequatorial flows determined by ATS-1 photographs, noting frictional convergence factor
TL;DR: In this paper, the authors examined the behavior of the error in the forecast, as represented by the rms deviation of the ensemble members from their mean, for a few simple equations and concluded that optimum procedures for forecasting, i.e., solving prognostic equations, require including terms in the equations to represent the influence of the initial uncertainties.
Abstract: When the initial values, or the parameters, of prognostic equations are not known with certainty, there must also be errors in the solution. The initial conditions may be represented by an ensemble, each member of which is consistent with all available knowledge. The mean of this ensemble is a reasonable "best" solution to the prognostic equation. Following Gleeson, we have examined the behavior of the error in the forecast, as represented by the rms deviation of the ensemble members from their mean, for a few simple equations. We have further examined the time-dependent behavior of the ensemble mean, as opposed to the solution obtained by applying the prognostic equation to the original mean values. These are, in general, different. It is concluded that optimum procedures for forecasting, i.e., solving prognostic equations, require includingterms in the equations to represent the influence of the initial uncertainties. Since the nature of these uncertainties may also have profound influences on ...