首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 718 毫秒
1.
Data collected during the french VOVES-1977 experiment are used for the determination of the functionsA() andB() of the stability parameter . It is found that, although pertaining to different geographic conditions, they lead to the same kind of dependency ofA andB upon as found previously considered data. The influence of baroclinicity onA andB is also studied and it is found in that, statistically, consideration of this parameter does not lead either to a decrease of the large scatter of experimental points or to a significant improvement of the similarity theory. It is also shown that a satisfactory estimation of the surface geostrophic wind can be made from the network of meteorological stations, to compute such functions.  相似文献   

2.
Summary Solar radiation (Qc), sunshine hours (n) and reflectance coefficients or albedo (A) were measured above, and photosynthetically active radiation (PAR) was measured above and within three levels in a tropical dry deciduous forest in western Mexico (19° 30 N, 105° 03 W).Values ofQc andn, and PAR andA showed a drastic change between rainy and dry season, and leafed and leafless period, respectively. The transmittance for solar radiation was high in dry season and showed a great variation on transition months from dry to rainy season. Midday albedo changed from 14 (August, leafed period) to 21% (May, leafless period).The transmittance of PAR within the forest was 0.92, 0.26 and 0.19 at levels of 10.0, 5.0 and 0.2m above ground, respectively, in leafed period. The mean tree height was 11.0 m. In leafless period, the transmittance was 0.75 and 0.46 at 5.0 and 0.2 m levels.With 5 Figures  相似文献   

3.
An expression is derived for the height of the stationary boundary layer during stable lapse rate conditions. It satisfies the conventional limits for neutral conditions and for large values of stability. Comparison with acoustic sounder observations near the meteorological mast at Cabauw (the Netherlands) shows that the steady-state height is not attained for large stability values. The observations are also used to investigate how the similarity functions A and B in the resistance laws depend on the stability parameters 0 = u */f L and = h/L. The function B shows a clear trend as a function of stability, which can be described in terms of . The dependence of A is masked by scatter in the data points. The general conclusion leads to the concept of a non-steady boundary layer during stable lapse rate conditions.  相似文献   

4.
Summary For the first time a method is presented to actually measure the radiative flux intercepted by cylindrical and conical objects in radiation fields of any unknown angular distribution.The horizontal component of solar radiationH is a newly introduced parameter expressed in Wm–2 and defined as specific radiative flux intercepted by the lateral surface of a vertical cylinder. The horizontal componentH can be measured and must be considered complementary to the vertical component of solar radiationG which is conventionally measured as Global radiation.Radiative fluxes intercepted by cylindrical and conical objects are expressed as simple analytic functions ofG andH in any irregular radiation field. Before the introduction of the H-concept, when onlyG was measured, intercepted fluxes had to be approximated on the basis of assumed angular distributions of the radiation field.The climatological characteristics ofH andG are different: under clear skies in the open field the H-climatology is more temperate than the G-climatology all over the world and in all seasons. In the radiative environment of elongate vertical bodies H is generally a more significant parameter thanG. With 4 Figures  相似文献   

5.
A simple mixed layer model is used to derive the following expressions for the maximum (daily) convective velocity scale. w *m = AQ m 1/2; w *m = Bz im The variables A and B are shown to vary within narrow limits thus allowing them to be treated as constants. This is very useful for routine computation of w *m , an important variable for dispersion under unstable conditions, from estimates of either the kinematic surface heat flux Q m (m-1) or the maximum mixed layer height z im .Analysis of observations made during the Minnesota boundary layer experiment shows that there is ample justification for assigning typical values to A and B in estimating w *m.  相似文献   

6.
Summary The mean daily march of pressure (hourly values) for each month of the 96 year period 1894–1989 in Athens, Greece is studied using Fourier analysis. The annual variation of the harmonic parameters (amplitude, time of maximum,x andy-components) is examined. The globally excited 2nd and 3rd harmonics show in general the same behaviour as in other places of the Earth. Similar features show the corresponding parameters of the daily solar radiation march. The first harmonic displays some local characteristics. The long period fluctuations study revealed statistically significant trends in most parameters of the 2nd harmonic, most strikingly the 0.5 h shift in the time of its maximum during the 20th century. Power spectrum analysis showed the existence of a biennial oscillation inB 1, thex-component of the first harmonic, but this oscillation is mainly confined to the second half of the entire period. A periodicity of about 6 years which could be associated to the Southern Oscillation was also found inB 1 while inA 1, they-component, a periodicity close to the 11-year solar cycle and another one close to the nutation of the Earth's axis are present. The lunar tides are too small to be detected by the same methods. However the semilunar tide was revealed to be 10–20 times smaller than the semisolar.With 8 Figures  相似文献   

7.
Zusammenfassung Im schweizerischen Alpengebiet wurde während des I.G.J. in einem Höhenbereich von 380 bis 2670 m ü. M. ein reichhaltiges Material an Intensitätswerten der direkten Sonnenstrahlung wie auch für die Bereiche der Schottschen Glasfilter OG 1, RG 2 und RG 8 gesammelt und unter Anwendung der vonW. Schüepp entwickelten, vom Verfasser vereinfachten Auswertemethode zur Berechnung der atmosphärischen Trübungsparameter benützt. Die auf diese Weise ermittelten Zahlenwerte des TrübungskoeffizientenB, des Wellenlängenexponenten und des WasserdampfgehaltsW (precipitable water) wurden einer Bearbeitung unter klimatologischen, aerologischen und synoptisch-dynamischen Gesichtspunkten unterworfen sowie dunstoptische Fragen behandelt. Über die Ergebnisse wird auf S. 206 ff. zusammenfassend berichtet.
Summary A large material of intensity values of the direct solar radiation as well as for the spectral parts of the Schott glass filters OG 1, RG 2 and RG 8 has been collected during I. G. Y. in the Swiss alpine region in altitudes between 380 and 2670 m a. s. l. It has been used for calculating the atmospheric turbidity parameters by employing the method developed byW. Schüepp and simplified by the present author. The numerical values of the turbidity coefficientB, the wavelength exponent and the precipitable waterW thus determined have been processed under climatological, aerological and synopticdynamical points of view as well as for the discussion of problems of the optics of haze. A summary of the results may be found on p. 206.
Résumé Pendant l'Année géophysique internationale l'auteur a rassemblé un matériel abondant de mesures d'intensité du rayonnement solaire direct ainsi que dans les gammes des filtres de Schott OG 1, RG 2 et RG 8, dans les Alpes suisses, entre 380 et 2670 m; simplifiant le procédé d'analyse deW. Schüepp, il a utilisé ce matériel pour le calcul des paramètres de trouble atmosphérique. Les valeurs du coefficient de troubleB, de l'exposant de longueur d'onde et de la teneur en vapeur d'eauW furent examinées du point de vue climatologique, aérologique et synoptique, en abordant aussi des questions d'optique de la brume. Les résultats sont résumes p. 206 sq.
Mit 31 TextabbildungenVon der Philosophisch-naturwissenschaftlichen Fakultät der Universität Basel genehmigte Dissertation (1960).  相似文献   

8.
Data collected during the Indo-Soviet Monsoon-77 expedition are used to determine quadratic expressions for the universal constants A and B, as functions of the stability parameter, . A quadratic expression has also been obtained for u *, in terms of the surface wind u s. It is shown, from the mean values of q and E , that the entire area covered by the expedition could be divided into four regions around the point 13° N, 78° E. The mean thermal characteristic of each region differs. It is shown that the northeastern quadrant is most favourable for the sustenance of a tropical storm once it has formed.  相似文献   

9.
Summary The broadband solar absorptivity concept is employed to parameterize the aerosol absorption effect. The solar radiation model developed by Liou and his associates was modified to incorporate the parameterization of solar radiative transfer in an aerosol layer. Comparison of the results from this method with other schemes exhibits close agreement. A Sahara dust storm case was also chosen to test the performance of the present model, and the computed heating rate profiles agree well with calculations based on optical properties derived from observations for both clear and dust cases. In general, enhanced heating due to aerosol absorption of solar flux occurs particularly in the lower troposphere (below 5 km). The heating rate is independent of the scattering partition factor (), but the planetary albedo increases with . Further study shows that the aerosol heating is sensitive to the surface albedo (r s ) and to the cosine of the solar zenith angle (µ 0). The decrease inr s and/or increase inµ 0 lower the solar heating rate, the planetary albedo and the atmospheric absorptivity, but raise the surface absorptivity due to reduced multiple reflection between the atmosphere and surface.With 9 Figures  相似文献   

10.
A theory is offered for the drag and heat transfer relations in the statistically steady, horizontally homogeneous, diabatic, barotropic planetary boundary layer. The boundary layer is divided into three regionsR 1,R 2, andR 3, in which the heights are of the order of magnitude ofz 0,L, andh, respectively, wherez 0 is the roughness length for either momentum or temperature,L is the Obukhov length, andh is the height of the planetary boundary layer. A matching procedure is used in the overlap zones of regionsR 1 andR 2 and of regionsR 2 andR 3, assuming thatz 0 L h. The analysis yields the three similarity functionsA(),B(), andC() of the stability parameter, = u */fL, where is von Kármán's constant,u * is the friction velocity at the ground andf is the Coriolis parameter. The results are in agreement with those previously found by Zilitinkevich (1975) for the unstable case, and differ from his results only by the addition of a universal constant for the stable case. Some recent data from atmospheric measurements lend support to the theory and permit the approximate evaluation of universal constants.  相似文献   

11.
Summary In addition to global solar radiationE g , the hourly diffuse componentE d incident on a horizontal surface has been measured from February 1993 to January 1995 at a meteorological station in tropical West Africa. The measured diffuse solar irradiance data was corrected for shadow band effects. The monthly mean diurnal variations of diffuse solar irradiance obtained for identical months in the two years have been compared and found to be generally consistent. The corresponding monthly mean hourly values ofE d for identical months in 1993 and 1994 agreed to within 9% while yielding correlation coefficients greater than 0.960. In addition, the monthly mean daily totals ofE d for identical months were found to agree mostly to within 6% and showed virtually the same annual variations in both years. The monthly mean daily total values of diffuse solar radiation for most months in the two years ranged between 7.94 MJm–2d–1 and 10.50 MJm–2d–1. The monthly mean of daily hourly maximum values ofE d obtained for identical months in the two years have been discussed in relation to the dominant atmospheric conditions during these months. The results been presented here have been compared with those of some investigators within and outside the Africa region.With 8 Figures  相似文献   

12.
Equilibrium evaporation beneath a growing convective boundary layer   总被引：1，自引：1，他引：0  
Expressions for the equilibrium surface Bowen ratio ( s ) and equilibrium evaporation are derived for a growing convective boundary layer (CBL) in terms of the Bowen ratio at the top of the mixed layer i and the entrainment parameter A R . If AR is put equal to zero, the solution for s becomes-that previously obtained for the zero entrainment or closed box model. The Priestley-Taylor parameter is also calculated and plotted in terms ofA R and i . Realistic combinations of the atmospheric parameters give values of in the range 1.1 to 1.4.  相似文献   

13.
Zusammenfassung In der vorliegenden Arbeit wird das Strömungsfeld im Bereich der Alpen untersucht. Für einen Vergleich der Windhäufigkeiten zwischen zwei Stationen stellte sich eine Darstellung der Häufigkeiten der Windrichtungen in Matrixform als sehr brauchbar heraus. Man kann aus einer solchen Windmatrix bei einer festgehaltenen Windrichtung in der StationA sofort die Häufigkeiten der gleichzeitigen Windrichtungen in der StationB ablesen. Die Häufigkeitsverteilungen der Windrichtungen an den einzelnen StationenA undB ergeben sich aus der Summe der Spalten bzw. der Zeilen der Windmatrix. Mittels einer solchen Windmatrix ist man auch in der Lage, für das betreffende StationspaarAB charakteristische Kenngrößen anzugeben, die das gleichzeitige Auftreten von Windrichtungen (Spur der Matrix), die Drehung des Windes und dergleichen mehr beschreiben.
Summary In the present paper the authors investigate the stream field over the Alpine region. For the comparison of the wind frequencies observed at two stations the representation of the frequencies of wind direction in matrix notation proved to be very useful. From such a matrix one can immediately read off the frequencies of the simultaneous wind directions at the stationB, when the direction at the stationA is held fast. The frequency distributions of the wind directions at the single stationsA andB result as the sums of the columns and of the rows of the wind matrix. The matrix allows to specify index numbers (e. g. the trace of the matrix) which characterize the simultaneous wind conditions at a pair of stations,AB, the change of direction from one station to the other and so on.
Résumé Dans le présent travail, on étudie le champ des courants dans la région des Alpes. Pour comparer la fréquence du vent à 2 stations, il est apparu que la représentation de la fréquence des directions du vent sous forme de matrice était parfaitement utilisable. Il est possible de tirer immédiatement d'une telle matrice la direction du vent dans une stationB en partant de la direction du vent observée au même moment en une stationA. La répartition des fréquences de la direction du vent aux stationsA etB résulte de la somme des colonnes, respectivement des lignes de la matrice. Une telle matrice permet également de tirer des grandeurs caractéristiques de la paire des stationsA etB. Ces grandeurs expliquent mieux l'apparition simultanée des mêmes directions (trace de la matrice), les rotations du vent d'une station par rapport à l'autre, etc.

Diese Arbeit stellt den Beitrag FRP Alpenwetter Nr. 9/67 eines vom Österreichischen Forschungsrat subventionierten Forschungsvorhabens dar.  相似文献   

14.
Zusammenfassung Für eine Reihe von Atmosphärenmodellen, die untereinander gleiche Temperaturschichtung und konstante relative Feuchtigkeit, aber verschieden hohe Temperatur und Feuchtigkeit im festen Niveau haben, wird der NettostrahlungsstromE in 400 mb und am Boden durch Berechnungen in den bekannten Strahlungsdiagrammen bestimmt. Es läßt sich zeigen, daßE 400 (E B ) als Funktion der Temperaturt 400 (t B ) und der Feuchtigkeit bzw. des Taupunktes 400 ( B ) dargestellt werden kann [Abb. 1 und 3, Gl. (1) und (3)], ählich, wie das für die effektive Strahlung des BodensE B bereits früher durch die Formeln vonÅngström, Brunt u. a. geschehen ist. Wolkenschichten können durch Korrektionsfaktoren berücksichtigt werden. Die Abweichungen zwischen den so gewonnenen Strahlungssummen und den durch Planimetrieren im Strahlungsdiagramm berechneten sind im Durchschnitt kleiner als 3,5% (11%), für die Differenz E=E 400–E B sind sie kleiner als 6%.
Summary For a series of model atmospheres which have the same stratification of temperature and constant relative humidity but different temperatures and humidities at a fixed level, the net radiation fluxE at 400 mb and at the surface are determined by computations in the well known radiation charts. It is shown thatE 400 (E B ) can be represented as a function of the temperaturet 400 (t B ) and humidity resp. dew point 400 ( B ) [Fig. 1 and 3, formula (1) and (3)], in a similar manner as the outgoing radiationE B is already approximated by the formulae ofÅngström, Brunt, a. o. Cloud layers may be accounted for by correction factors. The differences between the radiation fluxes found in this way and those computed by integration in a radiation chart are in the average smaller than 3.5% (11%); with E=E 400–E B , the differences are smaller than 6%.
Résumé Pour plusieurs modèles de l'atmosphère qui ont la même structure par rapport à la température et une humidité relative constante, mais à un niveau fixe des températures et humidités différentes, on calcule à l'aide de diagrammes de radiation connus le flux net de radiationE pour 400 mb et au sol. On peut montrer queE 400 (E B ) peut être représenté comme fonction de la températuret 400 (t B ) et de l'humidité, resp. du point de rosée 400 ( B ) [Fig. 1 et 3, formules (1) et (3)], tout comme cela a déjà été fait pour la radiation effective au solE B grâce aux formules d'Ångström, deBrunt et d'autres. Par un facteur de correction on tient compte des couches de nuages. Les écarts entre les sommes de radiation ainsi obtenues et celles calculées à l'aide des diagrammes de radiation sont en moyenne plus petits que 3,5% (11%), la différence E=E 400–E B ne dépasse pas 6%.

Mit 4 Textabbildungen.  相似文献   

15.
This paper examines the practical importance of stability, baroclinicity, and acceleration in the bulk ABL similarity formulations, in light of the random errors inherent in field measurements. This is done by propagating the measurement uncertainties through a theoretical model for the bulk ABL similarity functionsA 0 andB 0, under a range of assumed (but always unstable) conditions. It is shown that random measurement errors and acceleration effects may overwhelm most effects of baroclinicity and stability, once conditions are at least slightly unstable. Because of this, it is hard to discern a clear functional dependence ofA 0 andB 0 on degree of instability. Thus, for a given value ofh i/z0, whereh i is the inversion height andz 0 is the surface roughness, the geostrophic drag coefficient, which depends onA 0 andB 0, and weakly onh i/z0, may also be taken to be nearly independent of degree of instability.  相似文献   

16.
Summary Relationships between photosynthetically active radiation (PAR) and solar radiation (SR) and between diffuse radiation and global radiation at Bloemfontein, South Africa were investigated. The ratio of PAR to SR (PAR/SR) has been reported from many places in the northern hemisphere, but there were not many PAR/SR measurements documented from the southern hemisphere, including the study region. Based on the present observations, mean PAR/SR in the region (0.48) was not exceptionally different from other reported data (0.45–0.50). The effects of sky condition on PAR/SR were also investigated and confirmed the previous findings. PAR/SR increased as the clearness index (KT=ratio of global to extraterrestrial SR) decreased, as sky conditions varied from clear to cloudy. Thus, PAR/SR can be a simple function of the clearness index (the global PAR model). In this study, PAR/SR was explained by a quadratic function of KT. For the relationship between diffuse and global radiation, a simple linear threshold diffuse PAR model, as a linear function of KT, was proposed for the study region using long-term data of diffuse and global SR. Using the previous findings on the relationship between the ratio of diffuse to global SR (KSR) and the ratio of diffuse to global PAR (KPAR), at high KT, KPAR can be estimated as 30% higher than KSR, while at low KTKPAR is equivalent to KSR.  相似文献   

17.
Zusammenfassung Zur laufenden Bestimmung der Dunsttrübung der Atmosphäre standen bisher fast nur Aktinometer zur Verfügung. Diese Geräte besitzen zur Messung der Sonnenstrahlung thermische Empfangselemente; um die Dunsttrübung und ihre Wellenlängenabhängigkeit genau zu erhalten und von der Absorption des Wasserdampfes zu trennen, sind Filtermessungen (Differenzmessungen) und zeitraubende Auswertungen nötig.Es wurde nun ein handliches Kleinphotometer mit Selen-Photoelement als Empfänger entwickelt, mit dem die Blau- und die Rotstrahlung der Sonne gemessen wird. Zur Auswahl der geeignetsten Photoelemente wurden Messungen über kurzzeitige Ermüdung und Temperaturabhängigkeit des Photostromes sowie über die spektrale Empfindlichkeitsverteilung verschiedener Fabrikate und Typen angestellt. Auch die Temperaturabhängigkeit der Durchlässigkeit verschiedener Filter wird untersucht. Für die Sonnenphotometer werden das Schott-Filter BG 12 und eine dem RG 1 ähnliche, aber viel weniger temperaturabhängige Farbfolie benutzt; die Filterschwerpunkte liegen bei 0,44 und 0,64 . Eine besondere Einrichtung am Sonnenphotometer erlaubt die direkte Ablesung der optischen LuftmasseM. Die Auswertung der Messungen erfolgt mit dem abgeänderten Trübungsdiagramm nachSchüepp und liefert den TrübungskoeffizientenB sowie den Wellenlängenexponenten , durch den die Größenverteilung des Aerosols charakterisiert wird; aus der geschätzten SichtweiteS v undB kann die HöheH D der homogenen Dunstatmosphäre berechnet werden.
Summary Until now only actinometers have been used for the routine determination of the turbidity of the atmosphere by haze. These instruments have thermal receivers for solar radiation. Filter measurements (difference measurements) and laborious evaluations are needed to determine the haze extinction and its wavelength dependency and to separate it from the water vapour absorption.A handy little photometer has now been developed with the aid of which the blue and the red radiation of the sun can be measured. The receiver is a selenium photoelement. For a selection of the best type of photoelement the short time fatigue and the temperature coefficient of the photocurrent as well as the distribution of the spectral sensitivity have been measured. The temperature dependence of the transmission of different glass and foil filters has also been studied. For the new sun photometer the Schott filter BG 12 and a filter like the RG 1 are used; the effective wavelengths of incoming radiation are 0,44 and 0,64 . The photo-current is measured by a technical microammeter. A special device at the sun photometer allows the direct reading of the optical air massM. The evaluation of the radiation measurements with the modified turbidity diagram bySchüepp leads to the turbidity coefficientB and the wave-length exponent , by which the size distribution of the aerosol is characterized. From the estimated visibility rangeS v andB the scale heightH D of the homogenized haze layer can be calculated.
Résumé On ne disposait jusqu'ici pour déterminer le trouble atmosphérique que d'actinomètres à éléments récepteurs thermiques pour la mesure du rayonnement solaire. Il faut des filtres et des calculs fastidieux pour obtenir avec exactitude l'extinction de l'aérosol et pour séparer l'extinction de l'absorption par la vapeur d'eau.L'auteur a mis au point un petit photomètre maniable à cellule au sélénium permettant la mesure des radiations bleues et rouges du soleil. Pour choisir le meilleur type d'éléments photoélectriques, on a exécuté des mesures de fatigue, du coefficient de température du courant photoélectrique, de la distribution spectrale de la sensibilité, ainsi que de l'effet de température sur la transparence des filtres de Schott. Pour le nouveau photomètre on utilise le filtre BG 12 de Schott ainsi qu'une feuille colorée semblable au filtre RG 1 de Schott mais avec une dépendance de température moins prononcée; leurs longueurs d'onde effectives pour le rayonnement solaire sont 0,44 et 0,64 . Le courant se mesure au moyen d'un microampèremètre, et une échelle spéciale permet la lecture directe de la masse optiqueM. Le diagramme deSchüepp modifié donne le coefficient de troubleB ainsi que l'exposant de longueur d'onde qui caractérise la distribution de grandeur de l'aérosol. A partir de la visibilitéS v et deB on peut calculer la hauteur de l'atmosphère troublée homogène.

Mit 16 Textabbildungen  相似文献   

18.
As photosynthetically active radiation (PAR) variability and PAR estimating methods play an important role in climate change and ecological process research, PAR variation trends and broadband global solar radiation (R s ) ratios (PAR/R s ) in the North China Plain (NCP) are examined using in situ PAR and R s observed data for 2005 to 2011. The annual average PAR value found in the NCP is 22.9 mol m?2 d?1. The highest and lowest values were recorded at Changwu and Luancheng sites, respectively. The highest PAR/R s value was found in Jiaozhouwan due to large water vapor volumes present in this area. PAR/R s levels have increased in the NCP due to a decrease in fine aerosols and increase in water vapor concentration. From these analysis results, a parameterization model that can be applied to all sky conditions was checked. Empirical estimation model comparisons for obtaining PAR values indicate that model was least accurate when R s was used independently. When the model included R s, the clearness index (K s) and the solar zenith angle, the model estimated PAR values with acceptable accuracy. A parameterization model was constructed by considering K s and attenuation factors of PAR under clear weather conditions (ρ clear). The improved parameterization model more accurately predicts values for local sites and for various observation sites.  相似文献   

19.
Several formulations and proposals to determine the value of the radiometric scalar roughness for sensible heatz 0h,r are tested with respect to their performance in the estimation of the sensible heat flux by means of the profile equations derived from Monin-Obukhov similarity theory. The equations are applied to the data set of spatially averaged surface skin temperature and profiles of wind speed and temperature observed in a pasture field during a growing season. The use of a physical model developed for a dense canopy to estimate scalar roughness for sensible heatz 0h,r produced sensible heat fluxH with a correlation coefficientr=0.884, the ratio of means being H s /H=1.19 in a comparison with reference values ofH s . In comparison, a proposal for a fixed value ofz 0h yieldedr=0.887, H s /H=0.879. In both cases, the validity ofz 0h =z 0h,r was assumed. All expressions derived to estimatez 0h,r from a multiple linear regression with such predictors as leaf area index, solar radiation and the ratio of solar radiation to extraterrestrial radiation, were found to produce a better result, withr better than 0.90 and H s /H around 1.0. However, when the constantsc andf of a linear regression equationHs=cH+f are used to evaluate the equations, a marked difference in performance of each formulation appeared. In general, equations with smaller numbers of predictors tend to produce a biased result, i.e., an overestimation ofH at largeH s . These values ofH are used in conjunction with the energy balance equation to derive values of the latent heat fluxLE, which are shown to be in good agreement with the reference valuesLE s , withr greater than 0.97.  相似文献   

20.
Summary A dispersion model is proposed to predict the continuous vertical variation of the dispersion parameters y and z in case of hot pollutant release to the atmosphere. In such a case, the plume rises far above the ground and is subject to varying levels of turbulence. The framework in this paper can be divided into three approaches: (1) determination of the eddy diffusivitiesK y (z, y ) andK z (z, z ) as functions of height above ground and plume dimensions, (2) determination of both the plume rise and its vertical velocity using a modified version of Brigg's formula, and (3) numerical solution of actual problems with buoyant plumes at each time step. The model results have been applied to a case of pollutant release from fire destruction of a chemical storehouse roof.With 15 Figures  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号