bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of sampling and averaging on the spectrum of turbulence
Authors: Smith F. B. 
Published: February 2007

AbstractThe dual effect of averaging wind‐fluctuation data and subsequent sampling over periods of specified duration modifies the full spectrum of turbulence at both high frequencies and low frequencies. The nature of the wave filtering so implied has been known and used for some years, but apparently the derivation of the mathematical form of this filter so far has not been set down in the literature in a completely satisfactory form. This note is an attempt to meet this need.
A note on the equation of mean motion as used in numerical prediction
Authors: Jones D. E. , Graystone P. 
Published: February 2007

AbstractAn investigation is made into the behaviour of the individual terms in the vertically averaged vorticity equation. It is shown that certain minor terms are biased in sign, and that their inclusion may lead to gross errors in a numerical forecast. The separate terms are also shown to increase in magnitude in the course of a numerical forecast but at differing rates.
Evidence of geostrophic motion in the equatorial stratosphere
Authors: Reed R. J. 
Published: February 2007

AbstractThe characteristics of the temperature oscillation associated with the recently discovered 26‐month oscillation of the zonal wind component in the equatorial stratosphere are inferred from the thermal wind relationship. Computations based on actual wind data predict an amplitude of 2·5°C for the temperature oscillation near the equator and a phase difference of one to two months between wind and temperature cycles at 20 km increasing to seven months at 24 km. The close correspondence between predicted and observed characteristics supports the hypothesis that the 26‐month oscillation is in geostrophic equilibrium.The hypothesis is also supported by a consideration of relative sizes of the local wind acceleration and Coriolis force which indicates that the acceleration becomes an order of magnitude less than the Coriolis force at a distance of 40 km from the equator.
Gravity waves in the atmosphere as a three‐dimensional problem
Authors: Sawyer J. S. 
Published: February 2007

AbstractAn equation is derived (see Eq. (10)) for the vertical variation of the amplitude of standing waves when the wind direction varies with height and the wave is periodic both in the x‐ and y‐directions. The equation is solved numerically for specified two‐ and three‐layer atmospheres to determine possible wavelengths in the x and y directions for lee‐waves. The lee‐wave pattern is calculated for an isolated hill in specified cases.
The radar equation in meteorology
Authors: Probert‐Jones J. R. 
Published: February 2007

AbstractWhile meteorologists can obtain much useful information by using radar in a qualitative manner, great benefit can be derived by obtaining quantitative measurements. However, these measurements have been found, in general, to be below values calculated from radar theory by a factor of between two and five, and there has been no satisfactory explanation for this discrepancy. In this paper, the radar equation for a meteorological target is derived, particular attention being devoted to the effect of the shape of the main lobe of the beam, and of the radiation outside it. It is shown that previous theoretical expressions for both the gain and the echoing volume have been too large, and hence that previous equations overestimated the received power. The present equation gives good agreement with all the experimental data.
Transfer through the tropopause and within the stratosphere
Authors: Newell R. E. 
Published: February 2007

AbstractThe evidence for tropospheric‐stratospheric mass exchange is reviewed. A large fraction of the exchange appears to occur in the vicinity of the middle latitude tropopause discontinuity and the concomitant jet stream. Calculations of the flux of radioactive substances in the troposphere support this view. Computations of the horizontal flux of ozone in the lower stratosphere are presented for the I.G.Y. period divided into three‐month seasons. Indications are that the large‐scale quasi‐horizontal transient eddies can transport ozone polewards in sufficient quantities to account for the spring build‐up of ozone. Such large‐scale mixing, as opposed to mean meridional motions, also allows explanation of the distribution of radioactive tungsten in the stratosphere. Transports appear to be polewards and downwards between latitudes 20° and 60°. Independent meteorological evidence, in the form of isentropic cross‐sections and values of the covariance between the meridional and vertical components of the wind, support the mixing scheme. The observed counter‐gradient eddy flux of heat can be explained from the model. Distributions of certain other trace substances are not at variance with the model. From a preliminary examination of the angular momentum transport processes up to 60 km it appears that transient eddies are also important to these levels but there is not yet sufficient global coverage to evaluate the contributions due to mean motions and standing eddies.
Long‐wave radiation from clear skies
Authors: Swinbank W. C. 
Published: February 2007

AbstractAnalysis of the observations of long‐wave radiation from clear skies, R, made by Dines at Benson, yields a correlation coefficient of 0·99 between R and the black‐body radiation at the corresponding screen temperature T. A new series of measurements over wider ranges of temperature and humidity confirms this, with the same value for the correlation between R and σT4, the regression equation being: R = −17·195 σT4 (milliwatt cm−, T °K).An alterlative representation of equals accuracy is R = 5·31.10−14 T−6 (Milliwatt cm−2, T°K) The latter formulation is probably better founded physically, and brings out the temperature dependence of the ‘effective emissivity’ ϵ (i.e. R/σT4), which the atmosphere must exhibit. Either expression provides an estimate of R in terms of T with a probable error less than 0·5 mw cm−2.The present analysis omits any explicit reference to the influence of vapour pressure e on R, and so differs essentially from those due to Brunt and Angström. Re‐appraisal of these latter suggests that the relationships established therein between * and e result basically from a correlation between temperature and humidity. Both the nature and the degree of the correlation between RσT4 and e for a given locality would then depend on the temperature‐humidity regime occurring there. The wide variations from place to place, both in the values of the coefficients occurring in the Brunt and Angström equations, and in the degree of correlation found between R/σT4 and the corresponding function of e, are thereby explained.
Vertical temperature profiles over adjacent land and lake stations
Authors: Munn R. E. , Richards T. L. 
Published: February 2007

AbstractA comparison is made between vertical temperature profiles obtained concurrently from land and lake stations about one‐half mile apart. Tethered balloons were used to support modified radiosondes up to 1,000ft. The results of 46 ascents are time‐grouped to show significant differences between the profiles throughout most of the 24 hours. These differences are mostly obviously consistent with the difference in thermal properties of the underlying surfaces, but in some respects a more complex relation, associated with the lake breeze, may be involved.
A note on determining the scale of turbulence
Authors: Pasquill F. , Butler H. E. 
Published: February 2007

AbstractRecent observations of wind inclination near the ground in stationary conditions, are shown to possess properties consistent with an effectively complete description of the turbulence on the low‐frequency side. The results are therefore particularly suitable for determining the conventional time‐scale of turbulence, and the values obtained are found to be appreciably greater than many previous estimates. The results are then used to examine the accuracy of estimating the scale from data which are less complete on the low‐frequency side (shorter sampling duration), by making assumptions about the shape of the whole spectrum, and it is seen that assumptions which have hitherto seemed reasonable for this purpose can in fact lead to a two‐fold or greater underestimation of the scale. It is inferred that for adequate low‐frequency specification (hence reliable estimation of scale) the sampling duration over which measurements should be made and repeated many times must be at least 40 times the time‐scale.
The electrification of snowstorms and sandstorms
Authors: Latham J. 
Published: February 2007

AbstractAn analysis is made of available observations on the electrical properties of natural and artificial snowstorms. an explanation for this electrification is given in terms of a theory of charge transfer associated with temperature gradients in ice, which has been shown earlier to provide a tenable theory of thunderstorm electrification. Further analysis shows that sandstorms exhibit similar electrical effects to those of snowstorms, and it is suggested that the temperature gradient effect may provide an explanation for sandstorm electrification.
Trees and climatic history in scotland
Authors: Lamb H. H. 
Published: February 2007

AbstractScotland constitutes a gap in our information about the Early Middle Ages warm epoch (circa 1000–1300 A.D.). Evidence has been sought from vegetational history as well as documentary records.A sample tree found lying in a peat bog at an exposed part of the north‐west coast where trees no longer grow was discussed in the Quarterly Journal, 1945, when it was thought to have grown there in the Middle Ages or later. the result of a radiocarbon dating test on this tree contradicts all the opinions then expressed about its age. the tree and other remains from the same bog are now shown to have belonged to the latter part of the post‐glacial climatic optimum before 2000 B.C., and there is no tangible evidence that trees have grown at the point in question at any time since 1000 B.C. This compels a re‐assessment of the other evidence, of what we may hope to learn from it and how much we know so far about the climatic history of Scotland in medieval and post‐medieval times.Documents of the times concerned, already used but not so far quoted in this connexion by various historians, have yielded the most promising indications to date. the isolated facts and impressions gained from these sources seem most simply explained by assuming that Scotland shared the general experience in northern lands of a warm epoch, accompanying the period of high culture, from 1070 A.D. or earlier, to around 1300 and that the subsequent deterioration had serious effects upon the economy. the evidence from Scotland, as opposed to that from neighbouring countries, of frequent bad seasons and deteriorating condition of the land, is so far, however, almost entirely indirect and in itself inconclusive. Only after 1550 are enough facts known to make the latter stages of the decline culminating in the dire years of the 1690's reasonably clear and unmistakable.
A tentative model of the 26‐month oscillation in tropical latitudes
Authors: Reed R. J. 
Published: February 2007

AbstractA model of the three‐dimensional wind and temperature fields in the 26‐month oscillation is presented, based in part on empirical data concerning the temperature behaviour and its relationship to the zonal wind behaviour and in part on theoretical deductions from the thermodynamic energy and continuity equations.The empirical data show that equatorward of 16° latitude highest temperatures precede the west wind maximum by intervals varying from 4–5 months at the 20 mb level to 0–1 months at the 80 mb level. Near the Equator the amplitude of the temperature oscillation is approximately 2°C and varies little with height in the foregoing altitude range. In the subtropics the phase of the temperature cycle is nearly opposite to that at the Equator, lowest temperatures preceding the maximum (relative) westerlies. the amplitude at these latitudes increases from a fraction of a degree at 80 mb to about 1°C at 20 mb. the features of the temperature and zonal wind behaviours are shown to be consistent with the thermal wind relationship.The theoretical results indicate that the vertical velocity has a maximum amplitude of about 0·01 cm sec−1 at the Equator and that the phase of the vertical velocity oscillation reverses near 15° latitude. Maximum subsidence precedes highest temperatures by about one month. Meridional velocities are strongest near 15° latitude where they reach values of 1–2 cm sec−1. Maximum northerly winds follow maximum subsidence by about one‐quarter cycle.The observed quasi‐biennial oscillation of total ozone amount is shown to be qualitatively consistent with the model, and near the Equator, to be in quantitative agreement with the theoretical results.It is speculated that the 26‐month oscillation possesses two superposed modes: a tropical mode characterized by a vertically‐propagating wave and a hemispheric mode consisting of a Pole to Equator standing wave. Finally, it is proposed that the oscillation has its origin in a subharmonic response to the annual heating cycle.
The ‘southern oscillation’
Authors: Troup A. J. 
Published: February 2007

AbstractAn attempt is made to obtain a coherent picture of the extent and mode of operation of the ‘southern oscillation.’ This term is used here, following Sir Gilbert Walker, to describe a standing fluctuation of opposed pressure anomalies in both eastern and western hemispheres. The existence of this opposition has been verified, using more recent data, for stations in the Indian and Pacific Ocean regions; results show the oscillation was less marked in recent decades.The representativeness and physical meaning of the index devised by Walker to characterize the state of the oscillation are considered. The geographical extent of the phenomenon is examined using correlation and regression charts of pressures with Walker's index. The temperature and rainfall anomalies associated with it may be derived qualitatively from the pressure anomalies.Recent data are used to verify persistence and lag correlations between station pressures; while there has again been some decline, the lag correlations of elements with previous South America pressures still hold good. The decline in these various quantities is indicative of a minor secular change commencing in the 1920's, which is also evident in a decrease in the variability of pressure.What ‘periodicities’ appear to exist in elements affected by the southern oscillation may well be an outcome of sampling fluctuations in (often persistent) random series. This is suggested by the variety of supposed ‘periods’ reported, and their evanescence in space and time. An example of this evanescence in time is provided from the Darwin pressure record.A mechanism for the oscillation is proposed in terms of variations in a direct toroidal circulation between warmer eastern and cooler western hemispheres. These variations are attributed, (following a model by Palmer of the synoptic climatology of the tropical Pacific) to variations in the south‐east trades in the South Pacific and the consequent variations in cyclonic vortex generation in the West Pacific. The persistence of anomalies is then due to the extent of ocean areas in the south‐east Pacific where the sea temperature is lower than the air temperature. The lag correlations observed may be due to this persistence and to a transmission of anomalies along the trades through air‐sea interaction.
The computation of infra‐red cooling rate in planetary atmospheres
Authors: Rodgers C. D. , Walshaw C. D. 
Published: February 2007

AbstractA scheme is described for the calculation of the atmospheric infra‐red radiative cooling rate which is suitable for use at all levels. It uses the Curtis matrix method together with the Curtis‐Godson approximation in a form which includes the influence of temperature on line intensity. Doppler effect is included. Because of its simplicity the Goody random model is used for all the absorption bands considered (H2O rotation and 6.3μ, CO2 15μ, O3 9.6μ); the use of more accurate models as they become available presents no fundamental difficulty and in any case many of the topics investigated are not particularly sensitive to the spectral model used. A method of reducing the number of spectral intervals is described and its accuracy demonstrated. An accurate method of dealing with diffuse radiation is used to test the diffuse approximation, with the result that the constant factor 1.66 originally proposed by Elsasser is found to be quite adequate for most purposes. Cooling rate errors caused by the following factors are estimated: (1) random and systematic errors in the initial temperature and humidity profiles; (2) the size of the vertical step used in computation; (3) neglecting the temperature dependence of the Curtis matrix; (4) non‐linear effects in forming climatological means. It is shown that the easily computed ‘cooling to space’ is often a good approximation. All the error investigations are based on direct calculations of the cooling profile. Some comparisons with other techniques are presented and a number of examples of meteorological interest are used to illustrate the versatility of the computing scheme.
Isentropic relative‐flow analysis and the parcel theory
Authors: Green J. S. A. , Ludlam F. H. , McIlveen J. F. R. 
Published: February 2007

AbstractA discussion is given of the justification and usefulness of analysing on isentropic charts observations of the flow relative to a mature large‐scale motion system under the assumption that the system is in a steady state. It appears that trade wind air may rise over a front into a jet stream and that by an extension of the parcel theory into three dimensions the speed of a jet stream may be related to an area on the aerological diagram.
The role of deformation in the large‐scale dispersion of clusters
Authors: Djuric D. 
Published: February 2007

AbstractA study is made of the deformation of fluid bodies in horizontal flow in the absence of small‐scale turbulent diffusion. On the basis of a kinematic model, formulae for the increase of the separation of pairs of particles and of the dispersion of particles from the centre of gravity of each cluster of particles are given. The results are compared with statistical data from the dispersion of air trajectories in a barotropic model corresponding to the development of the flow in the Northern Hemisphere over a period of 8 days.The dispersion of clusters by deformation is used to demonstrate how the diffusion coefficient increases with the scale of motion.
A new method for the prediction of typhoon movement using the 700 mb chart
Authors: Tse S. Y. W. 
Published: February 2007

AbstractStorm tracks which crossed the area between the Equator and 35°N, 105°E and 160°E, during the period 1957 to 1960 have been analysed. For each storm position values of the 700 mb contour height (geopotential metres) He, Hw, Hs and Hn, were extracted at four selected grid points labelled as E, W, S and N respectively. E and W were at distances of 10° longitude east and west of the storm centre, S and N at distances of 10° latitude south and north of the storm centre. The differences (He − Hw) = ΔϕH and (Hs − Hn) = ΔϕH were computed for 516 storm positions and used as predictors. The subsequent 24‐hr meridional and zonal displacements of the storm in degrees latitude and longitude, Δϕ and Δλ, were chosen as predictands. The over‐all synoptic pattern at 700 mb was then introduced as an additional criterion. Regression lines corresponding to a few easily recognized synoptic patterns were derived from scatter diagrams of ΔϕH versus Δϕ and ΔλH versus Δλ. A nomogram was constructed to give Δϕ and Δλ for values of ΔϕH and ΔλH respectively.The method, tested in 44 forecasts on 8 storms during May to September 1961, gave an average error of 87 nautical miles; this compares favourably with other objective methods.
Local differences in the attenuation of solar radiation over Britain
Authors: Monteith J. L. 
Published: February 2007

AbstractIn relation to other British stations, radiation totals at Aberporth on the Welsh coast are anomalously high. On the basis of recorded sunshine, the annual mean intensity of direct radiation at Aberporth is 31 mw cm−2 compared with 25 mw cm−2 elsewhere. Allowing for the change of extra‐terrestrial radiation with latitude, the effective transmission of the atmosphere is greatest at Aberporth and Lerwick, less at Eskdale‐muir, and least at Kew, consistent with differences of air pollution. Measurements at a station installed near Aberystwyth suggest that the relatively clean air over Aberporth may be confined to a very narrow coastal strip.At Kingsway, the direct radiation per hour of sunshine increased from 21 mw cm−2 in 1957 to 26 mw cm−2 in 1963 consistent with the decrease of smoke in central London. Kingsway and Kew now record about the same intensity of radiation attenuated at roughly 1 per cent per 10 μg m−3 of smoke.Applying this analysis to the radiation balance of Britain, previous estimates of potential evaporation in north Scotland were raised from 13 to 17 inches per year, removing most of the difference in estimated evaporation over Britain.
Features of Transvaal hailstorms
Authors: Carte A. E. 
Published: February 2007

AbstractHailstorms in the vicinity of Johannesburg and Pretoria, South Africa, are being studied mainly by means of a dense network of voluntary observers. The storms have shown great variability. A characteristic of sustained storms is their tendency to move to the left of the mid‐tropospheric winds, whereas in the Northern Hemisphere movement is to the right. One of these storms appeared to be multicellular at a stage when hailstones up to 6 cm diameter were falling. Another produced large spongy hailstones along part of its path.
The melting of small ice spheres and cones
Authors: Drake J. C. , Mason B. J. 
Published: February 2007

AbstractThe times of complete melting of small ice spheres in airstreams of controlled temperature, humidity and velocity were measured and compared with the values computed from theory. The theory, which allows for heat transfer to the ice particle by conduction through the air and by condensation upon its surface, agrees quite well with the observations if allowance is made for the heat content of the water retained by the particle during the melting process. The melting times of small ice cones of various shapes did not differ from those of spheres of equivalent volume by more than 10 per cent. It was demonstrated both theoretically and experimentally that an evaporating ice sphere will acquire the same surface temperature as the ice‐coated junction of a thermocouple psychrometer placed in the same airstream provided that the radiation and conduction errors of the latter are rendered negligible by good design.
Annual variation of ozone in Antarctica
Authors: Dobson G. M. B. 
Published: February 2007

AbstractObservations of the total ozone at Halley Bay (75°S) during the I.G.Y. showed that the annual variation there was very different from that found at a similar northern latitude. Later observations now available show similar characteristics. Further, recent measurements at the South Pole and at Byrd (80°S) give similar results to those at Halley Bay, indicating that this type of annual variation is probably characteristic of Antarctica generally.
Objective analysis of the 100 mb level
Authors: Woodroffe A. 
Published: February 2007

AbstractThis paper describes an objective technique for the analysis of 100 mb contour charts. The method is basically an extension of a procedure that has proved successful at lower levels. The problems associated with the analysis of contour heights at 100 mb and above are discussed briefly and a sample analysis is shown. It is considered that the objective analyses are of similar standard to those produced by an analyst using conventional methods.