bluuebunny/crossref_metadata_2025_split huggingface dataset:
Note on the computation of heat sources and sinks in the atmosphere
Authors: Shaw D. B. 
Published: February 2007

AbstractThe contributions of various transport terms in the thermodynamic energy equation are calculated over the Northern Hemisphere for the four seasons. Local heating is found to be an order of magnitude less than the other terms. The computed fields due to mean horizontal motion cover a more extensive area than those of earlier investigations and extend over the Northern Hemisphere from surface to 100 mb for the four midseason months. An attempt to represent the effect of horizontal transient disturbances by relating it empirically to the mean temperature field is found to be unsatisfactory; direct computations are made of the eddy contribution over a large part of the hemisphere, for three successive winters and one summer. An estimate of the contribution due to vertical motions, both mean and transient, is obtained indirectly as the difference between results of the present study and those of earlier independent investigations of atmospheric heating.
Temperature and humidity changes in the lowest few thousand feet of atmosphere during a fine summer day in Southern England
Authors: Zobel R. F. 
Published: February 2007

AbstractAircraft observations are used to examine the temperature and humidity changes beneath a subsidence inversion on a fine day in Southern England, including some details of the breakdown of a nocturnal radiation inversion. The findings in regard to the latter are in substantial agreement with those of Izumi (1964). Consideration of the heat and moisture balances of the surface and of the layer of air beneath the subsidence inversion leads to the conclusion that daytime convection causes penetrations of the inversion which are compensated by the downward movement of air of higher potential temperature from above the inversion. In the case studied, the daytime rise in temperature of the air column beneath the inversion was found to be largely due to this downward flux of heat and to direct absorption of solar radiation, the heat flux from the surface being relatively small, since the net radiative flux was mainly expended on evaporation of water.
Evidence for a longer period tidal oscillation in the tropical atmosphere
Authors: Brier G. W. 
Published: February 2007

AbstractA tidal explanation is offered for the biennial oscillation observed in the stratosphere. Evidence is presented that the variations in the amplitude of the 12‐hour pressure oscillation (S2) at Batavia are significantly correlated to the changes in the magnitude of the luni‐solar tidal forces, which can be shown to have a period of approximately 27 months in tropical latitudes. The suggestion is made that the forces producing an amplification of the S2 oscillation are linked to the circulation changes through mechanisms involving increased cloudiness and precipitation.
Examination of certain terms appearing in Reynolds' equations under unsteady conditions and their implications for micrometeorology
Authors: Bernstein A. B. 
Published: February 2007

AbstractReynolds' equations are generally valid only when the bar operator represents an ensemble average. Such averages are rarely calculated in practice, the usual approach (especially in micrometeorology) being to calculate a time average instead. When conditions are at all unsteady, this practice necessitates consideration of additional terms in the expression for the Reynolds flux. It is shown, with the aid of a series of rapid‐response measurements of wind and temperature, that these terms are not necessarily negligible and that under unsteady conditions the complete Reynolds flux expression may differ considerably from the quantity generally computed; also, the vertical gradients of the two quantities will differ. A quantitative criterion of steadiness is proposed and is shown to be highly correlated with the difference between the complete Reynolds flux and the quantity usually calculated.
Antarctic stratospheric warming reviewed in the light of 1967 observations
Authors: Phillpot H. R. 
Published: February 2007

AbstractUnlike the Northern Hemisphere where a number of extremely well documented case studies to very high levels facilitate the study of polar stratospheric warming, most investigations so far in the Southern Hemisphere have been directed mainly to the 100 mb, or occasionally 50 mb level. In 1967 it was possible to draw a series of daily 30 mb contour charts through the spring period, and 30 mb isotherm charts for the month of October over the Antarctic. The contour charts showed that the polar vortex: changed little in depth until the end of September then filled steadily; was initially single centred, became double‐centred, then finally single centred again; developed a double‐wave pattern, the perturbations moving progressively and regularly around the vortex. The movement of these waves was accompanied by short period, but marked, temperature changes at a given point (warm ridges and cold troughs), but even after the major warming was completed at this level over the continent, the circulation was still predominantly cyclonic. From the limited information available it appears that in 1967 the short period temperature changes may have been more pronounced than in some earlier years, but the general warming trend was normal. Wave movement around the polar vortex could also be detected in an autumn and winter season, and apparent mid‐winter stratospheric warmings previously reported or observed may be ascribed to the passage of migratory warm ridges, although this explanation is not advanced for the mid‐winter warming event inferred over McMurdo in 1963.
The lunar and solar semidiurnal variations of barometric pressure at Copenhagen, 1884–1949 (66 years)
Authors: Chapman S. 
Published: February 2007

AbstractSixty‐six years of bihourly barometric data for Copenhagen (55°·7N) are used to determine the lunar atmospheric tide there, L2 (p), and also the harmonic components Sn of the solar daily barometric variation S (p), for n = 1, 2, 3, 4, For L2 (p) seasonal means are given as well as the annual mean; for S2 (p) monthly, seasonal and annual mean values are given. The determinations are made for groups of days with different upper limits of range, 6·0 microbars (μb) and 8·7 ph, as well as for all days. It is shown that it is advantageous to exclude the days of larger range from the determination of L2 (p). Days of larger range are most frequent in winter. At that season, for days of smaller range, the mean pressure is higher than in summer.The 66‐year mean annual value of L2 (p) is 10·3 sin (2r + 87°·3) μb, with probable error 2·5 μb; for S2 (p) it is 225 sin (2t + 130°·8), with probable error 2·8 μb; here r and t denote respectively lunar and solar mean local time. Thus, in amplitude, S2 is 21·9 times L2, and in phase S2 exceeds L2 by 43°·5; L2 and S2 at Copenhagen vary seasonally in different ways; in both cases these variations are similar to those observed elsewhere in northern Europe. The corresponding amplitudes for Oslo (59°·9N), found by Haurwitz and Cowley (1967), are somewhat smaller, as might be expected.
Microwave observations of sea state from aircraft
Authors: Nordberg W. , Conaway J. , Thaddeus P. 
Published: February 2007

AbstractMeasurements of the thermal radiation emitted by natural water surfaces at a wavelength of 1·55 cm have been measured from aircraft at up to 12 km altitude.The dependence of the radiation on surface roughness is studied in view of its possible importance to satellite observation of sea state.
On the interaction between the stratosphere and troposphere during the warming of December 1967‐january 1968
Authors: Miller A. J. , Johnson K. W. 
Published: February 2007

AbstractCalculations of the transfer of kinetic energy from the troposphere to the stratosphere by means of the pressure‐interaction term are carried out for the mid‐winter stratospheric warming of 1967‐1968. This term is computed in the wave number domain for the 100 mb level by means of the Eliassen and Palm (1960) approximation. There appears to be a distinct correlation between the stratospheric kinetic energy per wave number at the 10 mb level and the energy transfer by that wave number at the 100‐mb level. A comparison of the magnitude of the energy flux for 1963 versus that for this later warming suggests that this term is of the same order as the remaining terms in the kinetic energy equation calculated by Perry (1967). Results obtained using this approximation appear to give good agreement with those obtained by direct calculation of the vertical velocity field.
New lag associations between North Atlantic sea temperature and European pressure applied to long‐range weather forecasting
Authors: Ratcliffe R. A. S. , Murray R. 
Published: February 2007

AbstractA feed‐back relationship, at least in the statistical mean, between Atlantic sea surface temperatures on the one hand and monthly atmospheric circulation anomalies on the other hand, is demonstrated for the north‐east Atlantic and western Europe. The key area in the Atlantic is a wide area south of Newfoundland; colder than usual ocean surfaces in this area are shown to be associated with blocked atmospheric patterns the following month over northern and western Europe while a warmer than usual ocean in the same general area favours more progressive synoptic types to follow. Month to month changes in this general relationship are described in some detail and the application to long‐range forecasting in the British Isles is discussed. One other pattern of Atlantic sea surface temperature anomaly is also described and associated with atmospheric circulation patterns to follow.Possible inter‐relationship between the Atlantic and Pacific Oceans in respect of the effects of ocean surface temperatures on circulation patterns is also briefly considered.
Surface exchanges of sensible and latent heat in a 10‐level model atmosphere
Authors: Gadd A. J. , Keers J. F. 
Published: February 2007

AbstractThis paper describes a representation of the distribution of sensible and latent heat from the surface through the atmospheric boundary layer which has been formulated for use in a 10‐level primitive equation model atmosphere. The transfer process is represented in two parts : (i) the transfer of energy across the Earth's surface into the lowermost 100 mb layer of the model atmosphere; and (ii) the subsequent redistribution of this energy through two or more such layers by small‐scale convection. The fluxes of energy across the surface are calculated using empirical ‘bulk aerodynamic’ relationships. In land regions consideration of the energy balance at the surface is also necessary, and diurnal variations of radiation are taken into account. The redistribution of energy by small‐scale convection is represented by convective adjustments which ensure that a certain neutral lapse rate of temperature is never exceeded. Some results of the incorporation of these effects into the 10‐level model are described.
The water‐vapour infra‐red continuum
Authors: Bignell K. J. 
Published: February 2007

AbstractAll published work on the water‐vapour continuum in the region 8 μ to 50 μ is reviewed in the light of some new experimental results in the 11 to 21 ‐μ region. This new work employed a 15.5 m multiple‐reflection cell, giving total path lengths up to 500 m, and a high‐resolution (1–2 cm−1) grating spectrograph. Control of temperature (20–40°C), and water‐vapour partial pressure (3–35 mb) allowed simulation of tropospheric conditions and their extension to rather higher humidities, but the total pressure could not be varied from atmospheric.The results suggest that two mechanisms of absorption are involved. One of them is almost certainly the foreign‐broadening of water‐vapour lines and it is responsible for most of the continuum absorption noted by previous workers. The origin of the other is not clear; it gives rise to absorption which increases with partial water‐vapour pressure, e, equalling the foreign‐broadened component at e ∼ 15 mb. This behaviour was first reported by Bignell, Saiedy and Sheppard (1963) who then attributed it to self‐broadening of H2O lines. However, the present more sensitive work casts doubt on this interpretation because the absorption is found to have a negative temperature dependence of 2 per cent per °C over the range 21° to 45°C, which is greater than that of any water‐vapour line. Absorption of the same type, though weaker, is present near 4 μ.Reinterpretation of previous open‐air measurements in atmospheric conditions ranging from warm and damp to cold and dry shows that the systematic differences they exhibit might be a manifestation of the new absorption.No firm explanation can be given, but the possibility of continuum absorption by the recently reported water dimer molecule (H2O)2 should be investigated.
The analysis of a hailstone
Authors: Macklin W. C. , Merlivat L. , Stevenson C. M. 
Published: February 2007

AbstractAn analysis has been made of the bubble and crystal structure and of the isotopic composition of a hailstone from a severe storm which occurred near Cardiff on 1 July 1968. A trajectory for the stone has been deduced from the isotopic data which is consistent with its crystal and bubble structures. Updraught profiles have been calculated also and are in reasonable agreement with those inferred from the extended parcel theory.
Concentrations in mountain areas of particles released at low elevations
Authors: Gagin A. , Neumann J. 
Published: February 2007

AbstractConcentrations in the air of ice nuclei active at − 15°C have been measured in Jerusalem, Israel. It is found that the highest concentrations occur almost always on days when the mixing depth in the lower atmosphere over the coastal area to the west reaches Jerusalem's elevation (750–830 m) or an elevation not exceeding a few hundred metres above it. Most of the high concentrations and the mixing depths of about 1,000 m occur in the warm season when a low‐level subsidence inversion is a near‐permanent feature of the atmosphere.The results are consistent with the hypothesis that most of the particles originate in low‐level areas upwind of the city having been carried up to Jerusalem's altitude mainly by vertical mixing.
Tropical disturbances and the general circulation
Authors: Bates J. R. 
Published: February 2007

AbstractThe role of the Tropics in the general circulation of the atmosphere is discussed, with emphasis on the rising branch of the Hadley cell. The rising motion takes place largely in organized tropical disturbances and in the Intertropical Convergence Zone. To understand these systems, it is necessary to parameterize the latent heat release by cumulonimbus clouds in terms of the large‐scale flow. The various methods which have been devised to accomplish this are outlined and the results of large‐scale models incorporating these methods are discussed.
Systematic deviations of clear sky atmospheric thermal radiation from predictions of empirical formulae
Authors: Idso S. B. 
Published: February 2007

AbstractFour replicated measurements of atmospheric thermal radiation were obtained every half‐hour of seven clear days during February at Phoenix, Arizona. All indicated the existence of systematic deviations from the predictions of empirical formulae. By invoking an explanation for the existence of such deviations recently given by Paltridge (1970), the times of occurrence of these deviations could be predicted quite accurately.
Infra‐red heating calculations with a water vapour pressure broadened continuum
Authors: Cox S. K. 
Published: February 2007

AbstractPrevious heat budget studies relying on infra‐red radiation calculations have not used a water vapour pressure dependent continuum absorption in the 830‐1,250 cm−1 region of the infra‐red spectrum. The purpose of this study was to investigate the differences in the infra‐red divergence profiles caused by inclusion of the vapour pressure dependent continuum absorption.The results indicate only a very small change in infra‐red divergence from previous work for a typical midlatitude temperature, water vapour profile. However, for tropical temperature and moisture profiles, the new continuum data result in approximately 30 per cent more total tropospheric infra‐red cooling than obtained using earlier continuum absorption data. In addition, it is shown that within a realistic range of tropical atmosphere moisture content, the continuum infra‐red cooling may act to either stabilize or destabilize the lower layers of the troposphere.
Integrations of the primitive equations on a sphere using the finite element method
Authors: Cullen M. J. P. 
Published: February 2007

AbstractIntegrations of the shallow water equations on the sphere using the finite element method are performed and compared with published integrations of Doron et al. (1974). Better results are obtained with the finite element method than with a second order finite difference method using four times the number of grid points, in particular the breakdown of a Rossby wave of zonal wavenumber 8 is correctly predicted.
Gradient Richardson number profiles and changes within an intense mid‐tropospheric baroclinic zone
Authors: Bosart L. F. , Garcia O. 
Published: February 2007

AbstractThe three‐dimensional pattern of Richardson numbers in isentropic co‐ordinates is investigated for a case study of a mid‐tropospheric baroclinic zone for which special three‐hourly radiosonde data are available. Results show that the lowest Richardson number values are found within the baroclinic zone with most values between 0.25 and 1.0.An equation developed by Roach (1970) was used to relate observed versus computed changes of d/dt (In Ri) in isentropic co‐ordinates throughout the baroclinic zone. In general stretching deformation contributed to an increase of In Ri in downstream regions of the baroclinic zone whereas the converse was true for shearing deformation in mid‐ and upstream regions of the baroclinic zone. Overall agreement between computed and observed changes ranged from poor outside the baroclinic zone to fair to good within the zone.Air parcels entering the upstream region of the baroclinic zone underwent both frontogenesis and decrease in In Ri. The reverse was noted in the downstream region of the baroclinic zone.
Long‐wave radiation at the ground I. Angular distribution of incoming radiation
Authors: Unsworth M. H. , Monteith J. L. 
Published: February 2007

AbstractThe apparent emissivity of the atmosphere ϵ, defined as the ratio of incoming long‐wave radiation to black‐body radiation at screen temperature Ta, was measured under clear skies in the English Midlands and in the Sudan. At a zenith angle Z the emissivity was given by ϵ(Z) = a + bIn(usec Z) where u is the reduced depth of precipitable water (cm). For a set of 46 scans in England, the mean values of a and b were 0·70±0·05 and 0·090 ± 0·002. Systematic deviations about these mean values could be ascribed to: (i) temperature gradients; (ii) aerosol. The Sudan measurements gave a = 0·67 ± 0·03 and b = 0·085 ± 0·002 consistent with the English results and observations already published. There is some evidence that minimum values of a have increased over the past 50 years.Integration over the hemisphere gives the flux density (Wm−2) of atmospheric radiation as 1·06 σTa4 − 119 (T in K), where σ is Stefan's constant, or 5·5 Ta + 213 (T in °C).Radiation records by Dines and Dines (1927) for overcast skies are analysed to show that the angular distribution is the same as for cloudless skies; that the mean temperature of cloud base at their site was UK below screen temperature; and that when the mean fraction of cloud cover is c, the apparent emissivity is ϵa(c) = (1 − 0·84c)ϵa(0) + 0·84c.
The Risø profiles: A study of wind and temperature data from the 123‐m tower at Risø, Denmark
Authors: Peterson Ernest W. 
Published: February 2007

AbstractA new study has been made of the Risø profiles with the following conclusions:
roughness lengths determined from neutral wind profiles selected by gradient Richardson number are biased towards high roughness lengths. Selecting the profiles by using a bulk Richardson number criterion yields average profiles with lower roughness lengths. This roughness length is relatively independent of stability while that determined from profiles using a gradient Richardson number is greater than the roughness lengths for either stable or unstable cases;
it is doubtful whether ‘double kinks’ in some of the Risø wind profiles are caused by local terrain inhomogeneities, as has previously been suggested;
three‐dimensionality and unknown mesoscale and baroclinic effects make it difficult if not impossible to compare current change‐of‐terrain theory with the Riø 123‐m tower data.
Theoretically determined multiple‐scattering effects of dust on Umkehr observations
Authors: Deluisi J. J. , Herman B. M. , Browning S. R. , Sato R. K. 
Published: February 2007

AbstractAn earlier theoretical treatment by DeLuisi (1967) of the optical effect of dust on Umkehr observations, yielded some differences from dust effects determined by an experimental method. The differences were thought to be due to errors in the observations used to obtain the experimental results, and the primary‐scattering restriction imposed on the theoretical calculations. A theoretical investigation was performed recently to assess the effect of multiple‐scattering in an atmosphere with dust. The new results are in better agreement with the experimental data and apparently explain nearly all the differences encountered with the theoretical primary‐scattering results.
A representation of the effects of topography on surface rainfall within moving baroclinic disturbances
Authors: Collier C. G. 
Published: February 2007

AbstractA numerical ‘parameterization’ model has been developed in order to predict precipitation amount over hilly terrain in North Wales. The model enables calculations to be made of the vertical velocity profile resulting from orographic and large‐scale baroclinic effects at grid points one kilometre apart over an area of 2400km2. In the present study the precipitation falling on an area of 103km2, and on areas of order 102km2 within the larger area has been predicted, using as the input to the model large‐scale wind and humidity values derived from radiosonde ascents. Seven case studies are presented. All are examples of fast moving baroclinic systems. This type of system was chosen to minimize the effects of non‐orographic mesoscale or convective mechanisms, which are not parameterized in the present model. The mean error in the predicted rainfall over 103km2 was ± 10% and over 102km2 about ± 20%.
Global dynamics and climate ‐ a system of minimum entropy exchange
Authors: Paltridge G. W. 
Published: February 2007

AbstractIt is found that the mean meridional distribution of temperature, cloud cover and meridional energy flux can be predicted with extraordinary accuracy by application of a simple minimum principle to a multi‐box model of the globe which contains no direct specification of the system dynamics. The minimized quantity is related to the global net rate of production of entropy. It is the sum over all latitude zones of the ratio of net radiant energy input to the effective emission temperature of the zone. The result suggests that global dynamics is something of a passive variable which alters so as to satisfy a condition akin to minimum energy dissipation.
On the asymmetry of the land‐breeze sea‐breeze circulation
Authors: Pearson R. A. 
Published: February 2007

AbstractLand‐ and sea‐breeze circulations are simulated in a mathematical model, using a stably stratified atmosphere as a basic state. The results show that the land‐breeze is weaker than the sea‐breeze even although the heat contrast at the coast is identical in both cases. This is consistent with estimates of the corresponding model energy available potential.