bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: Gastroprotective Agents for the Prevention of NSAID‐Induced Gastropathy
Authors: ARES J. J. , OUTT P. E.
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Bacterial Degradation of Quinoline and Derivatives — Pathways and Their Biocatalysts
Authors: FETZNER S. , TSHISUAKA B. , LINGENS F. , KAPPL R. , HUETTERMANN J.
Published: July 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Wind structure near the ground and its relation to temperature gradient
Authors: Heywood G. S. P.
Published: July 2010

The wind velocities given in this paper were obtained by two anemometers at heights of 12·7 m. and 94·5 m. above the ground. Though the diurnal variation of wind velocity at different heights, has been worked out by numerous observers, there are not many results from anemometers as high as 95 m.; for this reason the ordinary diurnal variation at this height in summer and winter is given below, together with that at 13 m. for comparison.

The diurnal variation at the two heights in strong, moderate and light winds is then considered, somewhat on the lines of Hell‐mann's paper.1

The vertical gradient of temperature up to 87 m. is also. recorded. Wind gradient must depend largely on temperature gradient, and in the next part of the paper the relation between the difference in wind velocity and the difference in temperature over approximately the same height interval, is worked out for various wind strengths. The various factors controlling the wind gradient are investigated, and the results are found to agree with Taylor's, theory of turbulence.2

The gustiness of the wind is also studied in its relation to vertical temperature gradient and to wind direction.

Finally some individual charts, illustrating the various points, are reproduced.
Discussion of memoir
Authors: Roberts O. F. T.
Published: July 2010

From the hypothesis that the density distribution due to scattering satisfies a functional equation expressing uniformity of scattering power, it is shown that the square of the Standard Deviation of matter scattered from a plane source varies as the time. The method used to get this is extended so as to obtain the density distribution in a series of Hermite Polynomials, exhibiting directly the manner in which the distribution may differ from that due to the assumption of eddy scatter analogous to thermal diffusion in a solid. The infinite differential equation corresponding to the functional equation is obtained; and the similar result for homogeneous scattering in three dimensions is derived and extended to scatter from a fixed point or line into a medium with uniform mean flow.

Added june 21, 1933.‐In his application of the Functional Equation to the Brownian Movement, Einstein found it only necessary to use the single exponential solution, the analogy with thermal diffusion thus being exact; this was strictly only justified by experiment (Perrin). For the atmosphere we possess no such experimental evidence.
The effect of wind, temperature, humidity and sunshine on the loss of heat of a body at temperature 98°F.
Authors: Gold E.
Published: July 2010

1. Diagrams are given showing isopleths of the cooling power of the air in millicalories per cm.2 per second for winds up to 30 m.p.h. and for temperatures from 0° to 90°F. for—

(i) A “dry” body at 98°F.

(ii) A “wet” body at 98°F.

(a) For dry air.

(b) For saturated air.

(iii) A “wet” body at 98°F. for wet‐bulb temperatures from 0° to 90°F. They are based on the formulæ given by Hill.

2. The cooling power of the air at Croydon has been computed for each day of the year 1934, both for a dry body and for a wet body, and a frequency table is given showing the number of days in each month with different degrees of cooling power. In an exposed situation there is little difference on the average between the cooling power by day and by night.

3. The effect of reducing the wind to values similar to those ordinarily experienced in unexposed places has been examined for typical months. It is found that this smooths the differences and reduces the mean values of cooling power by about one‐third.

4. The effect on cooling power in the daytime of solar and sky radiation is computed: in a warm summer month the gain of heat in the middle of the day exceeds the loss of heat by a body at 98°F. in a situation where the wind is only one quarter of that recorded at Croydon at 100 feet above the ground. The effect of loss of heat by outward radiation to sky and earth at night is shown to be generally insignificant compared with the losses due to convection and radiation to the surroundings at the temperature of the air.

5. The relation between cooling power and the terms hot, warm, cold, is examined and a scale suggested, which agrees with a scale independently proposed by Conrad. From this scale a scheme of terms appropriate to different conditions of temperature, wind, and cloud is arrived at.

A further specification of terms in relation to wind temperature and wet‐bulb temperature is also given.
The distribution over the British Isles of the average durtion of bright sunshine: Monthly and annual maps and statistics
Authors: Glasspoole John , Hancock Dugald S.
Published: July 2010

In this paper the aiailable information as to the distribution of bright sunshine over the British Isles is reviewed. Maps are included defining the distribution of average amounts of bright sunshine during each month and the year. Estimates are also given of the general sunshine for each month and the year over England and Wales, Scotland, Ireland, and the British Isles as a whole.
A screen for sheathed thermometers
Authors: Bilham E. G.
Published: July 2010

After a brief survey of the history of the Stevenson thermometer screen, a new form is described in which the four sheathed thermometers, maximum, minimum, dry‐bulb and wet‐bulb, are all arranged approximately horizontally. This arrangement allows of a considerable reduction in the size and weight of the screen, and also has other advantages over the standard arrangement, in which the dry‐ and wet‐bulb thermometers are placed vertically.
The revolving storm of tropical origin which travelled across the Atlantic in September, 1936
Authors: Durst C. S.
Published: July 2010

During the first week of September, 1936, a tropical revolving storm moved over the Atlantic. Its behaviour relative to the polar front is described, and it is shown that it retained its character of a revolving fluid almost to the Irish coast.
On instability from water vapour
Authors: Normand C. W. B.
Published: July 2010

This paper summarises the general criteria for the stability of a particle and of a layer in the atmosphere under conditions when condensation may bring the latent heat of water vapour into play. It discusses briefly the relationship between “Feucht‐Labilitat” (Refsdal), latent instability (Normand) and convective instability (Rossby), and gives the reasons for the introduction in India 01 the classification based on latent instability. The conditions for latent instability are defined with the aid of the tephigram, and an example is given to show how by generating latent instability within a closed system, e.g., by raising the wet‐bulb temperature in the lower layers and leaving all else unchanged, the energy available for transformation into kinetic energy may rise from zero to the equivalent of a wind of 50 mi./hr. throug‐hout the system, without taking account of the energy that may become available from the evaporation of rain‐drops, in descending air. If, however, cvaporation from rain‐drops takes place in the descending air in a thermodynamically efficient manner, the available energy in the closed system of the chosen example is nearly trebled, i.e., the equivalent average velocity rises to more than 90 mi./hr.
Note on the variation of pressure accompanying a distortion of air flow
Authors: Crossley A. F.
Published: July 2010

It is known that certain meteorological stations frequently record a mean sea level pressure which is lower than that which would be expected from the general run of the isobars by amounts up to about one millibar. These stations are located in over exposed situations, such as the tip of a promontory, where the wind speed may be appreciably in excess of the speed in an ideal exposure. In steady motion, the flow of wind over or round the promontory conforms with Bernoulli's equation, which gives a relation between pressure and velocity at points on the same stream line. It is shown that a reasonable increase of wind speed above normal produces a decrease of pressure of the right magnitude. The equation is applied in the first instance to steady frictionless motion, but it is shown that the results apply with little variation to' the How of surface air, as modified by friction.
On development in the field of barometric pressure
Authors: Sutcliffe R. C.
Published: July 2010

The rate of change of surface pressure is defined by the horizontal divergence of momentum integrated vertically through the entire atmosphere. As geostrophic winds are rigorously non‐divergent, surface pressure cannot change when the motion is everywhere geostrophic (Jeffreys, 1919). Pressure changes are therefore determined by the field of geostrophic departure. Ignoring friction, the geostrophic departure is proportional to and directed at right angles to the horizontal acceleration whence pressure changes are defined solely by the field of acceleration, that is by dynamical considerations. Popular conceptions of pressure changes due to simple translation or advection of existing fields of pressure, or to thermal effects caused by direct heating or by advection of air of a different temperature, are invalid without a discussion of the dynamical processes involved.

The approach to the theory of the movement and development of depressions and anticyclones is through a study of the departure of the velocity from the geostrophic value, or what is the same thing, a study of the field of acceleration. By expanding the acceleration into partial derivatives to time and space four terms, one of which is the well known isallobaric term, are obtained. Some justification for considering the terms as physically distinct is given.

It is shown that isallobaric effects alone cannot account for the integrated divergence associated with pressure developments and it is suggested that all four terms may be significant. The effect of the vertical space derivative, proportional to the vertical velocity and to the horizontal gradient of temperature, previously enunciated as a formal proposition by Durst and Sutcliffe (1938), is stressed as a novel contribution which may be of fundamental importance.
Evaporation over catchment areas, II
Authors: Lloyd David
Published: July 2010

Information has been extracted from Government sources relating to drainage areas situate in northern Italy. Values of general rainfall, loss and weather details are tabulated. The provisional formula, advanced recently to estimate the probable loss by evaporation over catchment areas, is applied to these data. The values of loss, expected on account of the weather and permeability of sub‐surface, are shown to be of the right magnitude.
A new theodolite for following fast moving objects especially for making pilot balloon observations of greater accuracy
Authors: Pollak L. W. , Brunt D.
Published: July 2010

A new pilot balloon theodolite is described the essential feature of which is that the reading‐ arrangements (verniers) remain stationary relatively to the vertical and horizontal scales from one reading‐ until the next, so that the observer is able to follow the balloon continuously.
Cyclonic and anticyclonic development
Authors: Sutcliffe R. C.
Published: July 2010

Development of pressure systems involves horizontal divergence (positive or negative) approximately balanced by divergence of opposite sign in the upper troposphere, the total divergence integrated vertically and represented by the rate of change of surface pressure being a relatively small residual. It follows that a criterion for development is that there should be a significant difference between the lower and upper fields of divergence. Divergence is determined by the field of geostrophic departure or acceleration and it is shown that the difference between lower and upper divergence consists of two parts due respectively to shearing and to the development of thermal gradients. Rules concerning the distribution of surface divergence and convergence in different pressure and temperature distributions are inferred and a method of approaching the problem of forecasting on a three‐dimensional basis is put forward.
Variations of the amount of carbon dioxide in different air currents
Authors: Callendar G. S.
Published: July 2010

The first measurements to determine the composition of the atmosphere were made at least 180 years ago, but chemists worked more than a century before they obtained really accurate values for the amount of carbon dioxide in the air.

In the following: a brief review is given of the present state of knowledge concerning the variations of atmospheric carbon dioxide, together with some observations which appear to show that the amount of this gas in the air has increased of late years.
A new electrical weight barograph
Authors: Patterson J. , Middleton W. E. Knowles
Published: July 2010

An account is given of a new weight barograph which resembles that of Sprung in principle but differs almost entirely in detail. Its mechanism is driven electrically, and provides not only a clear graphical trace of the pressure but a printed numerical record of its value every hour. The usefulness of this lies not so much in facilitating the abstraction of the data from the charts as in adding materially to the accuracy, for changes in humidity have a decided effect on the width of the paper, and may under extreme conditions cause an error of a millibar in the trace.

The barometric tube and a counterweight hang from the ends of a beam, pivoted a t its centre, and on the beam is a rolling weight; when the beam is slightly tilted by a change of pressure a contact is made which through a sensitive relay brings into operation an electric motor. This moves the rolling weight until equilibrium is again reached and the position of the rolling weight controls both the trace and the number printed.

After a discussion of the fundamental principles the mode of construction is described in some detail, and finally the methods of adjustment and the compensation for temperature.
On stochastic perturbation and long‐term climate behaviour
Authors: Sutera Alfonso
Published: July 2010

A very simple energy‐balance equation for the mean surface temperature of the planet (Budyko‐type model) is perturbed by a stochastic term, simulating the numerous ‘weather’ processes not considered in the deterministic feed‐back term. In the first instance, a symmetrical deterministic process with three equilibrium states is considered. Using standard methods for determination of the probability density distribution, the characteristic time which the climate system spends in the neighbourhood of one stable equilibrium before shifting to the other is expressed in terms of the characteristic time of the feed‐back process and the time constant of the perturbing process. Realistic corresponding values are found. an Appendix discusses the possibility of using the analogy between stochastically perturbed Newtonian and quantum‐dynamical systems in research on climate change.
Two‐dimensional model studies of methyl chloroform in the troposphere
Authors: Derwent R. G. , Eggleton A. E. J.
Published: July 2010

The tropospheric measurements, atmospheric release rates, and OH reaction rates for methyl chloroform are consistent with present estimates of the tropospheric OH distribution and a methyl chloroform lifetime of about 5 years. Reaction with OH radicals is found to be the major atmospheric removal process for this species. Although excellent agreement is obtained in the northern hemisphere, recent southern hemisphere observations have indicated a much more rapid growth than can be accounted for by model calculations. A comparison of the two‐dimensional model with simpler formulations such as global, hemispheric or one‐dimensional models, shows that the simpler models may not adequately represent tropospheric transport and removal by OH radicals.
An analysis of wave height records for the N.E. Atlantic
Authors: Jardine T. P. , Latham F. R.
Published: July 2010

The analysis of records, for the period 1962‐1975, reveals that the wave height observations exhibit a seasonal variation in both the average value and the standard deviation. Examination of the seasonally adjusted wave heights indicates that these values may be approximately described by first order autoregressive time series models. the validity of these models is checked using statistical tests, comparing short‐term forecasts of wave heights with actual observations and by simulating observations and examining the frequency and duration of storms and calm periods. Methods of improving the models for wave height are examined.
On the proper employment of evaporation pans and atmometers in estimating potential transpiration
Authors: Thom A. S. , Thony J.‐L. , Vauclin M.
Published: July 2010

To investigate the feasibility of estimating Penman's potential transpiration (Erp) without recourse to sophisticated instrumentation, the rates of evaporation from a Class‐A pan and from a Piche atmometer exposed within a thermometer screen were analysed in detail using continuous micrometeorological measurements taken on the same site. Evaporimeter and other associated manual measurements were made not only on a routine daily basis but also on certain days from hour to hour. the latter measurements were of particular help in interpreting physically the behaviour of both evaporimeters.

It is shown:

that the evaporation from the Piche was closely proportional to the (complete) second term in Penman's (Erp) equation;

that evaporation from the Class‐A pan was adequately described by a combination‐type equation including an effective psychrometric constant γp = 2.1 γ (where γ = 0‐66mb(°C)−1, near sea level) and the wind function fp(u) = 0.12(1 + 1.35 u) mmd−1(mb)−1;

that the deduced daily (24 h) net radiation absorbed by the pan was consistently 31% larger than that on the short, green (but unirrigated) grass covering the site;

by applying (iii), that close to 8.5% of rainfall was lost by splashout from the pan, and

that on applying (iv), wet‐day values of pan evaporation lost much of their supposedly inaccurate and paradoxical nature.

The franework for the general application of conclusions (i) and (iii) in generating a synthetic series of values of Erp is introduced and discussed.
Some effects of convection on geostrophic flow
Authors: Manton M. J.
Published: July 2010

Convection in the lower troposphere produces a deficit in the local surface pressure caused by heating of the air in the well‐mixed convection layer. Variations in the surface heat flux can therefore induce horizontal pressure gradients in the convection layer. These pressure gradients can in turn lead to significant geostrophic flows, such as cyclonic ‘heat lows’ in the vicinity of local maxima in the surface heat flux. Turbulent mixing causes the motion in the convection layer to generate vertical velocities, which lead to some geostrophic flow being generated in the middle troposphere above the convection layer.
A sudden warming in the middle atmosphere of the southern hemisphere
Authors: Al‐Ajmi D. N. , Harwood R. S. , Miles T.
Published: July 2010

This paper presents a case study of a wave‐mean flow interaction, or minor warming, near the southern hemisphere stratopause for 15‐30 July 1974. the analysis is based mainly on data from the selective chopper radiometer carried by Nimbus 5.

A deceleration of the zonal mean wind of 70 m s‐1 from 20 to 25 July is observed in middle latitudes at 0.5 mb, with an acceleration further south. the polar vortex is, however, not disrupted.

Eliassen‐Palm cross‐sections are presented for the event and a good correlation found between the E‐P flux convergence and the deceleration. the channelling of the E‐P fluxes from the tropopause to the convergent region is in broad agreement with the distribution of refractive index but there is a region of E‐P flux divergence at high levels in polar latitudes suggesting a source of wave activity there.

The residual circulation is calculated both from the momentum budget and from an omega equation, both methods diagnosing a region of modest equatorward flow near the region of E‐P flux divergence embedded in the stronger poleward flow elsewhere.

Maps of potential vorticity on the isentropic surface of 0 = 1640 K are presented and the evolving pattern related to zonal mean and isobaric descriptions. the event is shown to be associated with an incursion of low latitude air into middle latitudes with a corresponding irreversible mixing of potential vorticity reminiscent of the ‘wave breaking’ in northern hemisphere events reported by McIntyre and Palmer (J. At. Ter. Ph., 46, 825), but of much smaller amplitude.
Size spectra of ice particles in frontal clouds: Correlations between spectrum shape and cloud conditions
Authors: Herzegh Paul H. , Hobbs Peter V.
Published: July 2010

Ice particle size spectra measured by optical particle size spectrometers during airborne sampling of clouds associated with several frontal precipitation systems in the Pacific Northwest are presented and discussed. In the majority of the spectra measured, the concentration densities of particles <2 mm in diameter deviated significantly below or above the exponential curve fitting larger diameters (we term these sub‐exponential and super‐exponential spectra, respectively). Sub‐exponential spectra were found to be dominant in regions of weak stratiform cloud, where liquid water was scarce. Super‐exponential spectra were dominant in convective regions between the ‐1 and ‐9°C levels, where supercooled liquid water was present in amounts up to 0.2 gm‐3. Exponential spectra were dominant in convective regions at the ‐11 °C level and above.

Microphysical processes as well as shear‐induced particle size sorting were found to play a role in the development of spectrum shapes. Depletion of small particles due to aggregation appears to have been an important cause of sub‐exponential spectra. Secondary ice crystal production appears to have been responsible for the formation of super‐exponential spectra. the role of particle size was largely to broaden the range of spectrum shapes present, rather than to promote the dominance of a particular spectrum type.

The impact of spectrum deviations on the relationship between radar reflectivity factor and snowfall rate, though observable, is found to be small with respect to other sources of error often found in radar estimates of snowfall.
Statistical forecasting of tropical cyclone movement in the australian region
Authors: Keenan T. D.
Published: July 2010

The forecasting of tropical cyclone motion in the Australian region was investigated by various statistical approaches which included a synoptic forcing. Both forward stepwise regression and empirical orthogonal function methods were tested using analysis data to represent the synoptic flow. the stepwise regression approach proved superior although both schemes exhibited more skill than previous Australian objective aids and the present operational forecasts. Experiments conducted with the perfect prognosis approach did not lead to any significant improvements due to the limited skill of the numerical prognoses in tropical regions.
Structure of a cold front over the ocean
Authors: Bond Nicholas A. , Fleagle Robert G.
Published: July 2010

The kinematic and thermodynamic structure of a strong cold front over the Gulf of Alaska has been determined using aircraft, dropsonde, and radiosonde data obtained during the Storm Transfer and Response Experiment. Synoptic‐scale analysis using the Sawyer‐Eliassen secondary circulation equation shows that friction and diabatic heating, as well as the geostrophic forcing, are important in accounting for the secondary circulation at the front. A fine‐scale analysis, with horizontal resolution of 700m and vertical resolution of 100 m, shows strong relative inflow of warm boundary layer air toward the front from the east and a weaker inflow of cold air from the west. Updraught velocities of greater than 6 m s−1 over a 2 km width were measured at 875 mb near the leading edge of the front. the frontogenetical effects of confluence, turbulent mixing, and tilting of isentropic surfaces are evaluated in the region of the front and compared with the results of previous studies. the high resolution of the thermodynamic fields provides new data for comparison with high resolution numerical models.
A shallow water intercomparison of three numerical wave prediction models (Swim)
Authors: Group Swim , Bouws E. , Ephraums J. J. , Ewing J. A. , Francis P. E. , Gunther H. , Janssen P. A. E. M. , Komen G. J. , Rosenthal W. , De Voogt W. J. P.
Published: July 2010

Three operational shallow water wave models are intercompared for two artificial experiments and verified for a severe storm hindcast, with the objectives of further understanding the effects of the parametrization of shallow water wave processes in numerical models.

The models used are the HYPAS (Max‐Planck Institute) and GONO (KNMI) coupled‐hybrid models, and the BMO (Meteorological Office) coupled‐discrete model which are all briefly described. In the first case, depth‐dependent fetch‐limited wave growth in a steady wind is examined. In the second case a steady onshore wind is specified over an idealized constant slope coastal shelf, and the stationary wave spectra at various depths are intercompared. For the third case the wind fields for the North Sea storms of 18‐26 November 1981 were accurately reconstructed and used by each model in its operational configuration to produce a wave hindcast for this period.

In case 1 the GONO and BMO models exhibit similar behaviour in the evolution of energy and peak frequency, whereas HYPAS displays less depth attenuation and little variation in peak frequency. In case 2 the energy values at different shelf depths are approximately as predicted in case 1 for HYPAS though rather higher for BMO and GONO. However, GONO and HYPAS show little change in peak frequency with depth here whereas BMO wave spectra become double‐peaked with a wind‐sea peak migrating to higher frequencies in shallower waters. In case 3, the hindcasts, all models produce qualitatively similar results. the time series of wave height and period agree well with measurements, BMO and HYPAS predicting correct energy levels except at storm peaks and GONO generally overpredicting both at lower energy levels and in a duration‐limited strong wind case. the r.m.s. error in wave height at the southern shallow water verification site is 0.5 m for all models, and varies between 0.9 m (GONO) and 1.5m (HYPAS) at the northern deep water site. Some wave spectra are presented and the directional relaxation of wind‐sea in each model is illustrated.

The results of cases 1 and 2 are readily explained by the formulation of shallow water processes adopted in each model, but it is difficult to isolate and identify these mechanisms in the measured or modelied spectra from the hindcast. It is suggested that future studies involving detailed verification and intercomparison of wave models should be confined to more carefully designed wave‐measuring experiments so that less ambiguous results are obtained.
A comparison of a numerical model of radiation fog with detailed observations
Authors: Turton J. D. , Brown R.
Published: July 2010

A one‐dimensional numerical model designed to study the formation and growth of radiation fog is described. the realism of the model in simulating the formation of fog is assessed by critical comparisons with detailed observations made on two nights. the comparisons show that the model is unable to reproduce the very light winds which occur near the surface in stable conditions. As a consequence the formation of radiation fog is inhibited in the model unless the afternoon relative humidity is very high. It is suggested that the discrepancy is caused by the use of a turbulence formulation tuned to match observations over an ideally flat site. the influence of turbulence, radiative cooling, advection and frost deposition on the formation of fog during the two nights is also discussed.
On the derivation of the divergent flow from the rotational flow: The χ problem
Authors: Sardeshmukh Prashant D. , Hoskins Brian J.
Published: July 2010

The vertical component of the vorticity equation in pressure coordinates involves only the divergent and rotational components of the horizontal motion. Taking the dominant rotational component as specified, the equation may be considered as an equation for the velocity potential, χ, of the divergent motion. Solving this χ problem yields a divergence pattern which is dynamically consistent with the generally much better observed rotational flow (provided, of course, that the vorticity dynamics is represented correctly). A simple way of doing this is described, and applied to seasonally averaged and instantaneous winds analysed at the European Centre for Medium Range Weather Forecasts (ECMWF). In view of the delicate nature of the vorticity balance, a comparison of δ, the horizontal divergence obtained in this manner, with D, derived directly from the analysed winds, provides a stringent test for the data assimilation system.

For seasonal averages, D̃ based on an inviscid vorticity equation in the upper troposphere is generally found to agree well with D, even in the deep tropics. However, some features achieve a more interesting and believable structure than in the analyses. Allowing for a vorticity sink in regions of strong organized convection changes this estimate of δ only slightly, well within the range of observational uncertainty, and not always in the sense of improving the agreement with D. It is therefore possible that on the large scale, ‘cumulus friction’ is only important in areas of strong convection, and if so, is not large enough to be determined unambiguously from existing data sets.

Solution of the χ problem at a particular initial time requires an additional piece of information, the vorticity tendency, which could be obtained operationally using a suitable backward time‐differencing scheme. This contrasts with the use of the usual balance procedures, which require a knowledge of the less readily accessible diabatic heating rate.
The albedo of broken cloud fields
Authors: Kite Anne
Published: July 2010

A Monte Carlo model of short‐wave radiative transfer in a broken cloud field is described. Output from the model is presented and the effect of cloud shape and depth, droplet absorption and water vapour absorption on the effective fractional cloud cover, Ne, is investigated. Inhomogeneities are introduced into the cloud field in the form of a variable cloud width and a cloud optical depth which is dependent upon cloud cover. It is shown that these inhomogeneities lead to much better agreement between the modelled values of Ne and experimental values derived from data collected with the Meteorological Research Flight Hercules. the conclusion is that Ne is a nonlinear function of the fractional cloud cover, N, which may be approximated by the relationship Ne = N2.
Large‐Scale Circulation Departures Related to Wet Episodes In North‐East Brazil
Authors: Sikdar Dhirendra N. , Elsner James B.
Published: July 2010

This study examines the large‐scale tropical environment of north‐east Brazil during its 1979 rainy season. Data were primarily from the First GARP Global Experiment (FGGE). Results show that in the mean NE Brazil is south of the intertropical trough zone (ITZ) and north‐west of the South Atlantic high. This pattern results in a westward low‐level flow over the region. Immediately over NE Brazil, middle‐level subsidence and low‐level moisture divergence dominate, producing a mean local environment which is unfavourable for precipitation. During wet episodes cloudiness departures show a more active ITZ over the equatorial Atlantic. Strong sea level pressure departures are found in the vicinity of the subtropical highs indicating short period fluctuations in the Hadley cell. Locally, weaker middle‐level subsidence and weaker moisture divergence during wet episodes allow for increased convection.
Modelling the Quasi‐Equilibrium Dynamics of the Atmosphere
Authors: Cullen M. J. P. , Norbury J. , Purser R. J. , Shutts G. J.
Published: July 2010

The prime need in forecasting atmospheric motions is to predict the synoptic pattern accurately, and to fill in as much mesoscale detail on it as possible. the problem is difficult because the atmospheric fields contain almost discontinuous structures such as fronts and inversions, and the large‐scale flow may separate around mountains. This paper demonstrates that such phenomena may be described as quasi‐equilibrium structures where the fluid remains close to a minimum energy state. This minimum is shown to correspond to geostrophic and hydrostatic balance, and the implied quasi‐equilibrium evolution to correspond to the Lagrangian form of the geostrophic momentum equations. Examples of flows that can be treated include boundary layers separating at surface fronts and mountain blocking with associated drag. By including diabatic effects, the inland penetration of sea breezes can also be studied. the quasi‐equilibrium idea can be applied globally, but describes only a limited subset of tropical motions.

Primitive equation models attempt to produce these structures by relying on explicit geostrophic adjustment. This paper presents evidence that this is not always adequate, especially when the structures contain discontinuities. Implicit algorithms are described which may be more effective.
A Comparison of the Impact of an Envelope Orography and of A Parametrization of Orographic Gravity‐Wave Drag On Model Simulations
Authors: Slingo A. , Pearson D. W.
Published: July 2010

Results are presented from extended annual‐cycle integrations of the Meteorological Office 11‐layer atmospheric general circulation model. an 8‐year control integration produces a good simulation in the southern hemisphere in both summer and winter and also in the northern hemisphere in summer. In northern winter, however, there is excessive westerly near‐surface flow polewards of about 40°N. It is argued that this indicates a lack of orographic forcing of the flow by the major mountain ranges. Two solutions which have been proposed for this problem are investigated. the first is envelope orography and the second is a parametrization of the effects of orographic gravity‐wave drag. Each was included separately in 3 1/2 year integrations in parallel with the control. Both produce substantial changes in the model's climatology, but envelope orography does not improve the westerly problem over the European area and it also degrades the summer circulation. the gravity‐wave drag scheme, however, gives results which in general are in very good agreement with the observations in both hemispheres and seasons. Comparison of the zonally averaged torques from the three experiments demonstrates that with envelope orography the northern hemisphere near‐surface westerlies are reduced because of a dramatic increase in the mountain pressure torque. In the experiment with the gravity‐wave scheme, however, the reduction is due to the gravity‐wave drag and the mountain torque is similar in magnitude to that in the control. A study of the variability of the 500mb height fields on synoptic timescales demonstrates the improvement in the positions of the northern hemisphere storm tracks in this integration. Some remaining errors in the simulations are identified, particularly in the stratosphere. Finally, it is argued that despite these results it may be too early to come to a final conclusion as to the role of gravity‐wave drag in the general circulation and also as to the relative importance of dynamical and radiative processes in the polar winter stratosphere.
A Numerical Simulation of Quasi‐Stationary Tropical Convective Bands
Authors: Dudhia J. , Moncrieff M. W.
Published: July 2010

A method of imposing large‐scale ascent on a three‐dimensional numerical model is introduced and this is shown to be crucial in maintaining the quasi‐stationary convective bands observed in GATE. the effects of ascent on the overall convective development are to enhance updraughts and particularly to maintain the development of new convection cells. the magnitutude of the forcing is varied to show the sensitivity of growth on convergence.

A quasi‐stationary convective band, aligned approximately parallel to the low‐level wind shear, is simulated in an initial environment defined from soundings obtained from the GATE ships Researcher and Oceanographer on 3 September 1974; the organization is therefore quite distinct from that of fast‐moving squall lines aligned at right angles to the shear. the simulated convective system has marked dynamical similarity to the observed bands; these consisted of a number of cumulonimbus cells with new cells developing on the eastern end of the hand with deeper cells to the west. the cells generally travel along the line.

The large shear due to the strong low‐level jet is crucial in influencing the band development and orientation. the dynamical structure of the convective band is investigated by a trajectory analysis, which indicates an organized three‐dimensional structure.

The transports of heat, moisture and momentum are calculated, and a quasi‐balance between large‐scale ascent and cloud‐induced descent on a time scale of a few hours is shown to exist. Apparent heat sources and moisture sinks are calculated and these have a bi‐modal vertical structure, in general agreement with those in observed tropical cloud clusters.
On the Two‐Dimensional Steady Upshear‐Sloping Convection
Authors: Xu Qin , Chang Lang‐Ping
Published: July 2010

A 2‐D inviscid steering‐level model due to M. W. Moncrieff is reexamined both analytically and numerically. It is found that the thermal effects on the distribution of energy and vorticity play opposite roles in determining the interface slope, with the former being dominant. By separating the two effects, a useful insight is obtained into how the interface is controlled by the internal flow regime. Consequently, a mixed jump and steering‐level model is proposed, in which the returning updraught and downdraught are separated by adjacent jump updraught and downdraught. By solving for the internal flow, upshear‐sloping convection is obtained in the mixed model. Numerical results indicate that the inferface slope increases towards the vertical, or even becomes downshear‐sloping, as (i) the jump outflow becomes shallow, (ii) the lifting condensation level (LCL) becomes low, and/or (iii) the Richardson number (proportional to the ratio between convective available potential energy and kinetic energy in the inflow) increases (except for the cases where the jump outflow is very deep and LCL is very high). These features are discussed in connection with the recent results of A. J. Thorpe et al., and the observed differences between tropical propagating squall lines and mid‐latitude steering‐level‐type squall lines.
Microphysical Properties of Glaciating Cumulus Clouds: Comparison of Measurements With A Numerical Simulation
Authors: Beheng K. D.
Published: July 2010

Observational data on the time evolution of the concentrations of drops and ice particles in glaciating cumuli exhibiting an ice particle enhancement mechanism are compared with results of a mathematical simulation model. the model deals with kinetic equations for each type of cloud particle. Sensitivity tests concerning parameters related to the rime‐splinter process show that observations and numerical simulation results agree well when a rate corresponding to 140 to 250 droplets with diameter greater than 20‐25 μm producing one ice splinter is applied. Moreover, in estimating from model results the time interval over which the ice particle concentration increases by a factor of 104, a reasonable span of 50 min is obtained.
Counter‐propagating rossby waves in the barotropic rayleigh model of shear instability
Authors: Heifetz E. , Bishop C. H. , Alpert P.
Published: July 2010

Wave development, using Rayleigh's 1880 model of barotropic, inviscid and incompressible flow, with a mean zonal wind which is linearly sheared between two edges, is described in terms of the interaction between two counter‐propagating Rossby waves (CRWs). Although the solutions described by this approach could also be described by a sum of the normal modes originally obtained by Rayleigh, we offer a CRW description of Rayleigh's model because it provides a useful pedagogical framework for illustrating, in a precise and quantifiable manner, the interacting Rossby wave view of instability. A CRW interpretation of a modified version of the Rayleigh model, consisting of a jet‐like flow featuring two strips of vorticity with opposite signs, is also given.
Evolution and mesoscale structure of a polar low outbreak
Authors: Hewson T. D. , Craig G. C. , Claud C.
Published: July 2010

An observational study of an unusual ‘polar low outbreak’ is described in which four lows formed in succession near south‐east Iceland. Because all the lows tracked south‐east, close to Scotland, an unusually dense network of surface observations was available for analysis, including radar. This complemented the geostationary and polar‐orbiting satellite data that are more commonly used in polar low studies.

Each of the four polar lows displayed a different structure and evolution. The first was a circular convective low, the second a relatively weak surface signature of an upper‐level feature, while the final two cyclones appeared as a wave train, with one cyclone decaying and the other developing into an intense disturbance.

Because of the high resolution of the surface data, it was possible to identify, unambiguously, mesoscale frontal features within the polar lows. These are described in detail. A close examination was made of the final intense low, which showed that its evolution and frontal structure closely matched those found in standard conceptual models of rapidly developing maritime cyclones. This polar low also showed evidence of a warm core, and symmetric instability within an extensive ‘cloud head’.
Biosphere—atmosphere interactions over West Africa. II: Multiple climate equilibria
Authors: Wang Guiling , Eltahir Elfatih A. B.
Published: July 2010

This paper presents both theoretical and numerical analyses on the multiple‐equilibrium nature of the regional climate system in West Africa. Based on simple analyses on how the coupled biosphere—atmosphere system responds to vegetation perturbations within the scope of a dynamic ecosystem, we propose that the regional climate system may have multiple equilibrium states coexisting under the same precessional forcing. Using a synchronously coupled biosphere‐atmosphere model which includes explicit representation of ecosystem dynamics, we show that the equilibrium state of the model is sensitive to initial vegetation distribution. This modelling result supports the existence of multiple climate equilibria. Using the same model, further experiments are canied out to investigate how the coupled system responds to non‐permanent vegetation perturbations. Our results demonstrate how transitions between different climate equilibria can take place when governed by the two‐way biosphere‐atmosphere feedback. These findings advance our understanding regarding the mechanisms of climate variability over West Africa.
The Impact of Relocating Vasectomies from Hospital Outpatient Departments to Non-Hospital Sites
Authors: Young Wendy , Goel Vivek
Published: July 2010

The objective of this study was to estimate the net dollar value of hospital resources that would be released if vasectomies currently performed in outpatient departments were performed in non-hospital sites. This article provides a descriptive analysis using administrative data for all non-hospital sites and all acute care institutions in Ontario performing vasectomies. It is based on 23,741 records of patients for whom a vasectomy was billed to the Ontario Health Insurance Plan (OHIP) in 1991–92.

No substantial differences in the age distribution of patients were seen in non-hospital sites and those in hospital settings. About 75% of hospital outpatients received a local anesthetic that could have been administered in a non-hospital setting. Approximately $4.4 million in hospital resources would be released if 75% of all outpatient vasectomies were performed in non-hospital settings while OHIP billings would increase only by about $140,000. The demands on hospital funds available for patient activity could have been decreased by about $6.2 million, if this shift had occurred in 1991–92.

Although opportunities exist in Ontario to release hospital resources by shifting vasectomies to non-hospital sites, current hospital and physician funding policies may represent a disincentive to shift activity away from institutional-based care.
Multiskilling — Re-Engineering Work Process
Authors: Marshall Kerry
Published: July 2010

Many North American companies have recognized the need to re-engineer their core processes to achieve breakthrough improvements in cost, service and efficiency. In fact, it is estimated that U.S. companies alone will spend millions on business re-engineering projects this year. But change experts say that most re-engineering is in name only, cautiously tackling only one process or department at a time. Even fewer hospitals have attempted this magnitude of change.

Toronto's Sunnybrook Health Science Centre is the first institution of its size in Canada to embark on a multifaceted re-engineering strategy toward a model of patient focused care. The following is an overview of Sunnybrook's experience with the first of these strategies: multiskilling service workers. The concept of multiskilling provides for a focus on redesigning job classifications to broaden the scope of responsibility. For Sunnybrook, this entailed the amalgamation of six service positions — unit aide, health care aide, dietary aide, orderly, porter, housekeeper and attendant into one service assistant position.
A Paradigm Shift in Providing Care for the HIV/AIDS Patient
Authors: Tsasis Peter , Tsoukas Christos
Published: July 2010

The authors report on a detailed cost study of HIV-infected patients receiving treatment at the McGill medical facilities. The results indicated that a home care setting is a cost-efficient site in which to care for an AIDS patient, with care provided in other settings when required.

As the number of people with AIDS increases, efforts are needed to develop alternative care services for those infected with the virus. What is required would seem to be a service delivery system which would ensure cost-effective continuity of care across a continuum of services geared to varying levels of independence and illness severity.