bluuebunny/crossref_metadata_2025 huggingface dataset:
3,3′‐diindolylmethane suppresses 12‐O‐tetradecanoylphorbol‐13‐acetate‐induced inflammation and tumor promotion in mouse skin via the downregulation of inflammatory mediators
Authors: Kim Eun Ji , Park Heesook , Kim Jongdai , Park Jung Han Yoon
Published: June 2010

3,3′‐Diindolylmethane (DIM) is a major acid‐condensation product of indole‐3‐carbinol and is present in cruciferous vegetables. In this study, we evaluated the effects of DIM on antiinflammatory and antitumor promotion activity in mouse skin and explored the relevant mechanisms. When 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) was applied topically to the mouse ear to induce inflammation, DIM pretreatment effectively inhibited TPA‐induced ear edema formation. To evaluate the mechanisms underlying DIM's antiinflammatory effects, DIM was topically treated to the shaved backs of mice 30 min before TPA treatment. DIM inhibited the TPA‐induced increases in the expression of cyclooxygenase (COX)‐2, inducible nitric oxide synthase (iNOS), chemokine (C‐X‐C motif) ligand (CXCL) 5, and interleukin (IL)‐6 in mouse skin. DIM also inhibited nuclear factor‐kappa B (NF‐κB)'s DNA binding activity, the nuclear translocation of p65, and the degradation of inhibitor of κB (IκB) α in TPA‐stimulated mouse skin. Furthermore, DIM reduced TPA‐induced increases in the activity of extracellular signal regulated protein kinase (ERK)‐1/2 and IκB kinase (IKK). When mouse skin papillomas were initiated via the topical application of 7,12‐dimethylbenz[α]anthracene (DMBA) and promoted with repeated topical applications of TPA, repeated topical applications of DIM prior to each TPA treatment significantly suppressed the incidence and multiplicity of the papillomas. DIM also reduced the expression of COX‐2 and iNOS, ERK phosphorylation, and the nuclear translocation of p65 in papillomas. Collectively, these results show that DIM exerts antiinflammatory and chemopreventive effects in mouse skin via the downregulation of COX‐2, iNOS, CXCL5, and IL‐6 expression, which may be mediated by reductions in NF‐κB activation. © 2010 Wiley‐Liss, Inc.
Development of a decision procedure for forecasting maximum wind gusts associated with thunderstorms
Authors: Bartha I
Published: June 2010

Weather warnings are of great importance for the protection of life and property. The Storm Warning Observatory at Lake Balaton was founded with the aim of providing holidaymakers with warnings 1‐2 hours ahead of expected wind gusts exceeding 12 or 17 ms−1. As a result of successive investigations an objective decision procedure has been developed which combines methods based on conventional data with the use of radar data. This procedure can be executed interactively on a computer. The permanence of wind hazards was investigated during frontal and convective weather situations using radar data and synoptic observations. The resulting distribution functions of empirical probability for the permanence of wind hazards associated with cumulonimbus can be used for the further optimisation of the decision method.
An assessment of environmental data for a computerised ship weather routeing system
Authors: Motte R , Calvert S , Wojdylak H , Fazal R , Epshteyn M
Published: June 2010

If the weather patterns that exist during an ocean crossing are known at the outset of a voyage the process of ascertaining an ‘optimal route’ would be precise and certain. The basis of advice to ship‐masters is the optimal route (related to a stated objective function of time, fuel or total cost); this is calculated for the weather predicted at the outset of a voyage and is updated as the ocean crossing proceeds. The hypothesis is that the accuracy of the optimal route calculated at the outset will be inversely proportional to the length of the voyage, as weather prognoses similarly deteriorate with time. This hypothesis is tested by analysing environmental data typically used in the routeing process. A brief description of the ORION automated system is given, with the implications that the attendant environmental data have for the optimal routeing algorithm. Data sources so used are listed, including the extended data (that in excess of ten days). A verification study of these data is described with comparisons of some of the products used, together with a brief analysis of the observed errors and accuracies, in order to indicate confidence levels in the routes provided. An example of a simple verification of moving average data is shown. A routeing study is included in order to illustrate the merit of using medium‐range forecast data and longer‐range extended data in the models.
Economic impact of weather forecasts for forest fires
Authors: Sol Bernard
Published: June 2010

In order to help in fighting forest fires, South‐cast Météo‐France has, for the past 20 years, been issuing forecasts for small zones about 900 km2 in size. These zones have been defined by taking into account relief, vegetation and micro‐climate. The main beneficiary of this, assistance is the Civil Security Force. This article describes the meteorological assistance that is given and the way this has developed, and makes an attempt to measure the economic impact of this assistance. It is relatively easy to estimate the direct costs of supplying the forecast services, the costs of the fire prevention implemented as a consequence of these forecasts, and the cost of fire fighting and replanting. Savings made to the prevention system and the area of forest due to the forecasts arc more difficult to evaluate. Nevertheless, estimates of these amounts are given.
The use of marketing principles to maximise economic benefits of weather
Authors: Ballentine V.
Published: June 2010

An understanding of the market place and business practice is essential to those providing meteorological information in order to maximise economic benefit to the customer. Case studies using information from companies in the Water Market Sector show that benefits gained are both qualitative and quantitative and that cost/benefit ratios in excess of 1:30 can be obtained by the Retail and Manufacturing Market Sector when provided with services that are tailored to meet their requirements. This increase in benefit is shown to be directly attributable not only to the application of marketing principles by weather‐service providers, and research and new technology, but also to educating the market place in the services and products that can be provided and how to use the information in their decision‐making process.
An investigation of possible systematic wind‐direction changes associated with sudden increases in wind speed
Authors: Brettle M J
Published: June 2010

There is a widespread belief among yachtsmen that, during a surface gust the wind veers in the northern hemisphere and backs in the southern hemisphere. Various studies have been directed at finding out if this is in fact true. These studies have all produced null results. In this article the theoretical background is examined and a gust definition appropriate to a yachtsman is defined. Watts (1992) has defined conditions most likely to produce veering in gusts. Therefore, data have been collected in these conditions, and the gust definition used to attempt to verify the yachtsman's belief. However, as with the previous studies, the result is still that there is no significant effect.
Numerical simulations of shading effect and road‐surface state
Authors: Shao J , Lister P J , Fairmaner W D
Published: June 2010

In winter road maintenance, accurate predictions of road‐surface temperature and state (dry, wet, frost or ice) are valuable information for road authorities and organisations that decide where and when to salt or grit the road. The obstruction caused by bids, buildings and trees near the forecast site in daytime (the shading effect) largely reduces the accuracy of such predictions in daytime. This paper describes recent developments of the Icebreak Model and gives encouraging results of validation in surface temperature and state predictions of the model.
Use of satellite imagery to diagnose events leading to frontal thunderstorms: Part I of a case study
Authors: Browning K A , Roberts N M
Published: June 2010

This paper presents a case study to illustrate the value of water vapour and other satellite imagery, when used in conjunction with a conceptual model, to help the forecaster identify deficiencies in numerical model forecast guidance and to diagnose what is happening on the mesoscale. The specific application discussed is the triggering of frontal thunderstorms by the pattern of overrunning and ascent associated with an upper‐level vortex in the vicinity of a trailing cold front.
The October‐1987 floods in Catalonia: Synoptic and mesoscale mechanisms
Authors: Ramis Clemente , Llasat Maria C. , Genovés Ana , Jansà Agustín
Published: June 2010

A heavy rainfall event which produced floods in Catalonia (Spain) during October 1987 is presented. Convection was located over the same area for several days, producing up to 431 mm of rain (67% of the mean annual rainfall). The synoptic‐scale pattern and forcing are studied using objective techniques, while mesoscale features are investigated with satellite imagery and subjective surface analysis. Strong quasi‐geostrophic forcing for vertical motion was diagnosed at low levels white only a weak forcing was evident at 500 hPa. Convective and latent instability characterized the region during the period of heavy rainfall. Also, there was strong low‐level moisture convergence combined with high ‐values of precipitable water over the north‐west Mediterranean Sea. Composite charts delineating the area covered by the indicated synoptic factors seem to be an effective tool for identifying the area where mesoscale focusing mechanisms became effective. Sub‐synoptic analyses show that the main focusing mechanism was a quasi‐stationary convergence line, located near the coast of Catalonia. This lay between the south‐eastern warm and humid flow, caused by a weak low centred north of the Algerian coast, and the cold outflow from a mesohigh located in Catalonia and mainly originated by the orographic blocking of the Pyrenees.
The performance of a C‐Band weather radar during a line convection event
Authors: Shepherd G W , Searson J , Pallot A , Collier C G
Published: June 2010

This paper reports on a storm event which, due to its extreme nature, produced severe attenuation and local anomalous propagation of the weather radar beam. The effect of this phenomenon on the perceived precipitation is reported, together with the synoptic situation.
Guidelines issued by the Royal Meteorological Society
Authors: Britter Rex , Collier Chris , Griffiths Richard , Mason Paul , Thomson David , Timmis Roger , Underwood Brian
Published: June 2010

These guidelines were prepared for the Royal Meteorological Society by a working group with the following membership: Dr Rex Britter (Cambridge University), Prof. Chris Collier (Meteorological Office), Prof. Richard Griffiths (UMIST), Dr Paul Mason (Meteorological Office), Dr David Thomson (Meteorological Office), Dr Roger Timmis (Her Majesty's Inspectorate of Pollution) and Dr Brian Underwood (AEA Technology Consultancy Services). The Chairman of the working group was Prof. Griffiths. The guidelines are published in collaboration with the Department of the Environment.
Association of sferics with a dry intrusion in Meteosat imagery
Authors: Roberts N M
Published: June 2010

A sequence of infrared and water vapour images from Meteosat are used in this short article to display some of the features associated with the development of a North Atlantic cyclone. Lightning reports are shown in conjunction with the imagery to reveal a connection between the formation of thunderstorms and a region of dry air seen in the water vapour pictures. These thunderstorms break out on the leading edge of this dry air near the low centre and along the forward edge of the associated trailing cold front.
The use of weather information to understand the annual distribution of asthma attacks in Switzerland: Influence of pollen and temperature
Authors: Frei Th.
Published: June 2010

The Federal Public Health Department in Switzerland has collected asthma data, amongst other epidemiological data, since 1988. According to these data there are two major peaks in asthma attacks each year: one is around May‐June and corresponds to the appearance of grass pollen whereas the other peak is around November and partly corresponds to the invasion of cold air. Also, there are some minor peaks in March‐April that correspond with the appearance of birch pollen and one in December or January that is probably partly induced by seasonal virus infections. It is found that the release and transport of grass and birch pollen are affected by the mean temperatures. Further investigations will be required to show whether meteorological models could be used to make pollen forecasts. This in turn could form the basis of asthma forecasts for medical doctors and hospitals (so that they could organise their resources) and for the public (so that they could control their use of medicine).
The use of sequential satellite images in forecasting road‐surface temperatures
Authors: McLean P J , Wood N L H
Published: June 2010

A preliminary study has been made to see if satellite images in real time can aid forecasting of road‐surface temperatures in the county of Devon, UK. Under steady synoptic conditions, linear tracking of large cloud masses produced forecasts of nocturnal minimum road temperatures to within ±0.5 °C of the measured values at widely spaced stations. The study highlights some of the problems facing the operational forecaster.
Withdrawal of the south‐west monsoon over India — A synoptic and climatological study
Authors: Subbaramayya I , Naidu C V
Published: June 2010

Though the monsoon is basically a wind phenomenon, the onset and withdrawal of the monsoon over India are determined by the India Meteorological Department on the basis of rainfall alone. However, its onset and withdrawal should also be associated with the seasonal wind changes. It is proposed in this paper that the withdrawal of the monsoon from any locality should be identified with the end of the last westward‐moving rainstorm of the season which is accompanied by the monsoon westerlies. Using this definition, the average withdrawal dates have been determined from the daily synoptic charts as well as from the mean cumulative rainfall curves. It was possible to segregate the north‐east monsoon rains from the south‐west monsoon rains in the present analysis and arrive at the proper dates of withdrawal. There are large differences in the dates of withdrawal arrived at in this study and those conventionally followed by the India Meteorological Department. The differences are mainly over (i) the east coast of the south peninsula, (ii) north‐east India, (iii) north‐west India and (iv) the Sub‐Himalayan region, and are due to the fact that for the conventional dates the rains due to the north‐east monsoon and the western disturbances were not treated adequately. It was found that the period of the summer monsoon varies over India from two months in the north‐west to six months in the extreme south. Hitherto, June to September has been considered as the period of monsoon rains for the whole country.
A new scheme for the initialisation of tropical cyclones in the UK Meteorological Office global model
Authors: Heming J T , Chan J C L , Radford A M
Published: June 2010

For several years the UK Met. Office has initialised tropical cyclones (TCs) in its global model by use of ‘bogus’ observations representing a simple symmetric vortex. Although this has yielded acceptable results, in terms of the verification of TC tracks in the short and medium range, it was felt certain improvements could be made. A new scheme has been developed which addresses two major deficiencies of the old scheme; the representation of the radial structure of winds and the asymmetry of the TC vortex. Preliminary tests of the new scheme resulted in the reduction of three‐day track forecast errors by 52%. Subsequently, a 19‐day trial of the new scheme running in parallel with the old scheme was undertaken. There were 12 active TCs during this period. The improvement in the track forecast verification statistics during the trial was striking. Analysis errors were cut by 65% (to 39 km); 72‐hour forecast errors fell from 528 km to 394 km and 120‐hour errors fell from 818 km to 440 km. The model's skill over a standard climatological/persistence forecast also improved dramatically. The new scheme was introduced operationally on 25 October 1994. Since then, mean forecast errors have been considerably lower than mean statistics from recent years.
Setting verification targets for minimum road temperature forecasts
Authors: Halsey N G J
Published: June 2010

Road temperature forecasts have become increasingly important over recent years with the advent of road temperature sensors. These sensors help both the forecaster and the customer in order to keep our roads in a usable state each winter and also provide a means by which forecasts can be verified and subsequently improved. Several verification measures have been used of which three are examined in this paper. It is demonstrated that potential targets for these measures need to be adjusted accordingly to the frequency of frost at any particular site and more appropriate targets are then suggested. These targets are obtained by the use of standard statistical distributions that are applied to data collected over the past few years from road temperature sensors across the British Isles.
A one‐dimensional interpretation model for detailed short‐range forecasting
Authors: Gollvik Stefan , Olsson Esbjörn
Published: June 2010

A one‐dimensional in situ model, to be used for short‐range forecasting, has been developed. It has been designed to describe the evolution of weather in an operational environment. The basic idea is to utilise the dynamical tendencies from a complete three‐dimensional model run, which have been stored at the places where the one‐dimensional model is to be run. Moreover, the initial state of the model is composed from the three‐dimensional model profile, and also from more recent local observations. Also, more local physiographical information is taken into account. It has been shown that this approach can produce extra skill for short‐range forecasts. Low‐level clouds are difficult to predict in both the three‐dimensional model and in this model approach, although some improvements have been achieved.
Economic benefits of Terminal Aerodrome Forecasts (TAFs) for Sydney Airport, Australia
Authors: Leigh R J
Published: June 2010

The study estimates the economic value of information contained in weather forecasts for the aviation industry known as Terminal Aerodrome Forecasts (TAFs); and estimates the economic benefits of improving the accuracy of the information. The response of an airline to a TAF, in terms of fuel load and the decision to divert the flight to another aerodrome, is modelled using a decision analytic framework. Relationships between expected direct airline cost, the value of the forecasts and TAF accuracy are derived using historical TAF verification data from 1972 to 1993 and actual airline operating costs based on 1994 economic conditions. This allows the cost savings due to improved TAF accuracy, and the value of TAFs at particular levels of accuracy and over a particular time period, to be estimated. The economic value of TAFs produced in 1993 for Sydney Airport, based on Qantas Airways Limited international routes into Sydney, was estimated at A$6.9 million. This is about 80% of the maximum potential value of ‘perfect’ forecasts. On the same basis the economic benefit of a hypothetical uniform increase in TAF accuracy of 1% was estimated at A$1.2 million per year.
Formation of dew and the drying process withincrop canopies
Authors: Jacobs Adrie F G , Nieveen Joost P
Published: June 2010

Outdoor dew profiles within a plant canopy have been measured after dewy nights in a maize canopy and in a barley canopy. It is found that dew profiles can have a similar shape for various dew events. Clear unique dew profiles occurred when the plants are stiff, the stems as well as the leaves. This result suggests that it is likely that the similar profiles are a consequence of the more‐or‐less constant foliage area distribution of a plant canopy during a growing season. Flexible plant canopies, however, have more complex behaviour depending on the structure of the canopy and on the wind regime during the early hours. The drying process within the plant canopy has also been monitored until the free liquid water that had collected within the canopy through the night was evaporated. Initially, the drying process was faster in the upper layers of the canopy. Later, when the moisture distribution became more‐or‐less even through the whole canopy, the drying rate became approximately uniform. The amount of dew and the drying rate during the morning hours have also been estimated by making simple model simulations. For the inflexible maize canopy, the calculated total amount of dew agreed with the measured amount to within 6%. The measured drying process, however, lagged about one hour behind the calculated one. Possible causes of this difference are the dripping effect and drainage down the stems, which were not included in the calculations. These causes, however, are difficult to model, especially for a flexible canopy like a barley crop.
Pattern recognition techniques for the identification of cloud and cloud systems
Authors: Pankiewicz G S
Published: June 2010

A wealth of often under‐used information is present in visible and infrared meteorological satellite imagery, in the form of cloud size, shape, texture and context. In an effort to provide an objective system that can identify meteorological objects over a range of scales, a study of currently available pattern recognition techniques has been undertaken. These techniques, which include supervised and unsupervised classification, image segmentation and scale context, are reviewed, together with a method for selecting the optimal image characteristics for the application of interest. This paper also considers a number of meteorological applications where these techniques can be used, such as cloud classification for operational or climatological purposes and the improvement of numerical weather prediction models. The result of the study has been the design of a synoptic‐scale object recognition system based on three layers of artificial neural networks, each operating at a different scale in a bottom‐up approach.
Synoptic situations related to spells of extreme temperatures over Argentina
Authors: Rusticucci Matilde , Vargas Walter
Published: June 2010

This study analyses some synoptic situations in which extreme temperatures occur. Cases of temperature‐anomaly spells from ten stations in Argentina are studied. The duration and the maximum deviation in each case are considered. The Lund correlation method or manual classification was used to analyse the synoptic situations. The cold spells in winter during the period 1971/80 occurred in three kinds of synoptic situation. Most of the days have a high‐pressure system to the west and a trough in the centre of the country, which is associated with south‐westerly winds. The coldest days have south‐easterly winds to the north (from the Atlantic), which blow around a high‐pressure system over the southern part of the country. There is a difference between this synoptic situation and the coldest synoptic situation in summer. The coldest conditions in summer take place in south‐westerlies when three or more cold fronts have passed over the area. The warmest spell in summer (January 1972) occurred with a cold front coming from the south, a low‐pressure centre in the middle of the country (between two high‐pressure systems), with a flow from the north over Argentina. In winter the warmest spells occur in similar situations, but there are also warm fronts present over the northern part of the country. Lund's method is appropriate for finding the synoptic situations connected with some special cases.
Data efficiency of meteorological and hydrological services in Bulgaria
Authors: Sharov Vladimir , Popova Maria
Published: June 2010

It is hard and very often not possible to demonstrate economic benefits to national economies from meteorological and hydrological activities. We propose making a relative estimate of these benefits by evaluating data efficiency. Data efficiency is a function of six parameters, each of equal weight: accuracy, availability, differentiation, timeliness, presentation and up‐date frequency. All these parameters depend on the level of data technology. Improvements in these data parameters result in a bigger volume of data and services sold. On the basis of data efficiency estimation we propose a methodology of how to create an improved strategy for up‐dating the data technology of meteorological and hydrological services. We show that the increase in usefulness of the National Meteorological Service during natural disasters and the rise in revenue from hydrometeorological services are the result of improvements in data efficiency by the new data technology. Alternatively, the increase in data efficiency could be used as good indicator of improvements in the economic benefits of meteorological and hydrological services.
Mesoscale forecasts with an atmospheric Limited Area Model
Authors: Nielsen Niels W , Sass Bent H , Jørgensen Jess
Published: June 2010

The prediction of mesoscale weather phenomena, such as local winds and heavy precipitation, has always been a big challenge because of their direct impact on people's lives. In recent years computer power has increased enough to make it possible to run regional numerical weather forecast models for the prediction of local weather. This paper describes examples of forecasts obtained from a nested mesoscale model currently run operationally at the Danish Meteorological Institute. The potential and problems associated with high‐resolution forecasts are discussed.
An object‐oriented technique for nowcasting heavy showers and thunderstorms
Authors: Hand W H
Published: June 2010

Accurate forecasting of heavy showers and thunderstorms with associated hazards is vitally important for many business sectors and national utilities. In the UK a fully automated procedure is being developed in the Met. Office for the National Rivers Authority. The GANDOLF (Generating Advanced Nowcasts for Deployment in Operational Land surface Flood forecasting) system seeks to provide warnings of heavy rain and forecast accumulations in sensitive river catchments to flood hydrologists. GANDOLF will automatically choose the most appropriate nowcasting technique depending upon synoptic conditions. In a convective situation an important method available to GANDOLF is an object‐oriented nowcasting procedure. Multi‐beam, high resolution radar data and Meteosat IR satellite data are used to analyse convective cells in all stages of growth; subsequent movement and development up to 3 hours ahead is then predicted using a conceptual life‐cycle model combined with mesoscale NWP data. This paper describes the object‐oriented technique and demonstrates its usefulness in a severe convective situation with a case study.
The formation of a dynamically unstable ridge at 500 hPa as a precursor of surface cyclogenesis in the central Mediterranean
Authors: Prezerakos Nicholas G , Flocas Helena A
Published: June 2010

An attempt is made to find the dynamical and physical characteristics of the atmospheric circulation which contributed to the development of a great storm in the vicinity of Greece on 5 October 1989. The surface cyclogenesis could be considered as a consequence of an upper‐tropospheric minor wave which formed upstream on the eastern flank of a blocking‐type anticyclone which was centred over Britain and dominated the atmospheric circulation over western Europe. This minor wave formed three days before the initiation of the surface cyclogenesis and could be explained by the theory of ‘a dynamically unstable ridge’. As the wave moved south‐eastwards, an elongated trough formed in the upper troposphere. The southernmost part of this elongated trough was disrupted by dynamical processes, leading finally to the formation of a cut‐off low. When the area of positive relative vorticity advection due to the low became superimposed upon a shallow frontal surface lying across southern Greece in the afternoon of 4 October 1989, a deep depression developed at the surface between Crete and Athens during the next 12 hours. To further elucidate the role played by the forcing conditions at the upper levels in the surface cyclogenesis, the potential vorticity has been analysed.
Classification of ensemble forecasts by means of an artificial neural network
Authors: Eckert P , Cattani D , Ambühl J
Published: June 2010

The problem of clustering the members of an ensemble forecast is addressed. Fields of 500 hPa height are classified by a self‐organising Kohonen artificial neural network, for which the learning process is described. The members of the ensemble are classified according to the learned situations. An objective measure of the predictability is proposed, using the concept of information entropy. This classification technique also provides a measure for comparing forecasts with their verifying analysis.
Fog detection and fog mapping using low cost Meteosat‐WEFAX transmission
Authors: Güls I , Bendix J
Published: June 2010

Nowcasting the extent of fog and diurnal fog dynamics is important for traffic management as well as for air‐quality studies. Imagery from operational weather satellites provide a spatial database several times a day which can be used for fog monitoring given a classification scheme which is nearly operational. Unfortunately, the use of high‐resolution imagery is often expensive and time consuming, so that it is not suitable for nowcasting at local weather offices. For that reason, a method for detecting fog based on easily accessible Meteosat‐WEFAX imagery has been developed. The algorithm uses the Meteosat VIS‐channel (C‐Format) and includes illumination correction and calibration of the WEFAX signal which provides a synthetic reflectance factor. The procedure is improved by making use of an additional image of surface texture. The discrimination between fog and other surfaces has been performed by the application of a bi‐dimensional threshold test based on both images of synthetic reflectance and texture and a final snow/ice/edge correction. The resulting binary fog image has proved to be of encouraging accuracy by comparison with a classification based on NOAA‐AVHRR data as well as visibility observations. Especially in cases of fog optical depths less than 4 or a patchy fog structure, classification results should be interpreted carefully. Binary fog masks are combined into daily fog maps which clearly show diurnal fog dynamics on a European scale.
The use of potential vorticity as an operational forecast tool
Authors: Mansfield D A
Published: June 2010

The results from a project to evaluate the use of potential vorticity in operational forecasting are presented. An analysis of the temporal and spatial coherence of analysed and forecast potential vorticity fields showed that features with space scales downn to a few hundred kilometres could be tracked for between one and two days. Of features in these fields, 90% had a corresponding signal in the vertical motion fields, showing that they were real features having an important influence on weather‐bearing systems. A comparison between potential vorticity fields and water‐vapour imagery shows a close relationship in the region of the polar front. Examples are given showing how this can be used to detect errors in model analyses and forecasts. The use of potential vorticity as a diagnostic of model behaviour is discussed. Many authors have stressed the role of potential vorticity anomalies in major cyclogenesis. In these cases the forcing is usually clear from other diagnostics. It is suggested here that it is in highlighting areas of weaker forcing or relatively small‐scale model errors where potential vorticity is most useful to the operational forecaster.
Forecasting road‐surface temperatures for different site characteristics
Authors: Jacobs Wilfried , Raatz Wolfgang E
Published: June 2010

In 1992/93 the Deutscher Wetterdienst (DWD) introduced SWIS (Straßenzustands‐ und Wetterinformationssystem) as a nationwide road weather information system. In order to forecast road conditions and road‐surface temperature over a time period of 27 hours, an energy balance model is used. The course of the energy fluxes is estimated by the meteorological parameters. It is thus very important that the forecaster provides an excellent synoptic input for the energy balance model. The energy balance model is able to account for five different road site characteristics; i.e. unobstructed road sections with regular and little traffic, respectively, shaded road sections, bridges and road sections within urban influences. To evaluate the model's quality, the technique of hindcasting was employed by running the model for a day in the past (running time 0900 UTC of a given day to 1200 UTC the following day), using measured values of a specific road weather monitoring station complemented by observations from a nearby synoptic station. Preliminary results show that from 1500 UTC to 1800 UTC the mean errors are 1 to 2 K, during the remaining forecast time the mean errors are often less than 1 K; results are even better during clear sky conditions.
Improving forecasting performance by combining forecasts: The example of road‐surface temperature forecasts
Authors: Brown Barbara G , Murphy Allan H
Published: June 2010

A recent paper by J. E. Thornes reported the results of a comparative evaluation of location‐specific, road‐surface temperature forecasts (RSTFs) formulated by two organisations, the UK Meteorological Office (MO) and Oceanroutes (OR). The present paper broadens the scope of this competition, by considering the possibility of combining the MO and OR forecasts. Combining forecasts can improve forecasting performance when one set of forecasts contains information – in this case, information about observed road‐surface temperatures – not contained in the other set of forecasts. Both simple averaging and regression modelling are examined in this study as methods of combining these RSTFs, with the former consisting of averaging the MO and OR forecasts and the latter consisting of regressing these two forecasts on the observed temperatures.

The simple average forecasts outperform the MO or OR forecasts, both when these RSTFs are evaluated as forecasts of a continuous variable and when they are evaluated as forecasts of a binary (i.e. frost/no frost) variable. Combining via regression modelling leads to further modest improvements in forecasting performance (based on in‐sample results). Overall, simple averaging captures a substantial fraction of the benefits that can be realised by combining the MO and OR forecasts for this small sample of road‐surface temperature data. Several issues related to the formulation and evaluation of combined forecasts, as well as some practical implications of the results, are briefly discussed.
The formation and forecasting of condensation trails behind modern aircraft
Authors: Ferris P D
Published: June 2010

The formation of a condensation trail behind an aircraft gives away its presence. Despite the current use of radar for aircraft detection, contrail formation is still important to military aviation. Seeing a contrail only requires the unaided eye. The theory of contrail formation for a dry environment, using values of engine‐dependent variables appropriate to modern jet aircraft, gives values of the critical temperature for contrail formation. These form a line nearly parallel to, but colder than, the MINTRA line on a tephigram. These values though, do not allow for the effect of environmental humidity, which may be significant at the levels where aircraft fly. A new forecasting technique is proposed which involves determining the exact critical temperature value. This can be done using a suitable contrail formation graph or with a tephigram, finding the necessary correction to the MINTRA temperature. If the atmospheric temperature is colder than this critical temperature, a contrail should be forecast to form.
Monitoring of NWP models by use of satellite data
Authors: Røsting Bjørn , Sunde Jens , Midtbø Knut Helge
Published: June 2010

This paper describes some cases where satellite information contributes to beneficial monitoring of NWP model output. The real‐time observations and NWP parameters required for the methods used are described. Selected examples, including successful and less successful NWP developments, are used to illustrate the applicability of the methods. Key elements are the localisation and isentropic advection of potential vorticity (PV). Positive upper and middle tropospheric PV anomalies may in several weather situations be detected in the Meteosat WV imagery as dark areas in the rear of developing cyclones. This study indicates that we may have confidence in the model description of weather development when the NWP model output showing areas with high‐level potential vorticity corresponds in time and space with dry areas inferred from the WV images. However, when such correspondence is only poor, the confidence is shown to be lower. In such cases there is a need to adjust the NWP model output. Also large‐scale isentropic advection fields and cross‐sections from the NWP models are used together with the multi‐spectral AVHRR information from the NOAA polar‐orbiters. Mesoscale events related to deep convection and small‐scale wind fields in connection with polar low developments are investigated.
Calibrating the exposure of anemographs
Authors: Cook N J
Published: June 2010

Measurements of wind speed near the ground surface are strongly influenced by the topography surrounding the anemograph site. The influence of a change in ground level is relatively local in comparison with the influence of a change of surface roughness, which persists many kilometres downwind of the change. These exposure effects are of a similar magnitude to other effects significant in the process of engineering design, such as the shape and size of a building, and therefore need to be assessed in a similar way. In this paper, a method of exposure assessment is described which utilises contemporary engineering models to show the effect of changes of surface roughness and ground level on wind speed. Results of the method are compared with measurements of extreme wind speeds obtained from a directionally inhomogeneous anemograph site. The method is seen to account for 85% of the observed directional variance.
Visibility: An investigation based on a multivariate adaptive regression spline technique
Authors: Taliani Marco , Siani Anna Maria , Palmieri Sabino
Published: June 2010

Visibility in the Po Valley in northern Italy is a meteorological parameter of extreme interest. In autumn and winter radiational cooling of the Valley bottom coupled with cold air drainage from surrounding mountain slopes leads to conditions favouring the formation of fog with a highly persistent character. This regime may be temporarily interrupted when vigorous northwest flow over the Alps produces descending dry currents in the lee of the range (foehn) or when an intense disturbance affects the area. A preliminary application of a statistical methodology called MARS (Multivariate Adaptive Regression Splines) to a visibility time series of Milan‐Linate Airport is carried out with the primary intent of investigating the efficiency of the technique in detecting the non‐linear dynamics of the series and the physical factors involved. Although the development of a statistical prediction scheme requires much more data in order to guarantee the stability of the model equation and reliable tests, results are interesting and indicate, beyond any doubt, the skill of MARS as a tool for making causal inferences from observables.
Case studies of cyclogenesis over South America
Authors: Gan Manoel Alonso , Rao Vadlamudi Brahmananda
Published: June 2010

A detailed case study of cyclogenesis over South America during the period 5‐9 June 1981 is undertaken. The intensification of the cyclone occurred first in the upper troposphere. The disturbance showed several characteristics found in baroclinic disturbances, such as eastward propagation, intensification with westward vertical tilt and barotropic decay. However, the vertical tilt was confined to upper levels only and the surface temperature gradient was low. This suggests that the mechanism of development might be somewhat different than the usual cases of baroclinic instability associated with low‐level vertical inclination. Internal baroclinic instability is suggested as a plausible mechanism of development. Cases of intense cyclogenesis are also studied during the period 1979 to 1988 using the Laplacian of the sea‐level pressure criterion in the autumn, winter and spring seasons. The case which occurred on 19 September 1984 over Uruguay and southern Brazil is presented; the pressure drop was 12 hPa in 24 hours over Paraguay and South Brazil.
Sonographic evaluation of the fetal conus medullaris at 20 to 24 weeks' gestation
Authors: Perlitz Yuri , Izhaki Ido , Ben‐Ami Moshe
Published: June 2010

Objective

To determine the normal level of the conus medullaris (CM) of the spinal cord of normal fetuses at 20 to 24 weeks' gestation using abdominal sonography.

Methods

Using a 4 to 8 MHz ultrasound abdominal transducer, CM was imaged in the midsagittal plane with the fetal spine facing toward the transducer. The CM ending level was located by counting the vertebrae caudal starting at T12, which was identified by lowest fetal rib. The CM locations were defined according to their positions relative to the vertebrae.

Results

One hundred and ten consecutive pregnant women were included in the study. The CM was clearly demonstrated in 78 (71%) of these cases. Most of the scanned fetuses had the CM ending height adjacent to vertebrae L2, L2–3 inter‐space and L3 (73/78, 93%). The L1–2, L2, L2–3, and L3 vertebral groups did not differ in mean gestational weeks, maternal age, or fetal gender.

Conclusion

The level of the CM can be determined at 20 to 24 weeks' gestation in about 70% of fetuses. Most of the scanned fetuses had the CM ending height adjacent to vertebrae L2, L2–3 vertebral space, and L3 (73/78, 93%). When detected lower than the third lumbar vertebra it should prompt prenatal and postnatal surveillance. Copyright © 2010 John Wiley & Sons, Ltd.
Using multiobjective evolutionary algorithms in the optimization of operating conditions of polymer injection molding
Authors: Fernandes C. , Pontes A.J. , Viana J.C. , Gaspar‐Cunha A.
Published: June 2010

A Multiobjective Optimization Genetic Algorithm, denoted as Reduced Pareto Set Genetic Algorithm with Elitism (RPSGAe), has been applied to the optimization of the polymer injection molding process. The aim is to implement an automatic optimization scheme capable of defining the values of important process operating conditions (such as melt and mould temperatures, injection time, and holding pressure), yielding the best performance in terms of prescribed criteria (such as temperature difference on the molding at the end of filling, the maximum cavity pressure, the pressure work, the volumetric shrinkage and the cycle time). The methodology proposed was applied to some case studies. The results produced have physical meaning and correspond to a successful process optimization. POLYM. ENG. SCI., 50:1667–1678, 2010. © 2010 Society of Plastics Engineers
Sag in thermoforming
Authors: Giacomin A.J. , Mix A.W. , Mahmood O.
Published: June 2010

In thermoforming, flat sheets of plastics are transformed into complex shapes by first softening the sheet, and then by shaping it. While softening, the sheet can extend under its own weight, making it concave. Called sag, this affects how each element of the sheet surface views the heater bank. This can worsen the variations in the heat flux distribution across the sheet. It can also cause the heat flux over and under each element on the sheet to differ. The resulting temperature gradients, either across the sheet or through its thickness, can complicate processability. To suppress sag, practitioners stretch the sheet laterally, using cambered transfer rails to keep the sheet taut. In this article, we model sag analytically, using transport phenomena in cylindrical coordinates, for a thin wide rectangular Newtonian isothermal sheet. We uncover a universal dimensionless relation between sag and time, and a useful dimensionless group that we call sagability. We find that the middle of the sagging sheet, unsuppressed, descends, to leading order, with the cube root of time, and our experiments confirm this. Also, we discover that at a particular time the sag increases rapidly without bound, and we call this phenomenon sag runaway. POLYM. ENG. SCI., 50:2060–2068, 2010. © 2010 Society of Plastics Engineers
Effect of the consolidation degree on the fracture and failure behavior of self‐reinforced polypropylene composites as assessed by acoustic emission
Authors: Izer András , Stocchi Ariel , Bárány Tamás , Pettarin Valeria , Bernal Celina , Czigány Tibor
Published: June 2010

In this work, the fracture and failure behavior of self‐reinforced polypropylene composites (SRPPC) was studied. As reinforcement woven fabric, whereas as matrix materials α and β crystal forms of isotactic polypropylene (PP) homopolymer and random PP copolymer (with ethylene) were used. Composite sheets were produced by a film‐stacking method and compression molded for constant holding time and at constant pressure but at different processing temperatures to obtain SRPPC sheets with different consolidation quality. The failure behavior of tensile specimens was assessed by the acoustic emission (AE) technique and the typical failure behavior was deduced for the differently consolidated composites. Both the number of AE events and the shape of the cumulative AE events versus deformation curve depend on the adhesion between phases. Correlations between the dominant failure mechanisms and AE events amplitude for model specimens were established which can be used to monitor the damage growth process in SRPPCs. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Organic–inorganic hybrid copolymer fibers and their use in silicone laminate composites
Authors: Swart Morne , Olsson Richard T. , Hedenqvist Mikael S. , Mallon Peter E.
Published: June 2010

Nonwoven organic–inorganic fiber mats of poly(methyl methacrylate)‐graft‐poly(dimethyl siloxane) copolymers with various PDMS contents were produced by the electrospinning process. The average fiber diameter increased from 0.7 to 3 μm with increasing PDMS content. The fiber mats were used in the preparation of silicone‐laminated composite materials by distributing them (single, double and triple layer mats) in a silicone matrix prior to thermal curing. The composites showed a remarkably good fiber distribution in the silicone matrix. In general the stiffness and strength increased in the presence of fiber, and surprisingly, so did the toughness/extensibility. An interesting feature was that the most silicon‐rich fibers showed clear signs of yielding after tensile testing and failure. This, together with the greater compatibility of the fibers with the matrix because of the higher PDMS content, most probably favored composite toughness. All composite fracture surfaces were characterized by clear signs of fiber pull‐out. Fracture initiation areas were difficult to locate, and this is accredited to an even distribution of the individual fibers in the matrix. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers