bluuebunny/crossref_metadata_2025 huggingface dataset:
Infinite Iterated Function Systems
Authors: Fernau Henning
Published: June 2010

We examine iterated function systems consisting of a countably infinite number of contracting mappings (IIFS). We state results analogous to the well‐known case of finitely many mappings (IFS). Moreover, we show that IIFS can be approximated by appropriately chosen IFS both in terms of Hausdorff distance and of Hausdorff dimension. Comparing the descriptive power of IFS and IIFS as mechanisms defining closed and bounded sets, we show that IIFS are strictly more powerful than IFS. On the other hand, there are closed and bounded non‐empty sets not describable by IIFS.
Bounded Solutions of Dynamical Systems in the Plane under the Conditions of Instability
Authors: Kalas J. , Osička J.
Published: June 2010

In this paper the asymptotic behaviour of the solutions of x' = A(t)x + h(t,x) under the assumptions of instability is studied, A(t) and h(t,x) being a square matrix and a vector function, respectively. The conditions for the existence of bounded solutions or solutions tending to the origin as t → ∞ are obtained. The method: the system is recasted to an equation with complex conjugate coordinates and this equation is studied by means of a suitable Lyapunov function and by virtue of the Wazevski topological method. Applications to a nonlinear differential equation of the second order are given.
On the Exact Values and Bilateral Estimates of Certain Capacities
Authors: Kalyabin Gennadiy
Published: June 2010

The quantities v(E) of combinatorical nature introduced by YU. V. Netrusov and equivalent to the capacities with respect to generalized Besov and Triebel‐Lizorkin spaces (Bp.q(β,N)(Rn) and Fp.q(β,N)(Rn)) are studied.

It is shown that for q = p three exists the fast algorithm of calculating v(E) for E being the arbitrary finite union of elementary bricks.

The simple general upper estimate for capacity of the compact sets is established which appeared to be bilateral for regular structures (such as lattices and convex sets).
Random Polytopes and Affine Surface Area
Authors: Schütt Carsten
Published: June 2010

Let K be a convex body in Rd. A random polytope is the convex hull [x1, …, xn] of finitely many points chosen at random in K. IE(K, n) is the expectation of the volume of a random polytope of n randomly chosen points. I. Bárány showed that we have for convex bodies with C3 boundary and everywhere positive curvature

where x(x) denotes the Gauß‐Kronecker curvature. We show that the same formula holds for all convex bodies if x(x) denotes the generalized Gauß‐Kronecker curvature.
Nonlinear Riemann‐Hilbert Problems with Unbounded Restriction Curves
Authors: Wegert Elias
Published: June 2010

Using a norm inequality for singular integral operators in pairs of weighted Lebesgue spaces we prove new existence and uniqueness results for solutions of nonlinear Riemann‐Hilbert problems with noncompact restriction curves.
Characterization of Weighted Besov Spaces
Authors: Ansorena José Luis
Published: June 2010

We find conditions on the weight w in order to characterize functions in weighted Besov spaces Bp.q/w.φ in terms of differences Δxf.
Valuing weather radar benefits for winter road maintenance: A practical case example
Authors: Smith Keith , Vick Sandra D
Published: June 2010

A simple decision‐analysis model is used to determine the financial benefits accruing to one highway authority in Scotland from the use of weather radar imagery for u‐inter‐road‐maintenance operations. Over a three‐month period, the savings are some £23 000 greater than the benefits derived from the use of the particular OPEN ROAD forecast service employed by that authority.
Operational monitoring and forecasting of mesoscale weather phenomena in ocean regions surrounding Norway
Authors: Sunde J. , Rønting B. , Breivik L. A. , Midtbø K. H. , Ulstad C.
Published: June 2010

A description is given of the operational system used by the Norwegian Meteorological Institute (DNMI) to monitor and forecast mesoscale weather phenomena. The system uses a combination of conventional observations, data from polar orbiting satellites (this includes cloud images and information about sea‐ice concentrations, sea‐surface temperatures arid surface winds) and output from the Limited Area Model. A case study involving mesoscale developments, which used output from the operational system, is described.
The Canadian operational procedure for forecasting total ozone and UV radiation
Authors: Burrows William R , Vallée Marcel , Wardle David I , Kerr James B , Wilson Laurence J , Tarasick David W
Published: June 2010

In the spring of 1992 Environment Canada started daily forecasts of ultraviolet‐B radiation reaching the ground for locations in Canada. The forecast quantity is a ‘UV Index’ based on an empirical formula relating UV flux at the ground to solar zenith angle, total depth of ozone in a vertical column, and the time of year. The primary subject of this paper is the procedure for forecasting total ozone that has been used operationally since June 1993. The UV forecast is produced in three steps. First, total ozone it estimated over all of the northern hemisphere using a regression relationship between upper atmospheric variables and total ozone. Second, a correction is made to the forecast based on current measurements of ozone over Canada. Third, the total ozone estimates are fed to the formula to obtain the UV Index. The procedure runs in a ‘perfect prog’ real‐time forecast mode, with values of the atmospheric variables taken from predictions of the Canadian global spectral model.

The predictand data consisted of total ozone observations for the northern hemisphere for the period 1987‐1991, measured by the Total Ozone Mapping Spectrometer (TOMS) instrument aboard the Nimbus‐7 spacecraft. The predictors were obtained from an assortment of upper‐tropospheric and lower‐stratospheric meteorological variables, analyses of which were processed into a set, of predictors known from previous work to be related to total ozone. To these variables were added climatological total ozone and various functions of latitude to represent the observed large‐scale latitudinal and seasonal variations in total ozone. Six equations were developed, one for each of three latitude bands in each of two seasons. Selection of the latitude bands toot designed so that separate regressions would be applied in tropical and extra‐tropical latitudes in winter and summer, since there are significant differences in total ozone patterns.

It was found that up to about 82% of the variance in total ozone could be explained with six predictors. Further tests with independent data suggested root mean square error (RMSE) levels of about 16 Dobson units in regression forecasts for Canadian locations for the summer of 1992 and about 23 Dobson units for the summer of 1993, which was an abnormal period of persistent record‐low stratospheric ozone. Although the forecasts show considerable skill, they are improved by the application of a correction procedure before the UV Index formula is applied. The correction procedure uses observations from a network of 13 Brewer spectrophotometers in Canada and a standard successive correction objective analysis procedure to obtain a field that is used to correct the next day's forecast. The correction procedure successfully removes the bias and reduces the RMSE of the ozone forecasts to about II Dobson units in both summers of 1992 and 1993.
Using statistical techniques to deduce local climate distributions. An application for model validation
Authors: Noguer M.
Published: June 2010

Due to increasing interest in the prediction of detailed regional climate, a method to deduce local climate distributions from large‐scale variables is proposed. Since surface parameters are difficult to reproduce with the current resolution of General Circulation Models (GCMs), a statistical approach is used to fill the gap between GCM outputs and regional climate. The idea is to find relationships between local climate variables (the predictands) and predictors based on the large‐scale flow using Canonical Correlation Analysis, and then to find a regression model to relate the important canonical variables to each of the local surface variables‐ Predictor variables are provided by the monthly average mean sea‐level pressure field simulated by the Hadley Centre coupled model over the North Atlantic region. The predictands are the simultaneous monthly average precipitation Simulated over the Iberian Peninsula at four grid points, where the grid‐point values are interpreted as a proxy for station data. The results suggest that the technique can reproduce the major variations in regional climate on the monthly time scale.
Validation of computed power station plume trajectories using aircraft observations
Authors: Buckland A T
Published: June 2010

Aircraft measurements of SO2 were made on seven separate occasions to test whether trajectory methods could be used to predict realistic concentrations for the UK composite plume and identify individual sources. The profiles between computed and observed concentrations in south‐westerly meteorological situations were comparable but the agreement is less marked in different and more complex conditions.
A Bayesian approach to estimating benefits of improved forecasts
Authors: Kite‐Powell Hauke L. , Solow Andrew R.
Published: June 2010

We describe a Bayesian approach to estimating the economic benefits from improved forecasts. The approach takes explicit account of how decision makers use forecast information, and can provide more reliable estimates of benefits than methods based on mitigated impacts. We discuss some practical considerations in applying the approach to weather and climate forecasts, and describe the results of an application to ENSO prediction.
Forecasting the movement of tropical cyclones at the Met. Office
Authors: Radford A M
Published: June 2010

Over the last decade global numerical weather prediction models have become sufficiently sophisticated to forecast the movement of tropical cyclones with a reasonable degree of accuracy. This paper describes the work being done at the Met. Office in Bracknell, UK, to improve and verify track forecasts, looking particularly at methods of ‘bogussing’ the initial conditions and of verifying the forecasts.
The importance of convective gusts
Authors: Bradbury W M S , Deaves D M , Hunt J C R , Kershaw R , Nakamura K , Hardman M E , Bearman P W
Published: June 2010

This paper examines the practical importance of convective gusts for operators of wind‐sensitive systems and for designers of Wind‐sensitive structures. The mechanics of gusts associated with turbulence (driven by momentum) and convective eddies (driven by buoyancy) are discussed‐Statistical analysis of gusts and gust factors is presented. This shows that extreme gust factors are always produced by the convective mechanism whereas extreme gusts can be produced by either mechanism. Severe convective gusts are shown to have important consequences for operators of Wind‐sensitive systems because they defy precise prediction, they can be isolated in their occurrence, they can occur in quite moderate mean winds and they can be associated with sudden changes of wind direction. Extreme convective gusts are of less importance to designers of wind‐sensitive structures. They are shown to have a relatively small influence on the magnitude of the predicted extreme gusts taken as design criteria for such structures. Nevertheless, there is a significant chance that when such extreme gusts occur, they are produced by the convective mechanism. When this occurs, the predicted aerodynamic effect may be underestimated, to some extent, because of inertial forces which change the nature of the flow and may increase the loading.
A study of the influence of topography on the climate of the region of Aegion, Greece
Authors: Ahmed Sh I , Mantas G P
Published: June 2010

Measurements of air temperature and wind speed and direction during the months of February, March and April 1988, at Aegion, Greece (38°14.25′ N, 22°7.5′ E) are analysed to detect topographic influences on the climate of this region. The analysis shows that this climate is controlled by nighttime weak cold katabatic winds from the south–south‐west sector, which is bounded by mountains, and stronger warmer daytime winds from the east–north–west sector, which is bounded by the Gulf of Corinth. The presence of weak katabatic winds is also supported by nighttime measurements of the air temperature along the Corinth–Patras road, which show significant temperature depressions at the openings of the several ravines that are found in this region.
Forecasts and warnings of natural disasters: The roles of national and international agencies
Authors: Hunt J C R
Published: June 2010

Natural disasters are caused by natural events, which can be grouped as (i) extreme unstable events; (ii) large ‘variability’ events associated with extremes of the inherent variability and chaotic behaviour of geophysical systems; and (iii) global change events. These primary events are usually followed by equally harmful secondary events, such as mud slides or tsunamis following volcanic eruptions. Whether these events lead to disasters depends to a large extent on the preparedness and resistance of the afflicted community – i.e. its vulnerability. Forecasts for these different categories of event are of two types: ‘risk’ forecasts based on data of previous events, and real‐time forecasts. For group (i) events, these forecasts only begin following some initial detection, whereas for groups (ii) and (iii), forecasts are made before any indication of the event. Many (but not all) types of secondary event may also be forecast with increasing accuracy using local geophysical data and computational models of relevant processes. In this paper the organisation of forecasts and warnings is described, as is how it involves geophysical and disaster or emergency centres at the national, regional and international level. Satisfactory arrangements for issuing, receiving and acting on forecasts and warnings between countries (including the use of broadcasting media) require carefully negotiated procedures at the intergovernmental level. It is pointed out that international procedures developed for meteorology need to be extended to include other types of geophysical event and disaster. The final section of this paper reviews the need for defining targets for improvement in forecasting during the current International Decade for Natural Disaster Reduction (IDNDR), and that this should be preceded by establishing the accuracy of current methods, i.e. the baseline. Clarification of our objectives and targets may well lead to greater financial support from governments and other donors.
Data filtering for thermal mapping of road surface temperatures
Authors: Shao J , Lister P J
Published: June 2010

‘Thermal mapping’ is the name given to the measurement of the variation in road surface temperatures across a region on winter nights. The method involves the use of infrared thermometers and data loggers mounted in modified vehicles. The signal recorded by the data logger is composed of two parts: that due to the road surface temperature and that due to error. Because relative temperature differences, as opposed to absolute temperatures, are important for thermal mapping, a low pass filter to remove or reduce high‐frequency errors or ‘noise’ is required. This paper examines the required features of such a filter and tests the applicability of one such filter with a thermal mapping data set. The results show that high‐frequency noise may be reduced without losing the spatial resolution necessary to detect cold spots in the road network. It is also demonstrated that in order to achieve this goal, a sufficiently high spatial resolution of raw observations is required.
The weather sensitivity of the UK food retail and distribution industry
Authors: Agnew Maureen D , Thornes John E
Published: June 2010

This paper focuses attention on the weather sensitivity of the food and drinks sector within the UK retail and distribution industry. The potential benefits to accrue from the application of meteorological knowledge are evaluated in light of current advances in retail information systems and management. Subsequently, the viability of using weather forecasts in operational decision‐making is discussed from both the meteorological and industrial standpoints.
Monthly characterisation of the tropical weather combining satellite and raingauge data
Authors: Hidalgo L G
Published: June 2010

A computerised procedure has been developed for helping meteorologists produce a monthly characterisation of tropical weather. Inputs are a regional value of outgoing longwave radiation (OLR) from the TIROS/NOAA satellites and a rainfall amount from a local raingauge within the region, both for a given month and year. OLR has been incorporated to help complete information conveyed by the rainfall because this is influenced by short‐period episodes responsible for tropical rainfall. The main output is a category for the month. Analyses of anomalies and weather spell are also included. Meteorologists may apply the procedure on a near‐real‐time basis since OLR and rainfall data are available via the Internet (ftp). When raingauge data are missing the satellite estimates of rainfall can be used.
Automated measurements of snow temperature profiles in the Cairngorm mountains, Scotland
Authors: Purves R S , Barton J S , Wright D S B
Published: June 2010

A programme to measure snow temperature profiles using thermistors with automatic data logging and telemetry is described for sites in the Cairngorm mountains, Scotland. The data for 1992/93 and 1993/94 are discussed in terms of snow metamorphic processes. Equilibrium forms and melt‐freeze dominate, but temperature gradients high enough to produce faceting can occur. These data have been utilised in the successful adaptation of the NXD (Nearest Day) avalanche forecasting model to the Northern Cairngorms.
Tropical cyclones in the south‐west Indian Ocean: Track prediction and verification of the UKMO model for 1991–92
Authors: Vermeulen Jan H
Published: June 2010

The aim of this paper is to evaluate tropical cyclone (TC) track forecasts of the United Kingdom Meteorological Office model in the south‐west Indian Ocean for 1991–92. These results are then compared with similar results for 1989–90 and 1990–91. Displacement errors are used for the evaluation of TC track predictions of individual TCs for forecast days 1 to 5. The Dvorak‐number is used to determine TC intensity. The skill of the numerical weather prediction model of the UKMO varies from high for the intense TCs to low for the weak TCs. Similar results were found for the western North Pacific by other researchers and is probably caused by deficiencies in the bogussing techniques. The weak TCs Davilia, Bryna and Celesta were forecast by only 18% of the model runs. For days 1, 2 and 3 the seasonal mean TC track forecast errors of 1991–92 compare well with those from 1989–90 and 1990–91.
Diagnosis of a rapidly deepening depression: 16/17 January 1995
Authors: Carroll Edward B
Published: June 2010

The development of a vigorous mid‐latitude depression as simulated in the UK Met. Office operational limited area model is examined. Water vapour imagery is compared with forecast fields, and it is shown that such imagery can be used to visualise the distribution of absolute vorticity and also to verify the model forecast. It is suggested that the similarity between the water vapour imagery and the absolute vorticity fields is greater than that previously noted between the water vapour imagery and the potential vorticity fields.
Radiosonde balloon drift — does it matter for data assimilation?
Authors: MacPherson Bruce
Published: June 2010

Operational data assimilation systems for numerical weather prediction (NWP) neglect the space‐time drift of radiosonde balloons during their ascent. The validity of this assumption is assessed by reference to the equations of motion and a sensitivity experiment with a mesoscale NWP model. In the experiment, balloon drift is explicitly accounted for in the case of one key ascent which had a significant impact on a short‐period forecast of small‐scale baroclinic development. It is found in this case that, while the impact of balloon drift can indeed be detected, it is small compared with the impact from the observation when assimilated with neglect of balloon drift.
Weather, air quality and health
Authors: Collier C G , Hardaker P J
Published: June 2010

Relationships between weather and health have been studied throughout recorded history. This century, air quality has been recognised as an important complicating feature in many urban and industrial locations. In this paper, having defined the difference between climate and weather, we outline some of the relationships which have been defined between both climate and weather conditions, air quality and human health. Links between conditions ranging from mental illness, respiratory and heart disease to flu have been reported. Unfortunately, much of the published work over the years has lacked scientific credibility or has used widely differing analysis tools. However, increased availability of data, and an understanding of the need to follow good scientific practice, are offering the opportunity to place some of the relationships on a more sound foundation. Recent studies identifying susceptible genetic conditions may lead to understanding of previously unexplained linkages. The need for research collaboration between the meteorological, atmospheric chemistry, epidemiology and, most importantly, the medical communities to investigate sometimes complex trigger mechanisms, is highlighted.
A statistical method for predictions of mean monthly precipitation in Cuba
Authors: Naranjo‐Díaz Lino R , Centella Abel , Cardenas Pedro
Published: June 2010

Statistical methods for predicting the mean monthly precipitation in Cuba have been developed. Two different approaches have been used: multiple linear regression (MLR) and an adaptive scheme using a LVQ algorithm. Three main climatic divisions were defined over the Cuban territory using 180 observation points with a nearly homogeneous geographical distribution. A 50‐year (1941–1990) period was considered. Three types of variable were used as predictors: The Southern Oscillation Index and the Sea Surface Temperature anomaly in the central equatorial Pacific as the ENSO related variables, the Wolf Sunspot Index as a solar activity related variable and variables related to seasonality and persistence. The last of these was found to be the most important in producing high skill. A cross‐validation approach was used to test the prediction quality. This indicated that the LVQ algorithm provided a greater number of correct forecasts but the MLR method showed a slightly higher level of skill. The feasibility of using a LVQ algorithm for predicting mean monthly precipitation is established. However, the high skills found for the MLR method suggest that it should be used as a complementary tool in the decision‐making process.
A mesoscale vortex diagnosed from combined satellite and model data
Authors: Browning K A , Roberts N M , Sim C S
Published: June 2010

Mesoscale vortices originating as tropopause folds can lead to cyclogenesis, cloud formation and/or convective overturning. The presence of such mesoscale vortices can often be inferred from the nature and behaviour of dry zones in Meteosat water vapour imagery. Diagnostics from an operational limited‐area forecast model are presented for one such dry zone, which appeared to rotate in the water vapour imagery. Model and imagery show that a vortex‐induced combination of potential instability and ascent led to the development of a small band of cloud and thundery rain.
Investigating a SSM/I microwave algorithm to calibrate Meteosat infrared instantaneous rainrate estimates
Authors: Levizzani V , Porcú F , Marzano F S , Mugnai A , Smith E A , Prodi F
Published: June 2010

Simultaneous rainfall analyses using Special Sensor Microwave/Imager (SSM/I) passive microwave measurements and thermal infrared measurements from Meteosat are presented for two storms over northern Italy that caused damaging floods. Upwelling brightness temperatures over precipitating clouds in the mm‐cm spectrum are directly associated with precipitation microphysics throughout the cloud column down into the rain layer. In contrast, brightness temperatures in the thermal infrared window, which arise from emission near cloud top, are not directly responsive to precipitation processes. However, because of the diffraction‐limited nature of passive microwave detectors, microwave radiometer ground footprints are considerably larger than those characteristic of infrared sensors, even those flown at geosynchronous altitude. Furthermore, passive microwave radiometers are flown on low‐earth orbiters, which produce less than ideal sampling rates, whereas optical‐infrared radiometers flown on geosynchronous orbiters produce high frequency sampling concomitant with precipitation time scales. In this study, we investigate how these two types of measuring systems could be used in a complementary fashion to improve rainfall estimation. A physically based microwave algorithm is used to estimate rainfall with SSM/I measurements, whereas a two‐threshold statistical technique is used for corresponding estimates from Meteosat. Results suggest that an infrared‐based analysis of rainfall derived from half‐hourly geosynchronous images can be improved with a calibration‐transfer approach using a microwave algorithm sensitive to vertical cloud structure.
Cyclogenesis over the Aegean Sea: Identification and synoptic categories
Authors: Flocas Helena A , Karacostas Theodore S
Published: June 2010

An attempt is made to identify and investigate the structure, behaviour and synoptic characteristics of cyclogenesis over the Aegean Sea. A simple, realistic and easily used methodology of identification, in an analytical form, was established. This combines two types of criteria: synoptic and dynamic/thermodynamic. Six synoptic categories that could favour cyclogenesis over the Aegean Sea are distinguished according to the synoptic criteria. Grid‐point values of geopotential height and temperature are used to calculate the dynamic/thermodynamic criteria, which are used to identify potential cases of cyclogenesis with respect to the thermodynamic prerequisites and the time continuance. It is demonstrated that cyclogenesis over the Aegean Sea is not as rare as was believed. The majority of cases result from the prevalence of a south‐westerly flow, a long‐wave trough and a closed system over the Aegean Sea. The cyclogenesis appears to occur primarily in the cold period of the year, mainly from October to May, and to have a small intensity and lifetime.
The quality and accuracy of a sample of public and commercial weather forecasts in the UK
Authors: Thornes John E
Published: June 2010

At a time when the commercialisation of weather forecasting is proceeding at an alarming rate around the world, it is essential to review the quality and accuracy of weather forecasts to ensure that current standards are at least maintained. The privatisation of meteorological services in some countries (e.g. New Zealand) and the vigorous commercialisation of established Met. Offices such as in the United Kingdom, France and Sweden suggests that customer satisfaction, increased income and reduced expenditure will dominate the weather forecasting scene over the next decade. It is important that the quality of weather forecasts is closely monitored before and after commercialisation to ensure that the accuracy of weather forecasts continues to improve and that public weather forecasting does not suffer. The improved technologies for data collection such as weather satellites, weather radar, wind profilers, road weather information systems, sferics, etc. should make it easier to assess forecast accuracy ‐ but with the exception of road weather forecasts there is little sign that the new technology has been used for this purpose. The current accuracy of a sample of weather forecasts in the UK is discussed and a framework for publishing future weather forecast verification statistics is presented.
Short‐term forecasts of biologically effective UV radiation: Comparison between modelled and measured irradiation
Authors: Feister Uwe
Published: June 2010

Ultraviolet (UV) radiation from the sun affects the biosphere and chemical processes of atmospheric trace gases. The amount of atmospheric ozone as well as the amount of clouds and atmospheric aerosols determine the UV radiation reaching the earth's surface at a definite place and time. Using numerically forecast meteorological parameters such as temperature and relative vorticity at different pressure levels, a short‐term forecast of atmospheric ozone was calculated. This ozone value and the numerically forecast cloud cover were fed into a UV forecasting model to determine a short‐term forecast of biologically effective UV radiation. UV radiation forecasts were calculated for three stations in the northern, central and southern part of Germany. Comparisons between ozone forecasts and ground‐based as well as satellite‐based ozone measurements for the summer months of 1994 showed the uncertainty of ozone forecasts to be within ±3% and ±6%. Values of the modelled biologically effective UV radiation were compared with measured UV radiation data taken with UV filter instruments and with a spectro‐radidmeter at Potsdam in the period September 1993 to September 1994. It turned out that for a cloud cover of less than 4/8 to 5/8, the model calculations overestimated the measured irradiation by about 10 to 15%. The main reason for the discrepancy between model calculations and measurements may be the cloud parameterization in the model. Also, the method of estimating the aerosol load as well as uncertainties in the measured UV radiation may have contributed to the differences.
Assessment of the benefits of an enhanced weather information service for the cotton industry in Australia
Authors: Anaman Kwabena A , Lellyett Stephen C
Published: June 2010

The benefits derived from using an enhanced weather information service, the Cottonfielcis Weather Service, produced by the Australian Bureau of Meteorology were determined via a survey of producers of the Namoi Cotton Co‐operative. The economic benefits were estimated using two methods: (a) the change in aggregate gross producer benefits (producers' surplus) due to reduction of unit costs of production from use of the service, and (b) the maximum amounts of money users would be willing to pay (WTP) for use of the service. Results indicated that the average annual WTP for the service was about 223 Australian dollars (A$). The WTP value was modestly higher than the average annual phone facsimile charges of A$190. The change in aggregate gross producer benefits derived were based on the estimated average 1 % cost reduction in the production of raw cotton from using the service based on elicited survey data. The annual aggregate gross benefits were about A$397 150 for cotton production only. The total annual costs incurred by cotton producers for use of the service were A$31 590. Hence the benefit‐cost ratio (for cotton production only) was about 12.6. Reported indirect benefits included time savings for producers and use of the service to plan household and social activities.
Estimations of Probable Maximum Precipitation (PMP) for the Evinos catchment in Greece using a Storm Model approach
Authors: Hardaker P J
Published: June 2010

A Storm Model is used to estimate Probable Maximum Precipitation (PMP) for the Evinos catchment in Greece. The model determines the maximum dew‐point temperature from the effects of solar heating, orographic lifting and convergence, in terms of the change in temperature of a rising parcel of air. From this the model estimates the maximum precipitable water over the catchment and together with storm efficiency calculates PMP. For the Evinos catchment the 12‐hour PMP is estimated to be 478 mm and the 24‐hour PMP is 494 mm, occurring in late July. Further, the total water from a maximum rainfall event taken together with a rare snowmelt is unlikely to exceed the amount of water produced by a maximum rainfall in late July; hence, the latter is taken as the catchment PMP.
Exploring the effects of different types of model initialisation: Simulation of a severe air‐pollution episode in Athens, Greece
Authors: Lagouvardos K , Kotroni V , Kallos G
Published: June 2010

A combined modelling system consisting of a meteorological model (Colorado State University/ Regional Atmospheric Modelling System) and a transport package (Hybrid Particle and Concentration Transport Model) is used. The simulations were performed using two types of model initialisation: the first with ECMWF gridded analysis data and the second with one sounding profile. The modelling system has been used to simulate an important air‐pollution episode in the Athens urban area. This area is characterised by complex and variable topographic features, and the associated local atmospheric circulations play a significant role in defining the transport and dispersion conditions over the area. The advantages and shortcomings of both types of initialisation, and more specifically the capability of the model to represent and reproduce the local‐scale conditions and the dispersion of air pollutants, are discussed.
Prediction of near‐surface gusts generated by deep convection
Authors: Nakamura K , Kershaw R , Gait N
Published: June 2010

An equation for the prediction of near‐surface gusts generated by convection is tested against observations and against simulations made with a model which resolves convectve clouds, in order to investigate the phenomenon, and to validate the equation in a range of convective regimes. These include two types of severe weather which affect the UK: mid‐latitude depressions and thunderstorms. The prediction equation works well in both convective regimes. Two processes are shown to be important. The first is the production of horizontal momentum by pressure gradient forces, as convective downdraughts are blocked by the surface and distorted to spread out horizontally. The second is the downward transport of horizontal momentum by the convective downdraughts, in the presence of vertical shear. The equation should be tested by forecasters, especially when deep convection occurs in conjunction with strong geostrophic winds. It could also be applied in Numerical Weather Prediction models to automate the prediction of convective gusts.
Test of indices for classification of winter climate
Authors: Gustavsson Torbjörn
Published: June 2010

Three types of index were tested which classified winter climates in relation to winter road maintenance activities. The indices were tested with data from December 1994, from one open, well‐exposed station which forms part of the Swedish Road Weather Information System. All three types of index gave different results when applied to the test period. The selection of the weather parameters in the index, as well as the definition of weather types, are considered important, since they control the number of severe weather conditions which are summed over a period of time. Another important controlling factor was found to be the character of the summation, i.e. whether it was on a daily basis or whether the summation was over severe weather situations.
Dropsondes with GPS windfinding
Authors: Cogan J , Greenling T , Luces S A , Thomas J
Published: June 2010

Detailed, quantitative, atmospheric data are essential for accurate analysis and forecasting of mesoscale phenomena for both military and civilian applications. Small manned or unmanned aircraft can carry small sensors and dropsondes into remote or hazardous regions, at little or no risk to personnel and at a very low cost. This paper describes two prototype dropsondes that used the Global Positioning System (GPS) for measuring wind velocity. Flight tests using a helicopter produced results that gave an accuracy in wind velocity about the same as coincident rawinsondes. The test data suggest that it may be possible to delineate zones of significantly different wind velocity that are less than 200 metres thick, although further tests are needed to evaluate this possibility thoroughly.
Modelling evapotranspiration in semi‐arid terrains: Comparison of two schemes
Authors: Fernández C , Nieto G , Prego J A
Published: June 2010

The importance of choosing a relatively detailed parameterisation for plant transpiration in semi‐arid terrains is evidenced by comparison of model results and observations from a European field experiment recently performed in La Mancha (Spain). In severe drought periods the contribution of the vegetation cover to the total latent heat flux is greater, since the evaporation from the bare soil fraction is small. Also, the observed heterogeneity of vegetation types in semi‐arid regions, such as the Iberian peninsula, is an additional argument to recommend the inclusion of somewhat sophisticated parameterisations in mesoscale models. A set of sensitivity tests and different formulations for the stomatal resistance illustrates fairly well the importance of the vegetation properties in regions where plants are scarce.
Analysis of the operational calibration of the Meteosat infrared‐window channel
Authors: Gube Marianne , Gärtner Volker , Schmetz Johannes
Published: June 2010

The operational procedure for the calibration of the Meteosat infrared (IR: 10.5‐12.5 m̈m) channel is studied. Since no adequate onboard calibration is available, calibration techniques have been developed which use conventional meteorological data together with model calculations. The operational calibration technique for the IR channel relies on radiation model calculations for clear‐sky which take independent data on the atmospheric and surface temperature as model input. Satellite observations (radiometric counts) over the ocean are correlated with radiances calculated from independent sea‐surface temperature analyses and short‐term forecast fields of temperature and humidity. The sensitivity of the radiation calculations to humidity profiles and to different parameterisations of the water vapour continuum is studied. The operational calibration coefficients are based on averaging over previous calibration calculations. This method is reviewed and a new approach, based on daytime satellite observations only, is proposed. The new method reduces calibration coefficients by about 1%, which yields better agreement with a previous cross‐calibration study.
Medium range weather forecasts in India during Monsoon 1994
Authors: Rao P Sanjeeva , Saseendran S A , Rathore L S , Bahadur J
Published: June 2010

Aiming to enhance and sustain farm production in India, an Agromet Advisory Service has been started. Numerical weather prediction output from a spectral model (T80L18) is fine‐tuned by employing statistical and synoptic methods to prepare 24 h, 48 h and 72 h weather forecasts for 20 locations during the principal crop growing period of 1994. Also, weekly rainfall forecasts for 35 meteorological sub‐divisions during monsoon period are produced. The accuracy of location‐specific rain/no‐rain event forecasts was found to be 70%. However, the root mean square error for the quantitative rainfall forecast was 17 mm; hence, there is a need for further improvement. The accuracy of maximum temperature (at 10 locations) and minimum temperature (at 18 locations) was 2 °C. The forecasts of rainfall event, temperature, cloud cover and wind speed showed considerable skill over random forecasts. The performance of trends and temporal variability in weekly sub‐divisional rainfall forecasts were evaluated.
Meteorology and forest fires: Some case studies
Authors: Palmieri Sabino , Inghilesi Roberto , Siani Anna Maria
Published: June 2010

The role of the physical and meteorological factors involved in forest fires is outlined. The index used by the Meteorology Group of Rome University is then described. The methodology is based on the computation of an aridity factor which is a non‐linear function of precipitation and evapotranspiration in the last 40 days. The aridity is then coupled with an exponential function which takes into account actual or predicted meteorological conditions (temperature, wind, relative humidity and rainfall) to give the fire‐risk index. The results of applying the index to cases of fires in Liguria and Tuscany are given. It is suggested that the development of fine‐mesh non‐hydrostatic meteorological models coupled with fire spread and burn rate models is a promising approach for scientific progress in this field.
Fetal tricuspid valve Doppler at 11–13 weeks and 6 days: reference values and reproducibility
Authors: Ninno Milena Almeida Prado , Liao Adolfo Wenjaw , Lamberty Clarissa Oliveira , Miguelez Javier , Zugaib Marcelo
Published: June 2010

Objective

To determine normal blood flow velocities across the fetal tricuspid valve (TV) at 11–13 weeks and 6 days of gestation and to examine the reproducibility of these measurements.

Methods

A prospective study involving 166 normal singleton pregnancies examined at 11–13 weeks and 6 days was carried out. Descriptive analysis of E‐ and A‐waves' maximum velocities, E/A ratio, duration of the cardiac cycle (C) and diastole (D) and D/C ratio were calculated. Intraobserver and interobserver agreement analysis was performed in a subgroup of 12 cases.

Results

Average ( ± SD) flow velocities were: E‐wave, 25.0 ( ± 4.6) cm/s; A‐wave, 42.9 ( ± 5.9) cm/s; E/A, 0.58 ( ± 0.07); cardiac cycle, 390 ( ± 21.1) ms; diastole, 147 ( ± 18) ms and D/C, 0.38 ( ± 0.04). Significant correlation was observed between all parameters (except A‐wave) and gestational age but not with nuchal translucency (NT). Intraclass correlation coefficients (interobserver, intraobsever examiner 1 and intraobserver examiner 2) were: E‐wave, 0.53, 0.53 and 0.64; A‐wave, 0.45, 0.46 and 0.49; cardiac cycle, 0.70, 0.79 and 0.84 and diastole, 0.63, 0.85 and 0.82, respectively.

Conclusions

The present study establishes normal Doppler parameters for blood flow across the TV at 11–13 weeks and 6 days and demonstrates that these parameters do not correlate with NT measurement and have good/moderate reproducibility. Copyright © 2010 John Wiley & Sons, Ltd.
Two‐ or three‐dimensional ultrasonography: which is the best predictor of pulmonary hypoplasia?
Authors: Vergani Patrizia , Andreani Marianna , Greco Massimiliano , Farina Giuliano , Fedeli Tiziana , Cuttin Serena
Published: June 2010

Objective

The aim of our study is to compare the three‐dimensional (3D) ultrasound fetal lung volume measurements with two‐dimensional (2D) ultrasound biometric parameters in predicting pulmonary hypoplasia (PH).

Methods

From June 2006 to November 2008, we identified 35 fetuses at high risk for developing PH, including premature preterm rupture of membranes (17), fetal skeletal malformations (7), hydrothorax (7), and bilateral renal dysplasia (4). 3D lung volumes adjusted for gestational age (GA) or estimated fetal weight (EFW), thoracic circumference adjusted for GA or femur length, thoracic/abdominal circumference ratio, and thoracic/heart area ratio were measured.

Results

Three infants were excluded because no clinical or histological information regarding lung hypoplasia was available. Of the 32 remaining infants, 13 (41%) were diagnosed with PH at postmortem examination or by clinical and radiological examination. 3D lung volume measurements had a better diagnostic accuracy for predicting PH either when adjusted for GA [sensitivity, 12/13 (92%); specificity, 16/19 (84%); positive predictive value 12/15 (80%); negative predictive value, 16/17(94%)] or EFW [sensitivity, 11/13 (85%); specificity, 18/19 (94%); positive predictive value 11/12(92%); negative predictive value, 18/20(90%)] compared to the 2D biometric measurement.

Conclusion

3D lung volume measurements seem to be useful in the prenatal prediction of PH. Copyright © 2010 John Wiley & Sons, Ltd.
An IR molding system for direct shaping of thermoplastics
Authors: Quadrini Fabrizio , Santo Loredana , Tagliaferri Vincenzo , Trovalusci Federica
Published: June 2010

A new molding technique is proposed to directly mold small parts from thermoplastic pellets. A small molding machine was designed and fabricated: the mold consisted of a transparent glass and a metallic frame; an infrared (IR) lamp provided the heat for the pellet melting. Molding tests were carried out by using three commercial thermoplastics and two metallic molds. Molding time and IR lamp power were changed to extract a moldability window for each combination of material and metallic mold. In the best process conditions, a high quality of the samples was obtained in terms of mold filling and surface aesthetics. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Effect of microfiber reinforcement on the morphology, electrical, and mechanical properties of the polyethylene/poly(ethylene terephthalate)/carbon nanotube composites
Authors: Yesil Sertan , Koysuren Ozcan , Bayram Goknur
Published: June 2010

In situ microfiber reinforced conductive polymer composites consisting of high‐density polyethylene (HDPE), poly(ethylene terephthalate) (PET), and multiwalled carbon nanotube (CNT) were prepared in a twin screw extruder followed by hot stretching of PET/CNT phase in HDPE matrix. For comparison purposes, the HDPE/PET blends and HDPE/PET/CNT composites were also produced without hot stretching. Extrusion process parameters, hot‐stretching speed, and CNT amount in the composites were kept constant during the experiments. Effects of PET content and molding temperature on the morphology, electrical, and mechanical properties of the composites were investigated. Morphological observations showed that PET/CNT microfibers were successfully formed in HDPE phase. Electrical conductivities of the microfibrillar composites were in semi‐conductor range at 0.5 wt% CNT content. Microfiber reinforcement improved the tensile strength of the microfibrillar HDPE/PET/CNT composites in comparison to that of HDPE/PET blends and HDPE/PET/CNT composites prepared without hot stretching. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Creep behavior of high density polyethylene after aging in contact with different oil derivates
Authors: Habas‐Ulloa Amelia , D'Almeida Jose‐Roberto Moraes , Habas Jean‐Pierre
Published: June 2010

The creep behavior of a high density polyethylene (HDPE), currently used as raw material for pipe manufacture, was evaluated before and after exposure to oil derivates using transient rheometry. The creep behavior of the original HDPE was satisfactorily described using a generalized Kelvin‐Voigt model based on two retardation times. The values of these critical times were quite different from each other, indicating a large distribution of macromolecular weight. The aging procedure was performed by immersing the polymer in two model fluids chosen to discriminate and understand the action of aromatic and paraffinic fractions of fuel derivatives (white oil, gas‐oil). The batch operation was also carried out at two different temperatures to investigate the thermal activation of plausible degrading mechanisms. In the case of the aging performed in the paraffinic fluid, the polymer compliance continuously increased with the immersion duration. This behavior was attributed to a plasticization induced by the diffusion of the liquid in the polymer matrix. The same phenomenon was observed in the early stage of the HDPE aging carried out with the aromatic fluid. However, for longer aging times, the extraction of low molecular weight species produced the stiffening of the thermoplastic. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers