bluuebunny/crossref_metadata_2025_split huggingface dataset:
A 3D stochastic cloud model for investigating the radiative properties of inhomogeneous cirrus clouds
Authors: Hogan Robin J. , Kew Sarah F. 
Published: November 2005

AbstractThe three‐dimensional structure of clouds is known to be important for determining their radiative effects, but it is difficult to obtain this structure directly from observations. In this paper a stochastic model is described that is capable of simulating the structural properties unique to cirrus: fallstreak geometry and shear‐induced mixing. We first present an analysis of time–height cloud radar sections from southern England to extract the cirrus parameters of interest. It is found that horizontal power spectra of the logarithm of ice‐water content (estimated from radar reflectivity factor and temperature) typically exhibit a spectral slope of around −5/3 near cloud top that decreases with depth into the cloud, to values as low as −3.5 in some cases. This decrease can be explained by wind shear coupled with a spread of particle fall speeds leading to a homogenization that acts preferentially at smaller scales. The power spectra exhibit a distinct scale break, becoming flat at scales larger than around 50 km (the ‘outer scale’). The orientation of the fallstreaks may be predicted from the profile of mean wind and mean ice fall speed. We then describe the stochastic model, which takes as input profiles of the mean and fractional standard deviation of ice‐water content, spectral slope, outer scale and wind speed. It first generates an isotropic 3‐D fractal field by performing an inverse 3‐D Fourier transform on a matrix of simulated Fourier coefficients with amplitudes consistent with the observed 1‐D spectra. Random phases for the coefficients allow multiple realizations of a cloud with the same statistical properties to be generated. Then horizontal slices from the domain are manipulated in turn to simulate horizontal displacement and changes to the spectra with height. Finally the field is scaled to produce the observed mean and fractional standard deviation of ice‐water content. Vertical 2‐D slices extracted from the domain are very similar in appearance to cloud radar observations. Radiative‐transfer calculations using the independent column approximation are used to show that the different fallstreak orientation resulting from different wind shears can change mean top‐of‐atmosphere radiative fluxes by in excess of 45 W m−2 in the short‐wave and 15 W m−2 in the long‐wave. The effect of wind shear to induce horizontal mixing causes an additional but smaller radiative effect. We also investigate the biases that would be expected from the assumptions made in the radiation schemes of general‐circulation models (GCMs). It is found that there is some compensation between the errors arising from the assumptions of horizontal homogeneity and maximum‐random overlap; if a GCM were to improve the overlap assumption but still assume clouds to be horizontally homogeneous then the total error in cloud radiative effect would be likely to increase. Copyright © 2005 Royal Meteorological Society.
Use of randomization to diagnose the impact of observations on analyses and forecasts
Authors: Desroziers G'erald , Brousseau Pierre , Chapnik Bernard 
Published: November 2005

AbstractA method is proposed to diagnose the impact of a complete set, or subsets, of observations on the reduction of error variance in an analysis and in the subsequent forecasts run from this analysis. A practical method to estimate the error reduction, based on a randomization procedure, is also introduced and investigated in a simple framework given by the analysis and forecast of wind on a circular domain using the nonlinear Burger's equation. The randomization procedure is also applied and tested in the French ARPEGE 4D‐Var assimilation. The first results in a real‐size data assimilation system are realistic and provide useful information on the use of observations in an operational analysis. Copyright © 2005 Royal Meteorological Society
Water‐vapour variability within a convective boundary‐layer assessed by large‐eddy simulations and IHOP_2002 observations
Authors: Couvreux F. , Guichard F. , Redelsperger J.‐L. , Kiemle C. , Masson V. , Lafore J.‐P. , Flamant C. 
Published: November 2005

AbstractThis study presents a comprehensive analysis of the variability of water vapour in a growing convective boundary‐layer (CBL) over land, highlighting the complex links between advection, convective activity and moisture heterogeneity in the boundary layer. A Large‐eddy Simulation (LES) is designed, based on observations, and validated, using an independent data‐set collected during the International H2O Project (IHOP_2002) field‐experiment. Ample information about the moisture distribution in space and time, as well as other important CBL parameters are acquired by mesonet stations, balloon soundings, instruments on‐board two aircraft and the DLR airborne water‐vapour differential‐absorption lidar. Because it can deliver two‐dimensional cross‐sections at high spatial resolution (140 m horizontal, 200 m vertical), the airborne lidar offers valuable insights of small‐scale moisture‐variability throughout the CBL. The LES is able to reproduce the development of the CBL in the morning and early afternoon, as assessed by comparisons of simulated mean profiles of key meteorological variables with sounding data. Simulated profiles of the variance of water‐vapour mixing‐ratio were found to be in good agreement with the lidar‐derived counterparts. Finally, probability‐density functions of potential temperature, vertical velocity and water‐vapour mixing‐ratio calculated from the LES show great consistency with those derived from aircraft in situ measurements in the middle of the CBL. Downdraughts entrained from above the CBL are governing the scale of moisture variability. Characteristic length‐scales are found to be larger for water‐vapour mixing‐ratio than for temperatureThe observed water‐vapour variability exhibits contributions from different scales. The influence of the mesoscale (larger than LES domain size, i.e. 10 km) on the smaller‐scale variability is assessed using LES and observations. The small‐scale variability of water vapour is found to be important and to be driven by the dynamics of the CBL. Both lidar observations and LES evidence that dry downdraughts entrained from above the CBL are governing the scale of moisture variability. Characteristic length‐scales are found to be larger for water‐vapour mixing‐ratio than for temperature and vertical velocity. In particular, intrusions of drier free‐troposphere air from above the growing CBL impose a marked negative skewness on the water‐vapour distribution within it, both as observed and in the simulation. Copyright © 2005 Royal Meteorological Society.
Assimilation of ozone data from the Michelson Interferometer for Passive Atmospheric Sounding
Authors: Wargan Krzysztof , Stajner Ivanka , Pawson Steven , Rood Richard B. , Tan Wei‐wu 
Published: November 2005

AbstractGlobal ozone profiles from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) were added to an assimilation system that includes ozone data from the Solar Backscatter Ultraviolet/2 (SBUV/2) instrument. Substantial impacts were found and investigated. MIPAS ozone profiles have a vertical resolution close to 3 km, retrieved from infrared limb emission radiances, with a height‐dependent error of 4–8%; they were used over 12 layers, spanning between 60–80 hPa and 0.15–0.25 hPa. As a research instrument, MIPAS provides variable coverage from day to day, with occasional data gaps of several days. The operational SBUV/2 data give regular temporal coverage in sunlit areas, yielding total columns and partial profiles, assimilated for Umkehr layers 3 (126–63 hPa) to 12 (<0.25 hPa), with errors comparable to MIPAS near the ozone maximum but increasing substantially at higher and lower levels. The higher accuracy of MIPAS data leads to substantial improvements in the assimilated ozone below the ozone maximum when compared to accurate in situ (ozonesonde) and space‐based (occultation) data; vertical gradients in the lower stratosphere are improved. In the Arctic winter of 2002/03, the ability of MIPAS to sample the vortex interior leads to substantial beneficial impacts. In the tropics, assimilation of MIPAS profiles improves analyses in the lower stratosphere and provides substantially better agreement with occultation data in the middle stratosphere, near the ozone maximum. This offsets an underestimate in the SBUV‐only analyses caused by transport errors in the forecast. The global improvements in the assimilation lead to local improvements when compared against individual measured ozone profiles, where vertical structures are determined by height dependence in horizontal advection from diverse regions. The spatio‐temporal variability in the assimilation is more realistic when MIPAS data are included. Experiments to examine the impacts of temporal gaps in the MIPAS data reveal a ‘memory’ of 5–10 days in the transport‐dominated lower stratosphere. In the middle stratosphere, the impact of missing MIPAS data is more complex; transport errors cause a large initial impact followed by ozone values typical of SBUV assimilation. Copyright © 2005 Royal Meteorological Society.
The diurnal cycle of the West African monsoon circulation
Authors: Parker D. J. , Burton R. R. , Diongue‐Niang A. , Ellis R. J. , Felton M. , Taylor C. M. , Thorncroft C. D. , Bessemoulin P. , Tompkins A. M. 
Published: November 2005

AbstractUsing numerical model analyses, it is shown that there is a coherent diurnal cycle of the West African monsoon winds. As has been observed in previous studies of arid and semi‐arid areas, the winds are at their weakest in the afternoon when the convective boundary layer (CBL) is deep, and intensify overnight when the boundary‐layer turbulence is much weaker. This diurnal cycle is maximized in the northern part of the monsoon layer, where the meridional pressure gradient and the diurnal cycle of the CBL are both strong.The diurnal cycle can also be resolved in surface and upper‐air data, which show how the nocturnal meridional circulation acts to stratify the lower part of the monsoon layer. In contrast, mixing in the daytime CBL acts to maintain the baroclinicity, as has been observed in laboratory flows. This pattern has implications for the efficiency of the monsoon circulation in the continental water budget, as well as in mixing of trace gases and aerosols between the surface layer and the free troposphere. Vertical mixing occurs by day, while meridional advection, with isentropic upgliding and downgliding, is most efficient at night.Finally, high‐resolution observations from the JET2000 experiment are used to show that there is mesoscale structure in the diurnally varying monsoon circulation. In the nocturnal flows, local circulations have been observed and appear to represent a response to recent deep convective events. In contrast, the daytime CBL properties at these scales have been shown in a previous study to map closely onto patterns of soil moisture, with horizontal advection playing a weaker role. Copyright © 2005 Royal Meteorological Society
Dynamics and microphysics of orographic precipitation during MAP IOP3
Authors: Pujol Olivier , Georgis Jean‐Francois , Chong Michel , Roux Frank 
Published: November 2005

AbstractA dynamical and microphysical four‐dimensional study of an intense orographic precipitating system is carried out in the frame of MAP IOP3 (25–26 September 1999). High precipitation opportunely occurred in the range of the Swiss operational Doppler radar at Monte Lema (Switzerland), the US SPOL polarimetric Doppler radar and the French Ronsard Doppler radar both located near Lago Maggiore (Italy). Radar data have been combined to deduce four‐dimensional precipitation and wind fields during the most intense precipitation period (1600–2000 UTC on 25 September). The organization and evolution of the microphysical field have been obtained through an analysis of SPOL polarimetric data: nine hydrometeor classes (light, moderate and heavy rain, hail, rain–hail and graupel–hail mixtures, dry and wet snow, and ice crystals) are inferred by means of a fuzzy‐logic method initially developed by Vivekanandan et al.The temporal mean study of reflectivity fields reveals that the precipitation presents a convective pattern and is primarily located on the foothills and over the first mountain. Mean microphysical fields reveal rain below the 0 °C level, wet snow, ice crystals and dry snow above with an embedded 2 km deep layer of graupel–hail mixture. This suggests convective microphysical processes.Temporal series of precipitation and wind fields are then analysed in order to characterize in detail the organization and evolution of the system. Three stages were identified: first an elongated structure growing and intensifying over the lake while moving towards the Alps, then a spreading of the system over the mountains and finally a weakening over Lago Maggiore and the mountains. It has to be noted that the lake and the first mountainous peaks were important factors in the generation and the intensification of convective cells: the lake acts as a secondary moisture source which can favour local convection, and mountainous slopes favour updraughts which permit a downwind extension of the system by ejection of precipitating particles according to the fountain particles concept. Finally, through a temporal and spatial microphysical study, coalescence below the 0 °C level, riming and freezing above, are concluded to be the major processes in the formation of intense precipitation. The essential role of ice phase in the formation and enhancement of precipitation has been highlighted. Copyright © 2005 Royal Meteorological Society
A monotonic and positive–definite filter for a Semi‐Lagrangian Inherently Conserving and Efficient (SLICE) scheme
Authors: Zerroukat Mohamed , Wood Nigel , Staniforth Andrew 
Published: November 2005

AbstractA new monotonic and positive–definite filter is incorporated into an existing Semi‐Lagrangian Inherently Conserving and Efficient (SLICE) scheme for transport problems in both Cartesian and spherical geometry. The SLICE scheme is based on a control‐volume approach that uses multiple sweeps of a one‐dimensional O (Δx4) conservation remapping algorithm along predetermined cascade directions. The new filter combines a selective detection algorithm, to pinpoint regions of non‐monotonic behaviour, with a hierarchical reduction of the degree of the piecewise reconstruction in such regions, to re‐establish monotonicity. The enhanced, monotonic and positive–definite, SLICE scheme is tested in one dimension, and then applied to standard two‐dimensional test problems in both Cartesian and spherical geometries. Comparisons with published results of other conservative semi‐Lagrangian schemes show that it performs well. © Crown copyright, 2005.
Probabilistic physically based cloud screening of satellite infrared imagery for operational sea surface temperature retrieval
Authors: Merchant C. J. , Harris A. R. , Maturi E. , Maccallum S. 
Published: November 2005

AbstractWe propose and demonstrate a fully probabilistic (Bayesian) approach to the detection of cloudy pixels in thermal infrared (TIR) imagery observed from satellite over oceans. Using this approach, we show how to exploit the prior information and the fast forward modelling capability that are typically available in the operational context to obtain improved cloud detection. The probability of clear sky for each pixel is estimated by applying Bayes' theorem, and we describe how to apply Bayes' theorem to this problem in general terms. Joint probability density functions (PDFs) of the observations in the TIR channels are needed; the PDFs for clear conditions are calculable from forward modelling and those for cloudy conditions have been obtained empirically. Using analysis fields from numerical weather prediction as prior information, we apply the approach to imagery representative of imagers on polar‐orbiting platforms. In comparison with the established cloud‐screening scheme, the new technique decreases both the rate of failure to detect cloud contamination and the false‐alarm rate by one quarter. The rate of occurrence of cloud‐screening‐related errors of >1 K in area‐averaged SSTs is reduced by 83%. Copyright © 2005 Royal Meteorological Society.
Telomerase catalytic subunit gene expression does not influence survival of patients with squamous cell carcinoma of the larynx and hypopharynx: a case-control study
Authors: Luzar Boštjan , Poljak Mario , Fischinger Janez , Klopčič Ulrika , Gale Nina 
Published: November 2005

Aims: to determine correlations between relative quantities of telomerase catalytic subunit m-ribonucleic acid (hTERT mRNA) and conventional clinicopathological parameters (such as site, size and grade of tumour, the presence of regional lymph node metastases, and, in particular, survival) in patients with laryngeal and hypopharyngeal squamous cell carcinomas (SCCs).Material and methods: The relative quantity of hTERT mRNA was analysed by a commercially available LightCycler Telo TAGGG hTERT Quantification Kit in 56 cases of SCC (40 laryngeal and 16 hypopharyngeal). The association with cancer-specific survival was evaluated by univariate and multivariate analysis.Results: Location of the tumour in the hypopharynx was the only significant negative predictive factor for survival, as determined by univariate analysis (p = 0.028). Although a tendency towards a better overall survival was observed for female patients younger than 50 years, for lower tumour grades and sizes, and for the absence of regional lymph node metastases, the prognostic significance of these factors could not be confirmed. No differences existed in hTERT mRNA expression between laryngeal and hypopharyngeal SCCs. Furthermore, no correlation was found between the relative quantities of hTERT mRNA and the tumour size, regional lymph node metastases or survival of patients with laryngeal or hypopharyngeal SCCs.Conclusions: The results of the present study suggest that genetic abnormalities other than telomerase reactivation are responsible for progression of laryngeal and hypopharyngeal SCCs.
A multipurpose landmark for skull-base surgery: Henle’s spine
Authors: Ulug Tuncay , Ozturk Adnan , Sahinoglu Kayihan 
Published: November 2005

Objective: To determine whether Henle’s spine could be used as a reliable and multipurpose landmark for the other important structures of the skull base.Materials and methods: Ninety-two specimens from 46 cadaveric adult dry skulls were studied. Two imaginary lines and a triangle were defined: a spinopterygoidal line extending from Henle’s spine to the root of the medial pterygoid plate, a bispinal line extending from one Henle’s spine to the contralateral one, and a parapetrosal triangle lying between the spinopterygoidal line, the bispinal line and the sagittal midline. The parapetrosal triangle encompasses nearly all the main structures of the skull base, including the petrosal internal carotid artery.Results: Along the spinopterygoidal line the distance from Henle’s spine to the spine of the sphenoid was found to be about 3 cm, to the foramen spinosum 3.5 cm, to the posterior and anterior margins of the foramen ovale 4 and 4.5 cm, to the root of the lateral pterygoid plate 5 cm, to the root of the medial pterygoid plate 5.5 cm, and to the vomer 6.5–7 cm. Along the bispinal line, the distance from Henle’s spine to the stylomastoid foramen was found to be about 1.5 cm, to the lateral and medial margins of the jugular foramen 2.5 and 3.5 cm, to the external orifice of the hypoglossal canal 4 cm, and to the foramen magnum 5 cm.Conclusion: Henle’s spine with its superficial and central position can be used to localize important anatomical structures during skull-base surgery.
Videoendoscopic surgery for inaccessible glottic lesions
Authors: Schindler Antonio , Capaccio Pasquale , Ottaviani Francesco 
Published: November 2005

Objectives: Lesions in the anterior segment of the vocal fold are sometimes difficult to access by means of conventional suspension microlaryngoscopy under general anaesthesia because of anatomical factors such as short, stout and inflexible necks, reduced jaw protrusion, and long incisors. Various techniques have recently been proposed for the management of inaccessible glottic lesions, most of which are performed under general anaesthesia. The use of flexible videoendoscopic surgery under topical anaesthesia in two cases of anterior glottic lesions that could not be treated by means of conventional suspension laryngoscopy is described.Study design: Case report.Methods: A flexible videobronchoscope with an instrument channel was inserted transnasally on an out-patient basis. While the examiner carried out the endoscopy, an assistant manoeuvred the biopsy forceps through the instrument channel, and removed the lesion.Results: Both patients underwent successful removal of an anterior glottic polyp, and the one-year follow-up evaluation revealed normal anatomy of the vocal folds and normal vocal function.Conclusions: Flexible videoendoscopic surgery under topical anaesthesia is a safe, simple and minimally invasive procedure that can be considered as an alternative to traditional endoscopic surgery for inaccessible anterior glottic lesions.
Hyperhomocysteinemia, Endothelial Nitric Oxide Synthase Polymorphism, and Risk of Coronary Artery Disease
Authors: Kerkeni Mohsen , Addad Faouzi , Chauffert Maryline , Myara Anne , Ben Farhat Mohamed , Miled Abdelhedi , Maaroufi Khira , Trivin François 
Published: November 2005

Abstract
Background: Hyperhomocysteinemia is an independent, graded risk factor for coronary artery disease (CAD). The G894T variant of endothelial nitric oxide synthase (eNOS) was postulated to be associated with hyperhomocysteinemia and could influence individual susceptibility to CAD. The aims of this study were to investigate (a) the relationship of the eNOS G894T polymorphism with the presence and the severity of CAD and (b) the possible relationship between hyperhomocysteinemia and the eNOS G894T variant for the risk of CAD severity in a Tunisian population.
Methods: We used PCR with restriction fragment length polymorphism analysis to detect the G894T variant of the eNOS gene in 100 patients with CAD and 120 healthy controls. The severity of CAD was expressed by the number of affected vessels. Total plasma homocysteine concentrations were determined by direct chemiluminescence assay.
Results: The frequencies of the eNOS GG, GT, and TT genotypes in the CAD group were significantly different from those in the control group (45%, 44%, and 11% vs 60%, 35.8% and 4.2%, respectively; P = 0.035). There was no association between the eNOS G894T genotype frequencies and the number of stenosed vessels (P = 0.149). In the CAD group, the coexistence of the 894 GT or TT genotypes and hyperhomocysteinemia led to an increased risk of CAD severity.
Conclusion: The G894T polymorphism of the eNOS gene is associated with the presence of CAD, and in conjunction with hyperhomocysteinemia, increased the risk of CAD severity in a Tunisian population.