bluuebunny/crossref_metadata_2025 huggingface dataset:
On the impact of Doppler radar derived wind fields in a mesoscale non‐hydrostatic model
Authors: Nuret Mathieu , Chong Michel , Lafore Jean‐Philippe , Bousquet Olivier , Gouget Viviane
Published: February 2007

Fine‐scale three‐dimensional wind fields retrieved from airborne Doppler radar observations within an oceanic tropical mesoscale convective system (MCS), during the Tropical Ocean/Global Atmosphere Coupled Ocean‐Atmosphere Response Experiment, are used to enhance the initial conditions of a n on‐hydrostatic mesoscale model. They are incorporated into the French CANARI‐ALADIN analysis system, based on the optimal interpolation technique. The fine‐mesh (4 km) horizontal wind components are first averaged over subdomains of 20 km × 20 km in order to provide a series soscale wind profiles. Because of the absence of dense sounding data, the synthesized vertical‐velocity profiles are transformed into humidity profiles by considering that updraughts contain nearly saturated or saturated air, while downdraughts are associated with unsaturated air.

Comparison of the initial state using conventional data with the Doppler‐enhanced initial state clearly identifies the benefits of the addition of the observed mesoscale circulation features. In terms of the precipitation forecast, the control run that uses the conventional initial State dramatically fails to predict the existence of the MCS precipitation core. On the other hand, the reference run with the data‐enhanced initial state succeeds in forecasting it up to 12 hours in a way that is well consistent with the satellite imagery. In terms of the wind forecast, the mesovortex signature that could be identified from the radar observations becomes a persistent feature with the radar‐enhanced initial conditions. Sensitivity tests reveal the specific roles of wind and humidity data. As in previous studies, the initial state of humidity is fundamental for the forecast of the MCS precipitation by sustaining the convective activity, and also by forming and maintaining a vortex‐like circulation. These results suggest that moist convective processes play a major role. The inclusion of wind data is necessary for improving the system propagation by advective processes.
Use of GPS/MET refraction angles in three‐dimensional variational analysis
Authors: Zou X. , Wamg B. , Liu H. , Aathes R. A. , Matsumura T. , Zhu Y.‐J.
Published: February 2007

The Spectral Statistical Interpolation (SSI) analysis system of the National Centers for Environmental Prediction (NCEP) is modified to include GPS/MET data (meteorological data from the Global Positioning Satellite system) using a GPS ray‐tracing operator. The new system is tested by incorporating 30 actual GPS/MET observations of refraction angles obtained during the GPS/MET experiment. This is the first time that real radio occupation refraction angles and refractivities have been incorporated into a three‐dimensional variational analysis system. We examine the magnitude and the vertical distribution of the analysis adjustments that result from using refraction‐angle observations in the NCEP SSI analysis system. The average magnitudes of the adjustments in the temperature and specific‐humidity fields are approximately 0.4 degC and 0.6 g kg−1, respectively. Individual changes can be as large as 4 degC and 4g kg−1, respectively. The greatest adjustments to the temperature occur in the middle and upper troposphere and stratosphere, while the major changes in specific humidity occur in the lower troposphere.

An assessment of the impact of the GPS/MET observations on the analysis, verified by conventional (mostly radiosonde) data, is difficult because of the small number of GPS/MET data used. Nevertheless, it is found that, even over data‐rich regions (regions containing many radiosonde observations), and even when the verification data were the radiosonde data themselves, the use of GPS/MET refraction angles makes a slight improvement, overall, to the analysed temperatures and winds. The impact on the water‐vapour analyses, again as measured against radiosonde data, is mixed, with improvements shown in some layers and degradation in others. Compared with the background field, the use of refraction angles from one occultation results in an analysis whose simulated refraction angles are much closer to the withheld GPS/MET refraction angles at the two nearby occultation locations, and whose temperature and moisture profiles are also closer to those resulting from the direct assimilation of the two withheld occultations.

Although the forward model used in this study, with the ray tracing being carried out in a two‐dimensional plane, is much cheaper than a more accurate three‐dimensional forward model, it is still quite expensive. In order to further reduce the computational requirement for the assimilation of GPS/MET data, we test a scheme in which the GPS/MET‐retrieved refractivities (instead of refraction angles) are used above a selected height for each occupation. These heights are determined objectively based on the departures from spherical symmetry of the model field. It is shown that the mixed use of GPS/MET refraction angles and refractivities produces an analysis result similar to the one using refraction angles alone, while the computational cost is reduced by more than 30%.
Cloud‐resolving simulation of convective activity during TOGA‐COARE: Sensitivity to external sources of uncertainties
Authors: Guichard F. , Redelsperger J.‐L. , Lafore J.‐R
Published: February 2007

A one‐week convective period of the Coupled Ocean‐Atmosphere Response Experiment (10‐17 December 1992), prior to a westerly wind burst, has been simulated with a cloud‐resolving model. Large‐scale advection derived from observations is used to force the model, in the same way as usually done in single‐column models. Our aim is to evaluate this explicit simulation against observed large‐scale thermodynamic and radiative fields, and to investigate the sensitivity of model results to observational uncertainties. Precipitation, apparent heat source and moisture sink are fairly well reproduced by the model as compared to those diagnosed from observations. Temperature (T) and moisture (qv) fields are also reasonably well captured except for a moderate cold and moist bias. Simulated moist static energy is too high below 6 km and too low above, possibly because convection is slightly less active in the model than observed.

In order to investigate the sensitivity of mode results to observational uncertainties, results are analysed with the moist static energy budget together with independent observational radiative datasets. This analysis suggests that the atmospheric radiative rate that is in equilibrium with the applied large‐scale advection and observed surface fluxes is too weak and that its diurnal cycle is not realistic. The most likely reason for this problem is found to be related to uncertainties in the large‐scale advection diagnosed from observations. This analysis also indicates that the simulated high‐cloud cover is too large in the model. It is greatly improved by increasing the ice‐crystal fall speed. Additional tests show a large sensitivity of the simulated moist static energy, and thus T and qv, to the range of uncertainties previously found for large‐scale advection. The vertical structure of the model bias is not significantly modified by changing the intensity of these forcings, but it is most sensitive to their vertical structures.

It is argued that it is crucial to get some insights into the range of uncertainties of external forcings (large‐scale advection, surface fluxes and atmospheric radiative‐heating rate) so as to assess the relevance of any evaluation of simulated temperature and moisture when a model, either resolving clouds or parametrizing them, is forced with large‐scale advection deduced from observations.
The evolution of vortices in vertical shear. III: Baroclinic vortices
Authors: Jones Sarah C.
Published: February 2007

The evolution of baroclinic tropical‐eye lone‐like vortices in environmental vertical shear on an f‐plane is investigated. Idealized numerical calculations are performed using a primitive‐equation model. The vertical structure of the initial vortex is varied by changing the strength of the upper‐level tangential wind. The baroclinic vortices develop a vertical tilt and a cyclonic rotation of the mid‐level centre about the surface centre occurs. In most of the calculations the upper‐level part of the vortex is advected away from the surface centre. The motion of the upper‐level part of the vortex can be attributed to advection by the flow associated with large‐scale asymmetries in the potential vorticity and to the vertically penetrating flow associated with the potential vorticity of the lower portion of the tilted vortex. As in the case of initially barotropic vortices the cyclonic rotation is found to depend on the parameters in the Rossby penetration depth. The height at which the environmental flow is equal to the Speed of vortex motion is found to be higher for vortices with stronger flow at upper levels. This is consistent with observations of tropical cyclones.

Significant changes in the potential‐vorticity structure of the vortex occur, especially at upper levels. The vortex becomes elliptic in shape and may extrude filaments of potential vorticily. These filaments thin, and sometimes break away from the main vortex, which as a result becomes more symmetric. The separation of the filaments from the main part of the vortex is often accompanied by a decrease in the vortex tilt. A: some levels no filaments form and the elliptic vortex becomes more symmetric with time. Calculations with a barotropic model show that both the potential‐vorticity structure of the initial vortex, and the horizontally sheared flow associated with the vertical projection of the tilted potential‐vorticity anomaly, play a role in the changes in the vortex Structure.

The development of potential‐temperature asymmetries and an adiabatic vertical circulation are shown to be related to the direction of the vortex tilt. This occurs even when the direction of tilt changes with height. The changes in the low‐level static stability associated with the vortex tilt are investigated and the implications for tropical‐cyclone intensity change are discussed.
Parametrization of the effect of drizzle upon the droplet effective radius in stratocumulus clouds
Authors: Wood Robert
Published: February 2007

A method is presented to parametrize the effects of drizzle upon the droplet effective radius in stratocumulus clouds. The cloud‐droplet size distribution in stratocumulus is represented by the sum of a modified Gamma distribution to represent the small (radius <20 μm) droplets and an exponential Marsh all‐Palmer‐type distribution to represent the large (drizzle) droplets. Using this approach a relationship is derived to account for the effect of drizzle upon k, the cube of the ratio between the volume and effective radius. Observational evidence from flights in a range of different air‐mass types is presented to validate the approach. The results suggest that the value of k pertaining to the small droplets is better parametrized as a function of volume radius rather than of droplet concentration. The results also suggest that, as the ratio of liquid‐water content contained in the large droplets to that in the small droplets increases beyond 0.05, the value of it decreases significantly. This results in an underprediction of the effective radius if commonly used parametrizations for k are used.
Estimation of entrainment rate in simple models of convective clouds
Authors: Gregory David
Published: February 2007

A method for estimating lateral entrainment rate in clouds is suggested, linking its magnitude to buoyant production of vertical kinetic energy within a cloud updraught. In single‐column model studies the formulation captures the high values of entrainment seen in shallow convection and the values an order of magnitude lower in cases of deep convection, as suggested by observational studies and large‐eddy model simulations, together with a realistic vertical variation. Comparison is made with other recent attempts to parametrize entrainment.
The influence of the 1997–99 El Niňo Southern Oscillation on extratropical baroclinic life cycles over the eastern North Pacific
Authors: Shapiro M. A. , Wernli H. , Bond N. A. , Langland R.
Published: February 2007

The El Niňo Southern Oscillation (ENSO) strongly influences the interannual and seasonal atmospheric circulation over the North Pacific. The present study shows that the meridional displacement of the time‐mean upper‐level jet associated with ENSO modulates the time‐mean barotropic (meridional) wind shear over the central and eastern North Pacific storm track. Earlier theoretical and observational studies established the influence of barotropic wind shear on the life cycles of extratropical cyclones and their upper‐level potential vorticity (PV) waves. The present study suggests that differences in the time‐mean flow associated with the 1997–99 ENSO cycle had a similar impact on tropopause PV structure, meridional eddy fluxes of momentum and temperature, and predictability.
Ensemble prediction in a model with flow regimes
Authors: Trevisan Anna , Pancotti Francesco , Molteni Franco
Published: February 2007

The primary goals of ensemble prediction are the identification of particularly unpredictable situations, and the prediction of forecast error. In the medium range, major forecast failures are associated with regime transitions. The predictions of linear theories on error dynamics are inadequate to describe these situations, characterized by the rapid growth of errors which are far from being infinitesimal. Little is known about the efficiency of ensemble forecasting methods when applied to highly nonlinear situations like those associated with a change of regime. This problem is examined in an atmospheric model with two regimes and a small number of degrees of freedom by comparing current ensemble forecasting methods with ensemble forecasts that span all the degrees of freedom of the system. The study, performed in a perfect model environment, shows how the statistical properties of errors are affected by regime transitions. Results obtained selecting initial perturbations in the direction of the leading Lyapunov vectors (LVs) and singular vectors (SVs) are compared with those obtained with initially random vectors (RVs) spanning the whole phase space. It is found that the LV ensembles do not necessarily capture those particular perturbations that eventually lead to a regime transition, but closely reproduce the average RV distribution. On the other hand, the SV ensembles reproduce very closely the distribution obtained by selecting the maximum amplitude of random perturbations, although their consistency with the distribution of the full RV ensemble is poorer than in the LV ensembles.

When the spread of individual RV ensembles is analysed by an empirical orthogonal function (EOF) decomposition, one finds that the variations in the amplitude of the first EOF (which carries the bimodal signature of regime transitions) is better estimated by the SV than by the LV ensembles. In verification‐based contingency tables, incorrect categorical forecasts of transition probability are more frequent in the LV than in the SV ensembles.
A physically based parametrization for surface flux enhancement by gustiness effects in dry and precipitating convection
Authors: Williams Alastair G.
Published: February 2007

Enhancement of bulk surface fluxes by subgrid variability is reviewed, with special attention to conditions ranging from fair‐weather free convection to precipitating deep convection over uniform surfaces. Aircraft measurements in the Tropical Ocean/Global Atmosphere Coupled Ocean‐Atmosphere Response Experiment subcloud layer indicate that the predominant mechanism for flux enhancement is wind variability associated with both boundary‐layer‐scale coherent eddies (dry convective gustiness) and density currents beneath precipitating convection (moist convective gustiness). A new evaluation of the dry convective gustiness parameter, β, supports recent indications that its effective value is less than previously thought (0.60–0.80, rather than 1.00–1.25), due both to a discrepancy in the technique often used for its estimation from field data, and to contamination of datasets by meso‐γ‐scale (∼10 km) motions. A strong relationship is found in the aircraft time series between the moist convective gustiness velocity and the theoretical speed of density‐current gust fronts driven by the observed meso‐γ‐scale temperature variability. This prompts development of a simple theoretical model for the latter, based upon a known convective rainfall rate and ambient thermodynamic structure for the lower atmosphere. Parameters in the model are estimated using data from simultaneous aircraft and shipboard radar measurements, and model behaviour is compared with a simpler scheme developed by Météo‐France. It is concluded that an explicit representation of the rain evaporation process in the generation of density perturbations is crucial for accurate determination of the strength of moist convective gustiness in the model, and through it the degree of surface flux enhancement.
Second‐order accuracy of two‐time‐level semi‐Lagrangian schemes
Authors: Gospodinov I. G. , Spiridonov V. G. , Geleyn J.‐F.
Published: February 2007

The accuracy of the two‐time‐level semi‐Lagrangian semi‐implicit time integration scheme is analysed. Two relatively independent problems are identified–the discretization of the implicit trajectory equation and the treatment of the nonlinear residual. Two theorems giving conditions for second‐order accuracy of the two‐time‐level semi‐Lagrangian semi‐implicit scheme are stated. As a result, a new scheme for the trajectory equation is proposed and a class of schemes for the nonlinear residual, which are second‐order accurate in time, are introduced. A simplified one‐dimensional ‘shallow water’ model is developed in order to test the proposed scheme in comparison with other, previously known, ones. Some experiments proving stability, accuracy and conservation ability are presented.
Baroclinic developments in jet entrances and exits. I: Linear normal modes
Authors: Hare Sylvia H. E. , James I. N.
Published: February 2007

This study examines the effect of the ageostrophic circulations associated with jet entrance and exit regions on the structure and growth rates of baroclinic normal modes. A linearized GCM is used to find the most unstable normal‐mode disturbances for a zonally symmetric basic state consisting of a zonal jet and meridional circulation. Normal‐mode growth rates are reduced by up to 20% for realistic strengths of meridional overturning, and normal‐mode structures are significantly affected. For example, the normal‐mode poleward tilt with height varies, affecting the conversion of basic‐state available energy. A mechanism for the change in poleward tilt is proposed. Ageostrophic meridional circulations may play a significant role in determining the magnitude and length of mid‐latitude storm tracks.
Deterministic prediction of the ensemble variance for a barotropic vorticity‐equation model
Authors: Riishøjgaard Lars Peter
Published: February 2007

The problem of estimating the error variance of a meteorological forecast is important both for data assimilation purposes and in order to increase the value of the forecast to the end user. Current data assimilation systems have no–or at best a severely limited–capability to estimate this quantity. In principle, the prognostic equation for the forecast error covariance is known from the Kalman filter. However, in its full form this equation is prohibitively expensive to implement and solve. In this article, the possibility of evolving a variance‐only estimate is explored. It is shown that for a barotropic vorticity‐equation model, an approximate equation for the error variance evolution can be written in a closed form under certain assumptions. The cost of solving this equation is comparable to that of solving the model equation itself. Through a demonstration experiment, it is shown that the approximate equation tracks the actual variance of a model run–represented by the variance over a randomly perturbed ensemble of forecasts generated by the model–remarkably well, qualitatively as well as quantitatively.
Estimation of the representativeness error caused by the incremental formulation of variational data assimilation
Authors: Desroziers Gerald , Brachemi Omar , Hamadache Bachir
Published: February 2007

A formalization of the representativeness error caused by the use of a simplified increment in certain implementations of the variational formalism is introduced. The incremental representativeness‐error can be determined by summing up the part of the background‐error power‐spectrum that is beyond the truncation of the simplified increment. Thus, this error will be more important for fields, such as humidity, whose forecast errors have large components at small scales. The length scale and the oscillating structure of this incremental representativeness‐error are explained as the consequences of the application of a square window in spectral space to the corresponding background‐error covariances. A computation of the covariances of this error has been performed in a realistic framework given by the French numerical weather prediction system. In particular, it shows that this error is not negligible, and that its size is of the same order as that of observational instrument error which occurs when using a T63 spectral resolution of the analysis increment.
Aspects of interannual and intraseasonal variability of the tropopause and lower stratosphere
Authors: Kiladis G. N. , Straub K. H. , Reid G. C. , Gage K. S.
Published: February 2007

Radiosonde and National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data are utilized to consider aspects of large‐scale variability in tropopause height, temperature and pressure. This variability is related to coherent dynamical fluctuations in the troposphere and lower stratosphere through the use of linear correlation and regression. On interannual time‐scales, significant global‐scale tropopause fluctuations are tied to variability in sea surface temperature (SST) associated with the El Niňo/Southern Oscillation phenomenon. When SST is anomalously high in the central tropical Pacific, tropopause height (pressure) is high (low) throughout the Tropics, with largest perturbation amplitudes in the subtropical Pacific. At the same time, the tropopause is cold over the tropical and subtropical Pacific sector but warm elsewhere in the Tropics. Over the extratropics, wave‐like perturbations in the tropopause are seen, with anomalous cyclonic flow corresponding to a lower tropopause height and higher tropopause temperature and pressure, and vice versa. The sign of the temperature anomalies in the lower stratosphere tends to match that at the tropopause over much of the globe, with opposite‐signed anomalies in the upper troposphere. The vertical structure of these perturbations is consistent with the expected potential‐vorticity anomalies induced by quasi‐stationary Rossby waves and vertically propagating gravity waves forced by displacements of tropical convection. Similar relationships are associated with the eastward propprotion of tropical convection due to the Madden‐Julian Oscillation on intraseasonal time‐scales.
A data study of the influence of the equatorial upper stratosphere on northern‐hemisphere stratospheric sudden warmings
Authors: Gray L. J. , Phipps S. J. , Dunkerton T. J. , Baldwin M. P. , Drysdale E. F. , Allen M. R.
Published: February 2007

Equatorial winds in the stratosphere are known to influence the frequency of stratospheric midwinter sudden warmings. Sudden warmings, in turn, influence the Earth's climate both through their direct influence on polar temperatures and through the temperature dependence of ozone depletion in the lower stratosphere. The conventional (Holton‐Tan) explanation for the equatorial influence on sudden warmings is in terms of the equatorial winds in the lower stratosphere (∼20‐30 km) acting as a waveguide for midlatitude planetarywave propagation. This study employs stratospheric‐temperature analyses and equatorial rocketsonde wind data extending to 58 km to diagnose the relationship between the northern‐hemisphere polar temperatures and equatorial zonal winds at all height levels in the stratosphere. In addition to the recognized Holton‐Tan relationship linking the polar temperatures to the quasi‐biennial oscillation in equatorial winds in the lower stratosphere, a strong correlation of polar temperatures with equatorial winds in the upper stratosphere is found. We suggest that this may be associated with the strength and vertical extent of the westerly phase of the semi‐annual oscillation in the upper stratosphere, although the observations alone cannot provide a conclusive, causal relationship. The main diagnostic tools employed are correlation studies and composite analysis. The results underline the need for continued high quality, equatorial wind measurements at all stratospheric levels.
Estimation of the error distributions of precipitation produced by convective parametrization schemes
Authors: Errico Ronald M. , Stensrud David J. , Raeder Kevin D.
Published: February 2007

If a parametrization scheme for convective precipitation is to be used for assimilating observations of precipitation using a statistically based technique, then statistics of the errors produced by that scheme are required. These are the errors produced by the scheme's formulation itself, not counting any errors in the scheme's input. Such errors are extremely difficult to estimate, but examination of differences produced by various suitable schemes can yield qualitative descriptions of such errors. Here, hourly accumulated convective precipitation fields produced from six different versions of a short‐term forecast model are compared. The versions have identical initial and boundary conditions, but vary in the schemes used for either the convection or the planetary boundary layer, or both. The distribution of differences, or differences in logarithms of accumulations, between corresponding precipitating grid points for pairs of forecasts are examined using a simple binning technique. When the convection schemes differ, results reveal that if either a log‐normal or normal distribution is a better characterization of the distributions, it is the log‐normal one. The standard deviations of these logarithmic distributions correspond to different schemes at identical grid points producing values differing by factors of 2 or more. A large proportion of grid points that have non‐zero hourly accumulations using one model version may have no accumulation using another version. For most pairs of forecasts examined, however, grid points having larger values of accumulation for one scheme tend to have a smaller fraction of values having no accumulation in the other scheme. These results suggest that the finite probability that the model produces no precipitation when the corresponding, true atmospheric state does, should be considered in the statistical description of the model errors and that, because of the large standard deviation of model errors as well as large possible errors of hourly precipitation observations, the quantitative usefulness of assimilating such observations may be very limited.
Sensitivity of a heavy‐rain‐producing western Mediterranean cyclone to embedded potential‐vorticity anomalies
Authors: Romero R.
Published: February 2007

The development and track of a surface cyclone that produced heavy precipitation in the western Mediterranean region on 28–29 September 1994 is numerically simulated using a mesoscale model. Diagnostic calculations reveal that surface‐pressure falls‐and upward motion‐occur in response to a well‐defined pattern of upward quasi‐geostrophic forcing at all tropospheric levels. In addition, convective instability and low‐tropospheric water vapour flux convergence are significant over the western Mediterranean, and therefore the environment is highly supportive for convection development.

The appreciable dynamical forcing at upper levels appears to be associated with two positive potential‐vorticity (PV) anomalies that are embedded within the large‐scale trough and rotate about each other. Motivated by the fact that the small‐scale features of the PV field are more prone to analysis or forecast error than the large‐scale components, a sensitivity study is conducted in order to analyse the dependence of the mesoscale forecast on the initial intensity and position of the two embedded PV centres. This is accomplished by first applying a piecewise PV‐inversion technique which allows the balanced flow associated with each PV centre to be calculated, and then the inverted mass and wind fields are used to modify the model initial conditions. Eight simulations are run after doubling or removing one or both anomalies (sensitivity to intensity), and eight other simulations after displacing the anomalies towards or away from the Iberian peninsula (sensitivity to position).

The results exhibit a clear dependence of the track and shape of the surface cyclone and its associated pattern of low‐tropospheric warm air advection on the characteristics of the PV anomalies. Therefore, spatial details of the mesoscale forecast are shown to be highly sensitive to the precise structure of the upper‐level dynamic forcing. Nevertheless, for the full set of arbitrarily defined initial conditions, one or several low pressure systems develop in the western Mediterranean area and heavy precipitation always occurs. On the other hand, there is an overall tendency of the simulations to favour cyclone development leeward of the Atlas mountain range and local rainfall enhancements over the exposed mountains of eastern Spain. The relative roles of the orography and sea surface latent‐heat flux versus the action of the upper‐level PV centres are examined by means of additional simulations.
Empirical forecasts of 850 hPa air temperature anomalies over the North Atlantic
Authors: Gómez E. Sánchez , García F. Álvarez , Beviá M. J. Ortiz
Published: February 2007

The empirical forecasts presented here were developed as a benchmark for dynamical forecasts provided by uncoupled and coupled general‐circulation models. The predictand field is the variability of 850 hPa air temperature anomalies over the North Atlantic basin at timescales greater than eight months. The predictor field is chosen among different datasets (sea surface temperature anomalies, the predictand field itself, etc.). Some of the experiments make use of a single predictor field, whereas others use several. The performance of the forecasts, measured by the correlation between observed and forecast fields, is assessed against the skill of forecasts performed on a simple persistence basis.

The statistical scheme used to make the forecast is based on singular‐value decomposition (SVD) of the cross‐covariance matrix between the predictor and the predictand field at the lead requested for the forecast. Prior to the SVD calculations, we remove with a filter the variability of predictor and predictand fields at timescales below eight months. Forecasts of air temperature anomaly have been made over the period from 1970 to 1998, at different lead times. The highest skill is achieved when the predictors are computed from anomalies of sea surface temperature over roughly the same domain as the predictand. The skill of the forecast is important south of 45°N and is broadly consistent through the three decades. About 56% of the variance of the eight‐month filtered predictand field (36% of the variance of the original field) can be forecast nine months ahead. The best values of the forecast skill appear in two regions, one in the subtropics and the other around the Iberian peninsula. Only in this last region, and also in another region over the USA, does the skill of the forecasts beat the skill of persistence.

In order to identify the origin of the skill we study its dependence on the target season. We also investigate its dependence on the phase of the El Niño‐Southern Oscillation (ENSO) and the North Atlantic Oscillation. The skill is, in first place, related to the ability of the scheme at capturing the variability at biennial and ENSO‐related timescales.
Solubilization of selected polycyclic aromatic compounds by nonionic surfactants
Authors: Swe Mar Mar , Yu Liya E. , Hung Kun‐Chih , Chen Bing‐Hung
Published: February 2007

Solubilization of selected polycyclic aromatic compounds (PAC) by biodegradable nonionic surfactants, Tergitol 15‐S‐X (X=7 or 9) and Neodol 25–7, was investigated and correlated with micellar properties of these surfactants. These PAC include dibenzofuran, phenanthrene, acenaphthene, fluoranthene, and 9‐chloroanthracene. Tergitol surfactants are mixtures of secondary ethoxylated alcohols, and Neodol 25–7 is a mixture of similar species but has the alcohol group in the primary position. These surfactants have the same chain length of hydrophobic tails and similar numbers of ethylene oxides. The results show that the Neodol surfactant yields micelles having larger hydrophobic core volume and renders a higher solubilization capacity for the PAC solubilizates in comparison with Tergitol surfactants. In general, aggregation numbers and micellar sizes both increase at elevated temperatures still below the cloud point. The micellewater partition coefficients of these PAC by the nonionic surfactants were well correlated to their octanol‐water partition coefficients. Moreover, an estimated log Kow value of 9‐chloanthracene is 4.78.
Comparative study of neighboring group participation in reactions of N‐bromoor N‐chlorosuccinimide on methyl isoricinoleate
Authors: Singh Sukhprit , Singh Bhupinderpal
Published: February 2007

Reacting methyl isoricinoleate with N‐bromosuccinimide in the presence of excess diols [mono‐, di‐, tri‐, and tetraethylene glycol] gave the 1,4‐epoxy derivative in 80% yield along with the respective ß‐bromoethoxylates as minor products (20%). However, when the reaction was carried out with N‐chlorosuccinimide, the yield of 1,4‐epoxy derivative was reduced to 20%, and formation of ß‐chloroethoxylates was increased to 80%.
Parametric study of surfactant effect on mechanical and dissolution properties of detergent tablets
Authors: Chantraine F. , Viana M. , Brielles N. , Mondain‐Monval O. , Pouget C. , Branlard P. , Rubinstenn G. , Chulia D.
Published: February 2007

The aim of this study is to investigate the functional characteristics (mechanical strength and disintegration time) of effervescent detergent tablets containing chlorine provider in the presence of surfactant. A preliminary study high‐lighted that the presence of 2% of sodium dodecyl sulfate (SDS) was not favorable to the tablet mechanical properties, inducing a lower “bonding ability,” whereas the disintegration time increased, compared with the reference tablets without surfactant. The linear relationship between the disintegration time and the end‐dissolution time led us to consider just the disintegration time to express the behavior of the tablets in water. A parametric study has been completed to assess the influence of the mixing method, the nature, the hydrophilic‐lipophilic balance, the granulometry, and the concentration of the surfactant on the tablet properties. In all cases, surfactant presented adverse effects on the mechanical properties and had a retarding effect on disintegration time, but neither solubility, hydrophilic‐lipophilic balance, interfacial properties, nor ionic character could be clearly involved to explain surfactant contribution. Furthermore, tablet dissolution could not be correlated to surfactant available surface, as evidenced by granulometry comparison on one side and concentration impact on the other side (a similar effect was observed from 1 to 15%). On the contrary, mechanical properties were damaged as much as the area developed by surfactant particles increased. On the basis of this work, it has been concluded that SDS interacts with the other compounds of the formula by creating weak interparticle bonds and limiting water uptake responsible for disintegration.
Synthesis and interfacial properties of sugar‐based surfactants composed of homo‐and heterodimers
Authors: Castro Mariano J. L. , Cirelli Alicia Fernández , Kovensky José
Published: February 2007

Dimeric sugar‐based amphiphiles were synthesized starting from D‐glucose and a commercial mixture of dodecyl and tetradecyl alcohols by a simple procedure. Three different spacers (glutaryl, succinyl, and terephthaloyl) were used to link the sugar moieties through O‐2 or O‐6. Dimeric compounds are composed by mixtures of homodimers (C‐12/C‐12) and heterodimers (C‐12/C‐14). The interfacial properties of these nonionic gemini surfactants are described.
Water‐soluble metalworking fluid additives derived from the derivatives of 3‐mercaptopropionic acid
Authors: Kawato Yuichi , Kamiusuki Toshiro , Watanabe Shoji
Published: February 2007

A number of derivatives of thiocarboxylic acid were prepared from the reaction of 3‐mercaptopropionic acid and alkyl halides, and screened for anti‐rust properties in water‐soluble metalworking fluids. Aqueous metalworking fluids containing octylthiopropionic acid or hexylthioacetic acid showed excellent anti‐rust properties for water‐soluble metalworking fluids.
The inhibitory action of long‐chain fatty acids on the DNA binding activity of p53
Authors: Iijima Hiroshi , Kasai Nobuyuki , Chiku Hiroyuki , Murakami Shizuka , Sugawara Fumio , Sakaguchi Kengo , Yoshida Hiromi , Mizushina Yoshiyuki
Published: February 2007

The in vitro relationship between human p53 DNA binding domain (p53 DBD) and FA was investigated. We found that saturated and monounsaturated long‐chain FA inhibited the double‐stranded DNA (dsDNA) binding activity of p53 DBD. The strongest inhibitors of saturated and unsaturated FA were docosanoic acid (22∶0) and cis‐12‐heneicosenoic acid (21∶1n−9), respectively. n‐Octadecane, trans‐unsaturated FA, and FAME had no influence on the binding activity of p53 DBD, showing that the FA structures such as one or no double bond of cis configuration, hydrocarbon chain of length C20 to C22, and free carboxyl groups are important for the inhibition. The inhibitory effect of the R248A mutant of p53 DBD by saturated FA was as strong as that for wild‐type p53 DBD. On the other hand, the inhibition of dsDNA binding activity of the same mutant by the cis‐configuration of monounsaturated FA was weaker than that for the wild type. These results suggest that R248 in p53 DBD is important for binding to monounsaturated FA. This is the first report that long‐chain FA act as dsDNA binding inhibitor of p53, and it could be considered that FA in the cell membrane might regulate the activity of p53 for cell division, cell‐cycle checkpoint, and tumor suppression.
Pre-axial mirror polydactyly associated with tibial deficiency: A study of the patterns of skeletal anomalies of the foot and leg
Authors: Verghese Renjit , Shah Hitesh , Rebello Gleeson , Joseph Benjamin
Published: February 2007

Purpose

The study was undertaken to identify the patterns and spectrum of aberrant development of the skeletal elements of the leg and foot in children with pre-axial mirror polydactyly of the foot.

Methods

Case records and radiographs of eight children (ten feet) with pre-axial mirror polydactyly were studied. Four feet were seen in association with fibular dimelia, three feet with dysplastic trapezoid shaped tibia, two with tibial aplasia and one with tibial hypoplasia.

Results

Distinct patterns of anomalies of the hindfoot, midfoot and forefoot were noted, with different patterns of leg malformation. Fibular dimelia was associated with duplication of the calcaneum, cuboid and the lateral cuneiform. Talar duplication occurred in children with a trapezoidal tibia. No duplication of tarsal bones was seen in association with tibial aplasia or hypoplasia. The first metatarsal was hypoplastic wherever the tibia failed to develop. Mere resection of the supernumerary rays resulted in a near normal looking foot in feet without calcaneal duplication. The cosmetic appearance of the foot was poorest in children with fibular dimelia.
Neuroprotective effects of TJ‐23 (Tokishakuyakusan) on adult rat motoneurons following peripheral facial nerve axotomy
Authors: Ito Makoto , Masao Ohbayashi , Furukawa Mitsuru , Okoyama Shigeo
Published: February 2007

Objective

We investigated free radical scavenging activity and the possible neuroprotective effect of Tokishakuyakusan (TJ‐23) on facial motor nucleus (FMN) motoneurons after peripheral axotomy.

Study Design

In 40 adult rats, the right facial nerve was transected at the level of the stylomastoid foramen. Following axotomy, the effects of TJ‐23 on nitric oxide synthase were investigated using NADPH‐d histochemistry. FMN motoneurons were counted bilaterally in sections stained with cresyl violet.

Results

Rats administered TJ‐23 exhibited clear suppression of injury‐induced neuronal NADPH‐d expression in the ipsilateral FMN when compared to nontreated controls. The number of surviving motoneurons in the ipsilateral FMN was significantly greater among TJ‐23‐treated rats than nontreated controls on day 56 following axotomy.

Conclusion

The present study demonstrates the neuroprotective effect of TJ‐23 after peripheral facial nerve axotomy.

Significance

Antioxidants may have therapeutic potential in traumatic facial nerve dysfunction resulting from head injury, ear surgery, and parotid gland surgery.
Intranasal CpG DNA therapy during allergen exposure in allergic rhinitis
Authors: Suzuki Motohiko , Matsumoto Tamami , Ohta Nobuo , Min Wei‐Ping , Murakami Shingo
Published: February 2007

Objective

1) To estimate the effectiveness of intranasal administration of CpG DNA alone on allergic rhinitis compared with intradermal administration; and 2) to find out how CpG DNA therapy is useful in treatment of allergic rhinitis.

Study Design

Mice were intraperitoneally sensitized and intranasally challenged with Japanese cedar. Therapy with CpG DNA alone was also performed during challenge, either intranasally or intradermally. Immunologic variables and nasal symptom were studied.

Results

Intranasal administration of CpG DNA alone significantly reduced the levels of IgE, IL‐5 productions from nasal lymphocytes and splenocytes, nasal eosinophilia, and nasal symptoms, although intradermal administration of CpG DNA alone showed no significant reduction.

Conclusion

This study demonstrated that CpG DNA has effects not only on splenocytes but also on nasal lymphocytes to attenuate allergic rhinitis, and that intranasal administration, but not intradermal administration, of CpG DNA alone during allergen exposure is useful for control of allergic rhinitis.
Total thyroidectomy is the preferred treatment for patients with Graves' disease and a thyroid nodule
Authors: Boostrom Sarah , Richards Melanie L.
Published: February 2007

Objective

To identify the indications and outcomes of total thyroidectomy for Graves' disease in a North American cohort.

Study Design and Setting

Prospective database of 297 patients undergoing total thyroidectomy in a tertiary care center identified 49 patients with Graves'.

Results

There were 37 women and 12 men (mean age, 37.9 years). Common indications for surgery were: refusal of radioactive iodine (20%), thyroid storm (18%), a thyroid nodule (16%), failure of I131(14%), and ophthalmopathy (14%). Complications included: symptomatic hypocalcemia (14%), permanent hypoparathyroidism (0%), and symptoms of recurrent laryngeal nerve injury (0%). Graves' patients had more bleeding (117 mL versus 48 mL, P < 0.05). Clinical nodules were malignant in 38%. Papillary thyroid carcinoma occurred in 10% of patients, with 60% multifocal, and 60% lymph node metastases.

Conclusion

Total thyroidectomy for Graves' has minimal morbidity. Patients with Graves' and a thyroid nodule are at an increased risk for malignancy and should be treated with a total thyroidectomy.
Tympanometric volume: A predictor of success of tympanoplasty in children
Authors: Merenda Daniel , Koike Kazunari , Shafiei Majid , Ramadan Hassan
Published: February 2007

Objectives

To determine if preoperative tympanometric volumes have any predictive value in the success of pediatric tympanoplasty.

Study Design and Setting

Retrospective chart review in a tertiary referral center.

Main Outcome Measures

Success was defined as no evidence of tympanic membrane perforation via otoscopic examination and normal aeration of the middle ear.

Methods

Fifty‐eight pediatric patients who underwent tympanoplasty between 1996 and 2004 were studied; reviewed factors included recent discharge from the ear, perforation size, disease of the contralateral ear, age, gender, middle ear findings, and location of perforation.

Results

The overall success rate was 59 percent. The success rate was 89 percent for patients with a large preoperative tympanometric volume compared with 34 percent for patients with a small volume. Multivariate analysis demonstrated that disease of the contralateral ear and a large tympanometric volume were statistically significant.

Conclusion and Significance

A large tympanometric volume may be an important factor when considering tympanoplasty in children. In addition, disease of the contralateral ear may be a prognostic indicator.
Hydrogen peroxide ototoxicity in unblocking ventilation tubes: A chinchilla pilot study
Authors: Marc‐Elie Nader , Maria Kourelis , Daniel Sam Joseph
Published: February 2007

Objective

Some clinicians use hydrogen peroxide (H2O2) to clear the lumen of ventilation tubes that become blocked post‐operatively. The ototoxicity associated with H2O2 has been controversial.

Study Design

We designed an experiment to test if H2O2 damages the cochlear hair cells using a Chinchilla laniger animal model.

Methods

Nine chinchillas (18 ears) were included in this study. Each animal was used as its own control. Following the insertion of ventilation tubes in both ears and baseline recordings of the auditory brain stem responses (ABR), we instilled 2 ml of 3 percent H2O2 into their right external auditory canals (experimental ears). H2O2 was left in the external auditory canal for a total of 5 minutes and then was drained. We instilled a normal saline control solution in their left ears (control ears) in a similar fashion. ABR recordings were performed 1 day after the last instillation of H2O2 and 5 days later.

Results

There was no statistically significant difference in the ABR thresholds of the experimental and control ears.

Conclusion

H2O2 did not appear to cause ototoxicity in chinchilla ears with tympanostomy tubes exposed to H2O2 instillation using a standard clinical protocol.
The Russian Constitutional Court and the Communist Party case: Watershed or whitewash?
Authors: Henderson Jane
Published: February 2007

Constitutional Courts stand at the interface between law and politics, as the newly formed Russian Constitutional Court exemplified during Russia’s time of troubles between 1991 and 1993. One Constitutional Court case from that period had particular significance. The Russian court considered the constitutionality of the Communist Party of the Soviet Union (CPSU) and the Russian Communist Party (CP RSFSR). The seven month long hearing tested the court’s stamina and resolve. Described before it began as ‘Russia’s Nuremberg’, was the Communist Party case a turning point in Russia’s relationship with her past, or was it a staged showpiece with no real impact? This paper explores the Russian Constitutional Court’s longest case and its effects.