bluuebunny/crossref_metadata_2025 huggingface dataset:
Rain Reevaporation, Boundary Layer–Convection Interactions, and Pacific Rainfall Patterns in an AGCM
Authors: Bacmeister Julio T. , Suarez Max J. , Robertson Franklin R.
Published: December 2006

Sensitivity experiments with an atmospheric general circulation model (AGCM) show that parameterized rain reevaporation has a large impact on simulated precipitation patterns in the tropical Pacific, especially on the configuration of the model’s intertropical convergence zone (ITCZ). Weak reevaporation leads to the formation of a “double ITCZ” during the northern warm season. The double ITCZ is accompanied by strong correlation between precipitation and high-frequency vertical motion in the planetary boundary layer (PBL). Strong reevaporation leads to a better overall agreement of simulated precipitation with observations. The model’s double ITCZ bias is reduced. At the same time, correlation between high-frequency (periods < 15 days) vertical motion in the PBL and precipitation is reduced. Experiments with modified physics indicate that evaporative cooling by rain near the PBL top weakens the coupling between precipitation-related heating and vertical motion in high-frequency motions. The strength of high-frequency vertical motions in the PBL was also reduced directly through the introduction of a diffusive cumulus momentum transport (DCMT) parameterization. The DCMT had a visible impact on simulated precipitation in the Tropics but did not reduce the model’s double ITCZ bias in all cases.

Further analyses of mass and water vapor budgets, as well as vertical motion statistics, in the ITCZ complex, show that time-mean moisture convergence in the southern ITCZ is largely dominated by high-frequency modes, while in the northern ITCZ time-mean moisture convergence contains large contributions from slower modes. This may explain why the simulated southern ITCZ is more susceptible to parameterization changes that alter high-frequency coupling between moist heating and PBL convergence.
A Diagnostic Study of Waves on the Tropopause
Authors: Tomikawa Yoshihiro , Sato Kaoru , Shepherd Theodore G.
Published: December 2006

The spatial structure and phase velocity of tropopause disturbances localized around the subpolar jet in the Southern Hemisphere are investigated using 6-hourly European Centre for Medium-Range Weather Forecasts reanalysis data covering 15 yr (1979–93). The phase velocity and phase structure of the tropopause disturbances are in good agreement with those of an edge wave vertically trapped at the tropopause. However, the vertical distribution of the ratio of potential to kinetic energy exhibits maxima above and below the tropopause and a minimum around the tropopause, in contradiction to edge wave theory for which the ratio is unity throughout the troposphere and stratosphere. This difference in vertical structure between the observed tropopause disturbances and edge wave theory is attributed to the effects of a finite-depth tropopause together with the next-order corrections in Rossby number to quasigeostrophic dynamics.
In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part I: Wave Clouds
Authors: Baker Brad A. , Lawson R. Paul
Published: December 2006

The microphysical properties of wave clouds based on data collected during 17 missions flown by a Learjet research aircraft are presented and discussed. This extensive dataset expands upon previous aircraft studies of wave clouds and introduces some new findings. While most aspects of the observations are consistent with basic cloud physics, some aspects remain difficult to interpret. Most notable among these are ice nucleation and aspects of the dynamical structure of wave clouds. A new hypothesis to explain the ice nucleation behavior is presented.

The average and standard deviation of bulk microphysical parameters are presented for various locations within the wave clouds. Using digital imagery from a cloud particle imager (CPI), the shapes of ice particles are studied and crystal habits are classified. For certain categories—rosette shapes, columns, and irregular shapes—power-law parameterizations of particle area from particle length are presented. Polycrystals with rosette shapes dominate the ice mass while small spheroidal and irregularly shaped crystals dominate the ice number concentration.

The concept and difficulties of using wave clouds as natural cloud physics laboratories are discussed and evaluated. A study of the riming threshold size of columns is in good agreement with the results of previous studies, showing that column width is the predominate factor in determining riming threshold. The first reported studies of the riming threshold size of rosette shapes and the threshold size for side-plane growth are presented.
In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part II: Cirrus Clouds
Authors: Lawson R. Paul , Baker Brad , Pilson Bryan , Mo Qixu
Published: December 2006

A Learjet research aircraft was used to collect microphysical data, including cloud particle imager (CPI) measurements of ice particle size and shape, in 22 midlatitude cirrus clouds. The dataset was collected while the aircraft flew 104 horizontal legs, totaling over 15 000 km in clouds. Cloud temperatures ranged from −28° to −61°C.

The measurements show that cirrus particle size distributions are mostly bimodal, displaying a maximum in number concentration, area, and mass near 30 μm and another smaller maximum near 200–300 μm. CPI images show that particles with rosette shapes, which include mixed-habit rosettes and platelike polycrystals, constitute over 50% of the surface area and mass of ice particles >50 μm in cirrus clouds. Approximately 40% of the remaining mass of ice particles >50 μm are found in irregular shapes, with a few percent each in columns and spheroidal shapes. Plates account for <1% of the total mass. Particles <50 μm account for 99% of the total number concentration, 69% of the shortwave extinction, and 40% of the mass in midlatitude cirrus. Plots and average equations for area versus particle size are shown for various particle habits, and can be used in studies involving radiative transfer.

The average particle concentration in midlatitude cirrus is on the order of 1 cm−3 with occasional 10-km averages exceeding 5 cm−3. There is a strong similarity of microphysical properties of ice particles between wave clouds and cirrus clouds, suggesting that, like wave clouds, cirrus ice particles first experience conversion to liquid water and/or solution drops before freezing.
A Cascade-Type Global Energy Conversion Diagram Based on Wave–Mean Flow Interactions
Authors: Uno Sachiyo , Iwasaki Toshiki
Published: December 2006

A cascade-type energy conversion diagram is proposed for the purpose of diagnosing the atmospheric general circulation based on wave–mean flow interactions. Mass-weighted isentropic zonal means facilitate the expression of nongeostrophic wave effects, conservation properties, and lower boundary conditions. To gain physical insights into energetics based on the nonacceleration theorem, the wave energy W is defined as the sum of the eddy available potential energy PE and the eddy kinetic energy KE.

The mainstream of the energy cascade is as follows: The diabatic heating produces the zonal mean available potential energy PZ, which is converted into the zonal mean kinetic energy KZ through the mean meridional circulation. The KZ is mainly converted to W through zonal wave–mean flow interactions and the rest is dissipated through friction. Not only the dynamical conversion but also the diabatic heating generates W, which is dissipated through friction.

A diagnosis package is designed to analyze actual atmospheric data on the standard pressure surfaces. A validation study of the package is made by using the output from a general circulation model. The scheme accurately expresses tendencies of the zonal mean and eddy available potential energy equations, showing the diagnosis capability. On shorter time scales, PE changes in accordance with KE, good correlation indicating the relevance of the definition of wave energy.

A preliminary study is made of the climate in December–February (DJF), and June–August (JJA), using the NCEP–NCAR reanalysis. The dynamical wave energy generation rate C(KZ, W) is about 60% of the conversion rate C(PZ, KZ), which means that KZ is dissipated through friction at a rate of about 40%. In the extratropics, C(KZ, W) is almost equal to C(PZ, KZ), as is expected from quasigeostrophic balance. In the subtropics, however, C(KZ, W) is much smaller than C(PZ, KZ), which suggests the importance of nongeostrophic effects on the energetics. The energetics is substantially different between the two solstices. Both C(PZ, KZ) and C(KZ, W) are about 30% larger in DJF than those in JJA, reflecting differences in wave activity. Stationary waves contribute considerably to energy conversions in the Northern Hemispheric winter, while baroclinic instability waves do more in the Southern Hemispheric winter than in the Northern Hemispheric winter.
Simulation of Inertia–Gravity Waves in a Poleward-Breaking Rossby Wave
Authors: Zülicke Christoph , Peters Dieter
Published: December 2006

Poleward-breaking Rossby waves often induce an upper-level jet streak over northern Europe. Dominant inertia–gravity wave packets are observed downstream of this jet. The physical processes of their generation and propagation, in such a configuration, are investigated with a mesoscale model.

The study is focused on an observational campaign from 17 to 19 December 1999 over northern Germany. Different simulations with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) have been performed. For a high-resolution process study, three domains were set up that encompass the evolution of Rossby waves and that of inertia–gravity waves. To minimize the impact of model damping, the horizontal and vertical resolution has been adjusted appropriately.

With a novel statistical approach, the properties of inertia–gravity wave packets have been estimated. This method uses the horizontal divergence field and takes into account the spatial extension of a wave packet. It avoids the explicit treatment of the background field and works for arbitrary wavelength. Two classes of inertia–gravity waves were found: subsynoptic waves with a horizontal wavelength of about 500 km and mesoscale waves with a horizontal wavelength of about 200 km. The subsynoptic structures were also detected in radiosonde observations during this campaign. The similarity between simulated and observed wavelengths and amplitudes suggests that the simulations can be considered as near realistic.

Spontaneous radiation from unbalanced flow is an important process of inertia–gravity wave generation. Synoptic-scale imbalances in the exit region of the upper-tropospheric jet streak were identified with the smoothed cross-stream Lagrangian Rossby number. In a number of simulations with different physics, it was found that the inertia–gravity wave activity was related to the tropospheric jet, orography, and moist convection. The upward propagation of inertia–gravity waves was favored during this event of a poleward-breaking Rossby wave. The presence of the polar vortex induced background winds exceeding the critical line. Consequently, the activity of inertia–gravity waves in the lower stratosphere increased by an order of magnitude during the case study.

The successful simulation of the complex processes of generation and propagation showed the important role of poleward Rossby wave breaking for the appearance of inertia–gravity waves in the midlatitudes.
Advanced Doubling–Adding Method for Radiative Transfer in Planetary Atmospheres
Authors: Liu Quanhua , Weng Fuzhong
Published: December 2006

The doubling–adding method (DA) is one of the most accurate tools for detailed multiple-scattering calculations. The principle of the method goes back to the nineteenth century in a problem dealing with reflection and transmission by glass plates. Since then the doubling–adding method has been widely used as a reference tool for other radiative transfer models. The method has never been used in operational applications owing to tremendous demand on computational resources from the model. This study derives an analytical expression replacing the most complicated thermal source terms in the doubling–adding method. The new development is called the advanced doubling–adding (ADA) method. Thanks also to the efficiency of matrix and vector manipulations in FORTRAN 90/95, the advanced doubling–adding method is about 60 times faster than the doubling–adding method. The radiance (i.e., forward) computation code of ADA is easily translated into tangent linear and adjoint codes for radiance gradient calculations. The simplicity in forward and Jacobian computation codes is very useful for operational applications and for the consistency between the forward and adjoint calculations in satellite data assimilation.

ADA is implemented into the Community Radiative Transfer Model (CRTM) developed at the U.S. Joint Center for Satellite Data Assimilation.
High-Resolution Simulation of Shallow-to-Deep Convection Transition over Land
Authors: Khairoutdinov Marat , Randall David
Published: December 2006

Results are presented from a high-resolution three-dimensional simulation of shallow-to-deep convection transition based on idealization of observations made during the Large-Scale Biosphere–Atmosphere (LBA) experiment in Amazonia, Brazil, during the Tropical Rainfall Measuring Mission (TRMM)-LBA mission on 23 February. The doubly periodic grid has 1536 × 1536 × 256 grid cells with horizontal grid spacing of 100 m, thus covering an area of 154 × 154 km2. The vertical resolution varies from 50 m in the boundary layer to 100 m in the free troposphere and gradually coarsens to 250 m near the domain top at 25.4 km. The length of the simulation is 6 h, starting from an early morning sounding corresponding to 0730 local time. Convection is forced by prescribed surface latent and sensible heat fluxes and prescribed horizontally uniform radiative heating

Despite a considerable amount of convective available potential energy (CAPE) in the range of 1600–2400 J kg−1, and despite virtually no convective inhibition (CIN) in the mean sounding throughout the simulation, the cumulus convection starts as shallow, gradually developing into congestus, and becomes deep only toward the end of simulation. Analysis shows that the reason is that the shallow clouds generated by the boundary layer turbulence are too small to penetrate deep into the troposphere, as they are quickly diluted by mixing with the environment. Precipitation and the associated cold pools are needed to generate thermals big enough to support the growth of deep clouds. This positive feedback involving precipitation is supported by a sensitivity experiment in which the cold pools are effectively eliminated by artificially switching off the evaporation of precipitation; in the experiment, the convection remains shallow throughout the entire simulation, with a few congestus but no deep clouds.

The probability distribution function (PDF) of cloud size during the shallow, congestus, and deep phases is analyzed using a new method. During each of the three phases, the shallow clouds dominate the mode of the PDFs at about 1-km diameter. During the deep phase, the PDFs show cloud bases as wide as 4 km. Analysis of the joint PDFs of cloud size and in-cloud variables demonstrates that, as expected, the bigger clouds are far less diluted above their bases than their smaller counterparts. Also, thermodynamic properties at cloud bases are found to be nearly identical for all cloud sizes, with the moist static energy exceeding the mean value by as much as 4 kJ kg−1. The width of the moist static energy distribution in the boundary layer is mostly due to variability of water vapor; therefore, clouds appear to grow from the air with the highest water vapor content available.

No undiluted cloudy parcels are found near the level of neutral buoyancy. It appears that a simple entraining-plume model explains the entrainment rates rather well. The least diluted plumes in the simulation correspond to an entrainment parameter of about 0.1 km−1.
The Role of the Ocean in the Seasonal Cycle of the Hadley Circulation
Authors: Clement Amy C.
Published: December 2006

The influence of ocean heat transport on the seasonal cycle of the Hadley circulation is investigated using idealized experiments with a climate model. It is found that ocean heat transport plays a fundamental role in setting the structure and intensity of the seasonal Hadley cells. The ocean’s influence can be understood primarily via annual mean considerations. By cooling the equatorial regions and warming the subtropics in a year-round sense, the ocean heat transport allows for regions of SST maxima to occur off the equator in the summer hemisphere. This leads to large meridional excursions of convection over the ocean and a seasonal Hadley circulation that is strongly asymmetric about the equator. The broadening of the latitudinal extent of the SST maximum and the convecting regions by the ocean heat transport also weakens the annual mean Hadley circulation in a manner that is consistent with simpler models. The results are discussed in the context of prior studies of the controls on the strength and structure of the Hadley circulation. It is suggested that a complete understanding of the seasonal Hadley circulation must include both oceanic and atmospheric processes and their interactions.
Representing Convective Organization in Prediction Models by a Hybrid Strategy
Authors: Moncrieff Mitchell W. , Liu Changhai
Published: December 2006

The mesoscale organization of precipitating convection is highly relevant to next-generation global numerical weather prediction models, which will have an intermediate horizontal resolution (grid spacing about 10 km). A primary issue is how to represent dynamical mechanisms that are conspicuously absent from contemporary convective parameterizations. A hybrid parameterization of mesoscale convection is developed, consisting of convective parameterization and explicit convectively driven circulations.

This kind of problem is addressed for warm-season convection over the continental United States, although it is argued to have more general application. A hierarchical strategy is adopted: cloud-system-resolving model simulations represent the mesoscale dynamics of convective organization explicitly and intermediate resolution simulations involve the hybrid approach. Numerically simulated systems are physically interpreted by a mechanistic dynamical model of organized propagating convection. This model is a formal basis for approximating mesoscale convective organization (stratiform heating and mesoscale downdraft) by a first-baroclinic heating couplet.

The hybrid strategy is implemented using a predictor–corrector strategy. Explicit dynamics is the predictor and the first-baroclinic heating couplet the corrector. The corrector strengthens the systematically weak mesoscale downdrafts that occur at intermediate resolution. When introduced to the Betts–Miller–Janjic convective parameterization, this new hybrid approach represents the propagation and dynamical structure of organized precipitating systems. Therefore, the predictor–corrector hybrid approach is an elementary practical framework for representing organized convection in models of intermediate resolution.
Numerical Simulation of Cloud–Clear Air Interfacial Mixing: Effects on Cloud Microphysics
Authors: Andrejczuk Miroslaw , Grabowski Wojciech W. , Malinowski Szymon P. , Smolarkiewicz Piotr K.
Published: December 2006

This paper extends the previously published numerical study of Andrejczuk et al. on microscale cloud–clear air mixing. Herein, the primary interest is on microphysical transformations. First, a convergence study is performed—with well-resolved direct numerical simulation of the interfacial mixing in the limit—to optimize the design of a large series of simulations with varying physical parameters. The principal result is that all conclusions drawn from earlier low-resolution (Δx = 10−2 m) simulations are corroborated by the high-resolution (Δx = 0.25 × 10−2 m) calculations, including the development of turbulent kinetic energy (TKE) and the evolution of microphysical properties. This justifies the use of low resolution in a large set of sensitivity simulations, where microphysical transformations are investigated in response to variations of the initial volume fraction of cloudy air, TKE input, liquid water mixing ratio in cloudy filaments, relative humidity (RH) of clear air, and size of cloud droplets. The simulations demonstrate that regardless of the initial conditions the evolutions of the number of cloud droplets and the mean volume radius follow a universal path dictated by the TKE input, RH of clear air filaments, and the mean size of cloud droplets. The resulting evolution path only weakly depends on the progress of the homogenization. This is an important conclusion because it implies that a relatively simple rule can be developed for representing the droplet-spectrum evolution in cloud models that apply parameterized microphysics. For the low-TKE input, when most of the TKE is generated by droplet evaporation during mixing and homogenization, an inhomogeneous scenario is observed with approximately equal changes in the dimensionless droplet number and mean volume radius cubed. Consistent with elementary scale analysis, higher-TKE inputs, higher RH of cloud-free filaments, and larger cloud droplets enhance the homogeneity of mixing. These results are discussed in the context of observations of entrainment and mixing in natural clouds.
Direct Numerical Simulation of the Plumb–McEwan Laboratory Analog of the QBO
Authors: Wedi Nils P. , Smolarkiewicz Piotr K.
Published: December 2006

The laboratory experiment of Plumb and McEwan demonstrates the principal mechanism of periodically reversing winds observed in the stratosphere—the quasi-biennial oscillation (QBO). However, despite numerous studies, some aspects of the QBO and the connection to its laboratory analog remain unclear. Incorporating the rapidly undulating boundaries of the laboratory experiment into the numerical algorithm—via time-dependent curvilinear coordinates—allows for the reproduction of the experimental setup, while minimizing numerical uncertainties. Results are presented of the first direct numerical simulation of the phenomena that lead to the zonal-mean flow reversal in the laboratory analog The aim of this research is to narrow the widening gap between the theoretical understanding of laboratory-scale, internal-gravity wave processes and the complexity of global-scale circulations. A detailed study is presented on the parametric and numerical sensitivities of the oscillation. The results confirm a number of sensitivities, addressed in earlier studies. The analogy of radiative damping in the atmosphere and the role of molecular viscosity in the zonally varying laboratory flow are discussed, emphasizing the dominant role of wave–wave and wave–mean flow interactions in the latter, and in particular the retroaction of the induced mean flow on the waves. The findings elevate the importance of the laboratory setup for its fundamental similarity to the atmosphere. Implications are discussed for the theory and numerical realizability of equatorial zonal-mean zonal flow oscillations. The study corroborates the dependence of global-scale motions on small-scale wave-driven fluctuations, while being independent of parameterized or approximated means of forcing and wave dissipation.
A Multimoment Bulk Microphysics Parameterization. Part III: Control Simulation of a Hailstorm
Authors: Milbrandt J. A. , Yau M. K.
Published: December 2006

With continuous increase in the resolution of operational numerical weather prediction models, grid-scale saturation schemes that model cloud microphysics are becoming increasingly important. In Parts I and II of this study, the importance of the relative dispersion of the hydrometeor size distribution in bulk microphysics parameterizations was demonstrated and a closure approach for a three-moment scheme was proposed. In this paper, the full three-moment version of the new multimoment scheme is tested in a 3D simulation of a severe hailstorm. The modeled microphysical fields are examined, with particular attention paid to the simulated hail fields including the maximum hail sizes at the ground.

A mesoscale model was initialized using synoptic analyses and successively nested to a resolution of 1 km. When compared to observations of the real storm from a nearby radar, the simulated storm reproduced several of the observed characteristics including the direction and speed of propagation, a bounded weak echo region, hook echo, mesocyclone, and a suspended overhang region. The magnitudes of radar reflectivity and surface precipitation are also well simulated.

The mass contents, total number concentrations, equivalent reflectivities, and mean mass diameters of each hydrometeor category in the model were examined. The spatial distributions of the various hydrometeors throughout the storm appeared realistic and their values were consistent with published observations from other storms. Using the three predicted parameters of the gamma size distribution for hail, a method was introduced to determine the maximum hail size simulated from a bulk scheme that is physically observable. The observed storm produced golf ball–sized hail while the simulation produced walnut-sized hail at approximately the same time and location. The results suggest that because of the additional information provided about the size distribution, there is added value in prognosing the relative dispersion parameter of a given hydrometeor category in a bulk scheme.
A Multimoment Bulk Microphysics Parameterization. Part IV: Sensitivity Experiments
Authors: Milbrandt J. A. , Yau M. K.
Published: December 2006

This is the fourth in a series of papers exploring the effects of the number of predicted moments in bulk microphysics schemes. In Part III, the three-moment version of a new multimoment scheme was used to simulate a severe hailstorm. The model successfully reproduced many of the observed gross characteristics, including the reflectivity structure and the maximum hail sizes at the ground. In this paper, the authors compare a series of sensitivity experiments using various one- and two-moment versions of the scheme with the three-moment version to explore the effects of predicting additional moments on the simulated hydrometeor fields, precipitation, and storm dynamics.

Six sensitivity runs were performed. They varied in their ability to reproduce the precipitation pattern, storm structure, and peak values of microphysical fields of the control simulation. The two-moment simulations, which used diagnostic relations to prescribe the relative dispersion parameter, α, closely reproduced the spatial pattern, quantity, and phase of the precipitation at the surface as well as the overall storm structure, propagation speed, and peak values of several hydrometeor fields. The two-moment simulations, which used fixed values of α, on the other hand, differed more from the control. The runs using one-moment versions of the scheme were considerably different from each other and were poor at reproducing the control simulation.

The results suggest that there is a dramatic improvement in the simulation moving from one- to two-moment schemes. For the case studied, it was found that if maximum particle size is not of concern, a two-moment scheme with a diagnostic dispersion parameter can reproduce most of the important aspects in a hailstorm simulation with a three-moment scheme.
Eddy Influences on Hadley Circulations: Simulations with an Idealized GCM
Authors: Walker Christopher C. , Schneider Tapio
Published: December 2006

An idealized GCM is used to investigate how the strength and meridional extent of the Hadley circulation depend on the planet radius, rotation rate, and thermal driving. Over wide parameter ranges, the strength and meridional extent of the Hadley circulation display clear scaling relations with regime transitions, which are not predicted by existing theories of axisymmetric Hadley circulations. For example, the scaling of the strength as a function of the radiative-equilibrium equator-to-pole temperature contrast exhibits a regime transition corresponding to a regime transition in scaling laws of baroclinic eddy fluxes. The scaling of the strength of the cross-equatorial Hadley cell as a function of the latitude of maximum radiative-equilibrium temperature exhibits a regime transition from a regime in which eddy momentum fluxes strongly influence the strength to a regime in which the influence of eddy momentum fluxes is weak.

Over a wide range of flow parameters, albeit not always, the Hadley circulation strength is directly related to the eddy momentum flux divergence at the latitude of the streamfunction extremum. Simulations with hemispherically symmetric thermal driving span circulations with local Rossby numbers in the horizontal upper branch of the Hadley circulation between 0.1 and 0.8, indicating that neither nonlinear nearly inviscid theories, valid for Ro → 1, nor linear theories, valid for Ro → 0, of axisymmetric Hadley circulations can be expected to be generally adequate. Nonlinear theories of axisymmetric Hadley circulations may account for aspects of the circulation when the maximum radiative-equilibrium temperature is displaced sufficiently far away from the equator, which results in cross-equatorial Hadley cells with nearly angular momentum-conserving upper branches.

The dependence of the Hadley circulation on eddy fluxes, which are themselves dependent on extratropical circulation characteristics such as meridional temperature gradients, suggests that tropical circulations depend on the extratropical climate.
Superrotation Maintained by Meridional Circulation and Waves in a Venus-Like AGCM
Authors: Yamamoto Masaru , Takahashi Masaaki
Published: December 2006

Fully developed superrotation—60 times faster than the planetary rotation (243 days)—is simulated using a Venus-like atmospheric general circulation model (AGCM). The angular momentum of the superrotation is pumped up by the meridional circulation with the help of waves, which accelerate the equatorial zonal flow. The waves generated by solar heating and shear instability play a crucial role in the atmospheric dynamics of the Venusian superrotation. Vertical and horizontal momentum transports of thermal tides maintain the equatorial superrotation in the middle atmosphere, while equatorward eddy momentum flux due to shear instability raises the efficiency of upward angular momentum transport by the meridional circulation in the lower atmosphere. In addition to the superrotation, some waves simulated in the cloud layer are consistent with the observations. The planetary-scale Kelvin wave identified as the near-infrared (NIR) oscillation with periods of 5–6 days is generated by the shear instability near the cloud base, and the temperature structure of the diurnal tide is similar to the infrared (IR) observation near the cloud top.

Sensitivities to the bottom boundary conditions are also examined in this paper, since the surface physical processes are still unknown. The decrease of the equator–pole temperature difference and the increase of the surface frictional time constant result in the weaknesses of the meridional circulation and superrotation. In the cases of the weak superrotation, the vertical angular momentum transport due to the meridional circulation is inefficient and the equatorward eddy angular momentum transport is absent near 60-km altitude.
Comparison of the Stability, Efficacy, and Adverse Effect Profile of the Innovator 0.005% Latanoprost Ophthalmic Solution and a Novel Cyclodextrin‐containing Formulation
Authors: Gonzalez Jaime R. , Baiza‐Duran Leopoldo , Quintana‐Hau Juan , Tornero‐Montaño Ruben , Castaneda‐Hernandez Gilberto , Ortiz Mario , Alarcon‐Oceguera Felipe , Beltran‐Loustaunau Marco , Cortez‐Gastelum Marco , Garcidueñas‐Mejia Jorge , Gomez‐Bastar Pedro , Jimenez‐Roman Jesus , Korder‐Ortega Vincent , Paczka‐Zapata Jose , Torres‐Segura Marina , Velasco‐Gallegos Gustavo
Published: December 2006

Recently, a new latanoprost ophthalmic solution containing cyclodextrins was developed. The purpose of the present work was to compare the stability, clinical efficacy, and adverse effect profile of this formulation with the innovator product. The innovator formulation was stable at 4°C but exhibited degradation at higher temperatures, whereas the cyclodextrin‐containing formulation was stable at temperatures up to 40°C. Formulations were assayed in a randomized double‐blind clinical study in patients with primary open‐angle glaucoma and/or ocular hypertension. Both latanoprost ophthalmic solutions produced comparable reduction of intraocular pressure. Conjunctival hyperemia was observed in 11.9% and 11.3% of the patients treated with the innovator and the cyclodextrin‐containing formulations, respectively. There were no significant differences between the 2 ophthalmic solutions in efficacy or in the measured adverse effect. It is concluded that these 2 latanoprost ophthalmic solutions yield comparable efficacy and adverse effect outcomes. The cyclodextrin‐containing formulation, however, has an improved stability.
Comparison of Inhibitory Effects of Irbesartan and Atorvastatin Treatment on the Renin Angiotensin System (RAS) in Veins: A Randomized Double‐Blind Crossover Trial in Healthy Subjects
Authors: Schindler Christoph , Brosnihan K. Bridget , Ferrario Carlos M. , Bramlage Peter , Maywald Ulf , Koch Rainer , Oertel Reinhard , Kirch Wilhelm
Published: December 2006

Experimental studies point to an interplay between hypercholesterolemia and hypertension, acting through the renin angiotensin system. In a crossover study design with 8 healthy subjects, the authors tested the hypothesis that statin treatment exerts renin angiotensin system–modulating effects in veins by down‐regulation of AT1‐receptors, resulting in reduced Angiotensin II (Ang II)–induced venoconstriction and by increasing the pleiotropic Ang II–metabolite Ang‐(1–7). Irbesartan was used as positive control. Ang II–induced venoconstriction was 49% ± 9% before and 64% ± 10% after 30 days of atorvastatin treatment compared to 50% ± 8% before and 15% ± 9% after irbesartan (P = .004). Plasma angiotensin levels significantly increased only after irbesartan treatment (Ang II: 35 ± 4 vs 329 ± 101 pg/mL [P = .02]; Ang‐(1–7): 10 ± 3 vs 35 ± 6 pg/mL [P = .01]) compared to atorvastatin treatment (Ang II: 26 ± 5 vs 31 ± 4 pg/mL [P = ns]; Ang‐(1–7): 9 ± 2 vs 11 ± 3 pg/mL [P = ns]). The data indicate that atorvastatin does not inhibit Ang II–induced venoconstriction in vivo and point toward a supportive role of Ang‐(1–7) in contributing to the antihypertensive and beneficial vascular effects of irbesartan.
The Role of SN‐38 Exposure, UGT1A1*28 Polymorphism, and Baseline Bilirubin Level in Predicting Severe Irinotecan Toxicity
Authors: Ramchandani Roshni P. , Wang Yaning , Booth Brian P. , Ibrahim Amna , Johnson John R. , Rahman Atiqur , Mehta Mehul , Innocenti Federico , Ratain Mark J. , Gobburu Jogarao V. S.
Published: December 2006

Irinotecan, an anticancer drug, is associated with severe and potentially fatal diarrhea and neutropenia. The objective of this analysis was to evaluate the role of SN‐38 exposure, the active metabolite of irinotecan, UGT1A1 genotypes, and baseline bilirubin on the maximum decrease (nadir) in absolute neutrophil counts following irinotecan. This analysis extended the work of a previous study that examined the effect of UGT1A1 genotypes on the incidence of severe neutropenia in 86 advanced cancer patients following irinotecan treatment. Regression analysis showed that the absolute neutrophil count nadir depended on SN‐38 exposure (AUC) and UGT1A1*28 homozygous 7/7 genotype. An increased SN‐38 AUC and the 7/7 genotype were significantly associated with a lower absolute neutrophil count nadir (R2 = .49). An alternate model suggested that higher baseline bilirubin and the 7/7 genotype were also significantly associated with a lower absolute neutrophil count nadir, although with a lower coefficient of determination (R2 = .31). Based on these findings and other reports, the irinotecan label was modified to indicate the role of UGT1A1*28 polymorphism in the metabolism of irinotecan and the associated increased risk of severe neutropenia. The label modifications also included recommendations for lower starting doses of irinotecan in patients homozygous for the UGT1A1*28 (7/7) polymorphism.
Plasma and Cerebrospinal Fluid Concentrations of Indomethacin in Children After Intravenous Administration
Authors: Mannila Anne , Kumpulainen Elina , Lehtonen Marko , Heikkinen Marja , Laisalmi Merja , Salo Terhi , Rautio Jarkko , Savolainen Jouko , Kokki Hannu
Published: December 2006

The objective of this study was to evaluate the cerebrospinal fluid (CSF) permeation of indomethacin in healthy children. The participants (n = 31, aged 4–144 months) received indomethacin (0.35 mg/kg) as a 10‐minute intravenous infusion prior to surgery under spinal anaesthesia. A single CSF and plasma sample from each individual was collected 14 to 225 minutes after the infusion. Indomethacin concentrations were determined from the CSF, plasma, and protein‐free plasma. Total plasma, protein‐free plasma, and CSF concentrations of indomethacin ranged between 90 and 2200 ng/mL (median, 780 ng/mL), 0.3 and 0.8 ng/mL (median, 0.5 ng/mL), and 0.2 and 5.0 ng/mL (median, 1.4 ng/mL), respectively. The CSF to plasma concentration ratio remained less than 0.01. There was no correlation between the administration time and CSF concentrations. Eleven children developed 12 nonserious adverse effects, from which 5 were central nervous system (CNS) effects (agitation). In conclusion, indomethacin permeated into the CSF of children, which enables both desired and adverse CNS effects of indomethacin.
Returns to Local and Transport Infrastructure under Regional Spillovers
Authors: Moreno Rosina , López-Bazo Enrique
Published: December 2006

This article pays special attention to the spatial dimension of public capital in regional economic growth. We assume that the effect of infrastructure on productivity depends on the type of public infrastructure in question: that is, local infrastructures enhance economic activity in the area where they are located, whereas transport and communication infrastructure may produce both benefits in the area where they are located and positive or negative spillovers to other regions. We also obtain conclusions on whether the link between growth and public capital depends on the amount of existing public capital stocks. Results for the Spanish provinces during a long time period suggest that the returns to local infrastructure are much greater than the returns to transportation, although in both cases, we observe strong decreasing returns to their accumulation. Finally, negative spillovers across regions in transport capital investments are obtained.
Pathologic Characteristics of the Torn Human Meniscus
Authors: Mesiha Mena , Zurakowski David , Soriano Jamil , Nielson Jason H. , Zarins Bertram , Murray Martha M.
Published: December 2006

Background

Acellular meniscus tissue is at a high risk for degeneration and retear. Information that would help surgeons predict, preoperatively, or intraoperatively which torn menisci had few viable cells could be useful in deciding which patients might be at increased risk for retear and failure of surgical repair.

Hypothesis

Patient age, length of time since injury, and tear type are predictors of the cellularity of meniscus tissue.

Study Design

Descriptive laboratory study.

Methods

Gross and histologic evaluation of torn meniscus tissue from 44 patients and 10 control menisci was performed.

Results

The patient factors of age, time since injury, and tear type all had significant effects on the pathologic characteristics of the torn meniscus. Patients older than 40 years had lower cellularity in the torn menisci than did patients younger than 40 years (P < .01). As time since injury increased, so did the rates of DNA fragmentation in the midsubstance of the meniscus and rates of Outerbridge II changes in the adjacent cartilage. Worse meniscal histologic scores were found in menisci with degenerative and radial tear types.

Conclusion

Patient age had a significant effect on the cellularity of the torn meniscus, with patients older than 40 years having significantly fewer meniscus cells than did those younger than 40 years. Further studies are needed to define the relative importance of the individual histologic findings in the clinical setting of meniscus tear and repair.

Clinical Relevance

In light of their decreased cellularity, menisci from patients older than 40 years may be more vulnerable to degeneration and retear after repair than are menisci of younger patients.
Prolonged Superficial Local Cryotherapy Attenuates Microcirculatory Impairment, Regional Inflammation, and Muscle Necrosis after Closed Soft Tissue Injury in Rats
Authors: Schaser Klaus-Dieter , Disch Alexander C. , Stover John F. , Lauffer Annette , Bail Herman J. , Mittlmeier Thomas
Published: December 2006

Background

Closed soft tissue injury induces progressive microvascular dysfunction and regional inflammation. The authors tested the hypothesis that adverse trauma-induced effects can be reduced by local cooling. While superficial cooling reduces swelling, pain, and cellular oxygen demand, the effects of cryotherapy on posttraumatic microcirculation are incompletely understood.

Study Design

Controlled laboratory study.

Methods

After a standardized closed soft tissue injury to the left tibial compartment, male rats were randomly subjected to percutaneous perfusion for 6 hours with 0.9% NaCL (controls; room temperature) or cold NaCL (cryotherapy; 8°C) (n = 7 per group). Uninjured rats served as shams (n = 7). Microcirculatory changes and leukocyte adherence were determined by intravital microscopy. Intramuscular pressure was measured, and invasion of granulocytes and macrophages was assessed by immunohistochemistry. Edema and tissue damage was quantified by gravimetry and decreased desmin staining.

Results

Closed soft tissue injury significantly decreased functional capillary density (240 ± 12 cm-1); increased microvascular permeability (0.75 ± 0.03), endothelial leukocyte adherence (995 ± 77/cm2), granulocyte (182.0 ± 25.5/mm2) and macrophage infiltration, edema formation, and myonecrosis (ratio: 2.95 ± 0.45) within the left extensor digitorum longus muscle. Cryotherapy for 6 hours significantly restored diminished functional capillary density (393 ± 35), markedly decreased elevated intramuscular pressure, reduced the number of adhering (462 ± 188/cm2) and invading granulocytes (119 ± 28), and attenuated tissue damage (ratio: 1.7 ± 0.17).

Conclusion

The hypothesis that prolonged cooling reduces posttraumatic microvascular dysfunction, inflammation, and structural impairment was confirmed.

Clinical Relevance

These results may have therapeutic implications as cryotherapy after closed soft tissue injury is a valuable therapeutic approach to improve nutritive perfusion and attenuate leukocyte-mediated tissue destruction. The risk for evolving compartment syndrome may be reduced, thereby preventing further irreversible aggravation.
Integrated molecular profiling of SOD2 expression in multiple myeloma
Authors: Hurt Elaine M. , Thomas Suneetha B. , Peng Benjamin , Farrar William L.
Published: December 2006

Reactive oxygen species are known to be involved in several cellular processes, including cell signaling. SOD2 is a key enzyme in the conversion of reactive oxygen species and has been implicated in a host of disease states, including cancer. Using an integrated, whole-cell approach encompassing epigenetics, genomics, and proteomics, we have defined the role of SOD2 in multiple myeloma. We show that the SOD2 promoter is methylated in several cell lines and there is a correlative decrease in expression. Furthermore, myeloma patient samples have decreased SOD2 expression compared with healthy donors. Overexpression of SOD2 results in decreased proliferation and altered sensitivity to 2-methoxyestradiol–induced DNA damage and apoptosis. Genomic profiling revealed regulation of 65 genes, including genes involved in tumorigenesis, and proteomic analysis identified activation of the JAK/STAT pathway. Analysis of nearly 400 activated transcription factors identified 31 transcription factors with altered DNA binding activity, including XBP1, NFAT, forkhead, and GAS binding sites. Integration of data from our gestalt molecular analysis has defined a role for SOD2 in cellular proliferation, JAK/STAT signaling, and regulation of several transcription factors.
Sleep apnoea as an independent risk factor for cardiovascular disease: current evidence, basic mechanisms and research priorities: Fig. 1—
Authors: McNicholas W. T. , Bonsignore M. R. ,   the Management Committee of EU COST ACTION B26
Published: December 2006

Considerable evidence is available in support of an independent association between obstructive sleep apnoea syndrome (OSAS) and cardiovascular disease, which is particularly strong for systemic arterial hypertension and growing for ischaemic heart disease, stroke, heart failure, atrial fibrillation and cardiac sudden death.

The pathogenesis of cardiovascular disease in OSAS is not completely understood but likely to be multifactorial, involving a diverse range of mechanisms including sympathetic nervous system overactivity, selective activation of inflammatory molecular pathways, endothelial dysfunction, abnormal coagulation and metabolic dysregulation, the latter particularly involving insulin resistance and disordered lipid metabolism.

The present report, which arose out of a European Union Cooperation in the field of Scientific and Technical Research (COST) action on OSAS (COST B26), reviews the current evidence for an independent association and proposes research priorities to identify the underlying mechanisms involved, with a view to identifying novel therapeutic strategies.

Large-scale collaborative studies of carefully defined patient populations with obstructive sleep apnoea syndrome, adequately controlled for potential confounders, are needed. Such studies carry the prospect of evaluating potential interactions between different basic mechanisms operating in obstructive sleep apnoea syndrome and cardiovascular disease, and interactions with other related disorders, such as obesity, diabetes and dyslipidaemia. Furthermore, translational studies involving cell culture and animal models linked to studies of obstructive sleep apnoea syndrome patients are necessary to integrate basic mechanisms with the clinical disorder.