Unbalanced Dynamics Research Articles

Parameterization of Vertical Turbulent Transport in the Inner Core of Tropical Cyclones and Its Impact on Storm Intensification. Part II: Understanding TC Intensification in a Generalized Sawyer–Eliassen Diagnostic Framework

Abstract An analytical method for diagnosing the interaction between the primary and secondary circulations of a tropical cyclone (TC) and vortex intensification is developed. It includes a diagnostic equation describing the mean secondary circulation of a TC in an unbalanced framework by including the radial eddy forcing in the analytical system. It is an extension of the Sawyer–Eliassen equation (SEE) developed from the strict gradient-wind balance. This generalized SEE (GSEE) remediates some of the limitations of SEE and can be used to diagnose both balanced and unbalanced dynamical processes during the TC evolution. Using GSEE, this study investigates how the tangential and radial eddy forcing affects the TC intensification simulated by the Hurricane Weather Research and Forecasting Model (HWRF) with differently parameterized turbulent mixing. The diagnostic results show that the supergradient component of radial eddy forcing contributes positively to the acceleration of the peak tangential wind, whereas the subgradient component of the radial eddy forcing tends to lower the height of peak tangential wind. The relative importance of negative and positive effects of tangential eddy forcing on TC intensification varies depending on the details of turbulence parameterization. For a turbulent kinetic energy (TKE) scheme used in this study, a large sloping curvature of mixing length in the low troposphere causes the tangential eddy forcing to produce a net positive tangential wind tendency near the location of the peak tangential wind. In contrast, a small sloping curvature of mixing length generates a net negative tangential wind tendency at the peak tangential wind. Significance Statement The interaction between the primary and secondary circulations of a tropical cyclone (TC) plays a key role in TC evolution. Historically, the secondary circulation induced by turbulence and convection is often described by a so-called Sawyer–Eliassen equation (SEE). While SEE has provided much insight into the TC dynamics in the past, the assumption of gradient-wind balance used by SEE prevents it from understanding TC unbalanced dynamics. To remediate the limitation, we extended the analytical framework into the unbalanced regime by including radial eddy forcing in the analytical system and derived a generalized SEE (GSEE). Using GSEE, this study investigates how tangential and radial eddy forcing affects TC intensification. The result highlights the importance of multiple roles that turbulence plays in the intensification of TCs.

Numerical Investigation of Track and Intensity Evolution of Typhoon Doksuri (2023)

This study utilized the WRF model to investigate the track evolution and rapid intensification (RI) of Typhoon Doksuri (2023) as it moved across the Luzon Strait and through the South China Sea (SCS). The simulation results indicate that Doksuri has a smaller track sensitivity to the use of different physics schemes, while having a greater intensity sensitivity. Sensitivity numerical experiments with different physics schemes can well capture its northwestward movement in the first two days, but they predict less westward track deflection as the typhoon moves across the Luzon Strait and through the SCS. Moreover, all the experiments successfully simulated Doksuri’s RI, albeit with quite different rates and a time lag of 12 h. Among different combinations of physics schemes, there exists an optimal set of cumulus parameterization and cloud microphysics schemes for track and intensity predictions. Doksuri’s track changes as the typhoon moved across the Luzon Strait and through the SCS were influenced by the topographic effects of the terrain of the Philippines and Taiwan, to different extents. The track changes of Doksuri are explained by the wavenumber-one potential vorticity (PV) tendency budget from different physical processes, highlighting that the horizontal PV advection dominates the PV tendency throughout most of the simulation time due to the offset of vertical PV advection and differential diabatic heating. In addition, this study applies the extended Sawyer–Eliassen (SE) equation to compare the transverse circulations of the typhoon induced by various forcing sources. The SE solution indicates that radial inflow was largely driven in the lower-tropospheric vortex by strong diabatic heating, while being significantly enhanced in the lower boundary layer due to turbulent friction. All other physical forcing terms were relatively insignificant for the induced transverse circulation. The coordinated radial inflow at low levels may have led to the eyewall development in unbalanced dynamics. Intense diabatic heating thus was vital to the severe RI of Doksuri under a weak vertical wind shear.

MAPPING OVER 80 YEARS OF WETLAND SENSITIVITY TO HUMAN INTERVENTION. THE SPATIAL DYNAMICS OF THE LAKES AND WETLANDS OF THE JIJIA-IAȘI WETLANDS RAMSAR SITE IN 1935–2018

Wetlands are at the top of the list in terms of valuable ecosystem services, at the same time being one of the most sensitive ecosystems that are subject to human-induced changes. The delicate balance between their ever-changing waterlogged and dry areas, together with the associated rich flora and fauna, are easily disturbed by human drivers, which are also responsible for long-term land use conversions. This paper aims to 1) document the spatial dynamics of the wetland areas and lakes in the Jijia-Iași Wetlands Ramsar Site, using historical cartographic materials and modern land use data, and 2) pinpoint the anthropic drivers that shaped these dynamics, via a literature review. This Ramsar Site constitutes an eloquent example of a wetland landscape that was mainly shaped by human intervention. A timeline is used to put into perspective the resulting maps and synthesised findings, and several inferences regarding the past, present, and future sensitivity of the wetlands in the study area are formulated. In 1935–2018, the two analysed elements followed opposite trends: while the wetland areas decreased from 10.61% of the study area to 4.79%, the lake features increased in size, from 0.68% of the Jijia-Iași Wetlands to 10.84%. In order to explain these changes, anthropogenic interventions were divided into three types of management (detrimental high human pressure, beneficial high human pressure, and beneficial low human pressure). In the long term scientific works, the unbalanced dynamics proved to be beneficial to the environment, as the construction of water collections determined a biodiversity boost and the designation of the study area as a Ramsar Site. This paper complements the scientific work focusing on “the Delta of Moldavia”, highlighting the practical implications of the management strategies applied during the reference period.

What Are the Balanced and Unbalanced Dynamics of a Tropical Cyclone?

Abstract Recently, Ji and Qiao took into account the unbalanced components and derived an extended Sawyer–Eliassen (SE) equation. This study developed a new derivation of this extended SE equation from the perspective of restoring forces, and gives a physical interpretation for the coefficients that appear in the SE equation. For an unbalanced vortex, we demonstrated that the thermodynamic fields are only determined by the distribution of gradient wind, and thus, the gradient wind and thermodynamic fields always remain in balance as the unbalanced vortex evolves. Consequently, we attributed the gradient wind imbalance to the agradient wind rather than to the thermodynamic fields. Subsequently, we explored the effect of the agradient wind on the secondary circulation, and showed that the agradient wind strengthens the secondary circulation in its vicinity, which can be explained as a consequence of the restoring forces and mass continuity. Furthermore, we speculated that the SE equation, together with the radial velocity equation, could reproduce the primary characteristic of the axisymmetric boundary layer dynamics by prescribing the parameterization of subgrid-scale turbulent mixing. Specifically, the noU_BL and noVa_BL experiments conducted by Fei et al. in an article published in 2021 were reinterpreted, and the oscillation wavelength of the agradient wind in the eyewall was approximated based on this framework. Additionally, a new numerical solution algorithm to overcome the hyperbolicity near the boundary layer was proposed. This study attempts to develop a complete dynamic theory for tropical cyclones in both qualitative and quantitative perspectives.

Does Extended Sawyer–Eliassen Equation Effectively Capture the Secondary Circulation of a Simulated Tropical Cyclone?

Abstract The validity of the gradient wind balance in a tropical cyclone (TC) remains controversial, especially for the boundary layer and the upper outflow layer, even though this balance is assumed in the derivation of the Sawyer–Eliassen (SE) equation. This study derives an extended SE equation with the relaxation of the gradient wind and hydrostatic balance in cylindrical r–z coordinates, and then we diagnose the secondary circulation using this unbalanced SE equation and the azimuthally averaged tangential wind and thermodynamical fields from a three-dimensional numerical simulation of an intensifying TC. The gradient wind and hydrostatic imbalance produce two additional time-dependent forcing terms on the right-hand side (rhs) of SE equation, which are proved to be negligible for diagnosing the secondary circulation, even as the storm evolves rapidly. The use of the unbalanced basic state deforms the fields of coefficients that appear in the SE equation, and thus the forced secondary flows. The results indicate that the unbalanced solution captures the boundary layer inflow better than the balanced solution described by Bui et al. and the pseudobalanced solution described by Heng et al. The unbalanced solution is closer to the simulation because more unbalanced components are included. Many previous studies always employ the thermal wind balance relation to simplify the SE equation, which is invalid in an unbalanced vortex and result in an overestimation of the boundary layer inflow. These unbalanced dynamics could provide a reliable diagnosis of the secondary flow near the boundary layer.

Downwind Development in a Stationary Band Complex Leading to the Secondary Eyewall Formation in the Simulated Typhoon Soudelor (2015)

Abstract Previous studies have demonstrated the importance of the downwind development of a rainband in secondary eyewall formation (SEF) in tropical cyclones. However, the details of the transition from rainbands to a secondary eyewall are not well understood. This study examined the convection onset in the early stage of SEF in the numerically simulated Typhoon Soudelor (2015). Results show that the convection onset in the SEF region was associated with the organization of a stationary band complex (SBC), which resulted from the outward propagation of inner rainbands and downwind propagation of secondary rainbands, with convection enhanced in the downwind sector of the SBC. The outward propagation of the inner rainbands involved the mesoscale pressure perturbations-induced unbalanced boundary layer dynamics, which were responsible for the radial outflow above the boundary layer inflow and the related secondary circulation on the inward side of the rainband. In the downwind propagation, secondary rainbands evolved into stratiform precipitation in the downshear-left quadrant, where mesoscale descending inflow continuously occurred and transported low equivalent potential temperature (θe) and dry air downward and downwind, leading to a decrease in low-level θe on the outward side of the rainband. A balanced state of the cold pool dynamics was finally reached in the downwind sector of the SBC between the supergradient-induced vertical wind shear and the low-θe-induced cold pool, resulting in the convection enhancement. Our results strongly suggest that both the unbalanced dynamics and rainband processes were essential in the early stage of SEF. Significance Statement The purpose of this study is to better understand how spiral rainbands evolve into a stationary rainband complex (SBC), and the physical processes responsible for the convection enhancement in the downwind sector of the SBC. This is important because it is this downwind convective enhancement that leads to the secondary eyewall formation (SEF). Our results provide the details of the transition from rainbands to a secondary eyewall and suggest that both the unbalanced boundary layer dynamics and rainband processes are essential in the early stage of SEF.

CYCLIC-GENETIC METHODOLOGY OF PROJECT MANAGEMENT OF THE INTERMODAL HUB SYSTEM UNDER UNCERTAINTY

In the article, the authors consider the problematic aspects of project management, the research is devoted to the issues of wave crises in projects based on the method of simulation. The article provides a theoretical and methodological analysis of the theory of cycles, crises and innovations, developed in the theories of the classics of both economics and project management, which contributed to the way out of crises on a global scale and economic recovery thanks to the developed tools and models of N. Kondratyev, A. Bogdanov. Tugan-Baranovskyi, as well as the cyclical-genetic theory of project management, which can become the basis for more reliable forecasting of consistently unbalanced dynamics in the economic and managerial environment. This approach, in contrast to the existing ones, makes it possible to take into account the achievement of goals to a greater extent in the following procedures for determining the content of the competitiveness of a business. It has been found that synergy in business development programs is manifested in cost savings and an increase in the final value of business projects. The developed concept model of crises on the basis of simulation modeling of the behavior of the system "goals – value – competitiveness – man – machine" in the process of implementing programs on infrastructure projects, and in the world economy. The paper gives a general description of crises on the example of infrastructure business companies. The analysis of the conceptual apparatus of business projects, business teams, business processes is given. The given problems of forming teams of business projects. The authors analyzed and identified the main sources of the formation of the business synergy effect associated with these costs. Formalized the formation of the synergy effect in the models and theory of business projects, arising from the joint implementation of port business projects, arising from the joint implementation of business projects within the framework of the program, makes it possible to more reliably assess the achievement of the goals of infrastructure business companies and the necessary resources in conditions of risks and uncertainty.

Heat transfer and flow regimes in quasi-static magnetoconvection with a vertical magnetic field

Numerical simulations of quasi-static magnetoconvection with a vertical magnetic field are carried out up to a Chandrasekhar number of $Q=10^{8}$ over a broad range of Rayleigh numbers $Ra$. Three magnetoconvection regimes are identified: two of the regimes are magnetically constrained in the sense that a leading-order balance exists between the Lorentz and buoyancy forces, whereas the third regime is characterized by unbalanced dynamics that is similar to non-magnetic convection. Each regime is distinguished by flow morphology, momentum and heat equation balances, and heat transport behaviour. One of the magnetically constrained regimes appears to represent an ‘ultimate’ magnetoconvection regime in the dual limit of asymptotically large buoyancy forcing and magnetic field strength; this regime is characterized by an interconnected network of anisotropic, spatially localized fluid columns aligned with the direction of the imposed magnetic field that remain quasi-laminar despite having large flow speeds. As for non-magnetic convection, heat transport is controlled primarily by the thermal boundary layer. Empirically, the scaling of the heat transport and flow speeds with $Ra$ appear to be independent of the thermal Prandtl number within the magnetically constrained, high-$Q$ regimes.

Concentric Eyewall Formation in Typhoon Sinlaku (2008). Part III: Horizontal Momentum Budget Analyses

This is a follow-up work to two prior studies examining secondary eyewall formation (SEF) in Typhoon Sinlaku (2008). This study shows that, in the SEF region, the majority of the elevated winds are supergradient. About two-thirds of the rapid increase in tangential wind tendencies immediately prior to SEF are attributed to agradient wind tendencies. This suggests the importance of nonlinear, unbalanced dynamical processes in SEF in addition to the classical axisymmetric balanced response to forcings of heating and momentum. In the SEF region, analyses show two distinct responsible processes for the increasing azimuthal tangential wind in two vertical intervals. Within the boundary inflow layer, the competing effect between the mean radial influx of absolute vorticity and deceleration caused by surface friction and subgrid diffusion yields a secondary maximum of positive tendency. Analyses further demonstrate the major impact of the mean radial influx of absolute vorticity on SEF. Above the boundary inflow layer, the vertical advection acts to vertically extend the tangential wind jet via the lofting of the enhanced tangential momentum farther upward. The roles of the nonlinear unbalanced dynamics in these two processes are discussed in this paper. From a Lagrangian perspective, the persistently increasing agradient force outweighs the frictional loss, effectively decelerating boundary layer inflowing air across the SEF region. This explains the sharpening of the radial gradient of boundary layer inflow, which is shown to be responsible for the buildup of a zone with concentrated boundary layer convergence. The previously proposed unbalanced dynamical pathway to SEF is elaborated upon and supported by the current results and discussion.

Pair interactions in online assessments of collaborative problem solving: case-based portraits

This exploratory case study focuses on how pairs of students can build a shared understanding and acquire collaborative problem-solving (CPS) practices during an online assessment of CPS skills, which is seen in the context of the CPS construct, in a symmetrical and asymmetrical task type. Even though CPS is widely recognised as a core twenty-first-century competency, its nature is not yet well understood. Also, until recently, most of studies have focused on the individual’s solution to a problem or on the skills individuals bring into a problem-solving space. This study extends from an individual- to group-level focus in CPS, emphasising the role and quality of the social aspects in CPS processes and outcomes. Focusing on the group level because it mediates multiple levels of learning, including individual cognition and socio-cultural practices, may provide us with a better understanding of how pairs establish CPS practices. Because of the complexity of CPS and the general challenges of remote collaboration in an online context, the study relies on the triangulation of multiple data sources and phases of analysis. In this paper, the aim is to explore and visualise through contrasting case-based portraits of two pairs how micro-interaction processes evolve at the pair level. The results show that despite students’ similar CPS performance outcome scores and task designs aimed to facilitate collaboration, variations in micro-interactions occur across pairs, for example as individual and joint solution endeavours and as balanced and unbalanced dynamics of group interactions. Studying these patterns at the pair level may provide new insights into CPS and support strategies for acquiring these practices.

Destabilization of an Oceanic Meddy-Like Vortex: Energy Transfers and Significance of Numerical Settings

Abstract The increase of computational capabilities led recent studies to implement very high-resolution simulations that gave access to new scale interaction processes, particularly those associated with the transfer of energy from the oceanic mesoscales to smaller scales through an interior route to dissipation, which is still underexplored. In this context, we study spindown simulations of a mesoscale interior vortex, unstable to a mixed baroclinic–barotropic instability. Even though the global energy is almost conserved, some energy is transferred down to dissipation scales during the development of instabilities. However, in our parameter regime, there is no substantial forward energy cascade sustained by unbalanced dynamics. Rather than exploring the physical parameter range, we clarify numerical discretization issues that can be detrimental to the physical solutions and our interpretation of finescale dynamics. Special care is given to determining the effective resolution of the different simulations. We improve it by a factor of 2 in our primitive equation (PE) finite-difference Coastal and Regional Ocean Community (CROCO) model by implementing a fifth-order accurate horizontal advection scheme. We also explore a range of grid aspect ratios dx/dz and find that energy spectra converge for aspect ratios that are close to N/f, the ratio of the stratification N over the Coriolis parameter f. However, convergence is not reached in the PE model when using a fourth-order centered scheme for vertical tracer advection (standard in ROMS-family codes). The scheme produces dispersion errors that trigger baroclinic instabilities and generate spurious submesoscale horizontal features. This spurious instability shows great impact on submesoscale production and energy cascade, emphasizing the significance of numerical settings in oceanic turbulence studies.

SIRT 3 , a modifier of mitochondrial function in Huntington's disease

SIRT 3 is the major regulator of the mitochondrial acetylome, mediating adaptive responses of neurons to metabolic challenges. Here, we speculated that targeting SIRT 3 might influence mitochondrial function and oxidative status that are abnormal in models of Huntington's disease (HD), a motor neurodegenerative disorder mainly affecting the striatum. Protein and enzymatic analysis revealed that SIRT 3 is increased in several HD models. However, SIRT 3 knockdown aggravated mitochondrial-driven H 2 O 2 production and ATP levels. SIRT 3 levels in HD cells were normalized after antioxidant treatment, suggesting that augmented SIRT 3 may be triggered by oxidative stress. SIRT 3 overexpression (SIRT 3 OE) in HD striatal cells reestablished mitochondrial biogenesis markers, and functional imaging revealed improved mitochondrial membrane potential. Remarkably, the unbalanced mitochondrial dynamics observed in HD cells was reduced after SIRT 3 OE, with higher prevalence of tubular mitochondria due to decreased Drp1 accumulation. Additionally, overexpression of the Drosophila SIRT 3 ortholog dSirt 2 in HD model fruit flies reduced neurodegeneration of photoreceptor neurons. Overall, enhanced SIRT 3 activity ameliorates mitochondrial phenotypes, culminating in decreased neuronal damage in HD models.

On Boussinesq Dynamics near the Tropopause

Abstract The near-tropopause energy spectrum closely follows a −5/3 power law at mesoscales. Most theories addressing the mesoscale spectrum assume unbalanced dynamics but ignore the tropopause (near which the bulk of the data were collected). Conversely, it has also been proposed that the mesoscale spectrum results from tropopause-induced alterations of geostrophic turbulence. This paper seeks to reconcile these a priori mutually exclusive theories by presenting simulations that permit both unbalanced motion and tropopause-induced effects. The model integrates the nonhydrostatic Boussinesq equations in the presence of a rapidly varying background stratification profile (an idealized tropopause). Decaying turbulence simulations were performed over a wide range of Rossby numbers. In the limit of weak flow (U ≲ 1 m s−1), the essential features of the Boussinesq simulations are well captured by a quasigeostrophic version of the model: secondary roll-ups of filaments and shallow spectral slopes are observed near the tropopause but not elsewhere. However, these tropopause-induced effects rapidly disappear with increasing flow strength. For flow strengths more typical of the tropopause (U ~ 10 m s−1), the spectrum develops a shallow, near −5/3 tail associated with fast-time-scale, unbalanced motion. In contrast to weak flows, this spectral shallowing is evident at any altitude and regardless of the presence of a tropopause. Diagnostics of the fast component of motion reveal significant inertia–gravity wave activity at large horizontal scales (where the balanced flow dominates). However, no evidence points to such activity in the shallow range. That is, the mesoscale of the model is dominated by unbalanced turbulence, not waves. Implications and limitations of these findings are discussed.

Revisiting the Balanced and Unbalanced Aspects of Tropical Cyclone Intensification

Abstract The balanced and unbalanced aspects of tropical cyclone (TC) intensification are revisited with the balanced contribution diagnosed with the outputs from a full-physics model simulation of a TC using the Sawyer–Eliassen (SE) equation. The results show that the balanced dynamics can well capture the secondary circulation in the full-physics model simulation even in the inner-core region in the boundary layer. The balanced dynamics can largely explain the intensification of the simulated TC. The unbalanced dynamics mainly acts to prevent the boundary layer agradient flow in the inner-core region from further intensification. Although surface friction can enhance the boundary layer inflow and make the inflow penetrate more inward into the eye region, contributing to the eyewall contraction, the net dynamical effect of surface friction on TC intensification is negative. The sensitivity of the balanced solution to the procedure used to ensure the ellipticity condition for the SE equation is also examined. The results show that the boundary layer inflow in the balanced response is very sensitive to the adjustment to inertial stability in the upper troposphere and the calculation of radial wind at the surface with relatively coarse vertical resolution in the balanced solution. Both the use of the so-called global regularization and the one-sided finite-differencing scheme used to calculate the surface radial wind in the balanced solution as utilized in some previous studies can significantly underestimate the boundary layer inflow. This explains why the boundary layer inflow in the balanced response is too weak in some previous studies.

The unbalanced dynamics in Sino-South Korea scientific and technological collaboration: a triple helix perspective with insights from paper and patent network analysis

This study attempts to explore Sino-South Korea collaborations in science and technology, focusing on the networks of university–industry–government (UIG) relations embedded in co-authored papers and co-assigned patents at the institutional and global levels. Patents and scientific publications are examined over the period 2004–2014 to capture recent trends and patterns of collaborative innovation activities among UIG actors in China and South Korea. The analysis has been carried out from a triple helix perspective, investigating the structure and dynamics of the Sino-Korea scientific and technological collaborations. The result reveals an imbalance between science and technology in knowledge dynamics and the different extent and intensity of collaborative efforts of the two countries. Based on comparative analysis of co-authorship and co-inventorship networks, the scale and density of scientific collaboration networks appear much higher than those of the technological counterpart. In fact, the technological collaboration between China and Korea is not common in patents and its network needs to be further strengthened. Implications for both China and Korea of future collaborative relationships are discussed.

A global perspective of the limits of prediction skill of NWP models

This paper discusses the scale-dependent growth of the global forecast uncertainties simulated by the operational ensemble prediction system of the European Centre for Medium-Range Weather Forecasts. It is shown that the initial uncertainties are largest in the tropics and have biggest amplitudes at the large scales. The growth of forecast uncertainties (ensemble spread) takes place at all scales from the beginning of forecasts. The growth is nearly uniform in the zonal wavenumbers 1–5 and strongly scale-dependent in the larger wavenumbers. Moreover, the growth from initial uncertainties at large scales appears dominant over the impact of errors cascading up from small scales. A decomposition of the ensemble spread in components associated with the balanced and unbalanced dynamics shows that the initial uncertainties are primarily in the unbalanced modes, especially at the subsynoptic scales. The growth of uncertainties is found to be faster in the balanced than in the unbalanced modes and after 0.5–1 day of forecasts the balanced errors become dominant except at the subsynoptic scales.

Secondary Eyewall Formation in an Idealized Tropical Cyclone Simulation: Balanced and Unbalanced Dynamics

Abstract The secondary eyewall formation (SEF) in an idealized simulation of a tropical cyclone (TC) is examined from the perspective of both the balanced and unbalanced dynamics and through the tangential wind (Vt) budget analysis. It is found that the expansion of the azimuthal-mean Vt above the boundary layer occurs prior to the development of radial moisture convergence in the boundary layer. The Vt expansion results primarily from the inward angular momentum transport by the mid- to lower-tropospheric inflow induced by both convective and stratiform heating in the spiral rainbands. In response to the Vt broadening is the development of radial inflow convergence and the supergradient flow near the top of the inflow boundary layer. Results from the Vt budget analysis show that the combined effect of the mean advection and the surface friction is to spin down Vt in the boundary layer, while the eddy processes (eddy radial and vertical advection) contribute positively to the spinup of Vt in the SEF region in the boundary layer. Therefore, eddies play an important role in the spinup of Vt in the boundary layer during SEF. The balanced Sawyer–Eliassen solution can well capture the secondary circulation in the full-physics model simulation. The radial inflow diagnosed from the Sawyer–Eliassen equation is shown to spin up Vt and maintain the vortex above the boundary layer. However, the axisymmetric balanced dynamics cannot explain the spinup of Vt in the boundary layer, which results mainly from the eddy processes.

The Impact of Gradient Wind Imbalance on Tropical Cyclone Intensification within Ooyama’s Three-Layer Model

Abstract This paper addresses the validity of the gradient wind balance approximation during the intensification phase of a tropical cyclone in Ooyama’s three-layer model. For this purpose, the sensitivity to various model modifications is examined, given by the inclusion of (i) unbalanced dynamics in the free atmosphere, (ii) unbalanced dynamics in the slab boundary layer, (iii) a height-parameterized boundary layer model, and (iv) a rigid lid. The most rapid intensification occurs when the model employs the unbalanced slab boundary layer, while the simulation with the balanced boundary layer reveals the slowest intensification. The simulation with the realistic height-parameterized boundary layer model exhibits an intensification rate that lies in between. Intensification is induced by a convective ring in all experiments, but a distinct contraction of the radius of maximum gradient wind only takes place with unbalanced boundary layer dynamics. In all experiments the rigid lid and the balance approximation for the free atmosphere have no crucial impact on intensification, and a linear stability analysis cannot explain the found sensitivity to intensification. Most likely the nonlinear momentum advection term plays an important role in the boundary layer. It is found on the basis of a diagnostic radial mass flux equation that the source term for latent heat provides the largest contribution to intensification and contraction. Furthermore, it turns out that the position of the convective ring inside or outside of the radius of maximum gradient wind (RMGW) is of vital importance for intensification and most likely explains the large impact of boundary layer imbalance.

Nonlinear Response of a Tropical Cyclone Vortex to Prescribed Eyewall Heating with and without Surface Friction in TCM4: Implications for Tropical Cyclone Intensification

Abstract The recent debate on whether surface friction contributes positively or negatively to tropical cyclone (TC) intensification has been clarified based on two idealized numerical experiments, one without and the other with surface friction, using the fully compressible, nonhydrostatic TC model, version 4 (TCM4), with prescribed eyewall heating. The results show that with surface friction included, the intensification rate of the TC vortex is largely reduced, indicating that surface friction contributes negatively to TC intensification. Results from tangential wind budgets demonstrate that although surface friction largely enhances the boundary layer inflow and the contraction of the radius of maximum wind (RMW), the positive tangential wind tendency resulting from the frictionally induced inward absolute angular momentum (AAM) transport in the boundary layer is not large enough to offset the negative tendency due to the direct frictional loss of AAM to the surface. Results from the Sawyer–Eliassen equation suggest that the balanced response to eyewall heating is the major mechanism for TC intensification and the unbalanced dynamics due to the presence of surface friction seem to spin up tangential wind in the surface layer near the RMW where the flow is strongly subgradient and spin down tangential wind immediately above where the flow is strongly supergradient. Although surface friction shows an overall net negative effect on TC intensification, it plays a critical role in producing the realistic boundary layer structure with enhanced inflow, a low-level jet in tangential wind with supergradient nature, and a shallow outflow layer at the top of the inflow boundary layer.

Inter-hemispheric interaction of complex positive and negative emotional stimuli in psychopathy

From a neurobiological perspective psychopathy can be associated with altered and unbalanced interhemispheric dynamics. The main objective of this study is to determine whether emotional processing, such as decision making of complex emotional meanings, is more successfully accomplished with both hemispheres or separately with the left hemisphere (LH) or left hemisphere (RH) in psychopathic participants. Non-psychopathic participants were recruited from the Admission Unit of the hospital ( n = 19) and psychopathic participants were recruited from the Forensic Unit of the hospital in Gornja Toponica ( n = 22). The different positive or negative social situations with emotional meaning (96 photographs) were chosen from the IAPS, as well as a set of primary facial expressions of emotions of happiness, surprise, sadness, anger, disgust and fear. Psychopathy is not associated with an unbalanced interhemispheric dynamics in decision making in emotional processing. Complex negative emotions are more successfully processed with both hemispheres and complex positive emotions processed with equal success with both or just one hemisphere. When we exclude the emotional valence factor we get the result that suggests an advantage of interhemispheric cooperation in processing. Globally, in complex emotional tasks interhemispheric cooperation is inviolable, despite the undeniable hemisphere specialization for different functions.