Microphysical Approach Research Articles

Psychedelic: An Illustration that Reveals False Power in Rhythm 0 Performance Art

The performance art entitled Rhythm 0 by Marina Abramovic is controversial, raising various questions regarding its power and influence in the context of art. This research aims to illustrate the microphysical approach to power in the performing arts Rhythm 0, where power emerges from fear and shifts to the dominance of the ideology of power. A qualitative approach with visual analysis techniques was used in this research to explain the phenomenon of this performing arts from a very subjective view. This created illustration entitled "Psychedelic" reveals false powers in the form of intense hallucinations involving auditory, visual and feeling experiences in the Rhythm 0. The basic principles of art were used as the basis for creating this illustrative work. In this case, the use of gold leaf, peony flower elements and halos in the illustration also has a solid symbolic value, so semiotics is used as a basis for giving meaning to the symbols used. The results of this research show that the apparent power contained in the Rhythm 0 performing arts can be revealed through an illustration entitled "Psychedelic", which describes the context of the artwork in depth. This research contributes to understanding Rhythm 0's artwork and enriches knowledge about using psychedelic illustrations as a medium for artistic expression. This research also highlights how these illustrations can communicate complex themes in the performing arts, strengthening our understanding of power dynamics in arts contexts.

Performance of Lightning Potential Index, Lightning Threat Index, and the Product of CAPE and Precipitation in the WRF Model

AbstractLightning is a naturally occurring phenomenon with significant socioeconomic and environmental impacts, underlining the need for the application of advanced methods to predict it. This study aims to evaluate the performance of the Weather Research and Forecasting (WRF) model in the prediction of the lightning potential index (LPI), the lightning threat index (LTI), and the product of convective available potential energy (CAPE) and precipitation (CAPE × P). Based on the intensity of convection and the number of lightning flashes, we simulated seven thundercloud events that occurred in Tehran between 2008 and 2013. The simulated LPI, LTI, and CAPE × P values are compared both qualitatively and quantitatively against ground‐based lighting data obtained from the world wide lightning location network (WWLLN). LPI, LTI, and CAPE × P predict the location of lightning with relatively good accuracy, although LPI outperforms LTI and CAPE × P. We also compared the simulated area‐averaged LPI, LTI, and CAPE × P against the number of lightning flashes from the WWLLN data, based on which LPI shows a better performance. Overall, LPI can be used as an effective index for the prediction of lightning. As LPI is based on cloud microphysics and LTI and CAPE × P are thermodynamic‐based methods, a better performance of LPI implies that a method based on the microphysical approach can better predict lightning. The performance of LPI, LTI, and CAPE × P is also sensitive to the horizontal resolution of model simulations, with a considerable improvement in simulations with higher horizontal resolutions.

Bubble wall velocity during electroweak phase transition in the inert doublet model

The bubble wall velocity is essential for the spectra of phase-transition gravitational waves, electroweak baryogenesis and the dynamical dark matter mechanism. We perform detailed calculations of the bubble wall velocity in the well-motivated inert doublet model using the microphysical approach with some recent new methods.

Box model trajectory studies of contrail formation using a particle-based cloud microphysics scheme

Abstract. We investigate the microphysics of contrail formation behind commercial aircraft by means of the particle-based LCM (Lagrangian Cloud Module) box model. We extend the original LCM to cover the basic pathway of contrail formation on soot particles being activated into liquid droplets that soon after freeze into ice crystals. In our particle-based microphysical approach, simulation particles are used to represent different particle types (soot, droplets, ice crystals) and properties (mass/radius, number). The box model is applied in two frameworks. In the classical framework, we prescribe the dilution along one average trajectory in a single box model run. In the second framework, we perform a large ensemble of box model runs using 25 000 different trajectories inside an expanding exhaust jet as simulated by the LES (large-eddy simulation) model FLUDILES. In the ensemble runs, we see a strong radial dependence of the temperature and relative humidity evolution. Droplet formation on soot particles happens first near the plume edge and a few tenths of a second later in the plume centre. Averaging over the ensemble runs, the number of formed droplets and ice crystals increases more smoothly over time than for the single box model run with the average dilution. Consistent with previous studies, contrail ice crystal number varies strongly with atmospheric parameters like temperature and relative humidity near the contrail formation threshold. Close to this threshold, the apparent ice number emission index (product of freezing fraction and soot number emission index) strongly depends on the geometric-mean dry core radius and the hygroscopicity parameter of soot particles. The freezing fraction of soot particles slightly decreases with increasing soot particle number, particularly for higher soot number emissions. This weakens the increase of the apparent ice number emission index with rising soot number emission index. Comparison with box model results of a recent contrail formation study by Lewellen (2020) (using similar microphysics) shows a later onset of our contrail formation due to a weaker prescribed plume dilution. If we use the same dilution data, our evolution and Lewellen's evolution in contrail ice nucleation show an excellent agreement cross-verifying both microphysics implementations. This means that differences in contrail properties mainly result from different representations of the plume mixing and not from the microphysical modelling. Using an ensemble mean framework instead of a single trajectory does not necessarily lead to an improved scientific outcome. Contrail ice crystal numbers tend to be overestimated since the interaction between the different trajectories is not considered. The presented aerosol and microphysics scheme describing contrail formation is of intermediate complexity and thus suited to be incorporated in an LES model for 3D contrail formation studies explicitly simulating the jet expansion. Our box model results will help interpret the upcoming, more complex 3D results.

Hydraulicity of lime plasters from Teotihuacan, Mexico: a microchemical and microphysical approach

Hydraulicity is a well-known characteristic of mortars and plasters from the Roman, Late Roman, and Medieval periods, while the use of hydraulic mortars in pre-Columbian Mesoamerica and Central Mexico in particular, has not received equal attention. To address this issue, in this paper, we discuss the problem of hydraulicity and suggest a method to study it in Mesoamerican plasters. To prove the effectiveness of this method, we selected plaster samples from the archaeological site of Teotihuacan (Mexico), the main city of Central Mexico during the Classic period. The characterisation of plaster samples confirmed that, similar to other Teotihuacan plasters, they are made of two layers: the outermost layer (enlucido), composed of a mixture of lime and volcanic glass shards, and the underlying layer locally called firme, consisting of crushed volcanic scoria (tezontle) mixed with a mud-based binder. The compositional characterisation of the plasters confirmed their hydraulicity and the combination of microchemical (energy dispersive spectrometer (EDS) microchemical analysis), microphysical (Vickers microhardness), and petrographic (optical microscopy) measurements demonstrated that it was not the presence of glass shards in the external plaster layer which produced hydraulicity, as we originally thought. Instead, this was due to the reactivity of the tezontle, present in the lower layer.This suggests that the small thickness of the enlucido layer, in addition to save the amount of lime used, increased its performance, promoting chemical reactions with the tezontle in the contact layer and that the glass shards played another role in the mixture, rather than producing hydraulicity.

Rheological Transitions Facilitate Fault‐Spanning Ruptures on Seismically Active and Creeping Faults

AbstractPhysical constraints on the seismogenic potential of major fault zones may aid in improving seismic hazard assessments, but the mechanics of earthquake nucleation and rupture are obscured by the complexity that faults display. In this work, we investigate the mechanisms behind giant earthquakes by employing a microphysically based seismic cycle simulator. This microphysical approach is directly based on the mechanics of friction as inferred from laboratory tests and can explain a broad spectrum of fault slip behavior. We show that regular earthquakes are controlled by the size and distribution of (nominally) frictionally unstable asperities, whereas fault‐spanning earthquakes are governed by a rheological transition occurring in creeping fault segments. Moreover, this facilitates the nucleation of giant earthquakes on faults that are weakly seismically coupled (i.e., creeping). This microphysically based approach offers opportunities for investigating long‐term seismic cycle behavior of natural faults.

Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution

[1] In part I, the influence of cloud microphysics and dynamics on the shape of cloud radar Doppler spectra in warm stratiform clouds was discussed. The traditional analysis of radar Doppler moments was extended to include skewness and kurtosis as additional descriptors of the Doppler spectrum. Here, a short climatology of observed Doppler spectra moments as a function of the radar reflectivity at continental and maritime ARM sites is presented. The evolution of the Doppler spectra moments is consistent with the onset and growth of drizzle particles and can be used to assist modeling studies of drizzle onset and growth. Time-height radar observations are used to exhibit the coherency of the Doppler spectra shape parameters and demonstrate their potential to improve the interpretation and use of radar observations. In addition, a simplified microphysical approach to modeling the vertical evolution of the drizzle particle size distribution in warm stratiform clouds is described and used to analyze the observations. The formation rate of embryonic drizzle droplets due to the autoconversion process is not calculated explicitly; however, accretion and evaporation processes are explicitly modeled. The microphysical model is used as input to a radar Doppler spectrum forward model, and synthetic radar Doppler spectra moments are generated. Three areas of interest are studied in detail: early drizzle growth near the cloud top, growth by accretion of the well-developed drizzle, and drizzle depletion below the cloud base due to evaporation. The modeling results are in good agreement with the continental and maritime observations. This demonstrates that steady state one-dimensional explicit microphysical models coupled with a forward model and comprehensive radar Doppler spectra observations offer a powerful method to explore the vertical evolution of the drizzle particle size distribution.

Comparison of Modeled and Observed Accumulated Convective Precipitation in Mountainous and Flat Land Areas

Abstract Convective precipitation is the main cause of extreme rainfall events in small areas. Its primary characteristics are both large spatial and temporal variability. For this reason, the monitoring of accumulated precipitation fields (liquid and solid components) at the surface is difficult to carry out through the use of rain gauge networks or remote sensing observations. Alternatively, numerical models may be a useful tool to simulate convective precipitation for various analyses and predictions. This paper focuses on improving quantitative convective precipitation estimates that are obtained with a cloud-resolving model. This aim is attained by using the appropriate cloud drop size distribution and modified single sounding data. The authors perform comparisons between observations and three model samples of the areal-accumulated convective precipitation for a 15-yr period over mountainous and flat land areas with 45 and 29 convective events, respectively. They compare the results from a numerical cloud model that uses 2 different microphysical schemes—the unified Khrgian–Mazin size distribution of cloud drops—and an alternative scheme that is a combination of a monodispersed cloud droplet spectrum and the Marshall–Palmer size distribution for raindrops. The authors’ statistical analysis shows that the model version with the Khrgian–Mazin size distribution and the new initial conditions better simulates the observed areal-accumulated convective precipitation than the alternative microphysical approach for both study areas. The model simulations with the Khrgian–Mazin size distribution most closely match observations for the flat land area with a correlation coefficient of 0.94, while it is somewhat lower (0.89) for the mountainous area. Use of the alternative microphysical approach, on the other hand, underestimates the observed precipitation, and has the lowest correlation coefficient among the methods, 0.82 for the mountainous area and 0.85 for the flat land.

Lateral, radial, and temporal variations in upper mantle viscosity and rheology under Scandinavia

[1] The viscosity of the upper mantle has a large control on the dynamics of plate tectonic processes or the response of the Earth's crust after a period of glaciation. Temperature variations within the upper mantle, time-dependent stress changes due to glaciations, and/or variations in the microstructural characteristics of upper mantle rocks (grain size, water content) will result in orders of magnitude variations in upper mantle viscosity. In this study we have taken a microphysical approach to determine variations in viscosity under Scandinavia. We combined experimentally determined flow laws for olivine, data on olivine grain size from Scandinavian xenoliths and peridotites, and stress changes within the upper mantle over the last glaciation period (30 kyr B.P.–present) with two data sets of the temperature distribution within the upper mantle under Europe from Goes et al. (2000) derived from seismic tomography and Artemieva (2006) derived from heat flow measurements. Modeling of olivine viscosity under Scandinavia shows large lateral, radial, and temporal variations in upper mantle viscosity. Lateral temperature variations cause up to four orders of magnitude lateral viscosity variations. Glaciation-induced time-dependent changes of stress cause two orders of magnitude variations in viscosity. Mean viscosity values for a dry upper mantle under Scandinavia are expected to be larger than 1022 Pa s, whereas for a wet upper mantle lower viscosity values in the range of 1019–1022 Pa s are predicted. Estimates of the upper mantle viscosity under Scandinavia from glacial isostatic adjustment studies (1020–1021 Pa s) would indicate that a wet upper mantle below Scandinavia is most likely present. The viscosity modeling furthermore shows that the type of rheology of the upper mantle (linear versus nonlinear rheology) is very sensitive to the microstructural state of the upper mantle. Both mechanisms are active in the upper mantle under Scandinavia on timescales of glacial isostatic adjustment, and their relative contribution varies radially, laterally, and temporally.

Explanation of the patterns in Mie theory

The far-field scattered light intensity, or the related phase function, for a spherical particle is known to display an overall power-law structure when formulated in terms of the scattering wave vector. Empirically determined patterns in the intensity relating to the particle size and refractive index are known. The cause of the patterns, however, has not been satisfactorily explained. This work applies an exact microphysical model to explain most of the patterns, and specifically, to reveal the physical cause of crossovers from one power-law to another. A unique aspect of this microphysical approach is phasor analysis, which provides a visually based way to examine the angle-dependent wavelet superposition involved in the model. A simple color coding scheme connects the phasors to the interior of the particle, and it is this connection that reveals the meaning of the crossovers.

Multiple scattering by particles embedded in an absorbing medium. 2. Radiative transfer equation

This paper continues a systematic theoretical analysis of electromagnetic scattering by a group of arbitrarily sized, shaped, and oriented particles embedded in an absorbing, homogeneous, isotropic, and unbounded medium. The previously developed microphysical approach is used to derive the generalized form of the radiative transfer equation (RTE) applicable to a large group of sparsely, randomly, and uniformly distributed particles. The derivation of the RTE directly from the macroscopic Maxwell equations yields unambiguous and definitive analytical expressions for the participating quantities and thereby fully resolves the lasting controversy caused by the conflicting outcomes of several phenomenological approaches.

Multiple scattering, radiative transfer, and weak localization in discrete random media: Unified microphysical approach

The radiative transfer theory has been extensively used in geophysics, remote sensing, and astrophysics for more than a century, but its physical basis had remained uncertain until quite recently. This ambiguous situation has finally changed, and the theory of radiative transfer in random particulate media has become a legitimate branch of Maxwell's electromagnetics. This tutorial review is intended to provide an accessible outline of recent basic developments. It discusses elastic electromagnetic scattering by random many‐particle groups and summarizes the unified microphysical approach to radiative transfer and the effect of weak localization of electromagnetic waves (otherwise known as coherent backscattering). It explains the exact meaning of such fundamental concepts as single and multiple scattering, demonstrates how the theories of radiative transfer and weak localization originate in the Maxwell equations, and exposes and corrects certain misconceptions of the traditional phenomenological approach to radiative transfer. It also discusses the challenges facing the theories of multiple scattering, radiative transfer, and weak localization in the context of geophysical applications.

Reflection symmetry of a sphere's internal field and its consequences on scattering: a microphysical approach

We examine the reflection symmetries of the electromagnetic wave inside of a uniform spherical particle and identify the consequences of the symmetries for the Stokes parameters describing the polarization state of the far-field scattered wave. The connection between the two waves is described from a microphysical perspective that illustrates the wavelet-superposition origin of the scattered wave. In contrast to more conventional approaches, this microphysical perspective yields new insight into the physical character of the scattering of a plane wave by a sphere. The results of simulations are presented, which graphically demonstrate the relation between the symmetries present in the internal wave and the polarization state of the scattered wave.

Radiative transfer in clouds with small‐scale inhomogeneities: Microphysical approach

Several recent publications have indicated that cloud droplets belonging to a particular size range may tend to cluster by forming small random particle groups imbedded in an otherwise uniform cloud. To analyze radiative transfer in clouds with such small‐scale inhomogeneities, we invoke the concepts of statistical electromagnetics. We show that as long as the assumptions of ergodicity and spatial uniformity hold, one can still apply the classical radiative transfer equation in which the participating extinction and phase matrices are obtained by averaging the respective single‐particle matrices over all the particles constituting the cloud. This result implies that comparisons of in situ and remote‐sensing retrievals of the cloud‐particle size distribution can be problematic and should be performed with caution.

Maxwell's equations, radiative transfer, and coherent backscattering: A general perspective

This tutorial paper provides a general overview of the hierarchy of problems involving electromagnetic scattering by particles and clarifies the place of the radiative transfer theory and the theory of coherent backscattering in the context of classical electromagnetics. The self-consistent microphysical approach to radiative transfer is compared with the traditional phenomenological treatment.

Multiple scattering of light by densely packed random media of spherical particles: Dense media vector radiative transfer equation

The theory of light scattering by systems of spherical particles is applied to study the light scattering by discrete random media. A microphysical approach of statistical electromagnetics is used to derive the vector radiative transfer equation for semi-infinite densely packed media composed of identical spherical particles. The equation obtained corresponds to the sum of the ladder diagrams in the diagrammatic representation of the Bethe–Salpeter equation. The new vector radiative transfer equation is compared with that for sparse media. The effective refractive index as it enters in our equation is calculated from the known generalization of the Lorentz–Lorenz equation. Some numerical results of calculations of the reflection matrix are presented and compared with those for sparse media. The differences between the theoretical description of light scattering by closely packed and sparse media are discussed in detail.

The aerosol-climate model ECHAM5-HAM

Abstract. The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SU: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced.

Microphysical approach to polarized radiative transfer: extension to the case of an external observation point.

The self-consistent microphysical approach applied recently to the transfer of polarized radiation inside a volume of anisotropic discrete random medium is extended to the case of an external observation point. Specifically, it is demonstrated that the solution of the vector radiative transfer equation yields all quantities necessary to calculate the response of an external collimated detector of polarized radiation as a function of the detector orientation and position relative to the scattering volume.

Notes on the state-of-the-art numerical modeling of cloud microphysics

Despite significant advances in cloud physics, many problems exist in the state-of-the-art microphysical cloud modeling. The progress is hampered by (1) many remaining gaps and uncertainties in our knowledge of cloud microphysics and (2) limitations of numerical approaches in representing some of known microphysical processes. In this paper, we attempt to give an assessment of several important problems of warm and ice microphysics and model limitations and identify areas where improvements are most urgently needed. Because of the complexity and broadness of the subject, the review does not offer an exhausted analysis of the field or provide solutions for all discussed problems. We are concerned with the spectral (bin) microphysical approach, which does not restrict the particle size spectra to any particular shape and, therefore, claims to reproduce formation of size spectra of cloud particles.

Microphysical approach to nonequilibrium dynamics of quantum fields.

We examine the nonequilibrium dynamics of a self-interacting $\lambda\phi^4$ scalar field theory. Using a real time formulation of finite temperature field theory we derive, up to two loops and $O(\lambda^2)$, the effective equation of motion describing the approach to equilibrium. We present a detailed analysis of the approximations used in order to obtain a Langevin-like equation of motion, in which the noise and dissipation terms associated with quantum fluctuations obey a fluctuation-dissipation relation. We show that, in general, the noise is colored (time-dependent) and multiplicative (couples nonlinearly to the field), even though it is still Gaussian distributed. The noise becomes white in the infinite temperature limit. We also address the effect of couplings to other fields, which we assume play the r\^ole of the thermal bath, in the effective equation of motion for $\phi$. In particular, we obtain the fluctuation and noise terms due to a quadratic coupling to another scalar field.