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In this paper, we study the accretion process of a charged black hole in the background of cloud of strings in the framework of 4D Einstein–Gauss–Bonnet (EGB) gravity theory. Firstly, the steady spherical accretion process of ideal fluid on 4D cloud of strings EGB black hole is studied from the aspects of the radial velocity, the energy density, the mass accretion rate and the sound speed. Then, the general analytical expressions of the accretion process are determined, and the effects of the black hole parameters on the radial velocity, the energy density, the mass accretion rate and the sound velocity are discussed. When the GB coupling constant increases, the energy density and mass accretion rate increase, and the sound velocity and radial speed decrease. EGB gravity and charge have similar physical effects on the accretion process of black hole. [ABSTRACT FROM AUTHOR]

Shallow convective systems occasionally cause heavy precipitation through active warm-rain processes, although the mechanism is not well understood. In this study, a shallow line-shaped precipitation (SLSP) system, which produced heavy rainfall in the Kanto Region, Japan, was investigated using Ka-band and X-band radars, in addition to a numerical weather prediction model. The SLSP system exhibited features similar to squall lines (SLs), such as rapid movement perpendicular to the line, but the echo-top height remained below the 0 °C level, despite the rainfall intensity reaching approximately 78 mm h−1. Therefore, the SLSP system was considered to be dominated by a shallow convective system that contained cloud droplets, raindrops and drizzle rather than a deep convective system that included ice particles. The Ka-band radar observed a low-level cloud deck spreading to the front side of the convective system, and low-level cloud subsequently entered the SLSP system. In addition, large amounts of water vapor were transported by a super typhoon came from the southwest of the Kanto Region. Cloud water supplied from the cloud deck and that condensed from the water vapor supplied by the typhoon were considered to play an important role in the heavy precipitation associated with the SLSP system through the accretion of raindrops. This study provides insights into the microphysical structure of SLSP systems as well as the precipitation processes. • A shallow line-shaped precipitation system was observed by cloud radar. • Abundant water vapor and low-level stratocumulus clouds were transported by typhoon. • Active accretion process was responsible for driving production of heavy rainfall. [ABSTRACT FROM AUTHOR]

Abstract This study extended a method to evaluate rain microphysics in a shallow cumulus regime using space‐borne radar observational data with a forward simulator of satellite measurements. We compared a two‐moment bulk scheme with a two‐moment bin scheme. A dynamic‐kinematic model was used to isolate cloud microphysics processes from their interactions with dynamics. The relationship between horizontally averaged reflectivity Zm and optical depth from the cloud top τd, that is, the Zm‐τd relationship, was similar between the bulk and the bin schemes for clouds with large updraft velocity and clean cloud condensation nuclei (CCN). However, the differences in the Zm‐τd relationship between the two schemes became more apparent for clouds with smaller updraft velocity or polluted CCN. For these clouds, the differences resulted from differences in the autoconversion rate. We increased the autoconversion rate by decreasing the shape parameter of the cloud droplet size distribution in the bulk scheme. This reduced the differences in the Zm‐τd relationship between the two schemes, indicating that for these clouds, the autoconversion rate of a cloud microphysics scheme can be evaluated by the Zm‐τd relationship derived from satellite observations. Although the clouds with the smaller updraft velocity or the polluted CCN did not contribute to the rainfall amount significantly, the lifetime of these clouds greatly affected the radiation budget. Thus, the improvement in the autoconversion rate for such weak cumulus clouds provides a better representation of precipitation efficiency and is important for global climate evaluations.

This study extended a method to evaluate rain microphysics in a shallow cumulus regime using space‐borne radar observational data with a forward simulator of satellite measurements. We compared a two‐moment bulk scheme with a two‐moment bin scheme. A dynamic‐kinematic model was used to isolate cloud microphysics processes from their interactions with dynamics. The relationship between horizontally averaged reflectivity Zm and optical depth from the cloud top τd, that is, the Zm‐τd relationship, was similar between the bulk and the bin schemes for clouds with large updraft velocity and clean cloud condensation nuclei (CCN). However, the differences in the Zm‐τd relationship between the two schemes became more apparent for clouds with smaller updraft velocity or polluted CCN. For these clouds, the differences resulted from differences in the autoconversion rate. We increased the autoconversion rate by decreasing the shape parameter of the cloud droplet size distribution in the bulk scheme. This reduced the differences in the Zm‐τd relationship between the two schemes, indicating that for these clouds, the autoconversion rate of a cloud microphysics scheme can be evaluated by the Zm‐τd relationship derived from satellite observations. Although the clouds with the smaller updraft velocity or the polluted CCN did not contribute to the rainfall amount significantly, the lifetime of these clouds greatly affected the radiation budget. Thus, the improvement in the autoconversion rate for such weak cumulus clouds provides a better representation of precipitation efficiency and is important for global climate evaluations. Plain language summary: We investigated how space‐borne radar observations can improve the bulk cloud microphysics schemes used in regional and global numerical models. We conducted numerical experiments using the bulk and bin schemes. The results allowed us to calculate the radar reflectivity and optical thickness of clouds using a forward simulator of satellite measurements. The two schemes were compared, and we tested the sensitivity of the radar reflectivity and optical thickness of clouds to parameters in the bulk scheme. We found that the parameters in the bulk scheme could be constrained by space‐borne radar observations, provided that the observed data are classified by specific atmospheric conditions, such as cloud condensation nuclei, updraft velocity in clouds, and others. Key Points: Bulk and bin cloud microphysics schemes are compared using forward simulators of satellite sensorsThe parameters used in the bulk microphysics scheme can be constrained by observed data from satellite measurementsBulk schemes using a shape a parameter of cloud droplet size distribution near the cloud base can estimate rainfall amounts well [ABSTRACT FROM AUTHOR]

In this paper, we study the black hole spacetime structure of a model consisting of the standard Maxwell theory and a p -power-Yang–Mills term. This non-linear contribution introduces a non-Abelian charge into the global solution, resulting in a modified structure of the standard Reissner–Nordström black hole. Specifically, we focus on the model with p = 1 / 2 , which gives rise to a new type of modified Reissner–Nordström black hole. For this class of black holes, we compute the event horizon, the innermost stable circular orbit, and the conditions to preserve the weak cosmic censorship conjecture. The latter condition sets a well-established relation between the electric and the Yang–Mills charges. As a first astrophysical implication, the accretion properties of spherical steady flows around this new modified Reissner–Nordström black hole are investigated in detail. Concretely, we compute the critical radius that establishes the condition for having stable transonic flow in terms of the local sound speed and the involved charges. Extensive numerical examples of how the Yang–Mills charge affects the accretion process of an isothermal fluid in comparison to the standard Reissner–Nordström and Schwarzschild black holes are displayed. Finally, analytical solutions in the fully relativistic regime, along with numerical computations, of the mass accretion rate for a polytropic fluid in terms of the electric and Yang–Mills charges are obtained. As a main result, the mass accretion rate efficiency is considerably improved, with respect to the standard Reissner–Nordström and Schwarzschild solutions, for negative values of the Yang–Mills charge. • Exact black hole solutions in four dimensions with Abelian and Non-Abelian Charges. • The accretion properties of spherical steady flows around this new modified black hole. • Analytical solutions in the fully relativistic regime, along with numerical computations, of the mass accretion rate for a polytropic fluid in terms of the electric and Yang–Mills charges. [ABSTRACT FROM AUTHOR]

We report new field observations, zircon U-Pb ages and geochemical data for the discrete members of the Zhaheba ophiolite complex in northeastern Junggar of the Central Asian Orogenic Belt (CAOB) with the aim to understand the accretion process of the eastern Junggar terrane. The zircon age data reveal that the cumulates of the Zhaheba ophiolite crystallized at ~485 Ma while the volcanic sequences erupted at ~400 Ma. Thus, the volcanic sequences are not members of the Zhaheba ophiolite. Chromian spinels from the serpentinite have comparable elemental compositions to those of spinels from MORB-type ophiolites. Similarly, the rift affinity of clinopyroxene and positive zircon εHf(t) (13-20) and mantle δ18O (+5.37‰) values of the cumulates imply that the cumulates crystallized from primitive magmas derived from a depleted mantle source. Elemental and Nd isotopic compositions indicate that the basalts in the Zhaheba area were derived from partial melting of a mantle wedge metasomatized by adakitic melts and/or subduction-related fluids. The data presented in this contribution, together with previous studies, indicate that the Zhaheba-Almantai and Kelameili ophiolites were MORB-type, which implies that there were at least two mid-ocean ridges during Ordovician to early Devonian times in the Junggar Ocean. In the earlier stage, intra-oceanic subduction led to the formation of the intra-oceanic arc, and then the Kelameili ophiolite accreted to an intra-oceanic accretionary wedge. In the later stage, the Zhaheba-Almantai ophiolite accreted to the accretionary wedge along the southern margin of the Iritish suture zone during the roll-back of the subduction zone from north to south. [ABSTRACT FROM AUTHOR]

We attempt to apply the Eulerian approach to simulation of ice adhesion on structures and to investigate macroscopic models for ice accretion processes. The methodology of the Eulerian approach in icing simula-tion is summarized and two technical difficulties are pointed out: the accuracy deterioration in representing the shape of accreted ice, and the stiffness of unsteady simulations. A method of adequately generating grid points overcomes the former difficulty while the latter remains an unsolved problem. Some computational examples obtained with the Eulerian simulation are presented. In the present simulations, we consider the hard rime accretion, i.e., an ice deposit formed from the impingement of super-cooled water droplets, and thus it can clarify the meanings of the macroscopic models for the local impingement efficiency and the growing direction of ice. The shapes of accreted hard rime on a stationary airfoil and the accretion rates are simulated, and they are compared with experimental results. The computational results show the im-portance of the velocity component of uniform flow direction in the incoming droplet velocity. Also, the local impingement efficiency along a cylinder oscillating perpendicular to a uniform air flow is obtained. The present simulations demonstrate the potential of the Eulerian approach in the prediction of ice adhesion phenomena. [ABSTRACT FROM AUTHOR]

We consider the stationary spherical accretion process of perfect fluids onto a class of spherically symmetric regular black holes corresponding to quantum-corrected Schwarzschild spacetimes. We show that the accretion rates can differ from the Schwarzschild case, suggesting that the de Sitter core inside these regular black holes, which indeed precludes the central singularity, can act for some cases as a sort of antigravitational source, decreasing the fluid's radial infall velocity in the accretion process, and for others as a gravitational enhancer, increasing the fluid flow into the black hole horizon. Our analysis and results can be extended and also applied to the problem of black hole evaporation in cosmological scenarios with phantom fluids. In particular, we show that the mass of typical regular black holes can be used in order to constrain turnaround events in cyclic cosmologies. • Accretion process onto regular black holes differs from singular black holes. • The interior region of a regular black hole modifies the accretion process. • Accretion process of an exotic matter may decrease mass even of a regular black hole. • Black hole mass decreasing phenomenon is an interesting issue in cyclic cosmologies. [ABSTRACT FROM AUTHOR]