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This study utilizes data from 1979 to 2023 and employs a 1-year sliding window approach to construct networks for each 10-year period, analyzing the synchronization patterns of extreme rainfall events in Southwest China. The average weighted degree of these networks is defined as a synchronization index, which quantifies the synchronization between rainfall events across the region. The results reveal a significant upward trend in the synchronization index, indicating that extreme rainfall events occurring simultaneously in Southwest China are steadily increasing. Furthermore, through partial correlation, contribution rate, and composite analyses, the study demonstrates that the Indian Ocean Warm Pool Strength Index (IOWPSI) independently influences the synchronization patterns of extreme rainfall events in Southwest China. In contrast, the Western Pacific Warm Pool Strength Index (WPWPSI) exerts a comparatively weaker independent effect on synchronization in this region. However, the interaction between the IOWPSI and the WPWPSI modulates the Western Pacific Subtropical High, thereby enhancing its influence on the synchronization of extreme rainfall events in Southwest China. [ABSTRACT FROM AUTHOR]

The Southwest Vortex (SWV) is a mesoscale closed low-pressure system in Southwest China that significantly influences regional heavy rainfall. Understanding SWV characteristics and formation mechanisms is crucial for research in this field, with effective identification as the foundation. Currently, Chinese researchers lack a unified standard for SWV identification. Despite the availability of high spatiotemporal resolution reanalysis data, which provides a superior foundation for studying SWVs, existing methods struggle to fully exploit these datasets. Therefore, this study proposes PVSIA (Geopotential-Height-Field and Vector-Wind-Field based SWV Identification Algorithm), a method that integrates the geopotential height field and wind field characteristics. The PVSIA employs an innovative calculation method for wind vector rotation properties, enhancing identification speed and overcoming challenges posed by complex terrain. Furthermore, this study utilizes the ERA5 reanalysis dataset from 2019 to 2021 to systematically compare the performance of the PVSIA method with traditional geopotential height field methods in identifying SWVs, employing key evaluation metrics such as hit ratio, false alarm rate, and missing report rate. During this period, the PVSIA method achieved a hit rate of 94.25% in identifying SWVs, with a false alarm rate of 5.20% and a missing report rate of 5.74%. In contrast, the geopotential height field method, while achieving a higher hit rate of 98.85%, exhibited a significantly higher false alarm rate of 70.54%. In contrast, the PVSIA method maintains a high hit rate while significantly reducing the false alarm rate, demonstrating a more stable and reliable identification performance. [ABSTRACT FROM AUTHOR]

The Songshugang deposit is a large Ta–Nb deposit in South China, with Ta–Nb mineralization associated genetically with the granite and pegmatite. A diversity of quartz from topaz–albite granite, quartz–mica pegmatite, quartz–feldspar pegmatite, and quartz–fluorite pegmatite at Songshugang was studied by CL and LA–ICP–MS in order to constrain enrichment mechanisms of Nb and Ta and to find geochemical indicators of quartz for rare metal deposits. Cathodoluminescence image illuminates a canvas of complexity, the quartz from topaz–albite granite, quartz–mica pegmatite, quartz–feldspar pegmatite, and quartz–fluorite pegmatite, exhibits numerous dark CL streaks, patches, and a series of healed fractures. These textures suggest that the rocks were fractured because of deep crustal pressure, and underwent later hydrothermal metasomatism and quartz filling. The quartz from quartz–fluorite pegmatite present limited patches or fractures but distinct growth bands, indicating that the melt fluid composition during the formation of quartz at this stage varies greatly and is less affected by mechanical fragmentation. The LA–ICP–MS analysis of quartz shows that there is a positive correlation between Al and Li in the quartz from topaz–albite granite, quartz–mica pegmatite, quartz–feldspar pegmatite, to quartz–fluorite pegmatite, indicating that Al mainly enters the quartz lattice through charge compensation substitution mechanism with Li. However, our data deviate from the theoretical Li:Al mass ratio of ~ 1:3.89 in quartz, indicating that there may be competition between H+ and Li in a water-rich magmatic environment. The quartz from topaz–albite granite is enriched in K and Na elements, and the quartz from quartz–fluorite pegmatite is enriched in fluorite with a low Ca content in quartz, further elucidating that these rocks were subjected to hydrothermal metasomatism. From topaz–albitite granite to quartz–fluorite pegmatite, Al, Li and Ge content and Al/Ti, Ge/Ti, Sb/Ti ratios in quartz gradually increased, but Ti content gradually decreased, reflecting the high evolution of magma, which can enrich rare metal elements. Based on the characteristics of quartz CL textures and trace elements in topaz–albite granite, quartz–mica pegmatite, quartz–feldspar pegmatite, and quartz–fluorite pegmatite, combined with the albitization and K-feldspathization of rocks, it is suggested that the Nb–Ta mineralization in Songshugang may be influenced by the combined action of magmatic crystallization differentiation and fluid metasomatism. By comparing the quartz in the Songshugang pluton with the quartz in the granite type and pegmatite type rare metal deposits recognized in the world, the Songshugang pegmatite share similarities with the LCT-type pegmatite. Combined with previous studies, the Ge/Ti > 0.1 and Ti < 10 ppm, as well as Al, Li, Ge, Sb, K, Na contents and Al/Ti, Sb/Ti ratios in quartz have the potential to be a powerful exploration marker for identifying granite-like pegmatitic Nb–Ta deposits in other places. [ABSTRACT FROM AUTHOR]

Mitigation surface ozone pollution becomes increasingly pivotal in improving China's air quality. However, the impact of global sea surface temperature anomalies (SSTA) on the long-term predictability of China's surface ozone remains challenging. In this study, we employ eigen techniques to effectively characterize dominant surface ozone patterns over China, and establish cross-correlations between the dominant patterns and global SSTA time series. Our findings reveal that China's summer ozone pollution is strongly associated with crucial SSTA clusters linked to atmospheric circulations, i.e., the West Pacific Subtropical High and the Pacific-North American teleconnection pattern. For winter, ozone pollution is attributed to SSTA clusters related to the Southern Oscillation, the Madden-Julian Oscillation and others. We propose a multivariate regression model capable of predicting surface ozone patterns with a lead time of at least 3 months. Evaluation of our model using a testing dataset yields an R-value of around 0.5 between predicted and observed data, surpassing statistical significance threshold. This suggests the viability and potential applicability of our predictive model in surface ozone forecasting and mitigation strategies in China. [ABSTRACT FROM AUTHOR]

Herein, percolation phase transitions on a two-dimensional lattice were studied using machine learning techniques. Results reveal that different phase transitions belonging to the same universality class can be identified using the same neural networks (NNs), whereas phase transitions of different universality classes require different NNs. Based on this finding, we proposed the universality class of machine learning for critical phenomena. Furthermore, we investigated and discussed the NNs of different universality classes. Our research contributes to machine learning by relating the NNs with the universality class. [ABSTRACT FROM AUTHOR]

Southwest China (SWC) is located in the transition zone affected by the East Asia summer monsoons, India monsoon, and the Tibetan Plateau thermal activity. SWC is also an important hub for water vapor transport in the Asia–Pacific (AP) region. Here we study the dynamical and spatiotemporal characteristics of extreme rainfall events in AP by a synchronization network approach, providing insights for understanding of the relevant synchronization mechanisms of extreme rainfall between the SWC and AP. It is found that the probability of significant synchronization rainfall events between SWC and AP as a function of distance changes from a power-law decay behavior to a teleconnection one at around 2000 km. Specifically, the SWC—the middle and lower reaches of the Yangtze River—Japan band (SYJ) is an important teleconnection pattern of extreme rainfall in AP region. This SYJ teleconnection pattern is associated with the water vapor flux convergence along the main water vapor transport route from the low latitude ocean. Moreover, we find that the inter-annual variation of the SYJ teleconnections index can reflect the evolution of synchronization rainfall features from SWC to Japan, which could be useful for operational climate monitoring and prediction. It is also found that the SYJ index is strongly correlated with the sea surface temperature anomalies (SSTA) over the North Indian Ocean and the Western Pacific. The warm Indian Ocean and Western Pacific SST can motivate the transfer of water vapor from SWC to Japan, yielding the synchronization of extreme rainfall along the SYJ band. [ABSTRACT FROM AUTHOR]

The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China. The mineralization shows common characteristics in their tectonic setting, ore-forming fluid and metallogenic system. Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation, both of which consume sulfur in the ore-forming fluids. The escape of H2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold, but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite. Quartz solubility shows strong dependence on temperature, pressure, and CO2 content. The dependence of quartz solubility on pressure is weak at low temperatures, and progressively stronger at higher temperatures. Similarly, the temperature dependence of quartz solubility is relatively low at low pressures, but becomes gradually stronger at high pressures. The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the ore-forming veins and the formation mechanism of different types of quartz veins. The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins. Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale. The trace elements (mainly the coupling of As- and Au-rich belt) and sulfur isotope composition also display a certain regularity. The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata, while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids. There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits. Water/rock reaction (sulfidation) was the main ore-forming mechanism of early gold mineralization, forming relatively high fineness gold, while significant pressure drop in the shallow part accompanied by fluid phase separation promoted the late gold mineralization, forming low fineness gold. Under cratonic destruction setting, dehydration of the amphibolite and granulite facies metamorphic lower-crust resulted in the formation of Au-CO2-rich ore-forming fluids, which rose along the deep fault and secondary structure, and formed the largescale fault-controlled gold deposits in Jiaodong. [ABSTRACT FROM AUTHOR]

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In a hopper with cylindrical symmetry and an aperture of radius R, the vertical velocity of granular flow vz depends on the distance from the hopper's center r and the height above the aperture z and vz=vz(r,z;R). We propose that the scaled vertical velocity vz(r,z;R)/vz(0,0;R) is a function of scaled variables r/Rr and z/Rz, where Rr=R-0.5d and Rz=R-k2d with the granule diameter d and a parameter k2 to be determined. After scaled by vz2(0,0;R)/Rz, the effective acceleration aeff(r,z;R) derived from vz is a function of r/Rr and z/Rz also. The boundary condition aeff(0,0;R)=-g of granular flows under earth gravity g gives rise to vz(0,0;R)∝gR-k2d1/2. Our simulations using the discrete element method and GPU program in the three-dimensional and the two-dimensional hoppers confirm the size scaling relations of vz(r,z;R) and vz(0,0;R). From the size scaling relations, we obtain the mass flow rate of D-dimensional hopper W∝g(R-0.5d)D-1(R-k2d)1/2, which agrees with the Beverloo law at R≫d. It is the size scaling of vertical velocity field that results in the dimensional R-dependence of W in the Beverloo law. [ABSTRACT FROM AUTHOR]