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Abstract Coral reconstruction often serves as a major proxy of high-resolution sea surface temperature (SST) variability beyond the instrumental era. However, coral reconstructions are sparse and are usually studied for interannual variability, with few studies on the monthly features. In this study, we reconstruct the monthly SST spatial field by applying the paleoclimate data assimilation method to the coral records of the latest CoralHydro2k data set for the instrument period of 1880–2000. A comparison with observed SST variability shows that our assimilated tropical SST variability performs reasonably well for the seasonal cycle and monthly ENSO characteristics, notably the phase-locking and onset timing, and more realistic spatial fields relative to the model simulations. This study suggests the feasibility of applying paleoclimate data assimilation to reconstruct the monthly SST in the historical period.

Abstract Large-scale stretchable strain sensor arrays capable of mapping two-dimensional strain distributions have gained interest for applications as wearable devices and relating to the Internet of Things. However, existing strain sensor arrays are usually unable to achieve accurate directional recognition and experience a trade-off between high sensing resolution and large area detection. Here, based on classical Mie resonance, we report a flexible meta-sensor array that can detect the in-plane direction and magnitude of preloaded strains by referencing a dynamically transmitted terahertz (THz) signal. By building a one-to-one correspondence between the intrinsic electrical/magnetic dipole resonance frequency and the horizontal/perpendicular tension level, arbitrary strain information across the meta-sensor array is accurately detected and quantified using a THz scanning setup. Particularly, with a simple preparation process of micro template-assisted assembly, this meta-sensor array offers ultrahigh sensor density (~11.1 cm−2) and has been seamlessly extended to a record-breaking size (110 × 130 mm2), demonstrating its promise in real-life applications.

Abstract This thesis proposes a charging equalizer for hybrid energy storage systems, incorporating the Zeta converter, voltage multiplier, and multi‐winding transformer. The objective is efficient charging and equalization for battery and supercapacitor strings. The Zeta converter serves to charge the battery string, while the transformer with multi‐winding shares the inductor of Zeta converter as the primary side, facilitating battery string balancing through the utilization of current ripple in the inductor. Additionally, the voltage ripple generated by the Zeta converter is utilized to drive the voltage multiplier, enabling the charging and equalization of the supercapacitor string. The system's operation halts upon reaching the predefined threshold voltage for the supercapacitor strings. The proposed circuit transforms into a Zeta converter by employing a single‐pole double‐throw switch, facilitating the charging of the battery strings. Experimental validation uses four series‐connected supercapacitors and four series‐connected batteries, demonstrating successful equalization and charging for both energy storage components.

Pyramidal dislocations in magnesium (Mg) and other hexagonal close-packed metals play an important role in accommodating plastic strains along the c-axis. Bulk single crystal Mg only presents very limited plasticity in c-axis compression, and this behavior was attributed to out-of-plane dissociation of pyramidal dislocations onto the basal plane and resulted in an immobile dislocation configuration. In contrast, other simulations and experiments reported in-plane dissociation of pyramidal dislocations on their slip planes. Thus, the core structure and mode of dissociation of pyramidal dislocations are still not well understood. To better understand the dissociation behavior of pyramidal dislocations in Mg at room temperature, in this work, atomistic simulations were conducted to investigate four types of pyramidal dislocations at 300 K: edge and screw Py-I on {101¯1}, edge and screw Py-II on {112¯2} by using a modified embedded atom method (MEAM) potential for Mg and anisotropic elasticity dislocation model. The results show that when energy minimization was performed before relaxation, in-plane dissociation of edge dislocations on respective pyramidal plane could be obtained at room temperature for all four types of dislocation. Without energy minimization, the edge dislocations dissociated out-of-plane onto the basal plane. Calculations of potential energy and hydrostatic stress of individual atoms at the edge dislocation core show that the extraordinarily high energy and atomic stresses in the as-constructed dislocation structures caused the out-of-plane dissociation onto the basal plane. The core structures of all four types of pyramidal dislocation after in-plane dissociation were analyzed by computing the distribution of the Burgers vector.

BackgroundObservational studies have reported a possible association between metabolic syndrome (MetS) and thyroid autoimmunity. Nevertheless, the relationship between thyroid autoimmunity and MetS remains unclear. The objective of this research was to assess the causal impact of MetS on thyroid autoimmunity through the utilization of Mendelian randomization (MR) methodology.MethodsWe performed bidirectional MR to elucidate the causal relationship between MetS and their components and thyroid autoimmunity (positivity of TPOAb). Single nucleotide polymorphisms (SNPs) of MetS and its components were obtained from the publicly available genetic variation summary database. The Thyroidomics Consortium conducted a genome-wide association analysis, which provided summary-level data pertaining to thyroid autoimmunity. The study included several statistical methods, including the inverse variance weighting method (IVW), weighted median, simple mode, weight mode, and MR-Egger methods, to assess the causal link. In addition, to ensure the stability of the results, a sensitivity analysis was conducted.ResultsIVW showed that MetS reduced the risk of developing thyroid autoimmunity (OR = 0.717, 95% CI = 0.584 - 0.88, P = 1.48E−03). The investigation into the causative association between components of MetS and thyroid autoimmune revealed a statistically significant link between triglycerides levels and the presence of thyroid autoimmunity (IVW analysis, OR = 0.603, 95%CI = 0.45 -0.807, P = 6.82E−04). The reverse analysis did not reveal any causal relationship between thyroid autoimmunity and MetS, including its five components.ConclusionsWe have presented new genetic evidence demonstrating that MetS and its triglyceride components may serve as potential protective factors against thyroid autoimmunity.

Information technology is one of effective means to promote school health implementation. However, the existing school health information systems are fragmented, isolated, and lack of integration and suffer from serious information barrier. Additionally, some of the existing systems have incomplete functions, low level of intelligence, and slow update and iteration, witch seriously restricting the development of school health informatization. To break through the information barrier and promote the development of school health informationization, as well as to provide scientific means to improve the level of school health management and student health, it is imperative to build a smart and integrated school health management system platform. In this article, we briefly presented construction goal, technical framework, application, and utilization effects of the Shenzhen Intelligent Campus School Health Management System.

AbstractPurpose To explore the transformational leadership competency of graduates from one medical university in China and its influencing variables.Method From 2020 to 2021, 851 medical graduates from seven hospitals affiliated with the Capital Medical University participated in this survey. The authors conducted a cross-sectional study to assess transformational leadership competency, particularly from three aspects, including values, Emotional Intelligence (EI) abilities, and behaviors using the socially responsible leadership scale (SRLS), emotionally intelligent leadership, and student leadership practices inventory (EILI and SLPI).Results The SRLS scores were medium except for ‘controversy with civility’. The EILI scores were medium. The SLPI scores were high except for ‘enable others to act’ and ‘encourage the heart’. The influencing variables of SRLS, EILI, and SLPI were serving as student cadres, serving longer than two semesters (p = 0.01, 0.02 in EILI and SLPI), joining student organizations, participating in social practice, voluntary service (p = 0.001 in SLPI), in training classes for student cadres (p = 0.02, 0.01, 0.02 in SRLS, EILI, and SLPI), and attending lectures on leadership (except for indicated, p

BackgroundImmune-mediated liver injury caused by checkpoint inhibitors (ILICI) is a challenging clinical management issue. Although immunosuppressants are widely used to manage ILICI, no large-scale studies have proved definitive evidence for the most effective form of patient management.AimAnalysis of the effectiveness of immunosuppression for immune-related liver injury.MethodsWe performed a systematic review and meta-analysis of the clinical outcomes of immunosuppressive treatment of ILICI patients. A literature search of PubMed, Ovid, and Cochrane Library was completed for dates from 2000 to January 1, 2022. The primary outcome was the response rate to immunosuppressive therapy for ILICI, with subgroup analysis based on the type of cancer, immune checkpoint inhibitor regimen, and severity of liver injury. The secondary outcome was the median time to recovery from ILICI with immunosuppressive therapy.ResultsA total of 30 studies that included 1120 patients were collected. The pooled ILICI response rate was 79% (95% CI 0.73-0.84) for treatment with corticosteroids and 93% (95% CI 0.79-1.0) for treatment with mycophenolate mofetil. For ILICI treated with corticosteroids, the median recovery time was 47.59 (95% CI 39.79-55.40) days compared to 37.74 (95% CI 31.12-44.35) days for all forms of immunosuppression.ConclusionFindings support the effectiveness of corticosteroids and mycophenolate mofetil for the treatment of ILICI. The identified median time to recovery is a beneficial guide for patients and physicians, allowing for realistic expectations and appropriate treatment management. Future prospective randomized controlled trials are required to define a standardized management approach to immunosuppressive therapy of ILICI.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022313454.

Airborne tactical networks (ATNs) are driving the promising development of Internet of battle Things (IoBT) by enabling efficient information sharing, which is impeded by the network ossification problem due to the tightly coupled network architecture. As a solution, network virtualization (NV) can solve the ossification problem by breaking the tight coupling between applications and network infrastructure for ATNs. With complex interference and malicious attacks, the application of NV is challenged by network failures when instantiating virtual networks on a shared substrate network, which is known as survivable virtual network embedding (SVNE). However, existing SVNE algorithms, mostly designed for wired networks, are not necessarily optimal for the virtualization of ATNs due to the complex wireless interference. To this end, a fault-tolerant SVNE algorithm, termed SVNE-FT, is proposed to recover virtual networks from single node failure (end or switching node failure) under the complex wireless interference. To end node failure, SVNE-FT adopts a novel node ranking approach to select reliable substrate nodes for virtual nodes and remaps the failed virtual nodes by releasing part of the substrate paths to improve the resource utilization. In addition, to switching node failure, it adopts the improved pre-configured cycle (p-Cycle) technology to augment the reliable link mapping with differentiated p-Cycles that protect switching node and reduce the resource consumption of backups. Numerical simulation results reveal that SVNE-FT outperforms typical and latest heuristic SVNE algorithms under the complex interference of ATNs. For instance, average acceptance ratio of virtual networks improves at least 12%.

BackgroundIn the 21st century, the prevalence of tinnitus is increasing, impacting approximately one in five people. It is a very complicated condition that significantly affects quality of life. Despite the availability of hundreds of tinnitus treatment options, none are very successful. In light of this, there has been a steady increase in studies on tinnitus treatments in the recent past. To comprehend them better, this study used bibliometric approaches to analyze and summarize 21st century scientific research accomplishments in tinnitus treatment.MethodsThe Web of Science Core Collection (WoSCC) was searched for papers that had been published and related to the treatment of tinnitus. VOSviewer, CiteSpace, R, and Tableau software programs were used to conduct bibliometric studies. To evaluate and visualize the results.Results2,933 publications on tinnitus treatment were found in 74 countries. Between 2000 and 2021, publications increased steadily. Otolaryngology-Head & Neck Surgery had the highest impact factor, whereas Otology & Neurotology had the most magazines and the highest h, g, and m index. Langguth B was the most prolific author in terms of productivity during the past 21 years. Numerous eminent authors and organizations from multiple nations collaborated. With 626 papers, the United States of America (USA) contributed the most to this field, making them the leading contributor. Neuroplasticity, sound therapy, and cognitive behavioral therapy (CBT) have attracted the attention of researchers, leading to the development of innovative diagnostic and treatment strategies for tinnitus.ConclusionThis bibliometric study provides a comprehensive analysis of worldwide publications, cooperation, and research hotspots in tinnitus therapy, revealing the present status of research on this issue and guiding tinnitus treatment research in the coming years.

BackgroundThyroid cancer has been on the rise over the last decade. Papillary thyroid microcarcinoma (PTMC) accounts for more than half of all thyroid cancers. Micropapillary carcinoma of the thyroid is a common but non-fatal form of thyroid cancer. To better comprehend, nearly two decades of scientific outputs were analyzed and summarized using bibliometric methods in this study.MethodsApproximately 1098 publications from 2000 and 2021 were included in WoS database through systematic retrieval. The general information was characterized, and developmental skeleton and research frontiers were explored. CiteSpace, VOSviewer, and R, Tableau were used to evaluate and visualize the results.ResultsA total of 1098 publications from across 75 countries were identified. The annual number of publications showed an increasing trend in the past 21 years. China, Korea, the United States of America (USA), Italy, and Japan made remarkable contributions to the research of PTMC. Thyroid was the most productive journal. Miyauchi Akira published maximum articles. The utmost productive institution was the University of Ulsan. Risk stratification, active surveillance, and thermal ablation garnered the attention of researchers leading to novel approaches in the clinical diagnosis and treatment of micropapillary thyroid carcinoma.ConclusionsThis bibliometric study provides a comprehensive analysis of global productivity, collaboration, and research hotspots within PTMC field, which will aid in directing research toward PTMC in the coming years.

Airborne tactical networks (ATNs) is driving the growing development of network-centric warfare by maintaining coverage and providing reach-back to military units. However, the key function of ATNs is impeded by the network ossification that is deep-rooted in the tightly coupled, vertically integrated architecture of traditional ATNs. Network virtualization (NV) can provide a more flexible and scalable ATN architecture as a solution, breaking the tight coupling between applications and network infrastructure. One important aspect of NV is virtual network embedding (VNE), which instantiates multiple virtual networks on a shared substrate network. However, existing efforts are not necessarily optimal for the virtualization of ATNs due to the absence of QoS-compliant capacity for the complex interference in air-combat field. To tackle this difficulty, a reliable interference-aware VNE algorithm, termed VNE-RIA, is proposed to provide reliable guarantee in the coordinated node and link mapping for various airborne tactical virtual networks (ATVNs). In the node mapping, the VNE-RIA adopts a novel node ranking approach to rank all substrate and virtual nodes, considering the complex interference including link interference, environmental noise and malicious attacks. In the link mapping, an improved anypath link mapping approach, based on the anypath routing scheme, is adopted to improve the reliability and efficiency of mapping virtual links by exploiting the unique features of wireless channels and the influence of different transmission rates. Numerical simulation results reveal that VNE-RIA algorithm outperforms typical and latest heuristic wireless VNE algorithms under the complex electromagnetic interference of ATNs.

As an important part of the spatial information network, airborne network (AN), which connects air platforms with upper satellites and ground devices, has been increasingly important right now. Due to the heavy-tailed distribution of network traffic, elephant flow detection is usually used to catch and control the key part of network traffic with low costs, which is a practical strategy to strengthen network management and improve network performance. In this paper, we consider the problem of dynamic threshold elephant flow detection in AN, and an intelligent method based on regression with pre-classification is proposed to adapt to the limited and dynamically changing bandwidth. The filtering mechanism with waiting-window is used firstly to filter out parts of small flows to decrease the detection cost. Then, the pre-classification is used to divide the range to be predicted and the flow size regression can be carried out in a compressed range, which makes the results more accurate. Finally, the predicted size is compared with the specific detection threshold related to the specific moment, and the elephant flow is identified. Numerical experiments demonstrate that the proposed method has a better adaptability to dynamic threshold and the performance is much better.

With the ubiquitous use of networking technologies in the military domain, network-centric warfare, which aims at improving the system of systems (SoS) capability, is a no-way-back trend of military development. Recently, it has become increasingly important to construct an airborne backbone network (ABN) to maintain coverage and provide reach-back to military units because the terrestrial networks cannot be flexibly deployed and have poor survivability. Given the advantages of software-defined networking (SDN), a software-defined airborne backbone network architecture (SD-ABN) is proposed for the ABN to ensure network flexibility, openness, interoperability, and evolvability. To meet the challenges of traffic management in SD-ABN, segment routing (SR) is applied with some practical modifications for the SD-ABN. Moreover, a network traffic scheduling algorithm termed MRP-TS is designed based on SD-ABN to improve the transmission reliability and bandwidth utilization by balancing network traffic to multiple reliable transmission paths. Relevant theories have been proposed and proved to illustrate the correctness of the algorithm. The network simulation experiments have been conducted using the network simulator EXata 5.1, and the simulation results validate the effectiveness of our proposals.

When processing track sequences, it is time-consuming and difficult to separate clusters with substantial density variations to deal with the problem of classic clustering methods mining common flight patterns in airspace. To overcome these issues, this research proposes a clustering-based technique for mining air traffic trajectory operation patterns. The track data are first decoded and rebuilt using a motion-based track training approach; next, a compression based on a deep autoencoder (OFAE) is provided, allowing the model to deal with the high-dimensional trajectory vector containing derived information. The compressed trajectory data are made as compact and dense as feasible using the L21 norm constraint, which reduces the operation time and improves the performance of the clustering process. The compressed trajectory is then analyzed using a fast-clustering algorithm based on density peaks (DPCA). To save time, a more refined distance measurement technique is added into the model in order to achieve the usual aircraft operation mode in the terminal area. The accuracy of trajectory prediction can be improved by using the generated unitized and high-class similarity trajectory data.

The investigation aims to propose a refined model to analyze the parametric resonance under multicable systems such as cable-stayed bridges. Considering the interaction between the adjacent beam portions, the shear difference is applied to modify the vibration equations derived from the multi-degree-of-freedom stiffness method. Furthermore, the difference method is adopted to make the equations more accessible for numerical analysis. The comparison results indicate that the refined model exhibits the key character of parametric resonance and also further verified the simulation methods. The consequences show that the cable will resonate at the fundamental frequency under the support excitation. In particular, when resonance occurs, most of the energy in the subsystem is transferred to the cable, resulting in the resonance amplitude of the beam portion being weakened to some certain extent. Moreover, the global resonance will have a sufficient excitation on the local resonance only when the resonance condition is satisfied.

Considering the effect of the bridge deck’s bending stiffness and the indirect effect of adjacent cables (CEB), this paper aims to propose a refined model to reliably analyze the complex internal resonance mechanism of the tower–multicable–beam coupled system (MCS) under nonlinear geometric conditions. To accurately analyze the dynamic behavior, the shear difference effect is applied to simulate the continuous rigidity of the single beam. The dynamic equations of the whole resonance system are derived based on the D’Alembert Principle and the Finite Difference Method, the Galerkin Method and verified by the case study. The results of the numerical simulation based on the Fourth Runge–Kutta Method show that the dynamic parameter of each component is closely related to the coupled resonance of the system. The dynamic behavior under two conditions, tower–cable 1:1 resonance (TCR) or cable–beam 1:2 resonance (CBR), is deeply analyzed. Additionally, the excitation effect of the maximum amplitude by two excitation approaches, the initial displacement or initial velocity, both show a linear increase. The mutual transmission process of vibration excitation on the cable through the bridge beam or the tower as the medium is also further discussed.

With the battlefield becoming more challenging, the aviation swarm is considered a promising organization of air combat forces to execute both combat and non-combat air missions. As a critical component of the aviation swarm, the airborne tactical network (ATN) provides the communications capability, enabling information sharing between both manned and unmanned military aircrafts as well as surface and ground platforms. The deficiencies of legacy ATNs, particularly their inability to meet the communications demands of the aviation swarm, motivated us to employ the software-defined networking (SDN) paradigm to the ATN and to design an SDN-enabled ATN (SD-ATN) for the aviation swarm. For the SDN paradigm, the communications efficiency between the control plane and the data plane directly impacts the normal operations of the network, raising a fundamental problem of designing the SD-ATN, which is that how to ensure the QoS requirements of the non-elastic information transmitted between the control plane and the data plane (non-elastic C/D information) is met. To address this issue, a transmission framework is first proposed to make it practical to provide dedicated QoS guarantee for the non-elastic C/D information. Then, a communication protocol is designed based on the proposed framework, aiming at transmitting the non-elastic C/D information in a reliable and real-time manner. The simulation results show that, in the aviation environment, our scheme does improve the transmission efficiency of the non-elastic C/D information, which performs better than legacy solutions.

In low-power wireless neural recording tasks, signals must be compressed before transmission to extend battery life. Recently, compressed sensing (CS) theory has successfully demonstrated its potential in neural recording applications. In this paper, a deep learning framework of quantized CS, termed BW-NQ-DNN, is proposed, which consists of a binary measurement matrix, a non-uniform quantizer, and a non-iterative recovery solver. By training the BW-NQ-DNN, the three parts are jointly optimized. Experimental results on synthetic and real datasets reveal that BW-NQ-DNN not only drastically reduce the transmission bits but also outperforms the state-of-the-art CS-based methods. On the challenging high compression ratio task, the proposed approach still achieves high recovery performance and spike classification accuracy. This framework is of great values to wireless neural recoding devices, and many variants can be straightforwardly derived for low-power wireless telemonitoring applications.

In this study, the role of AD 1258 Samalas mega volcanic eruption in the summer hydroclimate change over Europe and the corresponding mechanisms are investigated through multi-member ensemble climate simulation experiments based on the Community Earth System Model (CESM). The results show that the CESM simulations are consistent with the reconstructed Palmer Drought Severity Index (PDSI) and the historical records of European climate. Europe experiences significant summer cooling in the first three years after the Samalas mega volcanic eruption, peaking at −3.61 °C, −4.02 °C, and −3.21 °C in year 1 over the whole Europe, Southern Europe, and Northern Europe, respectively. The summer surface air temperature (SAT, °C) changes over the European continent are mainly due to the direct weakening of shortwave solar radiation induced by volcanic aerosol. The summer precipitation over the European continent shows an obvious dipole distribution characteristic of north-south reverse phase. The precipitation increases up to 0.42 mm/d in year 1 over Southern Europe, while it decreases by −0.28 mm/d in year 1 over Northern Europe, respectively. Both simulations and reconstructions show that the centers with the strongest increase in precipitation have always been located in the Balkans and Apennine peninsulas along the Mediterranean coast over Southern Europe, and the centers with the strongest precipitation reduction are mainly located in the British Isles and Scandinavia over northwestern Europe. The negative response of North Atlantic Oscillation (NAO) with significant positive sea level pressure (SLP) anomaly in the north and negative SLP anomaly in the south is excited in summer. The low tropospheric wind anomaly caused by the negative phase of NAO in summer affects the water vapor transport to Europe, resulting in the distribution pattern of summer precipitation in Europe, which is drying in the north and wetting in the south. The knowledge gained from this study is crucial to better understand and predict the potential impacts of single mega volcanic eruption on the future summer hydroclimate change in Europe.

In this study, the influences on persistent droughts over Eastern China from tropical volcanic eruptions with three categories of magnitudes, i.e., 25 Tg, 50 Tg, and 100 Tg, were investigated through three groups of volcanic sensitivity experiments based on the Community Earth System Model (CESM). The results showed that, the 25 Tg tropical volcanic eruptions are too weak to significantly influence the regional precipitation changes over Eastern China, while the 50 Tg tropical volcanic eruptions can strongly intensify droughts and prolong the drought conditions for about five years. Both the extension and intensification of the drought conditions induced by 100 Tg tropical volcanic eruption are the largest among the three sensitivity experiments. These drought conditions are mainly caused by the weakened East Asia Summer Monsoon (EASM), and their extension and intensification depend on the strength of the volcanic eruptions. The intensities of weakened EASMs after volcanic eruptions are associated with the distinct ocean−land thermal contrast after eruptions. The ocean−land thermal contrast is the largest after the 100 Tg tropical volcanic eruptions, while it is much weaker after the 25 Tg volcanic eruptions. The durations of drought extensions are determined by the recovery rates of the West Pacific Subtropical High (WPSH), which are associated with the magnitudes of the volcanic eruptions.

Aviation swarm is considered to be a promising organization of air combat forces to execute combat and noncombat air missions. As a critical component of an aviation swarm, airborne tactical network (ATN) provides the communication capability. Considering the deficiencies of today’s ATNs, it is unable to meet the communication demands of an aviation swarm, which motivates us to employ the software-defined networking (SDN) paradigm and design a SDN-enabled airborne tactical network (SD-ATN). For the SDN paradigm, network monitoring information (M-info) is the source of knowledge that forms the globe network view of the control plane; therefore, how to ensure that the control plane collects M-info from the data plane in a reliable and real-time way is a fundamental problem of designing the SD-ATN. To address this issue, a transmission framework called the MCF-SD-ATN is first designed, which makes it practical to provide dedicated quality of service (QoS) guarantees for the M-info collection. Then, a communication protocol called the MCP-SD-ATN is designed to implement the M-info collection work based on the MCF-SD-ATN. We implement the MCF-SD-ATN and the MCP-SD-ATN in EXata 5.1 for simulation. Simulation results show that the proposed solution is appropriate for M-info collection in the SD-ATN.

The variability and mechanisms of multi-decadal megadroughts over eastern China during the last millennium were investigated using a control, full-forcing, and four sensitivity experiments from the Community Earth System Model (CESM) Last Millennium Ensemble (LME) archive. The model simulated megadroughts have comparable magnitudes and durations with those derived from reconstructed proxy data, although the megadroughts are not temporally synchronous. In all experiments, the megadroughts exhibit similar spatial structures, corresponding to a weakening of the East Asia summer monsoon (EASM) and a strengthening of the East Asia winter monsoon (EAWM). The results show that internal climate variability within the coupled climate system plays an essential role in triggering megadroughts, while different external forcings may contribute to persistence and modify the anomaly patterns of megadroughts. A pattern of meridional tripolar (warm-cold-warm) sea surface temperature (SST) anomalies in the western Pacific stretching from the equator to high latitude is responsible for the EASM weakening and EAWM strengthening. The weakening of the EASM and strengthening of the EAWM are essentially caused by negative SST anomalies over the northwestern Pacific and positive SST anomalies over the equatorial western Pacific, which are associated with a La Niña-like SST gradient across the tropical Pacific. The external forcings prolong the megadroughts through maintenance of the meridional tripolar SST anomalies and enlarge the megadrought spatial extent by magnifying the meridional tripolar SST anomalies.