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An empirical orthogonal function (EOF) analysis was conducted for spring precipitation gauge data over northeast China (NEC). The first EOF mode is characterized by a homogenous rainfall pattern throughout NEC. The corresponding principal component has both significant interannual and interdecadal variations. This leading mode explains a large portion of the total NEC spring rainfall (NECSR) variances and is statistically independent from other higher modes. The physical processes responsible for the interannual and interdecadal variabilities were investigated via observational diagnoses and numerical experiments. On the interannual time scale, NECSR is mainly affected by the SST anomalies (SSTAs) in the northern tropical Atlantic Ocean. When the SSTAs are positive, the subsequently induced positive precipitation and convection can stimulate two quasi-barotropic Rossby wave trains over the mid- to high latitudes. A cyclonic anomaly center of the Rossby wave train appears over northeastern Asia, leading to a positive rainfall anomaly in the region. On the interdecadal time scale, NECSR is mainly influenced by the SSTAs over the warm-pool region. Positive SSTAs in the warm-pool region result in enhanced convection (ascending motion) around the Maritime Continent and suppressed convection (descending motion) over the central equatorial Pacific Ocean. This zonal dipole convection pattern stimulates a quasi-barotropic circulation pattern with an anticyclonic anomaly over the Tibetan Plateau and a cyclonic anomaly over northeastern Asia. The cyclonic anomaly over northeastern Asia enhances the NECSR. Numerical experiments further suggested that the convective heating anomaly over the Maritime Continent, rather than cooling over the central equatorial Pacific, plays a more essential role in driving the interdecadal rainfall variability of NECSR.

We systematically evaluate the high‐latitude Joule heating of the recently released version 3.0 Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE‐GCM) by comparison to EISCAT incoherent scatter radar measurements. The model performance is examined using normalized root mean square deviations derived from test runs driven by different convection patterns from empirical and data‐assimilated models. The following features are revealed: (a) Data‐assimilated geomagnetic forcing improves the agreement between modeled and EISCAT‐derived Joule heating rates by 8%, 28%, and 54% for low, moderate, and high geomagnetic activity. (b) Increasing model grid resolution from 2.5° to 1.25° leads to ∼${\\sim} $ 20% higher Joule heating rates. (c) AMIE‐driven runs better reproduce the magnitude of the Joule heating rates, AMGeO‐driven runs the vertical profile. (d) Internal model time step resolution has no effect on the Joule heating rates.

Solar heating causes the periodic expansion and contraction of Earth’s atmosphere known as the atmospheric tide. This is observed at the surface as a semidiurnal pressure oscillation that appears to influence convection and rainfall. Roughly 0.5 to 1.0 billion years ago, when day length was roughly 21–22 hours, the tide would have been resonant, or close in frequency, with atmospheric Lamb waves of 10.5–11.0 hour periods. This ‘Lamb resonance’ would have amplified the pressure oscillation, perhaps strongly enough to affect the global or tropical climate. Here we run a general circulation model at different rotation rates to model the resonance and its impact on climate. The resonance exerts a dominant control on tropical cloud cover, convection and rainfall: sunrise and sunset are cloudy and rainy, whereas midday and midnight are clear and dry. Generally clear skies at noon lower the albedo, contributing 2–4 K warming in the global average, which would have helped counter the 10% fainter Sun. The hydrological cycle becomes more active, and the atmosphere moister. Our work highlights the role of tidally induced adiabatic expansion in controlling tropical precipitation, helping explain modern-day observations of a semidiurnal rainfall pattern. Climate simulations suggest atmospheric tides in resonance with atmospheric waves on early Earth when days were shorter could have modified tropical convection patterns and warmed the planet despite a fainter Sun.

We investigate the properties of two types of solar active regions: the small short-living groups (SSGs) and the large long-living groups (LLGs). The combined distribution of areas of active regions is bimodal. When deconvolved, the distributions of each population show a clear presence of cyclic variations with LLG and SSG number varying in phase with each other. We see these in-phase variations and the lognormal distribution of SSG/LLG areas as indications that both types of groups originate from the same mechanism, the solar dynamo action. However, the data also suggest that near-surface convection may play a role. The maxima in the bimodal distribution of sunspot group areas (one for LLG and the other for SSG components) coincide with the typical sizes of the supergranules for the LLG population and mesogranules for the SSG population, which suggests that the large-scale convection patterns may affect the sunspot group formation.

In subduction zones with slab‐slab interactions, the pattern of mantle convection is very complex and still unclear. In this study, we jointly invert a large number of P and S wave arrival time data of local earthquakes for 3‐D isotropic and anisotropic velocity structures of the Banda subduction zone. Along the curved Banda arc, the subducting Indo‐Australian slab is detected clearly as a high‐velocity zone, and its azimuthal anisotropy changes along the arc strike, representing fossil anisotropy within the slab and modified anisotropy by the subduction processes. Around the northern edge of the Banda slab, a semi‐toroidal pattern of anisotropy appears in low‐velocity anomalies, representing mantle flow extruded from the Banda arc and escaped from a gap of the Banda‐Molucca slab toward the northeast. Our 3‐D anisotropic tomography uncovers the mantle convection pattern induced by the slab‐slab interactions, shedding new light on the complex dynamical processes in this curved subduction zone. Plain Language Summary The study of mantle convection pattern can improve our understanding of plate tectonics and geodynamics. The mantle convection pattern is affected by several factors, including the subducting slab geometry and slab‐slab interactions. The tectonics in the Banda area is rendered particularly complex due to the subduction and interactions of multiple slabs. Hence, this region is an ideal natural laboratory to study the mantle flow pattern associated with slab‐slab interactions. Here we invert both P and S wave arrival times of local earthquakes for 3‐D anisotropic structure of the upper mantle beneath the Banda region. Our results show that in this curved subduction zone, the mantle convection pattern is different from that in normal subduction zones. Trench‐parallel anisotropy is revealed beneath Banda, which reflects extruded material flow in the curved subduction zone. Our results provide new insight into subduction dynamics and mantle convection. Key Points The first P and S wave anisotropic tomography of the Banda subduction zone is obtained Trench‐parallel anisotropy along the Banda arc reflects lateral mantle flow caused by the highly curved Banda slab Semi‐toroidal anisotropy around the northern edge of the Banda arc reflects extruded mantle flow from the arc

The African upper mantle is diverse, featuring several cratonic roots, active and magmatic continental rifting, abundant intra‐plate volcanism, and several oceanic hotspots offshore. Relatively small‐scale mantle convection processes, some possibly related to lithospheric thickness variations, have been proposed to account for patterns of volcanism and topography. A key constraint on such features and processes can be found via seismic anisotropy, but limited coverage of seismograph stations across the continent has resulted in sparse observations. Quasi‐Love waves, produced by scattering of Love to Rayleigh energy at lateral gradients in upper mantle seismic anisotropy, can provide information about seismic anisotropy well away from seismograph stations. We catalog 525 observations of Quasi‐Love waves across the region and back‐project to scattering points, revealing locations of lateral gradients in upper mantle seismic anisotropy. Quasi‐Love wave scattering occurs at craton edges, likely due to the contrast between lithospheric and asthenospheric anisotropy, and close to ancient orogenic belts, indicating changes in fossilized lithospheric anisotropy from past collisional events. Scattering surrounding the proposed Al‐Kufrah cratonic remnant in north‐east Africa supports its existence as cratonic lithosphere. Scattering also occurs below thin lithosphere, suggesting deviations in asthenospheric flow patterns (such as localized upwellings), notably beneath the East African Rift, oceanic hotspot tracks, and the Cameroon Volcanic Line. Quasi‐Love scattering is abundant in the Indian Ocean and beneath Madagascar, consistent with small‐scale dynamic processes in the asthenosphere that likely relate to the complex rifting history of this ocean basin and the dispersed micro‐continents within. Plain Language Summary Deformation of the Earth's mantle, through convection or plate tectonics, results in alignment of minerals that can be measured by the directional dependence of seismic velocities (seismic anisotropy). Seismic anisotropy is commonly measured directly below deployed seismograph stations, meaning observations are sparse where seismograph deployments are sparse, which is the case in much of Africa and the oceanic realm. We use observations of a type of seismic wave known as known as a Quasi‐Love wave to map lateral variations in seismic anisotropy well away from seismograph stations, to find evidence for past and current deformation in the African upper mantle. We find lateral gradients in seismic anisotropy where the plate changes from thin to thick, implying differences in anisotropy between the stiff plates and the convecting mantle. Evidence for abundant gradients in seismic anisotropy in regions where the plate is uniformly thin, such as below the western Indian Ocean and Madagascar, implies variations in the flow‐field of the convecting mantle, indicating relatively small‐scale convection patterns. Key Points 525 Quasi‐Love waves are cataloged, related to lateral gradients in upper mantle seismic anisotropy in and around Africa Many are associated with craton edges, including that of the proposed Al‐Kufrah cratonic remnant Small‐scale asthenospheric convection is inferred beneath hotspot tracks and much of the western Indian Ocean

The western North Pacific anomalous anticyclone (WNPAC) is the key circulation modulating the East Asian summer climate. In this study, the formation mechanism of the summer WNPAC that is independent of El Niño–Southern Oscillation (ENSO) is investigated. Although ENSO has a significant relationship with WNPAC, except for the super El Niño years, the WNPAC index remains almost unchanged after removing ENSO’s impact, suggesting the possibility of other origins of the WNPAC apart from ENSO. An Atlantic-to-Pacific two-step mechanism is proposed for the formation of ENSO-independent summer WNPAC. In boreal spring, diabatic heating induced by the positive sea surface temperature anomalies (SSTAs) over the tropical Atlantic could stimulate a stationary equivalent barotropic Rossby wave train that travels across the Eurasian continent and ends in the tropical North Pacific. At the end of the Rossby wave train, the lower-level anomalous anticyclone advects negative moist enthalpy into the equator, which suppresses the local convection over the tropical North Pacific and equatorial central Pacific, and thus triggers the lower-level equatorial easterly anomaly to its west. During boreal summer, the lower-level easterly anomaly leads to the zonal dipole SSTA pattern with a negative center in the tropical central Pacific and a positive one in the Maritime Continent. Then, this dipole SSTA pattern over the Pacific exerts a relaying effect that further reinforces and westward shifts the dipole convection anomaly pattern, generating the WNPAC as a Gill-type response. This study underpins the independent role of Atlantic oceanic forcing through the extratropical route in the formation of ENSO-independent summer WNPAC.

Using line‐of‐sight measurements of horizontal plasma drift from the Super Dual Auroral Radar Network (SuperDARN) located in the Northern and Southern hemispheres over a period extending from 1998 to 2002, statistical models of the high‐latitude convection electric field are derived for various ranges of interplanetary magnetic field (IMF) magnitude and orientation and for several ranges of dipole tilt angle. Direct comparison of the corresponding convection patterns in each hemisphere shows that under neutral tilt conditions (dipole tilt angle magnitude <10°) the patterns are most similar. However, a strong dipole tilt angle dependence is observed under northward (Bz+) and By dominated IMF conditions. For IMF Bz+, reverse convection is observed to be much stronger during positive tilt than negative tilt. For IMF By dominated conditions (IMF Bz = 0), the round convection cell is more enhanced for positive tilt than for negative tilt, particularly for IMF By < 0 in both hemispheres. The presence of a lobe cell is a likely cause of this enhancement, although it is not entirely clear why it occurs preferentially under IMF By < 0. In addition, the crescent‐shaped cells are weakened as tilt angle progresses from negative to positive, most likely due to vastly different solar produced conductivities under different tilt angles. For IMF Bz−, asymmetric values of the cross‐polar cap potentials (ΦPC) are observed between hemispheres, with ΦPC in the south being systematically larger than ΦPC in the north. Although neutral tilt patterns are similar enough to be used interchangeably, convection has a strong dipole tilt dependence and a Northern Hemisphere convection model should not be applied to the Southern Hemisphere if dipole tilt angle is not taken into account. When dipole tilt is accounted for, ΦPC differs between hemispheres by less than 10% on average, but the strength of the convection in the individual cells differs by 15% to 20% on average.

The Earth's mantle transition zone has significant control on material flux between upper and lower mantle, thus constraining its properties is imperative to understand dynamic processes and circulation patterns. Global seismic data sets to study the transition zone typically display highly uneven spatial distribution. Therefore, complementary geometries are essential to improve knowledge of physical structures, thermochemistry, and impact on convection. Here, we present a new automated approach utilizing machine learning to analyze large seismic data sets, and derive high‐resolution maps of transition zone discontinuity properties. Seismic measurements from ScSScS precursors are integrated with mineralogical modeling to constrain thermochemistry of the western Pacific subduction zone. Our models map recent subduction patterns through the transition zone, indicating stagnation of slabs and accumulation of basalt at its base, and interaction between stagnant slabs and plumes. These results suggest that the thermochemical properties of upper mantle discontinuities can provide high‐resolution images of mantle circulation patterns. Plain Language Summary Earth's upper mantle displays several discontinuous jumps in its physical properties, which result from changes in its mineral structure as pressure and temperature increase with depth. The major transitions near to 410 and 660 km depth are associated with physical changes that have significant influence on the flow of hot upwelling plumes and cold downgoing slabs. The depth and strength of the discontinuities depend on the local temperature and composition, and therefore constraining these properties can help to track mantle circulation patterns and better understand convection behavior. Global seismic data sets are highly uneven in spatial coverage, and therefore must be supplemented by data sets with different spatial sensitivity. Here, we present an automated approach based on machine learning to analyze seismic phases with such complementary geometry, and apply these techniques to investigate subduction zones beneath the western Pacific. We incorporate high‐resolution observations of the discontinuities with modeling from mineral physics, producing new models of temperature and composition in this region. The models track recent convection patterns through the transition zone, indicating ponding of slabs and plumes. These results suggest that the temperature and composition of the transition zone can be used to provide detailed maps of mantle circulation. Key Points New data sets of ScSScS precursors beneath the western Pacific subduction zones are compiled and analyzed with machine learning methods High‐resolution measurements of transition zone discontinuities and mineralogical modeling provide detailed maps of thermochemistry Thermochemical models track recent mantle circulation patterns, indicating slab stagnation, basalt accumulation, and interaction with plumes

Led by the National Space Science Center of the Chinese Academy of Sciences, we have built a Chinese dual auroral radar network in northern China, which is called the CN‐DARN. The CN‐DARN consists of three pairs of high‐frequency coherent scattering radar facilities and is one of the key parts of the Chinese Meridian Project Phase II. It has been fully constructed and started trial operations at the end of 2023. The detection range of the radar network extends longitudinally over approximately 9 hr of local times and covers the middle to high latitudes of the entire Asia region above 40°^{\\circ}$ . In this paper, we present the basic design of the CN‐DARN and its preliminary observations of ionospheric irregularities, subauroral polarization streams (SAPSs) and traveling ionospheric disturbances (TIDs). We also investigate its contribution to the ionospheric convection pattern of the Northern Hemisphere derived from Super Dual Auroral Radar Network (SuperDARN) observations. The results indicate that the CN‐DARN provides excellent measurements and better specifications of flows in the Asian sector, improving our understanding of the global‐scale ionospheric convection pattern in the Northern Hemisphere. These encouraging results lead us to believe that the CN‐DARN will play an important role in studies on the evolution of ionospheric irregularities, the characteristics and evolution of SAPSs, the propagation of TIDs, and global‐scale ionospheric convection dynamics.