Abstract We have assessed the plasma and electric environment within a lunar pit and its connected subsurface cave utilizing plasma simulations. It is shown that adjacent illuminated and shadowed regions along the interior walls of the pit induce differential charging, exceeding the levels typically observed on open planar surfaces. Within the illuminated sectors, the incident solar wind (SW) proton flux dominates over the electron counterpart. In this regime, photo‐emitted and secondary electrons imported from adjacent illuminated surfaces suppress excessive positive charging by acting as negative charge carriers to compensate for the scarce SW electrons. Deep inside the cave, a residual population of SW electrons induces significant negative charging despite their small flux. The relative significance of minor current components, such as ion‐induced secondary electrons and protons scattered off the lunar regolith, is also enhanced therein. The local equilibrium potential is thus governed by the current balance of these multi‐species particle populations.
Abstract Central Pacific (CP) El Niño‐Southern Oscillation (ENSO) variability has intensified since the late 1990s. Existing literature has emphasized the role of upper‐ocean stratification in modulating ENSO, primarily focusing on decadal thermal changes. This study further demonstrates that the regime shift of ENSO is modulated by the increasing salinity in the CP region. This decadal salinification enhances near‐surface density and weakens static stability, facilitating stronger vertical entrainment and a warmer subsurface at the base of the mixed layer. Consequently, thermocline feedback responsible for the growth of ENSO is reinforced during El Niño but weakened during La Niña, favoring stronger CP El Niño and weaker La Niña. Then the negative skewness of CP ENSO asymmetry is reduced. The CP salinification is primarily linked to a decadal intensification of the Walker circulation and reduced freshwater flux. Understanding these salinity‐driven processes is essential for improving ENSO predictions and mitigating climatic impacts on decadal‐to‐multidecadal timescales.
Abstract Transformational faulting in olivine has been widely invoked as a possible triggering mechanism for deep‐focus earthquakes, yet its dynamics remain debated. It is unclear whether it requires the combined effects of heat release, volume change and mechanical strength contrast, or whether it can be triggered by any one of these alone. Here, we tested if transformational faulting can be caused solely by a large volume change, through deformation experiments on novaculite during the quartz‐coesite transition. Under sluggish reaction kinetics, acoustic emissions and microstructural observations indicate strain localization and fault plane formation. Under fast kinetics, deformation was distributed and associated with fewer, lower‐magnitude events. b ‐values of ∼1 and ∼3 reflect these two regimes. Our results provide the first evidence of transformational faulting during the quartz‐coesite transition, suggesting that volume change is the primary driver of brittle failure at high pressure, broadening the range of mineral transitions generating deep and intermediate‐depth earthquakes.
Abstract Compound humid‐hot extremes bring growing threats to human society, yet land–atmosphere feedbacks regulating these events remain insufficiently understood. Using high‐resolution observational and reanalysis data, we reveal that the Yangtze River Basin (YRB) is a prominent hotspot for humid‐hot extremes, with rare hot‐only events. Comparing humid‐hot and non‐humid‐hot days, we find that humid‐hot extremes are sustained by positive feedbacks involving a high‐pressure anomaly, suppressed clouds and precipitation, drier soils, enhanced evapotranspiration, and lower relative humidity—mutually reinforcing the extreme state. Land–atmosphere coupling strengthens substantially for near‐surface variables, indicating stronger land surface control. Yet this enhanced coupling does not extend to cloud development: elevated lifting condensation levels and reduced relative humidity inhibit cloud formation, leading to a decoupling between convection and cloud development and allowing humid‐hot extremes to persist. Our findings highlight the role of land surface processes in modulating compound extremes and provide a foundation for improving their prediction.
Abstract Extreme winter warming events over the Antarctic Peninsula (AP) have potential impacts on ice‐shelf stability, but their mechanisms and teleconnections remain poorly studied. Using multi‐station observations, we report several warm extremes during May–June 2026, with early–June temperatures exceeding 0°C and peak anomalies reaching +22.32°C. These extremes were primarily driven by a pressure‐dipole pattern, featuring an enhanced Amundsen Sea Low and Drake Passage blocking, which directed frequent atmospheric river landfalls. The resulting moisture‐heat advection, alongside enhanced downward longwave radiation, dominated the rapid warming over the AP. Notably, record‐high sea surface temperatures in the tropical eastern Indian Ocean played a key role in this anomalous circulation, whereas the concurrent El Niño (still developing) had minimal direct impact. Our findings enrich the rare wintertime cases and identify the tropical Indian Ocean as a key precursor for improving projections of such events, which is also essential for estimating their impact on ice‐shelf stability.
