Abstract Irrigation alters the terrestrial water cycle, yet its spatial distribution and temporal variability remain poorly constrained because existing data sets often rely on indirect proxies or inventories rather than observations tied to land‐surface water‐balance dynamics. Here, we introduce a wavelet‐based method to detect irrigation from spectral differences between modeled and satellite‐observed soil‐moisture time series, implemented using Noah–MP simulations and Soil Moisture and Ocean Salinity (SMOS) observations. The method, applied across the contiguous United States, exploits differences in seasonal to sub‐seasonal soil‐moisture variability between irrigation‐off model simulations and satellite observations, particularly in the 6–18‐month band, enabling irrigation detection. The resulting soil‐moisture‐based irrigation classification complements high‐resolution optical irrigation data sets, while reflecting the coarse‐scale information contained in SMOS soil moisture. When incorporated into Noah–MP simulations, it improves the distribution of simulated irrigation water use. This framework supports scalable irrigation detection from satellite soil moisture and improved irrigation representation in Earth system models.
Abstract Satellite thermal infrared (TIR) observations, combined with machine‐learning methods, enable nighttime retrievals of cloud optical thickness (COT), but their cloud‐top‐dominated radiances provide ambiguous information for optically thick clouds. Passive microwave (MW) observations provide complementary sensitivity to column‐integrated liquid/ice clouds. Here we quantify this benefit by combining TIR and MW brightness temperatures within a U‐Net COT retrieval framework. Relative to a TIR‐only baseline, adding MW channels (TIR‐MW) increases the correlation with MODIS MYD06 COT from 0.70 to 0.77, and reduces mean absolute error by 18.3% on an independent test set. Improvements are largest for optically moderate‐to‐large clouds, where TIR‐only retrievals suffer from cloud‐top saturation and structural ambiguity. Results demonstrate that TIR‐MW synergy provides physically complementary, column‐integrated constraints that improve passive COT retrievals, strengthen the physical basis of machine‐learning cloud property retrievals, and reduce their tendency to underestimate optically thick clouds. This TIR‐MW integration strategy provides a physically grounded pathway for all‐day cloud‐property retrievals.
Abstract The Surface Water and Ocean Topography (SWOT) satellite mission offers unprecedented estimates of global river discharge. This study provides a first continental‐scale assessment of SWOT Consensus discharge performance across South America and compares it with a large‐scale hydrodynamic model and in situ observations. Consensus generally exhibits higher skill with a median Kling‐Gupta Efficiency (0.43) across the 569 benchmarked reaches. Performance varies systematically with physiographic settings. Random Forest and Spearman correlation analyses identify slope and distance to outlet as the top‐ranked controls among the variables tested, though no single variable explains performance, reflecting its multi‐dimensional nature. Consensus discharge inherits systematic bias from its machine learning prior, and substantial unexplained variability highlights that further work is needed to fully diagnose low‐skill reaches.
Abstract Lipari Island hosts an active magmatic–hydrothermal system, but its deep plumbing architecture remains poorly resolved due to strong seismic scattering. We apply passive seismic matrix imaging to public vertical‐component cross‐correlation functions from the dense 2018 Lipari nodal array, recovering relative‐reflectivity structures to ∼10 km depth. The images delineate steep reflectors aligned with the Tindari–Letojanni fault, consistent with a damage‐zone geometry that may focus magma and fluid transfer. Beneath the San Calogero hydrothermal field, a continuous reflector at 1–2 km depth is consistent with a contact between an altered shallow cap and a more competent intrusion complex, as suggested by reflectivity and published velocity constraints. Together, these features define a structural framework in which tectonically guided vertical transfer may connect with laterally partitioned shallow storage and possible hydrothermal sealing. This architecture provides a basis for interpreting magma–fluid transfer and identifies targets for monitoring hydrothermal pressure changes and fault‐zone seismicity.
Abstract The second winter response to ENSO in the Euro‐Atlantic sector is a surprising recent discovery, however, the underlying mechanisms remain uncertain and are challenging to determine from observations. Here we revisit the second winter response to ENSO using multiple large ensemble climate model simulations to examine its robustness and possible causes. Almost all the models demonstrate a significant second winter response in the Euro‐Atlantic sector, typically resembling positive phases of the North Atlantic Oscillation and/or East Atlantic pattern, but with a large variation across models. The models have strong, long‐lived anomalies in both tropical SSTs and atmospheric angular momentum into the second winter also with variation across models. A maximum covariance analysis approach shows that the preceding tropical SST anomalies explain almost the entire Euro‐Atlantic circulation anomalies. Further analysis reveals that the long‐lived SST anomalies generate substantial tropical precipitation anomalies and associated large‐scale teleconnection patterns in the northern extratropics.
Abstract Graph models of fractured media commonly vary edge weights while retaining one directed topology. We tested this assumption in a measured three‐dimensional rough fracture using steady Navier‐Stokes flow, flux‐closure recirculation zones, directed voxel graphs, and conservative graph transport. As the Reynolds numbers increased from 5 to 400, 11.9% of common edges reversed direction, cyclic nodes expanded from 0.073% to 14.35%, and the number of significant recirculation zones increased from 0 to 65. Median and 90th‐percentile travel times changed little, but the 99th percentile increased by 16.8% as late paths increasingly accessed recirculation‐linked strongly connected components. At the high flow rate, a uniformly scaled low‐inertia graph underpredicted the 99th percentile by 16.1%; matching the global Peclet number also failed to collapse transport. The results show that edge directions vary with Reynolds number and carry information about late retention associated with inertial recirculation.
Abstract Large intraplate earthquakes are paradoxical because they occur far from active plate boundaries. Northern Hainan Island (South China) hosts the 1605 Qiongbei M7.5 earthquake within a volcanic province linked to the Hainan mantle plume. New shear‐wave velocity images reveal two shallow low‐velocity zones extending to ∼10 km depth: a stronger anomaly beneath young volcanic cones and a weaker anomaly beneath the seismogenic fault system. Both anomalies connect near ∼6 km depth and merge into a deeper anomaly at 12–30 km depth that spatially coincides with low‐resistivity structures imaged by magnetotellurics, indicating a vertically connected crustal magmatic‐fluid system. Locally thinned crust and low uppermost‐mantle velocities further suggest ongoing plume‐fed mantle upwelling. We infer that volatile‐rich fluids ascended into shallow fault zones, reducing rock strength and promoting rupture during the 1605 earthquake. These results link mantle upwelling to brittle fault failure and suggest that plume‐derived magmatic fluids may govern large intraplate earthquakes.
Abstract The Clumping Index (CI) critically regulates canopy radiation, yet its role in reshaping global heat fluxes under land‐atmosphere (L‐A) interactions remains poorly quantified. We integrated satellite‐derived CI into the Community Earth System Model (CESM) to assess its impacts through L‐A coupled simulations. Results show that CI systematically shifts energy partitioning by increasing ground sensible heat and evaporation while reducing vegetation counterparts, with spatial patterns modulated by L‐A coupling. Rather than acting as a uniform amplifier, L‐A coupling modifies the regional expression of CI‐induced flux changes through atmospheric feedback pathways. Comparisons with FLUXCOM and flux‐tower observations provide complementary large‐scale and site‐level context, and suggest that including CI together with L‐A coupling generally improves simulated sensible and latent heat fluxes across most plant functional types, with needleleaf vegetation as an exception. Our study provides new insights into how vegetation structure regulates global energy balance within the L‐A coupling framework.
Abstract The Northern Recirculation Gyre (NRG) of the Kuroshio Extension (KE) has traditionally been viewed as subsurface‐intensified and difficult to identify at the sea surface. We combine a 2016–2025 subsurface mooring record, satellite altimetry, Argo trajectory‐based velocities, and historical near‐bottom velocities to reassess the sea‐surface expression of the NRG‐related westward flow and its relation to subsurface variability. At and near the mooring site, velocities show low‐frequency covariability across sampled depths and a westward time‐mean structure. In the altimetry‐defined surface‐expression region, westward surface flow becomes clearer and more frequent in the later record, while retaining strong interannual modulation. The clearer sea‐surface expression is accompanied by local eddy–mean adjustment in the adjacent KE–NRG shear band, as indicated by barotropic‐conversion and Reynolds‐stress diagnostics.
Abstract Organized convective systems produce a disproportionate fraction of warm‐season rainfall, yet satellite‐based analyses generally neglect propagation‐relative microphysical organization. We develop a propagation‐relative partitioning framework using FY‐4A geostationary satellite observations to characterize sector‐resolved cloud effective radius–temperature profiles for 162 eastward‐propagating convective systems over China. Results reveal pronounced horizontal and vertical heterogeneity: the frontal sector sustains a deep warm‐rain growth layer, while the rear sector exhibits larger glaciated particles at colder temperatures. Prior to surface rainfall intensification, these profiles evolve from near‐monotonic growth to a distinct unimodal structure with strengthening frontal‐to‐rear contrasts. These findings identify propagation‐relative microphysical organization as an observational precursor to rainfall intensification in propagating convective systems.
Abstract Declining monsoon rainfall over agriculture‐dependent Eastern Central India (ECI) during 1901–2014 threatens regional food and water security. Observations link ECI drying to rapid Northwest Indian Ocean (NWIO) warming, which weakens monsoon circulation. However, the widely used Community Earth System Model version 2 (CESM2) Large Ensemble fails to reproduce this drying, instead simulating increasing ECI precipitation while underestimating NWIO warming. Using the fully coupled CESM2 Large Ensemble and Pacific pacemaker experiments where realistic tropical Pacific SST anomalies are specified, we identify ocean biases limiting NWIO warming: (a) a lack of El Niño intensification diminishes Pacific‐to‐Indian Ocean heat transmission; (b) an overly deep southwestern Indian Ocean thermocline weakens the thermocline–SST feedback, constraining NWIO warming. The drying effect of NWIO warming‐induced monsoon weakening could be masked by thermodynamic forcing from global warming in the CESM2 Large Ensemble, leading to ECI wetting. Addressing these model biases is critical for monsoon rainfall projections.
Abstract Tropical deforestation driven by agricultural expansion to meet growing food demand poses a rising threat to the global carbon cycle. While previous studies quantified agriculture‐related carbon losses, the role of cropland expansion remains poorly resolved, partly because widely used agricultural driver data sets are too coarse to detect fine‐scale forest‐to‐cropland conversion, especially in topographically complex regions. Here we integrate multiple high‐resolution satellite observations to show that tropical forest‐to‐cropland conversion reached 1.08 Mha yr −1 during 2004–2019, accelerating by 0.35 ± 0.07 Mha yr −1 per four‐year period ( p < 0.05). These conversions shifted toward steeper terrains, with mean slope rising by 0.16 ± 0.05° per period. Annual forest carbon loss nearly tripled from 46 to 130 TgC yr −1 , increasing at 30 ± 6 TgC yr −1 per period ( p < 0.05). Our findings reveal a systematic shift of agricultural frontiers toward marginal, carbon‐rich tropical forests, underscoring the need for more targeted land‐use governance to support global climate mitigation goals.
Abstract East Asian Summer Monsoon (EASM) varied at orbital and millennial timescales during the Last Deglaciation (∼20–11 ka). The uniform δ 18 O response in East China is often linked to EASM circulation that drives a precipitation dipole in North and South China on orbital scale. Yet the relationship between stalagmite oxygen isotopes (δ 18 O c ) and regional rainfall remains ambiguous at millennial timescales. Combining proxy records with isotope‐enabled transient climate simulations (iTraCE), we demonstrate a decoupling between changes in δ 18 O c and regional precipitation in North China during millennial‐scale events. Although δ 18 O c responds uniformly across East China to AMOC changes and is correlated with South China rainfall, North China rainfall is instead largely driven by insolation, with negligible millennial‐scale variability. This reflects that East China δ 18 O c is driven by AMOC‐induced shifts in moisture source δ 18 O. Our findings emphasize that δ 18 O c records require forcing‐specific interpretation in East Asia across timescales.
Abstract Climate warming and degradation of glaciers and permafrost in High Mountain Asia is threatening the sustainability of the region's natural “water towers” and allied ecosystems and infrastructure. Approximately 25,000 Himalayan rock glaciers exist and, being more resilient to climatic change than glaciers, they represent important freshwater reservoirs. Yet these rock glaciers' ice content remains poorly quantified. Here, using Interferometric Synthetic Aperture Radar to track surface movement and Ground‐Penetrating Radar (GPR) to quantify buried ice, we present the first direct measurements of ice within the active Gokyo Rock Glacier, situated above 4700 m, in central Nepal (27.9416°N, 86.6920°E). Our unique data show surface movement up to 1 m a −1 , consistent with active rock glaciers elsewhere, while geophysical interpretation reveals two buried massive ice bodies up to 28.0 (±2.1) m thick, totaling an estimated freshwater volume of × 10 5 m 3 . These findings emphasize rock glaciers represent important, slowly released freshwater reserves as regional warming accelerates.
Abstract Arctic sea‐ice extent (SIE), a high‐accuracy observable, is a key indicator for assessing sea‐ice state and its physical evolution. Extreme SIE losses thus often spark debates over potential Arctic tipping behavior and nonlinear threshold responses. Employing Arctic SIE from 1979 to 2025, this study investigated the long‐term decline, anomalous years, abrupt changes, and partial recovery phases. We identified three pivotal extreme years (2012, 2020, and 2025) within the declining trend of Arctic SIE. They are characterized by persistent record lows, a near‐record annual minimum, and an unprecedented frequency of daily record lows, respectively. The monthly SIE series was decomposed into trend, seasonal, and remainder components, and we subsequently detected 2001, 2007, 2012, and 2020 as abrupt change points (ACPs) in the trend. However, each ACP is followed by a partial SIE recovery. These findings indicate that ACPs represent significant annual‐scale disturbances in SIE variability.
Abstract Decadal predictions are affected by initialization shocks and drift, typically diagnosed in ocean circulation or temperature. It is not known, however, to what extent the drift can affect atmospheric dynamics. Here we investigate how the drift causes spatial shifts in the location of key large‐scale atmospheric circulation features such as the Intertropical Convergence Zone (ITCZ). The asymmetrical changes in surface temperature (with warmer southern and cooler northern hemisphere) with increasing forecast times cause southward shifts in the location of ITCZ, the subtropical jets and tropical precipitation patterns. Such changes are larger in full‐field initialized models, however, the anomaly‐initialized models show large biases in their ITCZ location from the beginning. These artificial changes in the location of large‐scale circulation patterns pose important challenges to initialized climate predictions, potentially undermining the ability of current prediction systems to predict changes in climate aspects for which atmospheric circulation is an important driver.
Abstract Using interferometric synthetic aperture radar (InSAR) we show that hydraulic fracturing treatments near the subsurface deformation limit of the Rocky Mountain Fold and Thrust Belt produced 12 intraplate, aseismic, slow‐slip events with magnitudes 4.71–5.06 at 1,640–2,410 m depths. Sustained aseismic slip is inferred to occur on the bedding‐parallel roof detachment of a duplex, thrust‐fault system. Each slow‐slip event causes on average 10–20 cm shearing over several square kilometers. Most events are associated with reported casing deformation, but only about half display jointly occurring induced seismicity of magnitude . The cumulative seismic moment released by the detected slow‐slip events between 2017 and 2023 is orders‐of‐magnitude larger than that released by the approximately 2,300 earthquakes between 2005 and 2023. Although detected slow slip presents limited risk to surface infrastructure, it poses an economic risk to subsurface infrastructure such as hydrocarbon boreholes.
Abstract We investigate the nighttime equatorial ionosphere during the 19 January 2026 geomagnetic storm using Global‐scale Observations of the Limb and Disk OI 135.6 nm observations and ground‐based GPS Total Electron Content. The observations reveal a pronounced longitudinal asymmetry in the post‐sunset equatorial ionization anomaly (EIA). Over the South American sector, the two EIA crests converged and merged into a single equatorial peak across ∼35° longitude within ∼2 hr, while remaining separated with active equatorial plasma bubbles (EPBs) over the Atlantic and West African sectors. This behavior suggests a rapid, large‐scale post‐sunset crest merging under storm‐time conditions. Concurrent radar and magnetometer measurements indicate storm‐time westward electric fields drove the large‐scale merging. The timing of these electric fields relative to local sunset suppressed prereversal enhancement and inhibited EPB growth west of ∼45°W. These electrodynamic changes are consistent with a brief southward followed by prolonged northward interplanetary magnetic field Bz, suggesting overshielding‐driven downward drifts.
Abstract Near‐surface wind speed (NSWS) regulates the intensity of land‐atmosphere fluxes and the viability of wind energy systems, playing a pivotal role in human adaptation to climate change. However, at the current stage, global climate models exhibit a wide inter‐model spread in NSWS simulations, limiting the reliability of future wind energy projections. Here, we identify the primary drivers of this uncertainty over China. We show that the spread is concentrated in North and Northeast China. Models simulating extensive forest loss exhibit weak or negligible NSWS trends because deforestation smooths the land surface and counteracts the background surface stilling. In contrast, models with limited forest loss or forest gain yield pronounced NSWS declines. This substantial spread is mainly attributable to the varying magnitude of forest cover changes, accounting for approximately 74% of the inter‐model spread. Our findings suggest that constraining forest cover changes is critical for substantially reducing the uncertainty in surface wind projections.
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