Distribution and source of plutonium in seawater columns of the oligotrophic region in the North Pacific.

Implementation and evaluation of a new parameterization of submesoscale vertical flux in a mesoscale-resolving model in the North Pacific

Focus on the toxicology of deep-sea mining: Biotoxicity of heavy metals to Vibrio fischeri released from disturbed surface sediments of the western Clarion-Clipperton zone, Pacific Ocean.

Abstract El Niño–Southern Oscillation (ENSO) strongly modulates tropical cyclone genesis frequency (TCGF) at interannual time scales, yet how future sea surface temperature (SST) warming patterns may modify this relationship remains unclear. Here, we use high-resolution climate model simulations to quantify how three distinct SST warming patterns—uniform warming, El Niño–like warming (characterized by enhanced central/eastern Pacific warming), and La Niña–like warming (characterized by suppressed central/eastern Pacific warming)—alter the ENSO–TCGF linkage. We define a strengthening of the ENSO–TCGF relationship as an increase in the magnitude of the TCGF difference between El Niño and La Niña years and a weakening as a decrease in this magnitude. All three warming patterns generally project weakening across most tropical basins. Over the North Atlantic, ENSO’s influence is uniformly suppressed, with the suppression intensifying from uniform to El Niño–like to La Niña–like warming. However, in the southeastern western North Pacific, both uniform and El Niño–like warming strengthen the ENSO–TCGF linkage, while La Niña–like warming continues to weaken it. These divergent responses arise from pattern-dependent changes in atmospheric heating, which drive Walker circulation anomalies and in turn regulate local large-scale environmental conditions including vertical wind shear, low-level vorticity, and midtropospheric humidity, thereby modulating the ENSO–TCGF relationship. Our results highlight that the spatial patterns of SST warming, not its magnitude, play a pivotal role in modulating future ENSO–TCGF relationships, with implications for regional cyclone risk and seasonal forecasts. Significance Statement Tropical cyclone (TC) genesis is strongly modulated by El Niño–Southern Oscillation (ENSO), which serves as a key predictor for seasonal TC forecasts. However, future patterns in sea surface temperature (SST) warming remain uncertain, and it is unclear how diverse possible SST warming scenarios may influence the ENSO–TC genesis frequency (TCGF) relationship. This study demonstrates that spatial patterns of SST warming—not the magnitude of warming—play a dominant role in shaping future ENSO–TCGF linkages. While ENSO–TCGF relationships generally weaken under all warming scenarios, a notable strengthening (defined here as an increase in the magnitude of the TCGF difference between El Niño and La Niña years) occurs in the southeastern western North Pacific under uniform and El Niño–like warming. These results underscore the importance of considering SST pattern diversity in future projections and in improving seasonal TC prediction under climate change.

Record-breaking western North Pacific subtropical high during 2023

Development of a classification model for squids: Based on physicochemical and quality characteristics.

Abstract Based on seven reanalysis data sets and three atmospheric river (AR) detection algorithms, we investigate the dominant interdecadal modes of East Asian (EA) summer atmospheric rivers (ARs) from 1940 to 2024. The first mode exhibits a monopole pattern characterized by coherent AR enhancement, associated with a low‐level anomalous anticyclone and an intensified western North Pacific subtropical high (WNPSH). The anomalous anticyclone is maintained by the meridional wave train induced from the western tropical Pacific under the anomalous Indo‐West Pacific Walker circulation triggered by the negative sea surface temperature anomalies (SSTAs) over the southern Indian Ocean (IO), which is closely linked to the IO Basin mode. The second mode presents a zonal dipole pattern featured by opposite AR anomalies, corresponding to a pair of low‐level anomalous cyclonic and anticyclonic circulations and the northeastward WNPSH retreat. The dipole circulation is mainly sustained by the meridional wave train excited from the Maritime Continent (MC) when cold tropical eastern Pacific SSTAs and warm MC SSTAs generate an anomalous Pacific Walker circulation, accompanied by the combined effect of a wave train from the mid‐latitudes. The second mode is significantly modulated by the Pacific Decadal Oscillation. Particularly, the dominant EA AR mode varied from the monopole to dipole modes around 1977/1978 due to changes in oceanic forcing from the Indian to the Pacific Ocean, leading to a shift in EA AR frequency from an increasing trend to a relatively stable state.

Ocean Drilling Program Site 1256 was drilled in the Guatemala Basin, eastern Pacific Ocean, sampling superfast-spreading crust. It is one of the deepest drill holes sampling intact oceanic crust and the only site that has penetrated gabbroic rocks away from a tectonic window. Two gabbroic units were sampled at 1157 m and 1283 m below the basement. We collected seismic refraction and wide-angle reflection data across the drill site, and the resulting tomography models show that the first encountered gabbro does not mark the top of the seismic boundary between the upper (layer 2) and the lower (layer 3) crust, which we observe 500−600 m deeper. We propose that the drilled gabbroic rocks may represent either shallow intrusions or depth variations of the magma lens, marking the upper limit of a layer 2−layer 3 transition zone. Seismic tomography and wide-angle migration of mantle reflections reveal rather thin crust of 5 ± 0.2 km (i.e., ∼1.5 s two-way traveltime), being 1 km thinner than normal oceanic crust. The crustal deficit occurs solely within the lower crust. The observed thin crust distinctly differs from typical fast-spreading crust and may indicate the occurrence of a depleted mantle source. Yet, our preferred interpretation is that at superfast spreading rates of >200 mm/yr, the melt transport through the mantle is too slow to provide enough melts to form 6 km of oceanic crust.

Abstract. The western ocean boundaries of the North Pacific (NP) and North Atlantic (NA) set favourable conditions for upper-level jets and baroclinic weather systems that propagate downstream and form the storm tracks. Despite these similarities between the two ocean basins, distinct forcing mechanisms during the winter season give rise to differences in the jet intensity, structure, and variability, as well as in the storm track activity. In particular, the phenomenon of the NP midwinter suppression of the monthly averaged storm track activity sparked ongoing discussions about fundamental differences between jet-storm track interactions in the NP and NA. This study introduces an alternative method, which avoids monthly averaging, to study the relationship between the background jet core strength (U) and, as a measure of storm track activity, the eddy kinetic energy (EKE), both evaluated in the upper troposphere. With our approach, we find that the U-EKE relationship is remarkably consistent across the NP and NA, with previously observed differences largely attributable to the differing timescales of jet variability in the two basins. For our interpretation, the separate consideration of two distinct timescales is important: On seasonal timescales, baroclinic instability results in an increase of EKE with increasing U from summer to winter. In contrast, on sub-monthly timescales, particularly during winter, EKE decreases with increasing U, reflecting the effect of baroclinic conversion. Periods of enhanced baroclinic conversion lead to reduced baroclinicity (quantified by U) and high EKE, whereas periods of low baroclinic conversion are followed by high U and low EKE. In this framework, the NP midwinter suppression of monthly averaged EKE reflects that, in midwinter, U remains persistently high in the NP (because baroclinic conversion is suppressed) while EKE is reduced. In other words, in the NP, jet strength varies predominantly from month to month, whereas in the NA, it varies more within individual months such that the midwinter suppression of the monthly averaged storm track activity is less obvious in the NA. The observed U-EKE relationship implies that the jet core strength U alone cannot explain the EKE variability across seasons, and we reveal the additional importance of the jet width, which affects eddy characteristics. A reduced jet width likely plays a role in deforming and meridionally confining eddies, thereby reducing their baroclinic growth. For jets with comparable weak to moderate core strengths in summer and winter, the summertime jets tend to be narrower with smaller EKE. Similarly, very strong jets in winter are particularly narrow, which implies reduced EKE, supporting the observed U-EKE relationship in winter. Finally, cyclone composites show that the reduced EKE during strong jet episodes in winter is manifested by a reduction in the amplitude of the cyclones' surface pressure anomalies, and, in particular of their associated troughs and ridges. Therefore, the reduction of EKE with increasing U is not related to a decrease in cyclone frequency, but rather to a reduction in cyclone intensity and the associated upper-level wave pattern.

Abstract Atmospheric blocking exerts a profound influence on midlatitude circulation, yet its predictability remains elusive, due to intrinsic nonlinearities and sensitivity to initial conditions. While blocking dynamics have been extensively studied, the impact of geographical positioning on predictability remains largely unexplored. This study provides a comparative assessment of the predictability of western and eastern North Pacific blocking events, leveraging analogue‐based diagnostics applied to Coupled Model Intercomparison Project Phase 6 (CMIP6) Model for Interdisciplinary Research on Climate, version 6 (MIROC6) simulations. Blocking structures are identified using geopotential height gradient reversal, with their temporal evolution analyzed through trajectory tracking and error growth metrics. Results reveal that eastern blocks exhibit lower predictability, characterized by rapid error divergence and increased mean logarithmic growth rates compared with western blocks. Persistence analysis gives no significant difference between eastern and western North Pacific blocking events. Sensitivity analyses across varying detection thresholds validate the robustness of these findings.

ABSTRACT During the late summer (July–August) of 2024, the Northeast China (NEC) suffered extreme precipitation and severe floods, with rainfall in southern NEC marking the highest recorded since 1985. Using the daily precipitation records from 245 national meteorological stations across the NEC, this study analyses the characteristics of the rainfall anomalies and the associated large‐scale circulation patterns in the late summer of 2024. Based on the generalised equilibrium feedback analysis (GEFA) method, we investigate the response of precipitation and atmospheric circulation anomalies to sea surface temperature (SST) anomalies across various oceanic basins. The results indicate that the NEC precipitation anomalies in the late summer of 2024 exhibit a remarkable response to both the first empirical orthogonal function (EOF) mode of the North Pacific SST (NP1) and the second EOF mode of the tropical Atlantic SST (TA2). The NP1 features widespread positive SST anomalies extending from the Kuroshio Extension to the west coast of North America, and the TA2 is marked by positive anomalies in the northern tropical Atlantic and negative anomalies in the southeastern region. Both modes induce enhanced precipitation over NEC, with anomaly centres located southward, closely matching the observations. Specifically, the positive SST anomalies of the NP1 mode enhance the upward heat flux over the Japan Sea and its eastern regions, inducing positive geopotential height anomalies over Japan, thereby leading to an enhanced and northward anticyclone in the Northwest Pacific. Moreover, for the TA2 mode, the positive SST anomalies in the northern tropical Atlantic are closely associated with the downstream propagating Rossby wave train, resulting in an anomalous circulation pattern characterised by active Northeast China cold vortexes over the NEC and an intensified western Pacific subtropical high. These circulation anomalies facilitate the northward transport of warm and humid airflows to the NEC and promote the frequent convergence of cold and warm airflows over the NEC region, thereby contributing to the anomalously more precipitation over the NEC in the late summer of 2024. By quantifying the relative contributions of different SST modes, this study helps better target key precursors of NEC summer rainfall anomalies, which provides useful guidance for seasonal climate forecasting in NEC.

Immigrants are susceptible to marginalization within health care systems, and breast reconstruction after mastectomy is a procedure prone to disparities in delivery. We sought to measure differences in immediate and delayed reconstruction between immigrant and nonimmigrant females with breast cancer in urban Ontario, Canada. We conducted a retrospective population-based study using linked administrative databases held at ICES. We included female patients with stage I to III breast cancer, diagnosed from January 2010 through April 2016, who were treated with mastectomy. We excluded those with in situ disease only, missing staging data, another cancer diagnosis, no provincial health coverage, or rural residence. We categorized patients as immigrants if they arrived in Canada from 1985 onward. We compared the proportions of immigrants and nonimmigrants who underwent breast reconstruction. We identified 2174 immigrants and 12 052 nonimmigrants. Immigrants were younger (mean age 53.3 yr v. 62.2 yr) and more often had stage III disease (32.8% v. 29.7%). They were less likely to undergo reconstruction (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.48 to 0.62). In stratified analyses by age (< 50 yr and ≥ 50 yr), compared with nonimmigrants, the odds ratio for reconstruction was 0.51 (95% CI 0.44 to 0.60) in immigrants younger than 50 years and 1.12 (95% CI 0.94 to 1.30) in those aged 50 years and older. The difference between groups was more pronounced for delayed (OR 0.48, 95% CI 0.41 to 0.56) than immediate (OR 0.83, 95% CI 0.68 to 1.00) reconstruction. Immigrants were less likely to undergo reconstruction regardless of disease stage. Those from East Asian or Pacific, South Asian, and sub-Saharan African regions were least likely to undergo reconstruction. Immigrant females were less likely to undergo breast reconstruction than nonimmigrant females. This study identified subgroups for further research to understand how to ensure equitable access to this important health care resource.

Abstract. The mangrove ecosystem stands out for the numerous environmental services it provides, in addition to being one of the most vulnerable ecosystems to climate change. Marismas Nacionales is located in northwestern Mexico and hosts one of the most extensive areas of continuous mangrove ecosystem along the Pacific North coast of Mexico. Although vital, this mangrove ecosystem faces multiple pressures and is shifting inland in response to climate change —making ongoing monitoring of its size and health essential. Aiming for monitoring the health of mangrove and disturbed mangrove areas, a time series of monthly NDVI composites derived from Sentinel-2 imagery (10 m spatial resolution) was analyzed for the period 2019–2024. At the pixel level, the Mann-Kendall test was applied to determine significant trends. An inspection of the Z-statistic was conducted to identify gradual and relevant changes; when possible, these changes were validated with field data and high-resolution imagery. The results revealed heterogeneity in the behavior of pixel time series, reflected in the values of the Z-statistic. This heterogeneity is due to the fact that mangroves are subject to different change factors depending on their spatial location. Among the key factors identified were hurricane-induced damage, land-use change, inland colonization, recovery driven by restoration efforts, post-hurricane vegetation rebound, and losses resulting from coastal erosion. Across the 80,959 hectares encompassed by the study area, 47.08% exhibited a significant negative trend, 20.19% a non-significant negative trend, 18.07% a non-significant positive trend, and 14.66% a significant positive trend. The analyzed data revealed the dynamic nature of the mangrove ecosystem in response to various change factors, and the proposed method could serve as a foundation for integration into the national products generated by Mexico’s Mangrove Monitoring System.

This study presents a validated framework to quantify regional sea-level risk on U.S. coasts by (i) extracting trends and seasonality from satellite altimetry (ADT, GMSL), (ii) learning regional dynamical regimes via PCA-embedded KMeans on gridded ADT time series, and (iii) coupling these regimes with socioeconomic exposure (population, income, ocean-sector employment/GDP) and wetland submersion scoring. Relative to linear and ARIMA/SARIMA baselines, a sinusoid+trend fit and an LSTM forecaster reduce out-of-sample error (MAE/RMSE) across the North Atlantic, North Pacific, and Gulf of Mexico. The clustering separates high-variability coastal segments, and an interpretable submersion score integrates elevation quantiles and land cover to produce ranked adaptation priorities. Overall, the framework converts heterogeneous physical signals into decision-ready coastal risk tiers to support targeted defenses, zoning, and conservation planning.

Marine phytoplankton are central to global seascapes, acting as key conduits in element cycling and oceanic food webs. Phytoplankton cell size spans several orders of magnitude (0.2 to >200 µm) and is an important trait that governs metabolism. However, the vast taxonomic diversity within phytoplankton size classes makes it challenging to link specific taxa to bulk community changes in productivity and elemental stoichiometry. To explore phytoplankton biogeography and biogeochemical roles in field populations, we analyzed 3 years of 16S and 18S rRNA gene amplicon sequencing variant (ASV) data alongside biochemical measurements across the dynamic latitudinal gradient of the North Pacific Transition Zone. We identified picophytoplankton community members associated with patterns in net community production (NCP), particulate organic carbon (POC), and particulate organic nitrogen (PON) and uncovered co-occurring species that may influence their growth and abundance. Multivariate linear mixed modeling revealed that the occurrence of chlorophytes explained 22.6% of NCP values, followed by stramenopiles and cyanobacteria. In contrast, POC and PON spatial patterns were best explained by chlorophyte and dinoflagellate spatial patterns. Weighted co-expression network analysis further showed NCP, POC, and PON correlations with a subset of ~40 ASVs belonging to chlorophytes, cyanobacteria, stramenopiles, haptophytes, and dinoflagellates that range in trophic strategy. Association network inference recapitulated these findings and revealed additional co-occurring phytoplankton, grazers, and heterotrophic bacteria. Together, our integrated computational analyses identified key picophytoplankton and co-occurring mixotrophs as major contributors to shaping regional biogeochemical dynamics in the North Pacific Ocean.IMPORTANCEPhytoplankton mediate key biogeochemical processes in dynamic oceanic transition zones. However, their vast cell size range and taxonomic diversity make it challenging to link specific taxa to bulk community changes in productivity and elemental stoichiometry. By integrating molecular and biogeochemical measurements from the North Pacific Transition Zone using combined network and multivariate modeling, we identified specific picophytoplankton strongly linked to community production and organic nutrients levels. These picophytoplankton included specific members of cyanobacteria, pelagophytes, haptophytes, and chlorophytes and formed tight associations with several nano- and pico-sized protistan mixotrophs, highlighting how top-down interactions and microbial consortia shape community structure and elemental fluxes. Our work establishes key microbial players that may control fundamental ecosystem processes like carbon and nitrogen cycling and offers a computational framework to track and identify "microbial neighborhoods" that underpin biogeochemical features of an ecosystem.

ABSTRACT Measures of an organism's weight at a given length are often considered reliable indicators of energy reserves or ‘condition’, which can be related to fecundity and risk of mortality. Understanding the impact of environmental change on fish condition may therefore inform sustainable management of human activities in marine ecosystems. We investigated how changes in Canadian Pacific waters may be influencing the average condition of 35 commercially, culturally, and/or ecologically important demersal fish species. Because the condition of mature male and female, and immature individuals differs in its implications for population dynamics, ecological drivers, and measurement variability, we analysed these three maturity groups separately. We estimated density distributions, calculated Le Cren's relative body condition deviations, modelled spatiotemporal change in these deviations, and generated density‐weighted annual indices of body condition. We used Bayesian Dynamic Factor Analysis to identify common trends across species and tested for correlations with environmental variables. For most species, warmer sea surface temperature and lagged North Pacific Gyre Oscillation appeared neutrally or positively correlated with condition. Only the immature condition was also strongly correlated with primary production, but this effect was equally likely to be negative (e.g., Pacific Spiny Dogfish, Lingcod, and Sablefish) as positive (e.g., Quillback Rockfish, Southern Rock Sole, and Spotted Ratfish). Our approach propagates uncertainty from condition estimation through to environmental correlations to provide both ecosystem‐level and species‐specific inference. Robust estimates of relationships between condition and environmental variables can inform ecosystem approaches to fisheries management, including short‐term forecasts of weight‐at‐age or recruitment.

Sea ice variability in the Laptev and East Siberian Seas (LESS) notably affects Arctic climate and maritime safety. While El Niño–Southern Oscillation (ENSO) winter sea surface temperature anomalies influence global climate, their effect on subsequent autumn LESS ice remains unclear. This study reveals a post-2000 intensification of winter ENSO’s impact on subsequent autumn LESS ice, driven by accelerated ENSO phase transitions compared to the pre-2000 era. Rapid phase transitions of El Niño after 2000 generate persistent cold anomalies in the tropical central–eastern Pacific during the subsequent autumn, strengthening and displacing the Western North Pacific anticyclone (WNPAC) northward. This WNPAC triggers Rossby waves establishing an Arctic anticyclone, warming, and moistening the LESS atmosphere, thereby driving substantial ice loss. In contrast, pre-2000 slower El Niño decay exhibited weaker tropical-Arctic connectivity. These results identify ENSO phase transitions rate as a critical regulator of Arctic sea ice variability, with important implications for seasonal forecasting.

Abstract Tropical cyclones (TCs) can be considered as Carnot heat engines, where thermodynamic efficiency depends on the sea surface temperature (SST) and TC outflow temperature ( T o ) in the upper atmosphere. This study investigates how TC efficiency in the western North Pacific (WNP) Ocean varies under different El Niño‐Southern Oscillation (ENSO) conditions: the Eastern Pacific (EP), the Central Pacific (CP), and the Mixed El Niño types, as well as La Niña. We also explore how these changes affect a TC's theoretical upper bound (potential intensity (PI)). Using a reanalysis data set from 1979 to 2024, we find that TC efficiency decreases during La Niña, due to warmer T o , and increases during CP El Niño, where upper‐level cooling dominates. EP and Mixed El Niño show more heterogeneous responses. These efficiency changes contribute to PI variability from −38 to +27%, depending on ENSO type and region.

The El Niño-Southern Oscillation (ENSO) is a profound climatic and oceanographic phenomenon arising from the thermal contrast between the western and eastern Pacific Ocean, and has far-reaching influences on ocean heat distribution, monsoonal rainfall and thermal structure of the water column in the Pacific Ocean. The East China Sea (ECS) is a marginal sea in the western Pacific, significantly influenced by the Kuroshio Current (KC), which originates from the West Pacific Warm Pool. The warm and saline water transported by KC determines the surface-to-subsurface oceanographic conditions, including the thermocline structure of the ECS. Downcore variability of the thermocline-sensitive planktic foraminifera over ~400 ka at IODP Site U1429 has been considered to decipher the linkage of ENSO-like processes and the thermocline structure in the ECS. Singular Value Decomposition (SVD) analysis was applied to major thermocline planktic foraminiferal ( Neogloboquadrina dutertrei, Globoconella inflata , and Pulleniatina obliquiloculata ) abundance data to extract three modes representing three distinct palaeoclimate signals. Trend-synchronisation tests were carried out to study the linear/non-linear relationship between obtained SVD modes, KC strength, SST, Salinity, Insolation variability and paleo-ENSO Proxy. SVD Mode 1 corresponds to KC subsurface intrusion, Mode 2 represents KC-induced seasonal upwelling, and Mode 3 is found to be linked with the residual signal of ENSO-like processes in the ECS. This study reveals that stronger KC during interglacial phases (MIS 9, 7, and 5) corresponds to La Niña-like conditions, which deepens the thermocline as indicated by thermocline species P. obliquiloculata . The intensification of La Niña-like conditions in the ECS occurred during the last 150 ka, with no effect of local insolation on the thermocline depths in the ECS.

Deep-sea hydrothermal vent fauna is often regarded as highly endemic, although exceptions have been reported. We examined genetic connectivity across broad spatial scales within the alvinocaridid genus Rimicaris, which has undergone substantial adaptive radiation worldwide. We analyzed six Rimicaris species using three genetic markers, cytochrome c oxidase subunit I (COI), 16S ribosomal rRNA gene (16S), and histone h3 (H3), and complete mitogenomes, employing newly generated sequences combined with publicly available sequence data. A genetic tree and haplotype networks were constructed, and divergence analyses were performed. Three clades of paired Rimicaris species were identified, each made up of taxa from different oceanic regions but showing relatively low COI divergence (0.35-1.90%). In Clade I, Rimicaris chacei and Rimicaris hybisae are morphologically similar and exhibit bidirectional gene flow, implying a dispersal route between the Mid-Atlantic Ridge (MAR) and the Mid-Cayman Spreading Center (MCSC). In Clade II, Rimicaris exoculata and Rimicaris kairei are morphologically, genetically, and ecologically distinct, reflecting restricted connectivity between the MAR and the Carlsberg Ridge (CR)-Central Indian Ridge (CIR). In Clade III, Rimicaris variabilis and Rimicaris cf. variabilis differ in nutritional strategies, showing a unidirectional dispersal route from the CIR to the southwestern Pacific (SWP), but morphological data to distinguish them are currently lacking. Some Rimicaris lineages maintain connectivity across distinct oceanic regions while others still form unique regional populations. This finding highlights the need for conservation strategies that incorporate both global-scale connectivity and regional endemism, rather than treating individual vent ecosystems as a single homogeneous management unit.