North Pacific Research Articles

Relationship of Decadal Variations in East Asian Winter Monsoon and Northwestern North Pacific SST in CMIP6 Preindustrial Long-Term Simulations

Relationship of Decadal Variations in East Asian Winter Monsoon and Northwestern North Pacific SST in CMIP6 Preindustrial Long-Term Simulations

Spatiotemporal distribution of marine aerosols and gaseous species over the North Pacific Ocean.

Observational studies of marine aerosols are essential for understanding the global aerosol budget and its environmental impacts. This study presents simultaneous in-situ measurements of major ionic components (Cl-, NO3-, SO42-, NH4+, K+, Ca2+, Na+, and Mg2+) in aerosols and gaseous species (HCl, HNO3, HONO, SO2, and NH3) over the North Pacific Ocean from July 4 to 15 and September 19 to October 3, 2022. Using high temporal resolution instruments aboard the Republic of Korea's icebreaker research vessel Araon, this study aimed to (1) report the spatial and temporal distributions of aerosols and gaseous species, (2) estimate the source contributions of continental anthropogenic pollutants, and (3) assess the influence of aerosol chemical composition and gaseous species on aerosol acidity and water content. Our results revealed a significant decline in anthropogenic contributions, from 72.4±11.2% in the Yellow Sea and East Sea to 32.0±10.8% in the remote Pacific, accompanied by an increase in natural aerosols from 27.6±11.2% to 68.0±10.8%. Elevated concentrations of ammonia (NH3) and nitrous acid (HONO) were observed in the remote ocean, likely associated with the marine environment and biological activities. This increase in NH3, along with a decrease in sulfate concentrations, contributed to the formation of more alkaline aerosols in the remote ocean. Despite the limited availability of previous studies for direct comparisons, our findings align with observed trends and highlight the unique physicochemical properties of marine aerosols. These results enhance our understanding for the interactions between continental pollutants and marine environments, emphasizing the distinct characteristics of marine aerosols and their potential role in modifying atmospheric processes and influencing climate change.

Post-spawning migration and habitat use of adult Pacific bluefin tuna (Thunnus orientalis) in the western North Pacific

Pacific bluefin tuna (PBF, Thunnus orientalis), migrate widely throughout the north Pacific Ocean during all life stages. However, studies on the migration of adult fish in the northwestern Pacific Ocean, where spawning occurs, are limited. This study investigated the post-spawning migration and habitat use of PBF from the major spawning grounds of the Nansei Islands (approximately 23–31° N), Japan, using pop-up satellite archival transmission (PAT) tags. The PAT tags were deployed on 15 PBF individuals (estimated fork lengths: 170–260 cm) in the late spawning season (May–June) of 2021, and tracking data were collected for 3–103 days. Four tagged PBF individuals moved > 2,500 km north to the Kuroshio-Oyashio transition region at high latitudes (40° N) in July–September, immediately after the spawning season. During this northward movement, these PBF showed a spatiotemporal change in their vertical behavior, adapting to regional thermal habitat differences. At low latitudes near the spawning grounds (23.6–29.6° N), the PBF dived to deep depths (mean: 162.8 m) to avoid the warm surface layer (mean: 28.6 °C); however, once they reached higher latitudes (36.6–44.9° N), they spent most of their time in the cool surface layer (mean: 18.5 °C; 22.3 m). Our findings suggest that adult PBF move from spawning grounds to physiologically suitable low-temperature, food-rich waters through long-distance movements, and then exhibit a habitat preference behavior characterized by repeated short-distance movements in response to the feeding environments at high latitudes.

The very-high-resolution configuration of the EC-Earth global model for HighResMIP

Abstract. We present the very-high-resolution (VHR) version of the EC-Earth global climate model, EC-Earth3P-VHR, developed for HighResMIP. The model features an atmospheric resolution of ∼16 km and an oceanic resolution of 1/12° (∼8 km), which makes it one of the finest combined resolutions ever used to complete historical and scenario-like CMIP6 simulations. To evaluate the influence of numerical resolution on the simulated climate, EC-Earth3P-VHR is compared with two configurations of the same model at lower resolution: the ∼100 km grid EC-Earth3P-LR (LR) and the ∼25 km grid EC-Earth3P-HR (HR). Of the three configurations, VHR shows the smallest drift in the global mean ocean temperature and salinity at the end of a 100-year 1950s control simulation, which points to a faster equilibrating phase than in LR and HR. In terms of model biases, we compare the historical simulations against observations over the period 1980–2014. In contrast to LR and HR, VHR shows a reduced equatorial Pacific cold tongue bias, an improved Gulf Stream representation with a reduced coastal warm bias and a reduced subpolar North Atlantic cold bias, and more realistic orographic precipitation over mountain ranges. By contrast, VHR shows a larger warm bias and overly low sea ice extent over the Southern Ocean. Such biases in surface temperature have an impact on the atmospheric circulation aloft, connected with a more realistic storm track over the North Atlantic yet a less realistic storm track over the Southern Ocean compared to the lower-resolution model versions. Other biases persist or worsen with increased resolution from LR to VHR, such as the warm bias over the tropical upwelling region and the associated cloud cover underestimation, a precipitation excess over the tropical South Atlantic and North Pacific, and overly thick sea ice and an excess in oceanic mixing in the Arctic. VHR shows improved air–sea coupling over the tropical region, although it tends to overestimate the oceanic influence on the atmospheric variability at midlatitudes compared to observations and LR and HR. Together, these results highlight the potential for improved simulated climate in key regions, such as the Gulf Stream and the Equator, when the atmospheric and oceanic resolutions are finer than 25 km in both the ocean and atmosphere. Thanks to its unprecedented resolution, EC-Earth3P-VHR offers a new opportunity to study climate variability and change of such areas on regional and local spatial scales, in line with regional climate models.

‘Good Contact in Spite of Static’: Advocating a Radio Geopolitics Assemblage Approach Through Analysing the Lindberghs’ 1931 North Pacific Flight

ABSTRACT In the summer of 1931 famed US aviator Charles Lindbergh and his wife, Anne, flew their Sirius aircraft from Washington DC, westward across northern Canada, Alaska and the Bering Strait to Japan and China. Although touted as a vacation, they were in fact surveying for Pan American Airways’ first trans-pacific air route, an endeavour that would further project US power across the Pacific. This paper uses this example to advance a way of thinking about the capacities of radio to be geopolitical beyond the popular culture mass-media broadcaster focus on much extant work on radio geopolitics. Two examples, focusing on Anne Lindbergh’s role as radio operator for this flight, are used to bring assemblage thinking and radio geopolitics together to advocate for the creation of a radio geopolitics assemblage, which provides a way to engage with how different uses of radio can be inculcated in the projection of power across space.

Unusual and persistent easterlies restrained the 2023/24 El Niño development after a triple-dip La Niña

The 2023/24 El Niño, emerging after a rare triple-dip La Niña, garnered global attention due to its potential to evolve into an extreme event, given the largest accumulation of warm water in the equatorial western Pacific since 1980. Despite initial expectations, its growth rate unexpectedly decelerated in mid-2023, preventing it from reaching the anticipated intensity. Here, we show through observational analyses that unusual easterly anomalies over the tropical western-central Pacific, persisting after the end of the preceding La Niña, significantly contributed to this slowdown. A prominent east‒west sea surface temperature gradient in the region has been identified as the crucial factor associated with these unusual and persistent easterly anomalies. This temperature gradient is directly attributed to a negative North Pacific Meridional Mode and a deepened thermocline over the Philippine Sea. These findings offer a deeper understanding of the atypical transition from a prolonged multi-year La Niña to an El Niño.

Statistical Analysis of North Pacific Storm Track Precipitation Based on GPM Observation Data

Statistical Analysis of North Pacific Storm Track Precipitation Based on GPM Observation Data

Decadal Regime Shifts in Sea Fog Frequency over the Northwestern Pacific: The Influence of the Pacific Decadal Oscillation and Sea Surface Temperature Warming

Sea fog significantly impacts marine activities, ecosystems, and radiation balance. We analyzed the decadal variation characteristics of sea fog frequency (SFF) over the northwestern Pacific and investigated the roles of the Pacific decadal oscillation (PDO) and sea surface temperature (SST) warming in driving these changes. The results show that SFF experienced a significant and sudden decadal increase around 1978 (up by 12.9%) and a prominent decadal decrease around 1999 (down by 7.8%). The sudden increase in SFF around 1978 was closely related to the PDO. A positive PDO phase induced unusual anticyclonic circulation and southerly winds over the northwestern Pacific, enhancing low-level atmospheric stability and moisture supply, thus facilitating sea fog formation. Nevertheless, the decrease in SFF around 1999 was related to SST warming in the north Pacific. The rise in sea temperatures weakened the SST front south of the foggy region, reducing the cooling and condensation of warm air necessary for sea fog formation. This study enhances the understanding of the decadal variability mechanism of SFF over the northwestern Pacific regulated by large-scale circulation systems and provides a reference for future sea fog forecasting work.

Future changes and uncertainty in tropical cyclone genesis over the western North Pacific: insights from the dynamic genesis potential index using CMIP6 models

Future changes and uncertainty in tropical cyclone genesis over the western North Pacific: insights from the dynamic genesis potential index using CMIP6 models

High prediction skill of decadal tropical cyclone variability in the North Atlantic and East Pacific in the met office decadal prediction system DePreSys4

The UK Met Office decadal prediction system DePreSys4 shows skill in predicting the number of tropical cyclones (TCs) and TC track density over the eastern Pacific and tropical Atlantic Ocean on the decadal timescale (up to ACC = 0.93 and ACC = 0.83, respectively, as measured by the anomaly correlation coefficient—ACC). The high skill in predicting the number of TCs is related to the simulation of the externally forced response, with internal climate variability also allowing the improvement in prediction skill. The Skill is due to the model’s ability to predict the temporal evolution of surface temperature and vertical wind shear over the eastern Pacific and tropical Atlantic Ocean. We apply a signal-to-noise calibration framework and show that DePreSys4 predicts an increase in the number of TCs over the eastern Pacific and the tropical Atlantic Ocean in the next decade (2023–2030), potentially leading to high economic losses.

Contrasting the Intraseasonal Precipitation in the Western and Eastern North Pacific During Boreal Winter

AbstractThe wintertime North Pacific exhibits two types of intraseasonal periodicity in daily precipitation, with a period of 10–20 and 30–90 days in the western and eastern North Pacific. This study aims to identify and compare characteristics and mechanisms of intraseasonal precipitation in these two regions using daily observational data. Our results indicate their notable differences in atmospheric circulations and dynamical processes, despite similarities in moisture sources. A wave train associated with the intraseasonal precipitation in the western North Pacific characterized by anomalous cyclones and anticyclones from West Siberia into the North Pacific is observed, accompanied by anomalous wave activity. By diagnosing local finite‐amplitude wave activity (LWA) budget, we demonstrate that the baroclinic eddy generation initiates the upstream growth of wave activity, whereas its downstream development is primarily attributed to the zonal advection of wave train. The upstream wave train induces barotropic and baroclinic instabilities in Kuroshio‐Oyashio extension (KOE). In contrast, the anomalous atmospheric circulations related to intraseasonal precipitation in the eastern North Pacific feature a tripolar structure, with downstream propagation of wave activity from the eastern North Pacific to the North American continent. Diabatic heating, along with local eddy generation, contributes to the upstream growth of wave activity. Residual term, possibly linked to the wave activity dissipation associated with wave breaking, extends the wave activity downstream. Thermal and baroclinic instabilities, associated with the diabatic heating and local eddy generation, create favorable conditions for the precipitation. This study may contribute to the improvement of intraseasonal precipitation prediction over the pan‐North Pacific region.

The 2020 Mw 6.4 Koryak Highlands earthquake illustrates hidden seismic hazards in the northern Pacific Cordillera

Summary On 9th January 2020, a Mw 6.4 earthquake struck the central Koryak Highlands of eastern Siberia, northeast of the diffuse triple junction between the North American, Pacific and Eurasian plates. The largest earthquake recorded in the central Koryak Highlands to date, it provides an excellent opportunity to study the little-known active tectonics of this remote, sparsely instrumented region. We mapped coherent, coseismic surface deformation with Sentinel 1 Interferometric Synthetic Aperture Radar (InSAR), making this one of the highest-latitude earthquakes to be captured successfully with satellite radar, in spite of the rugged, snow-covered terrain. Elastic dislocation modelling, teleseismic back-projections, calibrated hypocentral relocations, and teleseismic moment tensor solutions are used to resolve a left-lateral fault trending northwestwards, proximal but perpendicular to a regional geological suture zone, the Khatyrka-Vyvenka Thrust. The earthquake probably ruptured unilaterally northwestwards along a 20 km long segment that appears indistinct in the local topography, and likely generated no surface rupture. We interpret that these observations are indicative of a structurally immature fault zone and estimate a seismogenic zone thickness of 10–15 km. The Koryak Highlands earthquake illustrates how terrane boundaries within cordilleran belts may continue to accommodate tectonic strain long after accretion, resulting in significant earthquakes even along hidden faults.

Multi-decade northward shift of loggerhead sea turtle pelagic habitat as the eastern North Pacific Transition Zone becomes more oligotrophic

The North Pacific Transition Zone (NPTZ) is known as a global marine hotspot for many endangered and commercially significant highly mobile marine species. In the last few decades, the region has undergone unprecedented physical and biological transformations in response to climate variability and change. Although it is anticipated that many highly mobile species will need to adapt and shift their distributions, current predictions have relied on short-term data sets or modeled simulations. This has left a critical gap in our understanding of long-term (decadal or longer) change and species’ responses within the NPTZ. Here, we integrate nearly 3 decades of satellite tracking data from a climate sentinel, the juvenile North Pacific loggerhead sea turtle (Caretta caretta), with concurrent observations of sea surface temperature (SST) and chlorophyll-a concentrations to examine higher trophic level response to climate-induced changes within the eastern bounds of the NPTZ. Between 1997–2024, the NPTZ has warmed by 1.6°C and experienced an approximately 19% decline in mean surface chlorophyll-a concentration, a proxy for reduced productivity, resulting in a 28% (1.65 million km2) increase in total oligotrophic habitat in the eastern NPTZ. Over the same period, the average latitude of loggerhead sea turtle foraging habitat in the NPTZ has shifted northwards by 450–600 km. This represents a distributional shift rate of 116–200km/decade. In most years both the southern and northern range limits for the loggerhead turtle have shifted northward in tandem, indicating a habitat range shift rather than a range expansion. Our findings reveal significant physical and biological change to the NPTZ over the last quarter century and the first empirical evidence illustrating the substantial spatial response of a highly mobile megafaunal species. As the NPTZ continues to become more oligotrophic, these insights can provide vital information for dynamic conservation and management strategies within this critically important ecosystem.

Impact of Tibetan plateau warming amplification on the interannual variations in East Asia Summer precipitation

The amplified warming on the Tibetan Plateau (TA) is a distinctive characteristic of global climate change, leading to various climate responses with far-reaching implications. This study investigates the influence of interannual variation of TA on summer precipitation over East Asia (Pre_EA) using observational data and a Linear Baroclinic Model (LBM). When TA exceeds the Northern Hemisphere average, summer precipitation in the Yangtze River Valley significantly decreases, while it increases in North China and South China, resulting in a tripole Pre_EA pattern. Notably, the relationship between TA and Pre_EA is independent of the El Niño-Southern Oscillation (ENSO) and explains more variance in Pre_EA than ENSO. Our analysis reveals that TA enhances the tripole Pre_EA pattern by modulating moisture transport and vertical motion in the East Asia-North Pacific regions. Specifically, positive TA is linked to significant local tropospheric warming, which intensifies and eastward expands the South Asian High, creating a double-gyre meridional circulation over East Asia. Additionally, positive TA induces an eastward-propagating wave, reinforcing a midlatitude anomalous high-pressure belt over East Asia and the western North Pacific regions. These circulation changes weaken the East Asian subtropical jet, form a notable double jet configuration, and promote subsidence over mid-latitude East Asia. Moreover, anomalously warm sea surface temperatures in the Northwestern Pacific reinforce the TA-Pre_EA relationship by contributing to the mid-latitude East Asia-North Pacific high-pressure belt. Our LBM model experiments support these findings. Our study provides an in-depth understanding of the physical processes influencing summer precipitation variability in East Asia.

Amplified Bimodal Distribution of Western North Pacific Tropical Cyclone Lifetime Maximum Intensity

AbstractThe impact of a warming climate on tropical cyclones (TCs) remains unclear. Here, we find that the probability density function for western North Pacific TC lifetime maximum intensity (LMI) has an amplified bimodal distribution in recent years. This change implies a trend toward more extreme TCs and fewer moderate TCs. Changes in the TC LMI distribution are associated with alterations in the occurrence of rapidly intensifying TCs. Changes in TC tracks, due to alterations in the steering flow linked to a weakening Hadley cell, cause more TCs to move northwestward into a more favorable environment for intensification with large ocean heat content. Consequently, more rapidly intensifying TCs reach higher intensities, significantly contributing to the observed amplified bimodal distribution. These findings provide new insights into changes in TC intensity and highlight the increasing threat to coastal areas from more intense TCs in a warming climate.

Pacific sailfish (Istiophorus platypterus) in the Eastern Pacific Ocean, association with ocean currents and seasonal effects of upwelling using real-time Argos locations

Pacific sailfish (Istiophorus platypterus) in the Eastern Pacific Ocean, association with ocean currents and seasonal effects of upwelling using real-time Argos locations

Improving tropical cyclone rapid intensification forecasts with satellite measurements of sea surface salinity and calibrated machine learning

Abstract Forecasting rapid intensification (RI) of tropical cyclones (TC) is a mission known for large errors. One under-researched factor that affects TC intensification is salinity, which is important for density stratification in certain ocean regions and can affect the surface enthalpy flux under a strengthening hurricane. To investigate the impact and efficacy of using salinity information in state-of-the-art forecasting, we use a statistical model consisting of a variety of machine learning (ML) methods. For salinity data, we use satellite measurements of pre-storm sea surface salinity (SSS) as a proxy for the salinity stratification. We train and test the model on various ocean basins, including the Atlantic, northern east Pacific, northern west Pacific. A calibrator was trained on top of the ML models to correct and enhance probability forecasts. The calibrator significantly improves probability forecasts relative to recent works. The ML model performance is improved with the addition of SSS in the Eastern North Pacific, western North Pacific, and the Caribbean subregion of the North Atlantic, and the overall model performance is better than previous studies. SSS decreases model skill for a model trained on the full Atlantic basin. In the Indian Ocean, SSS is also notably correlated with RI occurrence, but the TC samples are not sufficient to train ML models.

Who cares about caring? Gender stereotypes about communal values emerge early and predict boys' prosocial preferences.

Communal values (i.e., valuing care for and connection with others) are important to individual well-being and societal functioning yet show marked gender differences, with girls valuing communion more than boys do. We examined whether endorsement of gender stereotypes associating communal values more with girls than with boys relate to children's own communal values and interests, potentially giving rise to gender differences in preferences. We tested this relation across two studies with Canadian children between the ages of 4 and 11 years (N = 379; 92 girls, 287 boys; majority White and East Asian or Pacific Islander). We assessed children's stereotypes about communal values (Studies 1 and 2; e.g., "Who do you think cares more about always helping other people, even if it takes effort? Boys or girls?"), as well as the extent to which children themselves (a) valued communion and (b) displayed interest in communal activities (Study 2). In both studies, we found that children older than 6 consistently associated communal values with girls more than with boys. Younger children, in contrast, exhibited an ingroup bias-they associated communal values with their own gender. Study 2, which included only boys, found that endorsement of stereotypes associating communal values with girls predicted lower personal endorsement of communal values and lower interest in communal activities among boys older, but not younger, than 6. These results suggest that gender stereotypes about communal values are learned early and predict boys' disengagement from communal domains. Implications for gender differences in values and behavior are discussed. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Remote sensing of the subsurface chlorophyll maximum depth in the North Pacific Ocean

ABSTRACT Estimation of the subsurface chlorophyll maximum (SCM) depth is critical to constructing the vertical profile of chlorophyll a, which in turn is important in accurately assessing phytoplankton distribution, especially in the extensive tropical oceans. Current ocean colour algorithms generally detect a limited area only or use a suite of environmental variables, part of which may be difficultly quantified. By using field in situ observations, a two-step approach, in which the first step used a relationship between sea surface temperature and surface chlorophyll to detect the occurrence of the SCM and the second step used an algorithm based on the ratio of remote sensing reflectance, was developed to remotely estimate the SCM depth in the North Pacific. Although this approach, with the inputs of easily available ocean colour data, is simple, the deviation in the remotely sensed SCM depth was only about ± 17%. Our study may provide a promising approach to assess the stratification status of the water column and to help profiling the vertical variation of chlorophyll in the North Pacific and even in the global oceans.

Influence of Two Spatially Distinct Types of Arctic Oscillation on El Niño

AbstractThis study examines the cross‐seasonal influence of the Arctic Oscillation (AO) on winter El Niño, using atmospheric and oceanic reanalysis data sets. It has been revealed that the linkage between positive AO and subsequent El Niño is closest during spring, indicating the seasonal dependent and selective impact of AO on ENSO. Composition analyses illustrate that positive spring AO is often associated with a dipole circulation anomaly over the North Pacific. The corresponding cyclonic circulation anomaly in the subtropical North Pacific initiates the Pacific Meridional Mode (PMM), which persists and evolves through the wind‐evaporation‐SST (WES) feedback from, triggering the westerly anomalies in the tropical western Pacific and subsequently triggering the onset of El Niño. Further clustering analysis reveals that the positive spring AO events exhibit two distinct spatial patterns: Type1 with prominent positive SLP anomaly over the midlatitude North Pacific and Type2 with the positive SLP anomaly over the North Atlantic. Both types can trigger El Niño by stimulating the subtropical cyclone anomaly in the North Pacific but through different mechanisms. In Type1 events, high‐pressure anomalies in the midlatitude North Pacific trigger southward‐propagating atmospheric waves, generating the cyclone anomalies in the subtropical North Pacific. Although in Type2 events, the AO‐related circulation anomalies in the North Atlantic stimulate teleconnection wave trains that cross the Eurasian continent and propagate southward to the subtropical North Pacific, inducing the cyclone anomalies. However, Type1 events occur more frequently and are more closely linked to El Niño, highlighting the significant role of air‐sea coupling processes in the North Pacific in triggering El Niño.