West Pacific Research Articles

Ionospheric responses to the tropical cyclones from different oceanic basins over the globe

The perturbations in the ionosphere due to eight tropical cyclones (TCs), namely Iota, Haima, Harold, Willa, Amphan, Gaja, Vadrah and Bulbul, originated and grown in different oceanic basins, are investigated. Total Electron Content (TEC) data, from Global Positioning System (GPS) TEC receiver in operation at Agartala (AGT) or different International GNSS Service (IGS) stations near the cyclone landfall regions, are used in this study. Despite some differences, the ionosphere responds to all tropical cyclones in an almost similar manner. Though the geomagnetic conditions are quiet and there are no perturbations due to any other geophysical phenomena in the active cyclonic storm stage, in all the cases there is a fall in average vertical total electron content (VTEC) deviations below the monthly mean value either on the landfall day or on the following day or even on just previous day. Decrements in Vertical Total Electron Content are found higher for tropical cyclones over North Indian and South Pacific oceanic basins. Recoveries in vertical total electron content values are slower for cyclones over the North Atlantic and North West Pacific basins. Recoveries in vertical total electron content (VTEC) values are slow for tropical cyclones (TCs) over the North Atlantic and North West Pacific basins. But those over other basins are quick. The longer the track of a tropical cyclone (TC), the higher is the reduction in the vertical total electron content (VTEC) value. A negative correlation exists between the maximum sustained surface wind velocities and the total periods of different TCs and also the difference of lowest average differential VTECs with that on the previous day. The observed anomaly in ionospheric responses might be due to the combined effect of TC-inspired gravity waves, ejection of neutral particles from the terminator of a tropical cyclone (TC) and lightning electric fields. To explain the observed results convective activities during TC, with the help of outgoing long wave radiation (OLR) map, are also taken into account. This study provides the primary results regarding regional characteristics and hence a comparative idea for the responses of the ionosphere to different tropical cyclones (TCs) from different geographical positions on the globe, which needs further comprehensive investigation in future.

A dynamic rifting model of the Caroline Ridge, West Pacific

The dynamic rifting model of the Caroline Ridge, an oceanic plateau in the West Pacific, remains unclear. Previous studies have revealed that the crustal width of the Caroline Ridge clearly varies from the northwest to the southeast. Here, we investigate Caroline Ridge rifting using numerical simulation and reveal the relationships between different plateau sizes and rifting. For small-scale oceanic plateaus, the initial rift migration forms a symmetric structure. The strain transfers toward one side of the margin. The rifting manifests as a process from landward migration to seaward migration, accompanied by a transition from a symmetric to an asymmetric structure. With larger initial lithospheric thinning, larger ranges of crustal deformation appear with less basement tectonic subsidence. For large-scale oceanic plateaus, basement tectonic subsidence occurs within narrower ranges. The proximal half-graben structures rapidly abandon with relatively horizontal basement and small fault offsets on the rift flank, leading to a symmetric structure during breakup. With larger initial lithospheric thinning, crustal deformation occurs within a narrower region during the early stage. Landward rift migration dominates the deformation, resulting in an asymmetric structure. On the basis of these results, for the large-scale section of the Caroline Ridge, NW-trending normal faults originated from the landward rift migration. At present, seaward rift migration dominates the Caroline Ridge deformation, forming a relatively symmetric structure. For the small-scale section of the Caroline Ridge, the initial landward rift migration occurred. Larger initial lithospheric thinning may exist beneath the Caroline Ridge during the initiation of Miocene rifting.

Taxonomic characterization of five species of emperor fishes (Actinopterygii: Eupercaria: Lethrinidae) based on external morphology, morphometry, and geographic distribution in the northwestern Indian Ocean

Species of the genus Lethrinus, commonly referred to as emperor fishes, mainly distributed in the Indo–West Pacific, including the Persian Gulf and Gulf of Oman are poorly known. It is difficult to characterize them morphologically, as there are no distinguishing meristic features for the majority of species. We studied the morphological features of 65 specimens representing the genus Lethrinus to define and identify the species involved. Among the morphological characters commonly considered in this type of study, we also included new, previously undescribed characters. The results of Tukey’s post hoc HSD test for metric and meristic variables, which showed significant differences between species in ANOVA, indicate that most metric traits and the number of scale rows above the lateral line differ significantly among the five morphotypes distinguished. Principal component analysis (PCA) and discriminant function analysis (DFA) effectively showed the morphometric variation between these morphotypes. The characteristics of body depth, head length, pectoral fin length, and caudal fin length are the most distinguishing diagnostic at the species level. We determined that the collected fish specimens represented: Lethrinus borbonicus Valenciennes, 1830, Lethrinus crocineus Smith, 1959, Lethrinus lentjan (Lacepède, 1802), Lethrinus microdon Valenciennes, 1830, and Lethrinus nebulosus (Forsskål, 1775). We also confirmed their validity as distinct species. Notably, L. crocineus, previously known only from the western Indian Ocean (Africa and Socotra), is now reported for the first time from the Persian Gulf and the Gulf of Oman. Lastly, a distribution map for the Lethrinus species is included.

Dichichthyidae, a New Family of Deepwater Sharks (Carcharhiniformes) from the Indo–West Pacific, with Description of a New Species

The genus Dichichthys was resurrected for five species previously allocated to the genus Parmaturus in the family Pentanchidae. Supraorbital crests on the chondrocranium distinguish Dichichthys from Parmaturus and other members of the family Pentanchidae. A new family, Dichichthyidae, has been proposed to contain Dichichthys. The sequence of the NADH2 mitochondrial gene confirms the placement of Dichichthys outside of the Pentanchidae family, as well as separate from the Atelomycteridae and Scyliorhinidae families. Dichichthys albimarginatus was described using a holotype collected off the coast of New Caledonia. A second juvenile specimen collected off the coast of Papua New Guinea was tentatively assigned as D. cf. albimarginatus. Dichichthys bigus is known from the holotype collected in the Coral Sea off the coast of Queensland, Australia. A new, parasite-afflicted underwater observation was reported further north of Queensland. The type species Dichichthys melanobranchus, previously only known from juvenile specimens, was redescribed based on adult specimens. Dichichthys nigripalatum is known from the holotype collected off Sumbawa, Indonesia, and a tentatively identified photo record from West Java. Dichichthys satoi n. sp. is described from the West Norfolk Ridge and off the North Island of New Zealand. Members of the genus Dichichthys have unique curved egg cases which have pliable ridges made up of numerous fibres and long coiled tendrils on the posterior end.

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam.

The island of Guam in the west Pacific has seen a significant decrease in coral cover since 2013. Lafac Bay, a marine protected area in northeast Guam, served as a reference site for benthic communities typical of forereefs on the windward side of the island. The staghorn coral Acropora abrotanoides is a dominant and characteristic ecosystem engineer of forereef communities on exposed shorelines. Photoquadrat surveys were conducted in 2015, 2017, and 2019, and a diver-operated hyperspectral imager (i.e., DiveRay) was used to survey the same transects in 2019. Machine learning algorithms were used to develop an automated pipeline to assess the benthic cover of 10 biotic and abiotic categories in 2019 based on hyperspectral imagery. The cover of scleractinian corals did not differ between 2015 and 2017 despite being subjected to a series of environmental disturbances in these years. Surveys in 2019 documented the almost complete decline of the habitat-defining staghorn coral Acropora abrotanoides (a practically complete disappearance from about 10% cover), a significant decrease (~75%) in the cover of other scleractinian corals, and a significant increase (~55%) in the combined cover of bare substrate, turf algae, and cyanobacteria. The drastic change in community composition suggests that the reef at Lafac Bay is transitioning to a turf algae-dominated community. However, the capacity of this reef to recover from previous disturbances suggests that this transition could be reversed, making Lafac Bay an excellent candidate for long-term monitoring. Community analyses showed no significant difference between automatically classified benthic cover estimates derived from the hyperspectral scans in 2019 and those derived from photoquadrats. These findings suggest that underwater hyperspectral imagers can be efficient and effective tools for fast, frequent, and accurate monitoring of dynamic reef communities.

Moisture Sources and Pathways of Annual Maximum Precipitation in the Lancang‐Mekong River Basin

AbstractRecent extremely heavy precipitation has led to substantial economic losses and affected millions of residences in the Lancang‐Mekong River Basin (LMRB). This study analyzed the spatial‐temporal characteristics of the annual maximum precipitation (R1X) of the LMRB and identified the moisture sources and pathways conducive to R1Xs using a Lagrangian back trajectory model. Results show that India Ocean and Bay of Bengal (IO/BOB), local evapotranspiration, and West Pacific Ocean and East China (WP/EC) are the three main moisture transport pathways of the R1Xs in LMRB, contributing 68.3%, 20.4% and 11.3% of the trajectories, respectively. R1Xs in the downstream eastern area are affected by tropical cyclones bringing large amounts of moisture from the WP/EC. As tropical cyclones shifted northward under climate change impact, more extreme precipitation occurred over the LMRB due to moisture coming from WP/EC, but those from the IO/BOB had decreased because of the slowdown of flows across the Equator.

New evidence for CH4 enhancement in the upper troposphere associated with the Asian summer monsoon

The Asian summer monsoon (ASM) region is a key region transporting air to the upper troposphere (UT), significantly influencing the distribution and concentration of trace gases, including methane (CH4), an important greenhouse gas. We investigate the seasonal enhancement of CH4 in the UT over the ASM region, utilizing retrievals from the Atmospheric Infrared Sounder (AIRS), model simulations and in-situ measurements. Both the AIRS data and model simulation reveal a substantial enhancement in CH4 concentrations within the active monsoon region of up to 3%, referring to the zonal means, and of up to 6% relative to the pre-monsoon season. Notably, the spatial distribution of the CH4 plume demonstrates a southwestward shift in the AIRS retrievals, in contrast to the model simulations, which predict a broader enhancement, including a significant increase to the east. A cross-comparison with in-situ measurements, including AirCore measurements over the Tibetan Plateau and airline sampling across the ASM anticyclone (ASMA), favors the enhancement represented by model simulation. Remarkable CH4 enhancement over the west Pacific is also evidenced by in-situ data and simulation as a dynamical extension of the ASMA. Our findings underscore the necessity for cautious interpretation of satellite-derived CH4 distributions, and highlight the critical role of in-situ data in anchoring the assimilation of CH4.

Climate and land‐use change impacts on cultural use berries: Considerations for mitigative stewardship

Societal Impact StatementCultural use berries are prized foods and medicines across the United States and Canada, with almost 200 different species used by Indigenous Peoples. Berries are increasingly being impacted by environmental and land‐use change. Berry habitats, how and when berry plants reproduce, and the volume of berries available for harvest each year are shifting widely. These changes are impacting access to, availability of, and consumption of berries. Biocultural stewardship practices, like low‐intensity fire, transplanting, and thinning, can be used in response to these stressors to support berry plant health and productivity as well as a sustained relationship with this important food.SummaryAlmost 200 different species of berries are used for food and medicine by Indigenous Peoples, with unparalleled nutritional and cultural significance among plant foods. Environmental and land‐use change is increasingly compromising access to, availability of, and consumption of berries. In this review, I consider (a) how climate and land‐use change are impacting cultural use berries across species and places, as documented by Indigenous Peoples and in the scientific literature, and (b) how stewardship practices are being applied to promote resilience and sustainability in berrying landscapes experiencing stress. Climate impacts on Arctic and subarctic berry species include earlier ripening, changes in taste, or increased variability in abundance. These same regions are experiencing a proliferation of shrubs, while forests throughout the lower 48 and Canada are suffering from suffocating fuel loads and stand densities that are not conducive to berry habitat for many species. In the Pacific West, berries are influenced by prolonged droughts and increasing spring and summer temperatures. Climate change impacts are amplified by shifts in land use for forestry and agriculture. Biocultural stewardship practices, like low‐intensity fire, thinning, transplanting, and cultural care, can be used to mitigate these impacts and promote berry microclimate habitats. There is opportunity for intertribal networking and knowledge sharing around berry stewardship practices that will support local and regional climate change responses.

Orbital Controls on North Pacific Dust Flux During the Late Quaternary

AbstractAirborne mineral dust is sensitive to climatic changes, but its response to orbital forcing is still not fully understood. Here, we present a reconstruction of dust input to the Subarctic Pacific Ocean covering the past 190 kyr. The dust composition record is indicative of source moisture conditions, which were dominated by precessional variations. In contrast, the dust flux record is dominated by obliquity variations and displays an out‐of‐phase relationship with a dust record from the mid‐latitude North Pacific Ocean. Climate model simulations suggest precession likely drove changes in the aridity and extent of dust source regions. Additionally, the obliquity variations in dust flux can be explained by meridional shifts in the North Pacific westerly jet, driven by changes in the meridional atmospheric temperature gradient. Overall, our findings suggest that North Pacific dust input was primarily modulated by orbital‐controlled source aridity and the strength and position of the westerly winds.

Headquarters locations of the largest US corporations: uneven geographies and migrations

The headquarters of large corporations are the main asset of the economies of the largest cities in the developed world. Based on materials from Fortune-500 companies, an analysis of the spatial dynamics of corporate headquarters in US MSAs for 1980–2019 was carried out. Mapping and geographic analysis of the concentration and directions of migration made it possible to identify the main changes in the spatial pattern of the location of economic decision-making centers in the United States. Headquarters remain highly concentrated: half of them are located in the largest MSAs by population. In terms of revenue, MSA Fayetteville (Arkansas, headquarters of Walmart) stands out, in terms of market value - San Jose (the heart of Silicon Valley, only 36 in population), in terms of the number of employees - MSAs in which retail companies are located (Minneapolis, Atlanta). Geographic mobility of corporate headquarters has increased dramatically over the past 40 years. The main directions of migration: from the Northeast and from California to the MSA New York, the (Post-)Industrial Great Lakes (MSA Chicago), Texas, to the South (MSAs Atlanta and Charlotte) and the Pacific West. There are noticeable trends towards industry agglomeration: IT companies are moving to California, and financial firms are leaving it, moving to Texas. The main areas for the emergence of new headquarters of the largest corporations are: New York, (Post-)Industrial Great Lakes, the South, Texas and the Pacific West. In addition to the usual MSAs-leaders - New York (10% of all new headquarters), San Jose (10%), Chicago, Dallas and Houston - Denver and Richmond stand out. The spatial concentration of locations for new headquarters continues to increase. At the same time, at least one new headquarters appeared in ⅔ of the agglomerations. The identified trends in the migration of existing and the emergence of new corporate headquarters suggest significant shifts in the economic geography of the United States. The rapid growth of cities in the South and Inland South-West shows that the economies of these areas have reached a new level, expressed in the formation of their own “gateways” to the global economy.

The tropical convective evolution in different rain types over the West and East Pacific

The tropical convective evolution in different rain types over the West and East Pacific

Machine Learning-Based Estimation of Tropical Cyclone Intensity from Advanced Technology Microwave Sounder Using a U-Net Algorithm

A U-Net algorithm was used to retrieve surface pressure and wind speed over the ocean within tropical cyclones (TCs) and their neighboring areas using NOAA-20 Advanced Technology Microwave Sounder (ATMS) reprocessed Sensor Data Record (SDR) brightness temperatures (TBs) and geolocation information. For TC locations, International Best Track Archive for Climate Stewardship (IBTrACS) data have been used over the North Atlantic Ocean and West Pacific Ocean between 2018 and 2021. The European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) surface pressure and wind speed were employed as reference labels. Preliminary results demonstrated that the visualizations for wind speed and pressure matched the prediction and ERA5 location. The residual biases and standard deviations between the predicted and reference labels were about 0.15 m/s and 1.95 m/s, respectively, for wind speed and 0.48 hPa and 2.67 hPa, respectively, for surface pressure, after applying cloud screening for each ATMS pixel. This indicates that the U-Net model is effective for surface wind speed and surface pressure estimates over general ocean conditions.

Pollution status and source resolution of atmospheric mercury in the intersectional region of Northern Philippines, southern Taiwan, and northern South China Sea

A four-season sampling of speciated atmospheric mercury (SAM) was employed in East Asia. Three mercury species including gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate mercury (PHg) were measured at three background sites. This study explored the temporal variation, spatial distribution, gas-solid partition, transport routes, and source resolution of SAM. The yearly average concentrations of GEM, GOM, and PHg were 2.76 ± 0.36 ng/m3, 23.14 ± 8.67 pg/m3, and 0.23 ± 0.058 ng/m3. The highest GEM and PHg concentrations occurred at Laoag (northern Philippines) in spring, while that of GOM was observed at Laoag but in summer. The lowest GEM and PHg concentrations always occurred at Dongsha Islands (northern South China Sea) in summer, while that of GOM was also observed at Dongsha Islands but in fall. SAM was partition as showed 92.64–96.72% of total gas-phase mercury (TGM) and 3.28–7.36% of solid phase mercury. Eight clustered transport routes were resolved by a HYSPLIT model with polluted air parcels originating from Central/North China. Routes from Indochina Peninsula and South China showed the highest GEM concentration. Moreover, air parcels transported from West Pacific Ocean and South China Sea (SCS) had the lowest concentration of GEM. High concentrations of SAM in the region were mainly attributed to long-range transport (LRT) from Asian continental outflows (ACOs). We further revealed that GEM was positively correlated to SO2, CO, NOx, and PM2.5, but negatively correlated to O3. GOM was positively correlated to SO2, O3, NOx, and PM2.5, but negatively correlated to CO, While, PHg was positively correlated to SO2, CO, O3, NOx, and PM2.5.

Marine mammal strandings recorded in New Caledonia, South West Pacific Ocean, 1877 to 2022

Context Strandings are an important source of information for estimating marine mammal biodiversity, particularly in data-sparse ocean basins such as Oceania. Aims Here, we report on knowledge acquired from 218 stranding events recorded in the waters of New Caledonia (1877–2022). Methods We investigated spatio-temporal distribution, stable isotope signatures, trace element concentrations, biometry measurements, genetic diversity, and diet, for the four most commonly stranded taxa (dugongs, 35% of events; sperm whales, 19%; Delphinidae, 18%; pygmy and dwarf sperm whales, 14%). Key results Beginning in 1991, reports of stranding events increased (183 events, 322 individuals, 20 species from seven families: Dugongidae, Physeteridae, Delphinidae, Kogiidae, Ziphiidae, Balaenopteridae, Otariidae), with hotspots identified on the west coast (Bourail, Ouano, Nouméa) and in Prony Bay. Causes of death were not determined in 84% of stranding events, but were identified in the majority of expert-led necropsies (24 of 29 individuals from 10 species). Yet, valuable information regarding the impact of anthropogenic activities was gathered for some species of concern, such as the endangered dugong (28% human-caused). Since 2016, training and outreach have been provided to rangers, veterinarians, and various public safety officers to support their engagement in the scientific monitoring of marine mammal strandings. A website (www.rescue.ird.nc) was developed to facilitate standardised data collection and storage, and to provide public access to stranding records. Conclusion Although the number of individuals reported here remains modest, this study provides new information on poorly documented species in New Caledonia. Implications Long-term monitoring of strandings can help design effective conservation measures.

Virulence Dynamics of the Barley Leaf Rust Pathogen (Puccinia hordei) in the United States from 1989 to 2020.

Barley leaf rust, caused by Puccinia hordei, is an important disease of barley worldwide. The pathogen can develop new races that overcome resistance genes, emphasizing the need for monitoring its virulence. This study characterized 519 P. hordei isolates collected in the United States from the 1989 to 2000 and 2010 to 2020 survey periods on 15 Rph (Reaction to Puccinia hordei) genes. We analyzed linearized infection type data to detect virulence patterns across the United States and in five geographical regions: Pacific/West (PW), Southwest (SW), Midwest (MW), Northeast (NE), and Southeast (SE). Over 32 years, we observed high mean infection scores for Rph1.a, Rph4.d, and Rph8.h; intermediate scores for Rph2.b, Rph9.i, Rph10.o, Rph11.p, and Rph13.x; and low scores for Rph3.c, Rph5.e, Rph5.f, Rph7.g, Rph9.z, Rph14.ab, and Rph15.ad. Virulence for Rph2.b, Rph3.c, Rph5.e, Rph9.z, Rph10.o, Rph11.p, and Rph13.x significantly differed between the two survey periods. From 1989 to 2020, regional patterns of virulence were found for Rph5.e, Rph5.f, Rph7.g, and Rph14.ab, while regionalities of virulence for Rph3.c, Rph9.i, Rph9.z were only observed in the 2010 to 2020 survey period. Virulence associations were also detected in the P. hordei population. Notably, isolates that were virulent to Rph5.e and Rph6.f were more likely to be avirulent to Rph7.g and Rph13.x, and vice versa. In decreasing order of effectiveness, Rph15.ad, Rph5.e, Rph3.c, Rph9.z, Rph7.g, Rph5.f, and Rph14.ab were the most effective Rph genes in the United States from 1989 to 2020. Pyramiding Rph15.ad with other widely effective Rph and adult plant resistance genes may provide long-lasting resistance against P. hordei.

Palliative care usage in large cell lung carcinoma: An analysis of the National Cancer Database.

266 Background: The treatment approach for large cell lung carcinoma (LCLC) typically involves a multimodal treatment strategy, including chemotherapy, radiation therapies, and immunotherapy, to target both the primary tumor and any metastatic lesions. Palliative care (PC) optimizes the treatment of individuals with LCLC by relieving suffering improving quality of life for patients and their loved ones. When implemented early, PC can lengthen survival in patients with advanced non-small cell lung cancer (NSCLC) like LCLC. The association between PC utilization and race, ethnicity, insurance status, education level, income level, rural/urban geography, and facility type in the face of a LCLC diagnosis has not yet been investigated in isolation from other types of NSCLC. We will analyze these factors in this study to highlight key discrepancies in the implementation of PC when treating LCLC. Methods: A retrospective study was conducted using data collected from adults diagnosed with all subtypes of LCLC between 2004 and 2020 in the National Cancer Database to evaluate trends in PC utilization. Demographic characteristics were studied with regards to the use of PC. Multivariate with binary logistic regression was implemented to analyze the following variables: age, sex, Hispanic status, race, Charlson-Deyo comorbidity score (CDCS), education level quartile, income status quartile, facility region, geographic residence status, and primary insurance status. Exclusion criteria included missing values. Results: Among the 25362 patients diagnosed with LCLC, about 12.8% received PC (n = 3727). Patients who were more likely to receive PC had a CDCS of ≥3 (p = 0.017, CI = 1.04-1.47). Additionally, PC usage was more likely in rural (p = 0.003, CI = 1.05-1.27) and urban (p = 0.013, CI = 1.06-1.62) settings compared to metro settings. Patients who were less likely to utilize PC were Black (p = 0.018, CI = 0.77-0.98) and male (p < 0.001, CI = 0.82-0.95). Facility locations in the South (Atlantic) and West (Mountain and Pacific) regions were less likely to provide PC services. Patients paying primarily with Medicaid were the most likely to undergo PC compared to their counterparts lacking insurance or having different insurance (private, Medicare, other government). There was no statistically significant difference in PC usage among different education levels and income brackets. Conclusions: We identified patterns in PC utilization among individuals with LCLC. Variables correlated with PC usage include CDCS, race, facility location, and primary payor at diagnosis. Given that LCLC is aggressive, PC can complement curative treatments to provide comprehensive cancer care. We hope this study will serve as a foundation for reducing health disparities in the treatment of LCLC, thus advancing health equity.

ResU‐Deep: Improving the Trigger Function of Deep Convection in Tropical Regions With Deep Learning

AbstractModeling deep convection accurately in tropical regions is important. However, biases remain in current trigger functions. To alleviate the overestimation of frequency and wrong depiction of the diurnal cycle, we propose a deep convection trigger function, ResU‐Deep, based on the framework of U‐net with three modifications to better suit the problem of deep convection identification: (a) adding the upsampling process into the encoder part, (b) replacing the double convolution block with a residual‐convolutional block, and (c) adding a dynamic weight into the loss function. Thirty‐three environmental variables within tropical regions are used in ResU‐Deep, including 31 features from ECMWF atmospheric reanalysis (ERA5) data set, and two historical convection fields. Tropical Rainfall Measuring Mission 3B42 data set is used as the precipitation observation. Central America, North Africa, South and East Asia, and West Pacific Ocean within 0°∼30°N are selected as the study regions for the high frequency of deep convection activities. ResU‐Deep, incorporating the surrounding information, is separately trained and evaluated in four regions and has the F1‐scores of 58%, 53%, 60%, and 63% for the occurrence, outperforming the single‐column‐based machine learning methods. Also, a unified model has similar performance in four regions. Further comparisons are made with convective available potential energy‐based trigger functions in Southern Great Plains. Results show that ResU‐Deep can capture the trends and peaks of diurnal cycles on complex terrains in large regions. According to feature importance test, the contribution levels of environmental features are different in four regions, indicating the model can learn the mechanisms of deep convection in specific region, thus improving the prediction accuracy.

Earliest Neolithic occupation and maritime adaptation on the West Pacific coast

Maritime adaptation plays a significant role in the dispersal of modern humans and the transition of subsistence strategies. The real timing of the worldwide intensification of maritime adaptation has been debated mainly because of the presumed inundation of archaeological sites (prior to 7000 cal yr BP) by early Holocene sea-level rise. In this study, we present a coastal shell midden submerged ∼8 m below the present sea level at the Jingtoushan site, containing robust evidence of the earliest Neolithic occupation and maritime adaptation on the West Pacific. Bayesian modelling of 15 14C dates, cultural deposits, and microfossils (pollen, phytolith, and diatom) indicated that the Jingtoushan site was an anthropogenic deposit originally accumulated on the coastline during the stable sea-level period (8000–7600 cal yr BP) and subsequently submerged by sea-level jumps. In addition to being largely dependent on marine food resources, humans also utilised the stable sea-level window of meltwater pulses and began rice cultivation. This study not only pushed back the timing of maritime adaptation to 8000 cal yr BP but also provides promise for future investigations of coastal underwater settlements, shedding new light on the understanding of the West Pacific coastal environment and cultural succession.

Spatial lithological heterogeneity of the deep-sea sediments and its controlling factors in the northern West Caroline Basin, tropical West Pacific

Uncovering the spatial distribution of deep-sea sediment lithologies is crucial for the research on earth system science and the exploration of critical mineral resources. The conventional global deep-sea sediment lithology distribution maps showed that the lithologies were relatively uniform in the global major ocean basins. Furthermore, it was deemed that the deep-sea sediment lithologies were related to the productivity of surface seawater. However, later studies have illustrated that the distribution of deep-sea sediment lithologies exhibited greater variability and heterogeneity than conventional maps and that water depth played a more important role in controlling deep-sea sediment lithologies than productivity. In addition, few studies have focused on the relationship between the heterogeneous deep-sea sediment lithologies and the diverse seafloor topography in the West Pacific. In this study, we provide a high-resolution spatial distribution map of deep-sea sediment lithologies by systematic descriptions of 112 surface samples in the northern West Caroline Basin, tropical West Pacific, with a large range of water depth and a diverse seafloor topography to verify the previous prediction of sediment lithology distribution. Subsequently, based on the results of the determinations of carbonate and biogenic silica contents, the sediment redox-potential tests, and the calculations of multiple variables, we carried out quantitative studies and correlation analyses for these variables to reveal the relative contribution of different factors to the lithological heterogeneity in the northern West Caroline Basin. Our results show that the actual deep-sea sediments have greater heterogeneity in terms of lithological classes and distribution patterns than the earlier predicted lithology maps. Furthermore, our analyses reveal that water depth and seafloor topography are the more important controlling factors on the deep-sea sediment lithology to some extent than productivity and that water depth and topography may exert different effects on the different sediment components. For the calcareous component, water depth is the main controlling factor due to the increased solubility of carbonate with water depth. Carbonate materials can dilute other components in the waters above the carbonate compensation depth, which is around 4500 m below the sea surface in the study area. Meanwhile, the siliceous component may be enriched in the unique negative seafloor topography of the trench and trough with the specific lateral transport mechanism and the redox environment. These findings imply a more complicated actual deep-sea sediment lithology distribution than previously thought given that various water depths and diverse topography in the global oceans, which are significant for understanding deep-sea sedimentary processes and improving the models for predicting global sediment lithology in the deep sea.

Unravelling the Linkages between the Intraseasonal Variability of the West Pacific Subtropical High and Indian Summer Monsoon Rainfall

Unravelling the Linkages between the Intraseasonal Variability of the West Pacific Subtropical High and Indian Summer Monsoon Rainfall