Equatorial Plasma Bubbles(EPBs)are ionospheric irregularities that take place near the magnetic equator.EPBs most commonly occur after sunset during the equinox months,although they can also be observed during other s...Equatorial Plasma Bubbles(EPBs)are ionospheric irregularities that take place near the magnetic equator.EPBs most commonly occur after sunset during the equinox months,although they can also be observed during other seasons.The phenomenon significantly disrupts radio wave signals essential to communication and navigation systems.The national network of Global Navigation Satellite System(GNSS)receivers in Indonesia(>30°longitudinal range)provides an opportunity for detailed EPB studies.To explore this,we conducted preliminary 3D tomography of total electron content(TEC)data captured by GNSS receivers following a geomagnetic storm on December 3,2023,when at least four EPB clusters occurred in the Southeast Asian sector.TEC and extracted TEC depletion with a 120-minute running average were then used as inputs for a 3D tomography program.Their 2D spatial distribution consistently captured the four EPB clusters over time.These tomography results were validated through a classical checkerboard test and comparisons with other ionospheric data sources,such as the Global Ionospheric Map(GIM)and International Reference Ionosphere(IRI)profile.Validation of the results demonstrates the capability of the Indonesian GNSS network to measure peak ionospheric density.These findings highlight the potential for future three-dimensional research of plasma bubbles in low-latitude regions using existing GNSS networks,with extensive longitudinal coverage.展开更多
More than a simple concert pianist,Wilson Chu is an Indonesian musical diplomacy force.As a distinguished performer,composer,and educator,Wilson has left an indelible mark on the international stage by seamlessly blen...More than a simple concert pianist,Wilson Chu is an Indonesian musical diplomacy force.As a distinguished performer,composer,and educator,Wilson has left an indelible mark on the international stage by seamlessly blending Western classical music with Southeast Asian tradition.Since 2019,he has been the youngest Associate Professor of Piano at the College of Chinese and ASEAN Arts(CCAA)at Chengdu University,where he has dedicated himself to shaping the next generation of musicians.展开更多
The Indonesian Throughflow(ITF),mainly through the Makassar Strait,transports amounts of water and salt from the tropical Pacific Ocean to the Indian Ocean,playing a crucial role in modulating heat and energy budget b...The Indonesian Throughflow(ITF),mainly through the Makassar Strait,transports amounts of water and salt from the tropical Pacific Ocean to the Indian Ocean,playing a crucial role in modulating heat and energy budget between two oceans.The South China Sea Throughflow(SCSTF)significantly contributes to the net transport of the ITF via Karimata Strait and Mindoro-Sibutu Passage.However,the specific proportion and variability of South China Sea(SCS)water joining the ITF are still unclear.Based on high-resolution reanalysis data and a Lagrangian particle tracking method-Connectivity Modelling System(CMS),we quantified the proportion and variability of SCS water joining the ITF in the Makassar Strait.The results show that about 16.41%of the particles released in the Makassar Strait could be back-tracked from the SCS and 42.45%from the western Pacific Ocean.The particles through Mindoro Strait and Karimata Strait are about 10.55%and 3.39%,respectively.About 14.56%and 15.42%particles are trapped in the Sulu and Sulawesi seas.The proportion of SCS water shows significant interannual variability,which is highly related to El Niño-Southern Oscillation(ENSO)events.The correlation coefficient between interannual change of SCS water volume proportion and the Niño 3.4 index is 0.75,with an increase of about 24%during El Niño years and a decrease of about−22%during La Niña years.The proportion also varies with the depth of particles released,showing two peaks at surface and subsurface depths of 5 m and 110 m,respectively.展开更多
The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(E...The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole(IOD)events.The detailed processes of ENSO and/or IOD induced anomalies impacting on the ITF,however,are still not clear.In this study,this issue is investigated through causal relation,statistical,and dynamical analyses based on satellite observation.The results show that the driven mechanisms of ENSO on the ITF include two aspects.Firstly,the ENSO related wind field anomalies driven anomalous cyclonic ocean circulation in the western Pacific,and off equatorial upwelling Rossby waves propagating westward to arrive at the western boundary of the Pacific,both tend to induce negative sea surface height anomalies(SSHA)in the western Pacific,favoring ITF reduction since the develop of the El Niño through the following year.Secondly,the ENSO events modulate equatorial Indian Ocean zonal winds through Walker Circulation,which in turn trigger eastward propagating upwelling Kelvin waves and westward propagating downwelling Rossby waves.The Rossby waves are reflected into downwelling Kelvin waves,which then propagate eastward along the equator and the Sumatra-Java coast in the Indian Ocean.As a result,the wave dynamics tend to generate negative(positive)SSHA in the eastern Indian Ocean,and thus enhance(reduce)the ITF transport with time lag of 0-6 months(9-12 months),respectively.Under the IOD condition,the wave dynamics also tend to enhance the ITF in the positive IOD year,and reduce the ITF in the following year.展开更多
The Indonesian Throughflow(ITF), which connects the tropical Pacific and Indian oceans, plays important roles in the inter-ocean water exchange and regional or even global climate variability. The Makassar Strait is t...The Indonesian Throughflow(ITF), which connects the tropical Pacific and Indian oceans, plays important roles in the inter-ocean water exchange and regional or even global climate variability. The Makassar Strait is the main inflow passage of the ITF, carrying about 77% of the total ITF volume transport. In this study, we analyze the simulated ITF in the Makassar Strait in the Simple Ocean Data Assimilation version 3(SODA3) datasets. A total of nine ensemble members of the SODA3 datasets, of which are driven by different surface forcings and bulk formulas, and with or without data assimilation, are used in this study. The annual mean water transports(i.e.,volume, heat and freshwater) are related to the combination of surface forcing and bulk formula, as well as whether data assimilation is employed. The phases of the seasonal and interannual variability in water transports cross the Makassar Strait, are basically consistent with each other among the SODA3 ensemble members. The interannual variability in Makassar Strait volume and heat transports are significantly correlated with El Ni?oSouthern Oscillation(ENSO) at time lags of-6 to 7 months. There is no statistically significant correlation between the freshwater transport and the ENSO. The Makassar Strait water transports are not significantly correlated with the Indian Ocean Dipole(IOD), which may attribute to model deficiency in simulating the propagation of semiannual Kelvin waves from the Indian Ocean to the Makassar Strait.展开更多
BACKGROUND Recently, gut microbiota has been associated with various diseases other than intestinal disease. Thus, there has been rapid growth in the study of gut microbiota. Considering the numerous factors influenci...BACKGROUND Recently, gut microbiota has been associated with various diseases other than intestinal disease. Thus, there has been rapid growth in the study of gut microbiota. Considering the numerous factors influencing gut microbiota such as age, diet, etc., area-based research is required. Indonesia has numerous different tribes and each of these tribes have different lifestyles. Hence, it is expected that each tribe has a specific gut microbiota. A deeper insight into the composition of gut microbiota can be used to determine the condition of gut microbiota in Indonesians and to consider which treatment may be suitable and effective to improve health status.AIM To investigate the gut microbiota of Indonesian subjects represented by Javanese and Balinese tribes by analyzing fecal samples.METHODS Fecal samples were collected from a total of 80 individuals with 20 in each of the young groups ranging from 25-45 years and the elderly group aged 70 years or more from two different regions, Yogyakarta and Bali. Fecal sample collection was performed at the end of the assessment period(day 14 ± 1 d) during which time the subjects were not allowed to consume probiotic or antibiotic products.The quantification of various Clostridium subgroups, Lactobacillus subgroups,Enterococcus, Streptococcus, Staphylococcus, Bacteroides fragilis group and Prevotella,Bifidobacterium and Atopobium cluster, Enterobacteriaceae and Pseudomonas was performed using the Yakult intestinal flora-scan(YIF-SCAN).RESULTS The bacterial population in younger subjects' feces was higher than that in the elderly population, with a total of approximately 10.0 – 10.6 log10 bacterial cells/g feces. The most abundant bacteria in all groups were Clostridium, followed by Prevotella, Atopobium, Bifidobacterium and Bacteroides. In the elderly, an increase in Enterobacteriaceae, Coliform and Escherichia coli was found. In terms of bacterial counts in Yogyakarta, total bacteria, Clostridium coccoides(C. coccoides) group,Bifidobacterium, Prevotella, Lactobacillus plantarum subgroup, and Streptococcus were significantly higher(P < 0.05) in younger than elderly subjects, while the Lactobacillus gasseri subgroup, Lactobacillus casei subgroup, and Lactobacillus reuteri subgroup counts were significantly lower(P < 0.05) in younger subjects. In Balinese subjects, total bacteria, C. coccoides group, Clostridium leptum subgroup,Bacteroides fragilis group, and Prevotella were significantly higher(P < 0.05) in younger compared to elderly individuals, while the Lactobacillus ruminis subgroup, and Enterobacteriaceae were significantly lower(P < 0.05) in younger subjects. The results also revealed that, besides the C. coccoides group and Clostridium leptum group being the most abundant gut microbiota in both Yogyakarta and Balinese people, the latter was indicated by a higher Clostridium perfringens count, which was almost 10 times that of Yogyakarta subjects. This may be a response to different lifestyles in the different tribes; however, this phenomenon requires further extensive study.CONCLUSION Bacterial populations were higher in younger than in elderly subjects. Most abundant bacterial groups were Clostridium, Prevotella, Atopobium, Bifidobacterium,and Bacteroides. The level of Clostridium perfringens in Yogyakarta subjects was lower than that in Balinese subjects.展开更多
A quasi-global eddy permitting oceanic GCM, LICOM1.0, is run with the forcing of ERA40 daily wind stress from 1958 to 2001. The modelled Indonesian Throughflow (ITF) is reasonable in the aspects of both its water sour...A quasi-global eddy permitting oceanic GCM, LICOM1.0, is run with the forcing of ERA40 daily wind stress from 1958 to 2001. The modelled Indonesian Throughflow (ITF) is reasonable in the aspects of both its water source and major pathways. Compared with the observation, the simulated annual mean and seasonal cycle of the ITF transport are fairly realistic. The interannual variation of the tropical Pacific Ocean plays a more important role in the interannual variability of the ITF transport. The relationship between the ITF and the Indian Ocean Dipole (IOD) also reflects the influence of ENSO. However, the relationship between the ITF transport and the interannual anomalies in the Pacific and Indian Oceans vary with time. During some years, (e.g., 1994), the effect of a strong IOD on the ITF transport is more than that from ENSO.展开更多
The role of the Indonesian Throughflow （ITF） in the influence of the Indian Ocean Dipole （IOD） on ENSO is investigated using version 2 of the Parallel Ocean Program （POP2） ocean general circulation model. We dem...The role of the Indonesian Throughflow （ITF） in the influence of the Indian Ocean Dipole （IOD） on ENSO is investigated using version 2 of the Parallel Ocean Program （POP2） ocean general circulation model. We demonstrate the results through sensitivity experiments on both positive and negative IOD events from observations and coupled general circulation model simulations. By shutting down the atmospheric bridge while maintaining the tropical oceanic channel, the IOD forcing is shown to influence the ENSO event in the following year, and the role of the ITF is emphasized. During positive IOD events, negative sea surface height anomalies （SSHAs） occur in the eastern Indian Ocean, indicating the existence of upwelling. These upwelling anomalies pass through the Indonesian seas and enter the western tropical Pacific, resulting in cold anomalies there. These cold temperature anomalies further propagate to the eastern equatorial Pacific, and ultimately induce a La Nifia- like mode in the following year. In contrast, during negative IOD events, positive SSHAs are established in the eastern Indian Ocean, leading to downwelling anomalies that can also propagate into the subsurface of the western Pacific Ocean and travel further eastward. These downwelling anomalies induce negative ITF transport anomalies, and an E1 Nifio-like mode in the tropical eastern Pacific Ocean that persists into the following year. The effects of negative and positive IOD events on ENSO via the ITF are symmetric. Finally, we also estimate the contribution of IOD forcing in explaining the Pacific variability associated with ENSO via ITE展开更多
Changes in the Indonesian Throughflow （ITF） and the South China Sea throughflow-measured by the Luzon Strait Transport （LST）-associated with the 1976/77 regime shift are analyzed using the Island Rule theory and t...Changes in the Indonesian Throughflow （ITF） and the South China Sea throughflow-measured by the Luzon Strait Transport （LST）-associated with the 1976/77 regime shift are analyzed using the Island Rule theory and the Simple Ocean Data Assimilation dataset. Results show that LST increased but ITF transport decreased after 1975. Such changes were induced by variations in wind stress associated with the regime shift. The strengthening of the easterly wind anomaly east of the Luzon Strait played an important role in the increase of LST after 1975, while the westerly wind anomaly in the equatorial Pacific contributed significantly to the decrease in ITF transport after 1975; accounting for 53% of the change. After 1975, the Kuroshio Current strengthened and the Mindanao Current weakened in response to a decrease in the total transport of the North Equatorial Current. Both the North Equatorial Countercurrent and the South Equatorial Current weakened after 1975, and an anomalous cyclonic circulation in the western equatorial Pacific prevented the tropical Pacific water from entering the Indian Ocean directly.展开更多
So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera ...So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera Sea are diagnosed at seasonal and interannual timescales and at different vertical layers, using the state-of-the-art simulations of the Ocean General Circulation Model(OGCM) for Earth Simulator(OFES). Asian monsoon leaves clear seasonal footprints on the eastern Indonesian seas. Consequently, the subsurface waters(around 24.5σ_θ and at ～150 m) in both the Maluku Sea and the Halmahera Sea stem from the South Pacific(SP) during winter monsoon, but during summer monsoon the Maluku Sea is from the North Pacific(NP), and the Halmahera Sea is a mixture of waters originating from the NP and the SP. The monsoon impact decreases with depth, so that in the Maluku Sea, the intermediate water(around 26.8σ_θ and at ～480 m) is always from the northern Banda Sea and the Halmahera Sea water is mainly from the SP in winter and the Banda Sea in summer. The deep waters(around27.2σ_θ and at ～1 040 m) in both seas are from the SP, with weak seasonal variability. At the interannual timescale,the subsurface water in the Maluku Sea originates from the NP/SP during El Ni?o/La Ni?a, while the subsurface water in the Halmahera Sea always originates from the SP. Similar to the seasonal variability, the intermediate water in Maluku Sea mainly comes from the Banda Sea and the Halmahera Sea always originates from the SP. The deep waters in both seas are from the SP. Our findings are helpful for drawing a comprehensive picture of the water properties in the Indonesian seas and will contribute to a better understanding of the ocean-atmosphere interaction over the maritime continent.展开更多
Based on the high-resolution Eulerian fields of an ocean general circulation model simulation, the heat contribution of the Indonesian throughflow(ITF) to the Indian Ocean is estimated by Lagrangian tracing method.The...Based on the high-resolution Eulerian fields of an ocean general circulation model simulation, the heat contribution of the Indonesian throughflow(ITF) to the Indian Ocean is estimated by Lagrangian tracing method.The heat transport of each particle of ITF waters is calculated by tracing temperature change along the trajectory until the particle exits the Indian Ocean. The simulation reveals that the ITF waters flow westward and branch near Madagascar, further showing the ITF waters are redistributed in both northern and southern Indian Ocean.Heat budget analysis indicates that the ITF waters gain 0.41 PW(Petawatts, 1015 W) in the northern Indian Ocean and lose 0.56 PW in the southern Indian Ocean, respectively. As a result, the ITF waters warm the whole Indian Ocean basin with only 0.15 PW, which shows an "insignificant" role of ITF on the Indian Ocean because of the heat exchange compensation between northern and southern Indian Ocean. Furthermore, the tracing pathways show that the ITF waters mainly flow out the Indian Ocean at both sides of the basin via Agulhas Current and Leeuwin Current. About 89% of the ITF waters leave along western boundary and the rest 11% along eastern boundary. Compared to seeding section, 0.10 PW and 0.05 PW are released to the Indian Ocean, respectively.展开更多
On the basis of Argo data and historic temperature/salinity data from the World Ocean Database 2001 （ WOD01 ）, origins and spreading pathways of the subsurface and intermediate water masses in the Indonesian Through...On the basis of Argo data and historic temperature/salinity data from the World Ocean Database 2001 （ WOD01 ）, origins and spreading pathways of the subsurface and intermediate water masses in the Indonesian Throughflow （ITF） region were discussed by analyzing distributions of salinity on representative isopyenal layers. Results were shown that, subsurface water mostly comes from the North Pacific Ocean while the intermediate water originates from both the North and South Pacific Ocean, even possibly from the Indian Ocean. Spreading through the Sulawesi Sea, the Makassar Strait, and file Flores Sea, the North Pacific subsurface water and the North Pacific Intermediate water dominate the western part of the Indonesian Archipelago. Furthermore as the depth increases, the features of the North Pacific sourced water masses become more obvious. In the eastern part of the waters, high sa- linity South Pacific subsurface water is blocked by a strong salinity front between Halmahera and New Guinea. Intermediate water in the eastern interior region owns salinity higher than the North Pacific intermediate water and the antarctic intermediate water （ AAIW）, possibly coming from the vertical mixing between subsurface water and the AAIW from the Pacific Ocean, and possibly coming from the northward extending of the AAIW from the Indian Ocean as well.展开更多
Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neoglo...Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquedrina dutertrei, from a total of 62 core-top sediment samples from the Indonesian throughflow region. Results were compared to modern hydrologic conditions in order to explore potential of proxies in reconstructing fluvial discharge and upper ocean water column characteristics in this region. Our results show that, in the Makassar Strait, both of depleted δ^18 and δ^13 of these four species were linked to freshwater input. In the Bali Sea,however, depleted δ^18 and δ^13 for these species may be due to different reasons. Depleted δ^18 was a result of freshwater input and as well influenced by along-shore currents while depleted δ^13 was more likely due to the Java-Sumatra upwelling. Comparison of shell δ^18 records and hydrographic data of World Ocean Atlas 2005 suggests that G. ruber and G. sacculifer calcify within the mixed-layer, respectively at 0–50 m and 20–75 m water depth, and P. obliquiloculata and N. dutertrei within the upper thermocline, both at 75–125 m water depth. N.dutertrei calcifies at slightly deeper water depth than P. obliquiloculata does. In general, δ^13 values of both G.ruber and G. sacculifer are larger than those of P. obliquiloculata and N. dutertrei at all sites, possibly related to depth habitats of these species and vertical distribution of nutrients in the Indonesian throughflow region.展开更多
Based on monthly mean Simple Ocean Data Assimilation （SODA） products from 1958 to 2007, this study analyzes the seasonal and interannual variability of the North Equatorial Current （NEC） bifurcation latitude and t...Based on monthly mean Simple Ocean Data Assimilation （SODA） products from 1958 to 2007, this study analyzes the seasonal and interannual variability of the North Equatorial Current （NEC） bifurcation latitude and the Indonesian Throughflow （ITF） volume transport. Further, Empirical Mode Decomposition （EMD） method and lag-correlation analysis are employed to reveal the relationships between the NEC bifurcation location, NEC and ITF volume transport and ENSO events. The analysis results of the seasonal variability show that the annual mean location of NEC bifurcation in upper layer occurs at 14.33°N and ITF volume transport has a maximum value in summer, a minimum value in winter and an annual mean transport of 7.75×10^6 m^3/s. The interannual variability analysis indicates that the variability of NEC bifurcation location can be treated as a precursor of El Nino. The correlation coefficient between the two reaches the maximum of 0.53 with a time lag of 2 months. The ITF volume transport is positively related with E1 Nifio events with a maximum coefficient of 0.60 by 3 months. The NEC bifurcation location is positively correlated with the ITF volume transport with a correlation coefficient of 0.43.展开更多
Test geochemistry of planktonic foraminifera is an indispensable tool in reconstructing past ocean hydrological changes. It is essential to investigate region-specific implications of test geochemistry,although those ...Test geochemistry of planktonic foraminifera is an indispensable tool in reconstructing past ocean hydrological changes. It is essential to investigate region-specific implications of test geochemistry,although those established from other regions can be broadly applied. In this study, characteristics of6180 and Mg/Ca from tests of four planktonic foraminiferal species, Globigerinoides ruber sensu stricto(s.s.), Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquadrina dutertrei, from 60 coretop sediment samples retrieved from the Indonesian Throughflow(ITF) region were studied. These geochemical data were compared with modern hydrographic profiles in order to assess their relations and to investigate potential implications of test geochemical parameters in reconstructing past oceanographic change in the ITF region. Calcification depths of these four species were first estimated based on comparison between measured test δ180 and predicted calcite δ^(18)O that was calculated from modern temperature and salinity. The results indicate that G. ruber s.s. and G. sacculifer calcify within the mixedlayer at 0-50 m and 20-75 m, respectively, whereas P. obliquiloculata and N. dutertrei calcify within the thermocline at around 75 to 125 m. A combined study of excess Mg/Ca(difference between measured and predicted Mg/Ca) and salinity suggests that salinity exerts a negligible impact on test Mg/Ca of these foraminiferal species in the ITF region. Comparison of test Mg/Ca-derived temperatures with temperature profiles of the upper 200 m of the water column from the seas of the ITF region also indicate calcification depths of these species, which match well with the above estimations using test δ^(18)O. It further indicates that G. sacculifer may be more sensitive in reflecting changes in the depth of the mixedlayer, highlighting a potential use of Mg/Ca temperature difference between G. ruber s.s. and G. sacculifer in reconstructing the depth of the mixed-layer in the ITF region.展开更多
The gridded sea level anomaly（SLA） data-set provided by AVISO is used to track the propagation of intraseasonal Kelvin waves in the Indonesian Throughflow（ITF） region. The large root mean square of intraseasonal S...The gridded sea level anomaly（SLA） data-set provided by AVISO is used to track the propagation of intraseasonal Kelvin waves in the Indonesian Throughflow（ITF） region. The large root mean square of intraseasonal SLA along the Sumatra and Java coast is closely related to the propagation of intraseasonal Kelvin waves that derive from the equatorial Indian Ocean. These Kelvin waves are further found to propagate following different pathways at the Lombok Strait. Pathway A propagates eastward throughout the Sumba Strait and Savu Sea to reach the Ombai Strait. Pathway B penetrates into Lombok and propagates northward to reach the Makassar Strait. Pathway C propagates southeastward along the southwest coast of the Sumba Island. The equatorial Kelvin waves take around 15 days to travel from the equatorial Indian Ocean to Lombok Strait, and around 5 days to penetrate into the Makassar and Ombai straits. The Kelvin wave-induced SLA persists in the ITF region for an additional 5 days and then diminishes subsequently. The phase speeds of these intraseasonal Kelvin waves along Pathways A, B, and C are 1.91–2.86, 1.69, and 1.96 m s^-1,respectively—in agreement with the first two baroclinic modes of Kelvin waves.展开更多
Impacts of the Indonesian Throughflow(ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing ...Impacts of the Indonesian Throughflow(ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing from NCEP reanalysis data during 2000–2011. It can reproduce vertical profiles of mean density and buoyancy frequency of World Ocean Atlas 2013 data. The model also simulates well annual oscillation in the central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies(SLA) using satellite altimeter data, as well as the semiannual oscillation of surface zonal equatorial currents of Ocean Surface Current Analyses Real Time current data in the equatorial Indian Ocean. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on LICOM output. Wave analysis suggests that ITF blockage mainly influences waves generated from the Indian Ocean but not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillations of SLA and zonal current dif ferences in the equatorial Indian Ocean associated with ITF. Reconstructed ITF-caused SLA using wave decomposition coefficient dif ferences between closed and open ITF-passage experiments suggest both Kelvin and Rossby waves from the first baroclinic mode have comparable contributions to the semiannual oscillations of SLA diff erence. However, reconstructed ITFcaused surface zonal currents at the equator suggest that the first meridional-mode Rossby wave has much greater contribution than the first baroclinic mode Kelvin wave. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has a greater contribution than other baroclinic modes.展开更多
Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insuff...Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insufficient,posing a threat to the construction,maintenance,and protection of coastal structures.This study establishes a multiple nested wave model based on the third-generation wave model WAVEWATCHⅢ.This model includes sole forcing of Roaring Forties and combined forcing of Roaring Forties and cyclone Ernie to simulate the influence of disastrous waves under the Roaring Forties and tropical cyclones in the Indonesian offshore zone and coasts.The following results are obtained.The Indonesian offshore is prevailed by relatively stable southern to southwestern dominant swells and small wind waves under the impacts of the Roaring Forties without cyclone winds.Long propagating swells originated from the Roaring Forties dominate in nearshore coastal waters with deformed directions and strength because of the shoaling effect.展开更多
We observed a subthermocline eddy(STE)with a cold and fresh core during an observation cruise along a transect of 10°S in the southeastern tropical Indian Ocean(SETIO)in December 2017.The vertical scale,speed rad...We observed a subthermocline eddy(STE)with a cold and fresh core during an observation cruise along a transect of 10°S in the southeastern tropical Indian Ocean(SETIO)in December 2017.The vertical scale,speed radius,and maximum swirl velocity of the STE were about 200 m,55 km,and 0.5 m/s,respectively.The mean Rossby number and Burger number of the STE were then estimated to be about−0.7 and 2.4,indicating the STE was a submesoscale coherent vortex.The STE core water had characteristics of the Indonesian Throughflow(ITF)water and was distinct from that of surrounding areas.By examining Argo float data,another STE was well captured by five successive profiles of the same Argo float.Both STEs showed significant temperature and salinity anomalies at theσ0=26.0-26.5 kg/m3 surfaces.With the assumption that the low-salinity ITF water parcels could be carried only by surface eddies and the STEs,the Argo profiles,which detected low-salinity ITF water and were located outside a surface eddy,were believed to be inside an STE and were used to analyze the distribution,origin,and generation mechanism of the STE.The results suggested that the STEs carrying ITF water may be generated under topography-current interaction at the eastern coastal waters or under front-induced subduction in the area away from coastal waters.Those STEs may be widely distributed in the SETIO and may play a role in ITF water parcel transport.展开更多
基金the National Institute of Information and Communication Technology International Exchange Program 2024−2025(No.2024−007)for their invaluable support in this research.3D tomography software is available at Prof.Kosuke Heki’s(Hokkaido University,Japan)personal homepage(https://www.ep.sci.hokudai.ac.jp/~heki/software.htm).support from the 2024 Japan Student Services Organization Research Follow-up Fellowship for a 90-day research visit at the Institute for Space−Earth Environmental Research,Nagoya University,Japan.PA also acknowledges the support received from Telkom University under the“Skema Penelitian Terapan Periode I Tahun Anggaran 2024”,and the Memorandum of Understanding for Research Collaboration on Regional Ionospheric Observation(No:092/SAM3/TE-DEK/2021).
文摘Equatorial Plasma Bubbles(EPBs)are ionospheric irregularities that take place near the magnetic equator.EPBs most commonly occur after sunset during the equinox months,although they can also be observed during other seasons.The phenomenon significantly disrupts radio wave signals essential to communication and navigation systems.The national network of Global Navigation Satellite System(GNSS)receivers in Indonesia(>30°longitudinal range)provides an opportunity for detailed EPB studies.To explore this,we conducted preliminary 3D tomography of total electron content(TEC)data captured by GNSS receivers following a geomagnetic storm on December 3,2023,when at least four EPB clusters occurred in the Southeast Asian sector.TEC and extracted TEC depletion with a 120-minute running average were then used as inputs for a 3D tomography program.Their 2D spatial distribution consistently captured the four EPB clusters over time.These tomography results were validated through a classical checkerboard test and comparisons with other ionospheric data sources,such as the Global Ionospheric Map(GIM)and International Reference Ionosphere(IRI)profile.Validation of the results demonstrates the capability of the Indonesian GNSS network to measure peak ionospheric density.These findings highlight the potential for future three-dimensional research of plasma bubbles in low-latitude regions using existing GNSS networks,with extensive longitudinal coverage.
文摘More than a simple concert pianist,Wilson Chu is an Indonesian musical diplomacy force.As a distinguished performer,composer,and educator,Wilson has left an indelible mark on the international stage by seamlessly blending Western classical music with Southeast Asian tradition.Since 2019,he has been the youngest Associate Professor of Piano at the College of Chinese and ASEAN Arts(CCAA)at Chengdu University,where he has dedicated himself to shaping the next generation of musicians.
基金The Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contact No.SML2021SP309the National Natural Science Foundation of China under contract Nos 42276005,42430402,and 92158204.
文摘The Indonesian Throughflow(ITF),mainly through the Makassar Strait,transports amounts of water and salt from the tropical Pacific Ocean to the Indian Ocean,playing a crucial role in modulating heat and energy budget between two oceans.The South China Sea Throughflow(SCSTF)significantly contributes to the net transport of the ITF via Karimata Strait and Mindoro-Sibutu Passage.However,the specific proportion and variability of South China Sea(SCS)water joining the ITF are still unclear.Based on high-resolution reanalysis data and a Lagrangian particle tracking method-Connectivity Modelling System(CMS),we quantified the proportion and variability of SCS water joining the ITF in the Makassar Strait.The results show that about 16.41%of the particles released in the Makassar Strait could be back-tracked from the SCS and 42.45%from the western Pacific Ocean.The particles through Mindoro Strait and Karimata Strait are about 10.55%and 3.39%,respectively.About 14.56%and 15.42%particles are trapped in the Sulu and Sulawesi seas.The proportion of SCS water shows significant interannual variability,which is highly related to El Niño-Southern Oscillation(ENSO)events.The correlation coefficient between interannual change of SCS water volume proportion and the Niño 3.4 index is 0.75,with an increase of about 24%during El Niño years and a decrease of about−22%during La Niña years.The proportion also varies with the depth of particles released,showing two peaks at surface and subsurface depths of 5 m and 110 m,respectively.
基金The Fund of Laoshan Laboratory under contract No.LSKJ202202700the Basic Scientific Fund for National Public Research Institutes of China under contract No.2024Q02+1 种基金the National Natural Science Foundation of China under contract Nos 42076023 and 42430402the Global Change and Air-Sea InteractionⅡProject under contract No.GASI-01-ATP-STwin.
文摘The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole(IOD)events.The detailed processes of ENSO and/or IOD induced anomalies impacting on the ITF,however,are still not clear.In this study,this issue is investigated through causal relation,statistical,and dynamical analyses based on satellite observation.The results show that the driven mechanisms of ENSO on the ITF include two aspects.Firstly,the ENSO related wind field anomalies driven anomalous cyclonic ocean circulation in the western Pacific,and off equatorial upwelling Rossby waves propagating westward to arrive at the western boundary of the Pacific,both tend to induce negative sea surface height anomalies(SSHA)in the western Pacific,favoring ITF reduction since the develop of the El Niño through the following year.Secondly,the ENSO events modulate equatorial Indian Ocean zonal winds through Walker Circulation,which in turn trigger eastward propagating upwelling Kelvin waves and westward propagating downwelling Rossby waves.The Rossby waves are reflected into downwelling Kelvin waves,which then propagate eastward along the equator and the Sumatra-Java coast in the Indian Ocean.As a result,the wave dynamics tend to generate negative(positive)SSHA in the eastern Indian Ocean,and thus enhance(reduce)the ITF transport with time lag of 0-6 months(9-12 months),respectively.Under the IOD condition,the wave dynamics also tend to enhance the ITF in the positive IOD year,and reduce the ITF in the following year.
基金The Fund of Laoshan Laboratory under contract No. LSKJ202202700the National Natural Science Foundation of China under contract Nos 42076023, 42076024 and 41876027the Global Change and Air-Sea Interaction Ⅱ Project under contract No.GASI-01-AIP-STwin。
文摘The Indonesian Throughflow(ITF), which connects the tropical Pacific and Indian oceans, plays important roles in the inter-ocean water exchange and regional or even global climate variability. The Makassar Strait is the main inflow passage of the ITF, carrying about 77% of the total ITF volume transport. In this study, we analyze the simulated ITF in the Makassar Strait in the Simple Ocean Data Assimilation version 3(SODA3) datasets. A total of nine ensemble members of the SODA3 datasets, of which are driven by different surface forcings and bulk formulas, and with or without data assimilation, are used in this study. The annual mean water transports(i.e.,volume, heat and freshwater) are related to the combination of surface forcing and bulk formula, as well as whether data assimilation is employed. The phases of the seasonal and interannual variability in water transports cross the Makassar Strait, are basically consistent with each other among the SODA3 ensemble members. The interannual variability in Makassar Strait volume and heat transports are significantly correlated with El Ni?oSouthern Oscillation(ENSO) at time lags of-6 to 7 months. There is no statistically significant correlation between the freshwater transport and the ENSO. The Makassar Strait water transports are not significantly correlated with the Indian Ocean Dipole(IOD), which may attribute to model deficiency in simulating the propagation of semiannual Kelvin waves from the Indian Ocean to the Makassar Strait.
文摘BACKGROUND Recently, gut microbiota has been associated with various diseases other than intestinal disease. Thus, there has been rapid growth in the study of gut microbiota. Considering the numerous factors influencing gut microbiota such as age, diet, etc., area-based research is required. Indonesia has numerous different tribes and each of these tribes have different lifestyles. Hence, it is expected that each tribe has a specific gut microbiota. A deeper insight into the composition of gut microbiota can be used to determine the condition of gut microbiota in Indonesians and to consider which treatment may be suitable and effective to improve health status.AIM To investigate the gut microbiota of Indonesian subjects represented by Javanese and Balinese tribes by analyzing fecal samples.METHODS Fecal samples were collected from a total of 80 individuals with 20 in each of the young groups ranging from 25-45 years and the elderly group aged 70 years or more from two different regions, Yogyakarta and Bali. Fecal sample collection was performed at the end of the assessment period(day 14 ± 1 d) during which time the subjects were not allowed to consume probiotic or antibiotic products.The quantification of various Clostridium subgroups, Lactobacillus subgroups,Enterococcus, Streptococcus, Staphylococcus, Bacteroides fragilis group and Prevotella,Bifidobacterium and Atopobium cluster, Enterobacteriaceae and Pseudomonas was performed using the Yakult intestinal flora-scan(YIF-SCAN).RESULTS The bacterial population in younger subjects' feces was higher than that in the elderly population, with a total of approximately 10.0 – 10.6 log10 bacterial cells/g feces. The most abundant bacteria in all groups were Clostridium, followed by Prevotella, Atopobium, Bifidobacterium and Bacteroides. In the elderly, an increase in Enterobacteriaceae, Coliform and Escherichia coli was found. In terms of bacterial counts in Yogyakarta, total bacteria, Clostridium coccoides(C. coccoides) group,Bifidobacterium, Prevotella, Lactobacillus plantarum subgroup, and Streptococcus were significantly higher(P < 0.05) in younger than elderly subjects, while the Lactobacillus gasseri subgroup, Lactobacillus casei subgroup, and Lactobacillus reuteri subgroup counts were significantly lower(P < 0.05) in younger subjects. In Balinese subjects, total bacteria, C. coccoides group, Clostridium leptum subgroup,Bacteroides fragilis group, and Prevotella were significantly higher(P < 0.05) in younger compared to elderly individuals, while the Lactobacillus ruminis subgroup, and Enterobacteriaceae were significantly lower(P < 0.05) in younger subjects. The results also revealed that, besides the C. coccoides group and Clostridium leptum group being the most abundant gut microbiota in both Yogyakarta and Balinese people, the latter was indicated by a higher Clostridium perfringens count, which was almost 10 times that of Yogyakarta subjects. This may be a response to different lifestyles in the different tribes; however, this phenomenon requires further extensive study.CONCLUSION Bacterial populations were higher in younger than in elderly subjects. Most abundant bacterial groups were Clostridium, Prevotella, Atopobium, Bifidobacterium,and Bacteroides. The level of Clostridium perfringens in Yogyakarta subjects was lower than that in Balinese subjects.
基金This work was jointly supported by the Chinese Academy of Sciences“Innovation Program”under Grant No.KZCX2-SW-210the National Key Basic Research of China under Grant No.G2000078502the National Natural Science Foundation of China under Grant Nos.40233031,40375030,and 40405017.
文摘A quasi-global eddy permitting oceanic GCM, LICOM1.0, is run with the forcing of ERA40 daily wind stress from 1958 to 2001. The modelled Indonesian Throughflow (ITF) is reasonable in the aspects of both its water source and major pathways. Compared with the observation, the simulated annual mean and seasonal cycle of the ITF transport are fairly realistic. The interannual variation of the tropical Pacific Ocean plays a more important role in the interannual variability of the ITF transport. The relationship between the ITF and the Indian Ocean Dipole (IOD) also reflects the influence of ENSO. However, the relationship between the ITF transport and the interannual anomalies in the Pacific and Indian Oceans vary with time. During some years, (e.g., 1994), the effect of a strong IOD on the ITF transport is more than that from ENSO.
基金sponsored by the National Public Benefit (Meteorology) Research Foundation of China (Grant No. GYHY 201306018)
文摘The role of the Indonesian Throughflow （ITF） in the influence of the Indian Ocean Dipole （IOD） on ENSO is investigated using version 2 of the Parallel Ocean Program （POP2） ocean general circulation model. We demonstrate the results through sensitivity experiments on both positive and negative IOD events from observations and coupled general circulation model simulations. By shutting down the atmospheric bridge while maintaining the tropical oceanic channel, the IOD forcing is shown to influence the ENSO event in the following year, and the role of the ITF is emphasized. During positive IOD events, negative sea surface height anomalies （SSHAs） occur in the eastern Indian Ocean, indicating the existence of upwelling. These upwelling anomalies pass through the Indonesian seas and enter the western tropical Pacific, resulting in cold anomalies there. These cold temperature anomalies further propagate to the eastern equatorial Pacific, and ultimately induce a La Nifia- like mode in the following year. In contrast, during negative IOD events, positive SSHAs are established in the eastern Indian Ocean, leading to downwelling anomalies that can also propagate into the subsurface of the western Pacific Ocean and travel further eastward. These downwelling anomalies induce negative ITF transport anomalies, and an E1 Nifio-like mode in the tropical eastern Pacific Ocean that persists into the following year. The effects of negative and positive IOD events on ENSO via the ITF are symmetric. Finally, we also estimate the contribution of IOD forcing in explaining the Pacific variability associated with ENSO via ITE
基金supported by the Chinese Academy of Sciences' Knowledge Innovation Program (Grant Nos.KZCX2-YW-214 and KZCX2-YW-BR-04)the National Natural Science Foundation of China (Grant Nos.40806005,40640420557 and 40625017)supported by a grant from the City University of Hong Kong (Project No. 7002329)
文摘Changes in the Indonesian Throughflow （ITF） and the South China Sea throughflow-measured by the Luzon Strait Transport （LST）-associated with the 1976/77 regime shift are analyzed using the Island Rule theory and the Simple Ocean Data Assimilation dataset. Results show that LST increased but ITF transport decreased after 1975. Such changes were induced by variations in wind stress associated with the regime shift. The strengthening of the easterly wind anomaly east of the Luzon Strait played an important role in the increase of LST after 1975, while the westerly wind anomaly in the equatorial Pacific contributed significantly to the decrease in ITF transport after 1975; accounting for 53% of the change. After 1975, the Kuroshio Current strengthened and the Mindanao Current weakened in response to a decrease in the total transport of the North Equatorial Current. Both the North Equatorial Countercurrent and the South Equatorial Current weakened after 1975, and an anomalous cyclonic circulation in the western equatorial Pacific prevented the tropical Pacific water from entering the Indian Ocean directly.
基金The GASI Project under contract Nos GASI-IPOVAI-01-02 and GASI-02-SCS-YGST2-02the National Natural Science Foundation of China under contract Nos 41776034 and 41706025the Foundation of Guangdong Province for Outstanding Young Teachers in University under contract No.YQ201588
文摘So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera Sea are diagnosed at seasonal and interannual timescales and at different vertical layers, using the state-of-the-art simulations of the Ocean General Circulation Model(OGCM) for Earth Simulator(OFES). Asian monsoon leaves clear seasonal footprints on the eastern Indonesian seas. Consequently, the subsurface waters(around 24.5σ_θ and at ～150 m) in both the Maluku Sea and the Halmahera Sea stem from the South Pacific(SP) during winter monsoon, but during summer monsoon the Maluku Sea is from the North Pacific(NP), and the Halmahera Sea is a mixture of waters originating from the NP and the SP. The monsoon impact decreases with depth, so that in the Maluku Sea, the intermediate water(around 26.8σ_θ and at ～480 m) is always from the northern Banda Sea and the Halmahera Sea water is mainly from the SP in winter and the Banda Sea in summer. The deep waters(around27.2σ_θ and at ～1 040 m) in both seas are from the SP, with weak seasonal variability. At the interannual timescale,the subsurface water in the Maluku Sea originates from the NP/SP during El Ni?o/La Ni?a, while the subsurface water in the Halmahera Sea always originates from the SP. Similar to the seasonal variability, the intermediate water in Maluku Sea mainly comes from the Banda Sea and the Halmahera Sea always originates from the SP. The deep waters in both seas are from the SP. Our findings are helpful for drawing a comprehensive picture of the water properties in the Indonesian seas and will contribute to a better understanding of the ocean-atmosphere interaction over the maritime continent.
基金The Strategic Priority Research Program of Chinese Academy of Sciences under contract Nos XDA20060502 and XDA11010301the National Key Research and Development Program of China under contract No.2016YFC1401401+2 种基金the National Natural Science Foundation of China under contract Nos 41676013,41521005 and 41731173the Independent Research Project Program of State Key Laboratory of Tropical Oceanography under contract No.LTOZZ1702the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Based on the high-resolution Eulerian fields of an ocean general circulation model simulation, the heat contribution of the Indonesian throughflow(ITF) to the Indian Ocean is estimated by Lagrangian tracing method.The heat transport of each particle of ITF waters is calculated by tracing temperature change along the trajectory until the particle exits the Indian Ocean. The simulation reveals that the ITF waters flow westward and branch near Madagascar, further showing the ITF waters are redistributed in both northern and southern Indian Ocean.Heat budget analysis indicates that the ITF waters gain 0.41 PW(Petawatts, 1015 W) in the northern Indian Ocean and lose 0.56 PW in the southern Indian Ocean, respectively. As a result, the ITF waters warm the whole Indian Ocean basin with only 0.15 PW, which shows an "insignificant" role of ITF on the Indian Ocean because of the heat exchange compensation between northern and southern Indian Ocean. Furthermore, the tracing pathways show that the ITF waters mainly flow out the Indian Ocean at both sides of the basin via Agulhas Current and Leeuwin Current. About 89% of the ITF waters leave along western boundary and the rest 11% along eastern boundary. Compared to seeding section, 0.10 PW and 0.05 PW are released to the Indian Ocean, respectively.
基金the National Basic Research Program of China("973"program) under contract No.2006CB403601the National Natural Science Foundation of China under contract No.40576016
文摘On the basis of Argo data and historic temperature/salinity data from the World Ocean Database 2001 （ WOD01 ）, origins and spreading pathways of the subsurface and intermediate water masses in the Indonesian Throughflow （ITF） region were discussed by analyzing distributions of salinity on representative isopyenal layers. Results were shown that, subsurface water mostly comes from the North Pacific Ocean while the intermediate water originates from both the North and South Pacific Ocean, even possibly from the Indian Ocean. Spreading through the Sulawesi Sea, the Makassar Strait, and file Flores Sea, the North Pacific subsurface water and the North Pacific Intermediate water dominate the western part of the Indonesian Archipelago. Furthermore as the depth increases, the features of the North Pacific sourced water masses become more obvious. In the eastern part of the waters, high sa- linity South Pacific subsurface water is blocked by a strong salinity front between Halmahera and New Guinea. Intermediate water in the eastern interior region owns salinity higher than the North Pacific intermediate water and the antarctic intermediate water （ AAIW）, possibly coming from the vertical mixing between subsurface water and the AAIW from the Pacific Ocean, and possibly coming from the northward extending of the AAIW from the Indian Ocean as well.
基金The National Natural Science Foundation of China under contract No.41176044Shaanxi Provincial Technology Foundation for Selected Overseas Chinese Scholar under contract Shaan Renshe[2015]No.1190
文摘Horizontal and vertical distributions of δ^18 and δ^13 were investigated in shells of four planktonic foraminiferal species, Globigerinoides ruber, Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquedrina dutertrei, from a total of 62 core-top sediment samples from the Indonesian throughflow region. Results were compared to modern hydrologic conditions in order to explore potential of proxies in reconstructing fluvial discharge and upper ocean water column characteristics in this region. Our results show that, in the Makassar Strait, both of depleted δ^18 and δ^13 of these four species were linked to freshwater input. In the Bali Sea,however, depleted δ^18 and δ^13 for these species may be due to different reasons. Depleted δ^18 was a result of freshwater input and as well influenced by along-shore currents while depleted δ^13 was more likely due to the Java-Sumatra upwelling. Comparison of shell δ^18 records and hydrographic data of World Ocean Atlas 2005 suggests that G. ruber and G. sacculifer calcify within the mixed-layer, respectively at 0–50 m and 20–75 m water depth, and P. obliquiloculata and N. dutertrei within the upper thermocline, both at 75–125 m water depth. N.dutertrei calcifies at slightly deeper water depth than P. obliquiloculata does. In general, δ^13 values of both G.ruber and G. sacculifer are larger than those of P. obliquiloculata and N. dutertrei at all sites, possibly related to depth habitats of these species and vertical distribution of nutrients in the Indonesian throughflow region.
基金The National Natural Science Foundation of China under contract No.41476025the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers under contract No.U1406404+3 种基金the National High Technology Research and Development Program(863 Program) of China under contract No.2013AA09A506the National Program on Global Change and Air-Sea Interaction under contract No.GASI-03-01-01-04the International Cooperation Program of State Oceanic Administration of China under contract No.QY0213022the "Strategic Priority Research Program" of the Chinese Academy of Sciences under contract No.XDA11010301
文摘Based on monthly mean Simple Ocean Data Assimilation （SODA） products from 1958 to 2007, this study analyzes the seasonal and interannual variability of the North Equatorial Current （NEC） bifurcation latitude and the Indonesian Throughflow （ITF） volume transport. Further, Empirical Mode Decomposition （EMD） method and lag-correlation analysis are employed to reveal the relationships between the NEC bifurcation location, NEC and ITF volume transport and ENSO events. The analysis results of the seasonal variability show that the annual mean location of NEC bifurcation in upper layer occurs at 14.33°N and ITF volume transport has a maximum value in summer, a minimum value in winter and an annual mean transport of 7.75×10^6 m^3/s. The interannual variability analysis indicates that the variability of NEC bifurcation location can be treated as a precursor of El Nino. The correlation coefficient between the two reaches the maximum of 0.53 with a time lag of 2 months. The ITF volume transport is positively related with E1 Nifio events with a maximum coefficient of 0.60 by 3 months. The NEC bifurcation location is positively correlated with the ITF volume transport with a correlation coefficient of 0.43.
基金supported by the National Natural Science Foundation of China(Grant Nos.41176044 and 41576045)Shaanxi Provincial Technology Foundation for Selected Overseas Chinese Scholar(Grant No.Shaan Renshe[2015]No.1190)
文摘Test geochemistry of planktonic foraminifera is an indispensable tool in reconstructing past ocean hydrological changes. It is essential to investigate region-specific implications of test geochemistry,although those established from other regions can be broadly applied. In this study, characteristics of6180 and Mg/Ca from tests of four planktonic foraminiferal species, Globigerinoides ruber sensu stricto(s.s.), Globigerinoides sacculifer, Pulleniatina obliquiloculata and Neogloboquadrina dutertrei, from 60 coretop sediment samples retrieved from the Indonesian Throughflow(ITF) region were studied. These geochemical data were compared with modern hydrographic profiles in order to assess their relations and to investigate potential implications of test geochemical parameters in reconstructing past oceanographic change in the ITF region. Calcification depths of these four species were first estimated based on comparison between measured test δ180 and predicted calcite δ^(18)O that was calculated from modern temperature and salinity. The results indicate that G. ruber s.s. and G. sacculifer calcify within the mixedlayer at 0-50 m and 20-75 m, respectively, whereas P. obliquiloculata and N. dutertrei calcify within the thermocline at around 75 to 125 m. A combined study of excess Mg/Ca(difference between measured and predicted Mg/Ca) and salinity suggests that salinity exerts a negligible impact on test Mg/Ca of these foraminiferal species in the ITF region. Comparison of test Mg/Ca-derived temperatures with temperature profiles of the upper 200 m of the water column from the seas of the ITF region also indicate calcification depths of these species, which match well with the above estimations using test δ^(18)O. It further indicates that G. sacculifer may be more sensitive in reflecting changes in the depth of the mixedlayer, highlighting a potential use of Mg/Ca temperature difference between G. ruber s.s. and G. sacculifer in reconstructing the depth of the mixed-layer in the ITF region.
基金supported by the National Natural Science Foundation of China(NSFC)[grant numbers 41476025,41506036,41306031]NSFC-Shandong Joint Fund for Marine Science Research Centers[grant number U1406404]+1 种基金China Postdoctoral Science Foundation Funded Project[grant number 2014M561883]Postdoctoral Innovation Foundation of Shandong Province[grant number 201403019]
文摘The gridded sea level anomaly（SLA） data-set provided by AVISO is used to track the propagation of intraseasonal Kelvin waves in the Indonesian Throughflow（ITF） region. The large root mean square of intraseasonal SLA along the Sumatra and Java coast is closely related to the propagation of intraseasonal Kelvin waves that derive from the equatorial Indian Ocean. These Kelvin waves are further found to propagate following different pathways at the Lombok Strait. Pathway A propagates eastward throughout the Sumba Strait and Savu Sea to reach the Ombai Strait. Pathway B penetrates into Lombok and propagates northward to reach the Makassar Strait. Pathway C propagates southeastward along the southwest coast of the Sumba Island. The equatorial Kelvin waves take around 15 days to travel from the equatorial Indian Ocean to Lombok Strait, and around 5 days to penetrate into the Makassar and Ombai straits. The Kelvin wave-induced SLA persists in the ITF region for an additional 5 days and then diminishes subsequently. The phase speeds of these intraseasonal Kelvin waves along Pathways A, B, and C are 1.91–2.86, 1.69, and 1.96 m s^-1,respectively—in agreement with the first two baroclinic modes of Kelvin waves.
基金Supported by the National Natural Science Foundation of China(No.41206018)the National Natural Science Foundation of China(Nos.41176019,41421005,U1406401)+4 种基金the Chinese Academy of Sciences(No.XDA11010203)to WANG Jingthe Chinese Academy of Sciences(No.XDA11010301)the National Basic Research Program of China(973 Program)(No.2012CB956001)the Specialized Scientific Research Project for Public Welfare Industries(Meteorology)(No.GYHY201306018)the State Oceanic Administration of China(No.GASI-03-01-01-05)to YUAN Dongliang
文摘Impacts of the Indonesian Throughflow(ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing from NCEP reanalysis data during 2000–2011. It can reproduce vertical profiles of mean density and buoyancy frequency of World Ocean Atlas 2013 data. The model also simulates well annual oscillation in the central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies(SLA) using satellite altimeter data, as well as the semiannual oscillation of surface zonal equatorial currents of Ocean Surface Current Analyses Real Time current data in the equatorial Indian Ocean. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on LICOM output. Wave analysis suggests that ITF blockage mainly influences waves generated from the Indian Ocean but not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillations of SLA and zonal current dif ferences in the equatorial Indian Ocean associated with ITF. Reconstructed ITF-caused SLA using wave decomposition coefficient dif ferences between closed and open ITF-passage experiments suggest both Kelvin and Rossby waves from the first baroclinic mode have comparable contributions to the semiannual oscillations of SLA diff erence. However, reconstructed ITFcaused surface zonal currents at the equator suggest that the first meridional-mode Rossby wave has much greater contribution than the first baroclinic mode Kelvin wave. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has a greater contribution than other baroclinic modes.
基金Supported by the National Natural Science Foundation of China(Grant No.51920105013)。
文摘Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters.However,the understanding of the characteristics and propagation mechanisms of local disastrous waves is insufficient,posing a threat to the construction,maintenance,and protection of coastal structures.This study establishes a multiple nested wave model based on the third-generation wave model WAVEWATCHⅢ.This model includes sole forcing of Roaring Forties and combined forcing of Roaring Forties and cyclone Ernie to simulate the influence of disastrous waves under the Roaring Forties and tropical cyclones in the Indonesian offshore zone and coasts.The following results are obtained.The Indonesian offshore is prevailed by relatively stable southern to southwestern dominant swells and small wind waves under the impacts of the Roaring Forties without cyclone winds.Long propagating swells originated from the Roaring Forties dominate in nearshore coastal waters with deformed directions and strength because of the shoaling effect.
基金The Shandong Provincial Natural Science Foundation under contract No.ZR2022MD080the Basic Scientific Fund for National Public Research Institutes of China under contract No.2017Q01+6 种基金the National Natural Science Foundation of China(NSFC)under contract Nos 41706038,41576027,41376038,and 40406009the NSFC-Shandong Joint Fund for Marine Science Research Centers under contract Nos U1406405 and U1606405the International Cooperation Project of Indo-Pacific Ocean Environment Variation and Air-Sea Interaction under contract No.GASI-03-IPOVAI-05the National Programme on Global Change and Air-Sea Interaction under contract Nos GASI-03-01-01-02 and GASI-IPOVAI-01-05the Public Science and Technology Research Funds Projects of Ocean under contract No.2009050240the National Key Scientific Instrument and Equipment Development Projects under contract No.2012YQ12003908the National Science and Technology Major Project under contract No.2016ZX05057015.
文摘We observed a subthermocline eddy(STE)with a cold and fresh core during an observation cruise along a transect of 10°S in the southeastern tropical Indian Ocean(SETIO)in December 2017.The vertical scale,speed radius,and maximum swirl velocity of the STE were about 200 m,55 km,and 0.5 m/s,respectively.The mean Rossby number and Burger number of the STE were then estimated to be about−0.7 and 2.4,indicating the STE was a submesoscale coherent vortex.The STE core water had characteristics of the Indonesian Throughflow(ITF)water and was distinct from that of surrounding areas.By examining Argo float data,another STE was well captured by five successive profiles of the same Argo float.Both STEs showed significant temperature and salinity anomalies at theσ0=26.0-26.5 kg/m3 surfaces.With the assumption that the low-salinity ITF water parcels could be carried only by surface eddies and the STEs,the Argo profiles,which detected low-salinity ITF water and were located outside a surface eddy,were believed to be inside an STE and were used to analyze the distribution,origin,and generation mechanism of the STE.The results suggested that the STEs carrying ITF water may be generated under topography-current interaction at the eastern coastal waters or under front-induced subduction in the area away from coastal waters.Those STEs may be widely distributed in the SETIO and may play a role in ITF water parcel transport.
