Physical oceanography of the Caroline M4 seamount in the tropical Western Pacific Ocean in summer 2017

Physical oceanography plays an important role in the formation of submarine sediments,and the distribution of nutriments and biocenoses in seamounts.The M4 seamount is located in the Caroline Island Ridge of the Western Pacific Ocean.The physical properties around M4 seamount are preliminarily analyzed based on the in-situ data obtained in summer 2017 in Caroline M4 seamount and open-sourced data.We found that the water in the upper 200 m is controlled by the westward North Equatorial Current(NEC),while the water between 300-1000 m is dominated by the eastward North Equatorial Undercurrent(NEUC).The current direction fluctuates significantly below 300 m at upstream stations.At the same depth of the lee sides,the current direction changes with the distance from seamount.These are likely caused by the obstacle of M4 seamount.The calculation results show that there is an anticyclonic cap above M4 seamount caused by tidal rectification.Tidal currents in M4 seamount are squeezed by the topography and amplified,and the amplified tidal currents play a dominant role in M4 seamount.First,the circulation system generated by the interaction of the amplified tidal current and M4 seamount drives the upward/downward movement of the isotherms.Secondly,the thickness of the surface turbulent layer is changed with the tidal phase.Thirdly,high turbulent diffusivities are found in the bottom of M4 seamount,and these are most likely attributed to the turbulent mixing induced by the mutual effect between semidiurnal tidal currents and steep bathymetry.This article of physical oceanography provides scientific basis for further analysis of the distribution of biological community and deposition mechanism in M4 seamount.

Noble Gas Isotopic Compositions of Cobalt-rich Ferromanganese Crusts from the Western Pacific Ocean and Their Geological Implications

Noble gas isotopic compositions of various layers in three-layered （outer, porous and compact layers） cobalt-rich ferromanganese crusts and their basaltic and phosphorite substrates from the western Pacific Ocean were analyzed by using a high vacuum gas mass spectrum. The analytical results show that the noble gases in the Co-rich crusts have derived mainly from the ambient seawater, extraterrestrial grains such as interplanetary dust particles （IDPs） and wind-borne continental dust grains, and locally formation water in the submarine sediments, but different noble gases have different sources. He in the crusts derives predominantly from the extraterrestrial grains, with a negligible amount of radiogenic He from the eolian dust grains. Ar is sourced mainly from the dissolved air in the seawater and insignificantly from radiogenic Ar in the eolian continental dust grains or the formation water. Xe and Ne derive mainly from the seawater, with minor amounts of extraterrestrial Xe and Ne in the IDPs. Compared with the porous and outer layers, the compact layer has a relatively high 4He content and lower 3He/4He ratios, suggesting that marine phosphatization might have greatly modified the noble gas isotopic compositions of the crusts. Besides, the 3He/4He values of the basaltic substrates of the cobalt-rich crusts are very low and their R/R. ratios are mostly 〈0.1 R., which are similar to that of phosphorite substrates （0.087 R.）, but much lower than that of fresh submarine MORB （8.75±14 Ra） or seamount basalts （3-43 Ra）, implying that the basaltic substrates have suffered strong water/rock interaction and reacted with radiogenic ^4He and P-rich upwelling marine currents during phosphatization. The trace elements released in the basalt/seawater interaction might favor the growth of cobalt-rich crusts. The relatively low ^3He/^4He values in the seamount basalts may be used as an important exploration criterion for the cobalt-rich ferromanganese crusts.

Control factors of DIC in the Y3 seamount waters of the Western Pacific Ocean

An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014,and the distribution of dissolved inorganic carbon(DIC)and its relationship with environmental factors in this area were explored.The results show that DIC concentration was higher in the adjacent waters of the Y3 seamount area,and the uplift of DIC isolines at the stations was close to the seamount.Meanwhile,interaction between the North Equatorial Current(NEC)and the Y3 seamount affected the DIC distribution,i.e.,the upwelling in the same direction of the NEC was obvious,resulting in a decreasing trend of average concentration of DIC in the 200 m water column from the top to the two sides in this direction but in the cross direction.The DIC concentration increased with the water depth increase,and its distribution was affected by various environmental factors.In the surface water,high temperature was a decisive factor for the decrease of the DIC concentration,but the photosynthesis of phytoplankton showing only a weak influence.In the North Pacific Tropic Water(NPTW),DIC production rate from organic matter decomposition was higher than that of DIC consumption by phytoplankton photosynthesis,leading to a continual increase of DIC.In the North Pacific Intermediate Water(NPIW),organic matter decomposition played a leading role in the increase of DIC.In the deep water,decomposition of organic matter weakened,and the dissolution of CaCO3 controlled the carbonate system,and DIC had the smallest variation range.

Planktonic ciliate trait structure variation over Yap,Mariana,and Caroline seamounts in the tropical Western Pacific Ocean

Trait structure is increasingly used in plankton ecology to understand diversity and biogeography.However,our knowledge of micro zooplankton(e.g.planktonic ciliates)trait structure and its variation with hydrography is limited.In this study,we analyzed planktonic ciliate trait structure in waters with different hydrography and deep Chlorophyll a maximum(DCM)layers over three seamounts:Yap,Mariana,and Caroline seamounts.Mariana seamount had a lower surface temperature than the Yap and Caroline seamounts.DCM layers over Mariana and Caroline seamounts were deeper than Yap seamount.There was a weak upwelling in upper 50 m around top of Mariana seamount.The ciliate distribution showed bimodal pattern(high abundance appeared in the surface and DCM layers)over three seamounts.At surface layer,the large size-fraction(>30μm)abundance proportion to aloricate ciliate over Yap seamount(44.4%)was higher than Mariana(32.8%)and Caroline(36.1%)seamounts.For tintinnid abundance proportion to total ciliate,Mariana(12.0%)and Caroline(11.5%)seamounts at about 100-m depth were higher than that of Yap seamount(6.4%).Vertically,tintinnid could be divided into 4 groups over the three seamounts.At30-m depth,group I(species occurring from surface to 100 m only)was dominant component over Yap and Caroline seamounts,while group IV(species occurring at every depth)changed into dominant component over Mariana seamount,the weak upwelling might be the reason.Salpingella faurei was the top dominant species,which corresponded to deeper DCM layers over Mariana and Caroline seamounts.Our results showed that the upwelling and the deeper DCM could influence the planktonic ciliate trait structure.

Assessment of acoustic backscatter intensity surveying on deep-sea ferromanganese crust: Constraints from Weijia Guyot, western Pacific Ocean

Near-bottom observation data from the manned deep submersible Jiaolong with high-precision underwater positioning data from Weijia Guyot,Magellan Seamounts in the Western Pacific Ocean are reported.Three substrate types were identified:Sediment,ferromanganese crust,and ferromanganese crust with a thin cover of sediment.The ferromanganese crusts show clear zoning and their continuity is usually disturbed by sediments on areas of the mountainside with relatively gentle slope gradients.The identified substrate spatial distributions correspond to acoustic backscatter intensity data,with regions of high intensity always including crust development and regions of low intensity always having sediment.Therefore,acoustic backscatter intensity surveying appears useful in the delineation and evaluation of crust resources,although further more work is needed to develop a practicable methodology.

A new species of Nassarius(Gastropoda:Nassariidae) from the western Pacific Ocean

This paper describes a new species of Nassarius from the South China Sea,which was recognized when re-sorting the collection of Nassariidae in the Marine Biological Museum,Chinese Academy of Sciences,Qingdao,China.The shells were collected during several investigations,including the National Comprehensive Oceanic Survey in 1958-1959,and the China-Vietnam Co-Investigation on Marine Resource of the Beibu Gulf during 1959-1962.The morphology of the shell and the radula places the new species of Nassarius within the subgenus Zeuxis.It is named Nassarius(Zeuxis) nanhaiensis sp.nov.

Analysis of differences in nutrients chemistry in seamount seawaters in the Kocebu and M4 seamounts in Western Pacific Ocean

Comprehensive surveys were conducted in the Kocebu deep seamount and the M4 shallow seamount in the Western Pacific Ocean in March 2018 and May 2019,respectively.The distributions of nutrients in euphotic zone of the two seamount-areas were revealed,and the causative controlling factors were analyzed.Results show that the vertical distribution of nutrients in the two seamount-areas accorded with the general law of the oligotrophic ocean.The concentrations of NO_(3)-N,PO_(4)-P,and SiO_(3)-Si generally increased gradually with the increase of water depth,and they were extremely low in water layers within100 m.The area of high NO_(2)-N concentration well agreed with the Deep Chlorophyll Maximum Layer.On the other hand,the distribution of water masses and phytoplankton and hydrological conditions in the two seamount-areas were different,resulting in lower concentrations of NO_(3)-N,PO_(4)-P,and SiO_(3)-Si in the water layers below 100 m in the Kocebu seamount area than those in the M4 seamount area.In addition,NO_(2)-N was affected by the distribution of phytoplankton,and distributed mainly in the water layers of 150 and100 m.There was upwelling in the euphotic zone of M4 seamount area,causing accumulations of nutrients and phytoplankton around the seamount,forming a"seamount effect";however,no such an effect was found in Kocebu seamount area.Affected by the composition of biological community and the"seamount effect",the nitrogen limitation in the M4 seamount area was not significant,and the dissolved inorganic nitrogen(DIN):PO_(4)-P and SiO_(3)-Si:DIN were closer to the Redfield ratios.

The bacterial diversity and community composition altered in the oxygen minimum zone of the Tropical Western Pacific Ocean

The oxygen minimum zones(OMZs)are globally expanding,yet the variation pattern of microbial communities related to dissolved oxygen levels remain unclear.Spatial variability of bacterial diversity and community composition(repre sented by 16 S rRNA)of six stations was investigated within the water column in the seamount area of Tropical Western Pacific Ocean(TWPO)in May 2019.The seawater has dissolved oxygen(DO)concentration of 3.01-6.68 mg/L and the core of the oxygen minimum zones was located between the depths of 650 m and 1750 m.The bacterial alpha-diversity showed unimodal pattern with the decreasing DO with depths and peaked in the upper oxycline(UO)of OMZs.The bacterial community structure of the mixed layer(ML)and the bottom layer clustered and separated from each other,while those of UO and the OMZ core(OM)clustered and overlapped.Overall,bacterial community composition transitioned from being Alphaproteobacteria and Gammaproteobacteria-dominant in ML to being Gammaproteobacteria and Nitrososphaeria/Deltaproteobacteria-dominant in UO and OM,and then changed to being Clostridia and unidentified Actinobacteria-dominant in the bottom layer.Moreover,both bacterial alpha-diversity and the abundant classes fitted varying sectioned functions with DO.The DO solely explained 40.37%of the variation of bacterial community composition among layers(P<0.001).The predicted function profiling showed that the water column was predominant by chemoheterotrophy,cyanobacteria,and photoautotrophy in ML,by chemoheterotrophy and nitrate/sulfide cycling in UO and OM,and by chemoheterotrophy and ferme ntation in the bottom layer.Our findings revealed the DO-associated variation in bacterial diversity and community composition,and help to clarify the potential responses of microbes and their involved biogeochemical processes to the expansion and intensification of OMZs.

Relationship Between Zooplankton Community Characteristics and Environmental Conditions in the Surface Waters of the Western Pacific Ocean During the Winter of 2014

Understanding the effects of environmental heterogeneity on zooplankton communities has been a hot topic for several decades.However,relatively little is known about the responses of zooplankton communities to environmental conditions at large scales from inshore waters to the open ocean.Here,we used the abundance,biovolume,taxa and size spectra of zooplankton col-lected from the surface waters of the western Pacific Ocean during the winter of 2014 to study the relationship between zooplankton community characteristics and environmental conditions using multiple linear regression(MLR)analysis and redundancy analysis(RDA).According to a hierarchical cluster analysis based on hydrographic conditions,the study area was classified into five water masses.Significant correlations were identified between the limited nutrients and the zooplankton abundance and biovolume from inshore waters to the open ocean.Non-metric multidimensional scaling(NMDS)revealed two distinct zooplankton assemblages.In the northern inshore,Copepoda and Euphausiacea were the dominant zooplankton taxa and in other water masses,Chaetognatha and gelatinous zooplankton were the dominant zooplankton taxa in addition to Copepoda.Our results suggested that,on a large scale from inshore waters to the open ocean in the western Pacific Ocean,the spatial distribution of zooplankton taxa was mainly influ-enced by environmental conditions,while in the inshore waters,it was due to the top-down effect of the dominant zooplankton taxa.Finally,the slope of the normalized biovolume size spectra(NBSS)was negatively correlated with chlorophyll-a(Chl-a)concentra-tion and PO_(4)^(3−)-P concentration in the inshore waters,which indicated that the higher the trophic level the dominant zooplankton taxa were,the steeper the NBSS slope was.

The effect of altimetry data in estimating the elastic thickness of the lithosphere in the western Pacific Ocean

The elastic thickness of the lithosphere(Te)is a key parameter used to describe the strength of the lithosphere.It is usually estimated by a spectral analysis between gravity and topography.In previous research on the estimation of Te,altimetry data were used on both the gravity data and topography data,which could lead to deviations.The study described in this paper analyzed the effects of using gravity anomalies derived from different data sources on the estimation of Te,Taking the western Pacific region as an example,this study analyzed the impact of the repeated presence of altimetry satellite data on the calculation of the effective elastic thickness and found that if gravity anomalies and topography model both contain altimetry satellite data,they systematically overestimate effective elasticity.For a uniform area,the difference in Te can reach up to 30%.For a Te distribution,the difference can reach up to about16%.After eliminating this effect,the effective elastic thickness of the western Pacific region was found to be 10 km,and the statistical results of the effective elastic thickness distribution showed that the effective elastic thickness of the lithosphere in most areas of the western Pacific is about 12 km.The paper shows the importance of choosing the appropriate gravity model in evaluating the elastic thickness of lithosphere in the oceans.A figure of Te at seamounts with loading ages demonstrates that Te in the western Pacific is generally distributed within the 100-300℃isotherm depth and does not increase with loading age.

Seasonal variation of the surface North Equatorial Countercurrent (NECC) in the western Pacific Ocean

The North Equatorial Countercurrent(NECC) is an important zonal fl ow in the upper circulation of the tropical Pacifi c Ocean, which plays a vital role in the heat budget of the western Pacifi c warm pool. Using satellite-derived data of ocean surface currents and sea surface heights(SSHs) from 1992 to 2011, the seasonal variation of the surface NECC in the western tropical Pacifi c Ocean was investigated. It was found that the intensity(INT) and axis position(Y_(CM)) of the surface NECC exhibit strikingly different seasonal fl uctuations in the upstream(128°–136°E) and downstream(145°–160°E) regions. Of the two regions, the seasonal cycle of the upstream NECC shows the greater interannual variability. Its INT and Y CM are greatly infl uenced by variations of the Mindanao Eddy, Mindanao Dome(MD), and equatorial Rossby waves to its south. Both INT and YC M also show semiannual signals induced by the combined effects of equatorial Rossby waves from the Central Pacifi c and local wind forcing in the western Pacifi c Ocean. In the downstream region, the variability of the NECC is affected by SSH anomalies in the MD and the central equatorial Pacifi c Ocean. Those in the MD region are especially important in modulating the Y CM of the downstream NECC. In addition to the SSH-related geostrophic fl ow, zonal Ekman fl ow driven by meridional wind stress also plays a role, having considerable impact on INT variability of the surface NECC. The contrasting features of the variability of the NECC in the upstream and downstream regions refl ect the high complexity of regional ocean dynamics.

Living coccolithophores in the western Pacific Ocean with mesoscale eddies

Living coccolithophores(LCs)are regarded as a group of calcifiers and play important roles in global carbon cycle.This study used microscopic observations of LCs in the western Pacific Ocean to investigate their community structure and biodiversity,especially to test whether local physical traits(mesoscale eddies)could explain their biogeographic distributions during autumn of 2017.The coccolithophore calcite inventory based on carbon-volume transformation was estimated in this study.A total of 28 taxa of coccospheres and 19 types of coccoliths were identified from 161 samples.Gephyrocapsa oceanica was the most predominant species in all the coccolithophore community,followed by Florisphaera profunda,Emiliania huxleyi,Umbilicosphaera sibogae,Gladiolithusflabellatus and Umbellosphaera tenuis.The abundance of coccospheres and coccoliths ranged from 0 to 26.8×10^(3)cells/L and from 0 to 138.5×10^(3)coccoliths/L,averaged at 4.2×10^(3)cells/L and 10.9×10^(3)coccoliths/L,respectively.This study indicated that coccolithophore community in the survey area can be clustered into four groups.Three ecological niches of coccolithophores were characterized by their vertical profiles and multivariate statistical analysis.Coccolithophore abundance and species composition were remarkably different among warm-eddy region,G.oceanica dominated warm-eddy region,while F.profunda dominated warm-eddy and none-eddy region.The average values of estimated particulate inorganic carbon,particulate organic carbon were0.197μg/L and 0.140μg/L,respectively.The current field study widened the dataset of coccolithophores in western Pacific Ocean.

Geochemical speciation and spatial distributions of phosphorus in surface sediments from the basin of the Marcus-Wake seamounts in the western Pacific Ocean

The concentrations of five forms of phosphorus(P)including exchangeable or loosely adsorbed P(Ex-P),Febound P(Fe-P),authigenic P(Auth-P),detrital P(Det-P),and organic P(Org-P)from the basin among the Marcus-Wake seamounts(19.4°–24°N,156.5°–161.5°E)in the western Pacific Ocean were quantified using a sequential extraction method(SEDEX)to investigate the distribution and sources of different P species.Concentrations of total P(TP)varied from 14.0μmol/g to 44.1μmol/g,with an average of(32.4±7.7)μmol/g.Inorganic phosphorus,which was the major chemical form of sedimentary P,ranged from 12.6μmol/g to 40.6μmol/g,while the concentration of Org-P varied between 1.38μmol/g and 5.18μmol/g,accounting for 83.4%–93.4%and 6.6%–16.6%of the TP,respectively.The relative proportions of the five P species followed the order of Det-P>Auth-P>Org-P>Fe-P>Ex-P.On average,Det-P was the major P sink resulted from the atmospheric input and accounted for approximately 58.9%±12.4%of the TP.Auth-P and Org-P comprised 22.8%±11.4%and11.5%±3.0%of the TP,respectively,while Fe-P accounted for 5.1%±2.6%.Lastly,Ex-P comprised 1.6%±0.3%of the TP.Org-P exhibited a negative correlation with Fe-P and Auth-P,while Fe-P showed a positive correlation with Auth-P.This indicated that the formation of Fe-P and Auth-P was at the expense of the regeneration or remineralization of Org-P during early diagenesis.High concentrations of Det-P and Auth-P as well as a low ratio of total organic C to reactive P(TOC/Rea-P)suggested that the aeolian input may play a significant role in sedimentary P budget in the study area.Additionally,well-oxygenated bottom water and low sedimentation rate could be responsible for the low TOC/Org-P ratio in the sediment.

Helium and Oxygen isotopic evidence on exchange of waters betweenthe western Pacific Ocean and the South China Sea

The composition and distribution of helium and oxygen isotopes in samples of seawater ob-tained at depths from surface to 300 m in the western Pacific Ocean (7°-26°N, 122° - 130°E) were discussed in detail. The results shaw that both δ18O and δ3He isoline extend eastward in the Pacific side of the Bashi Channel, which may suggest that the South China Sea water intrudes into the western Pacific by the Bashi Channel.

The multifractal characters of temperature finestructuresin the equatorial western Pacific Ocean

By using part of CTD data collected at 2°S, 155° E during the fall cruise of TOGA project in 1992, themultifractal characters of temperature finestructures are investigated. The absolute temperature gradients are supposedto be multifractal and their moments are computed by conventional box-counting method. It is found that these moments have power dependence on the box size. This power dependence has two different scaling regimes, called Sregime and I-regime resistively, with different scaling exponents. This is consistent with the combined effects of internal waves and boxing. Accordingly, the generalized fractal dimensions (Renyi dimension) of temperature gradientsare derived. A nonlinear curve of the scaling exponents suggest a possible multifractal approach of the temperatureshear. In fact, both regimes can be approximated by Besicovitch- Cantor model, respectively, by suitably chosenmoduel parameters. A phenomenological model is developed on the basis of this two-regime mechanism. The model iscompared with field data and good agreement is achieved.

A survey on pollen dispersal in the western Pacific Ocean and its paleoclimatological significance as a proxy for variation of the Asian winter monsoon

Pollen grains deposited in marine sediments are transported from land to sea by wind or surface water flows.We analyzed pollen collected from the air and seawater from the coast of the Yellow Sea near China and into the western Pacific Ocean between December 2008 and January 2009 during the cruise "KX08-973".Results showed that abundant pollen grains of Artemisia and Chenopodiaceae were probably transported to the continental shelf of the East China Sea,the East Philippine Sea and the equatorial regions of the Pacific Ocean by the winter monsoon.Some pollen may have even traveled over 2000 km from the East Asia continent to the tropical Pacific Ocean.However,a gradual decline of temperate components and an increase in tropical components was observed towards the tropical regions.Fern spores were rare in the air samples,but much more abundant in seawater samples,even though they were collected in nearly the same areas,which indicates that most fern spores were carried to the ocean by flowing water.These results suggest that the winter monsoon may be the major pollen carrier and transporter in the study area during winter.

Dispersion relation of internal waves in thewestern equatorial Pacific Ocean

Based mainly on TOGA-COARE data, that is, the CTD data from R/V Xiangyanghong No. 5 (Pu et al., 1993), the temperature and current data from the Woods Hole mooring and other deep current data, the layered numerical profiles of buoyancy frequency and mean current components are figured out. A numerical method calculating internal wave dispersion relation without background shear current, used by Fliegel and Hunkins (1975), is improved to be fit for the internal wave equation with mean currents and their second derivatives. The dispersion relations and wave functions of the long crested internal wave progressing in any direction can be calculated conveniently by using the improved method. A comparison between the calculated dispersion relation in the paper and the dispersion relation in GM spectral model of ocean internal waves (Garret and Munk, 1972) is performed. It shows that the mean currents are important to the dispersion relation of internal waves in the western equatorial Pacific Ocean and that the currents make the wave progressing co-directional with (against) the currents stretched (shrink). The influence of the mean currents on dispersion relation is much stronger than that of their second derivatives, but that on wave function is less than that of their second derivatives. The influences on wave functions result in the change of vertical wavenumber, that is, making the wave function stretch or shrink. There exists obvious turning depth but no significant critical layer absorption is found.

Characteristics of Semi-diurnal Internal Tides in the Western Equatorial Pacific Ocean Around 1°45′S,156°E

The analyses of a data series obtained during TOGA- COARE show the existence of remarkable semi-diurnal intemal tides in the western equatorial Pacific Ocean around 1°45＇S, 156°E. Some characteristic parameters of the internal tides are vertical wavenumber -1.6×10^-3 m^-1, horizontal wavenumber （wavelength） 3.3×10^-2 km^-1 （210 km）, vertical propagation speed -3.8 cm/s and horizontal propagation speed 2.0 m/s. The waveforms propagate downwards slantingly, that is, the wave energy transfers upwards slantingly. Depth-distribution of the＇rotary spectral levels is a saddle-shape. The depths of the trough and the deeper peaks are almost coincident with those of the south boundaries of the South Equatorial Current and the Equatorial Undercurrent, respectively. The mean orientation of the rotary spectral ellipse changes with depth： 30° from north to east at 40 m, and changes into 14° from east to south at 324 m, and generally, it points to northeastward, which indicates ＂that waves come from the southwest.

Atmospheric input of trace elements to the western Pacific Ocean and the Kuroshio ocean area

In November 1992 to February 1993 (IOP TOGA -COARE), many aerosol samples, rainwater samples and dry depesition samples were collected on the vessel Xiangyanghong No. 5 in the ocean area of IOP (2°S, 155°E). The time variations of concentration of crustal elements, sea salt elements are not very large. The dry deposition fluxes of crustal elements are related to the sources of air flows. According to the aerosol samples collected in the western Pacific Oceanduring eight cruises under the China-U. S. joint TOGA project from December 1985 to July 1990 and the aerosol data collected in the Kuroshio ocean area from 1987 to 1991 (China-Japan Kuroshio joint-investigation), seasonal average dry deposition fluxes of crustal elements, pollutant elements and sea-salt elements are calculated. It is found that the dry deposition fluxes of elements Fe, Co, Zn and Sb have their highest values in spring in the Kuroshio ocean area because of the influencing of Asian dust-storm. But in the western Pacific ocean they reach the highest values in autumn. In the

Tracking typhoon-generated swell in the western North Pacific Ocean using satellite altimetry

This paper proposes a scheme for detecting the swell decay of a moving typhoon. We considered a typhoon that was neither far from a point source nor had a belt-like homogenous source,as previously studied. We tracked the swell close to the source during a typhoon in the western North Pacific Ocean. We used wind speed and significant wave height data derived from the Geophysical Data Record of the Jason-1 altimeter and the best-track information of the typhoon from the China Meteorological Administration tropical cyclone database. We selected three specific cases to reveal the decay characteristics of the swell generated by a moving typhoon. Based on an altimeter-based typhoon swell identification scheme and the dispersion relationship for deep water,we relocated the swell source for each altimeter measurement. The subsequent statistical decay coefficient was comparable to previous studies,and effectively depicted the swell propagation conditions induced by the typhoon. We hope that our results provide a new understanding of the characteristics and wave energy budget of the North Pacific Ocean,and significantly contribute to wave modeling in this region.