Predictability of the upper ocean heat content in a Community Earth System Model ensemble prediction system

Upper ocean heat content(OHC)has been widely recognized as a crucial precursor to high-impact climate variability,especially for that being indispensable to the long-term memory of the ocean.Assessing the predictability of OHC using state-of-the-art climate models is invaluable for improving and advancing climate forecasts.Recently developed retrospective forecast experiments,based on a Community Earth System Model ensemble prediction system,offer a great opportunity to comprehensively explore OHC predictability.Our results indicate that the skill of actual OHC predictions varies across different oceans and diminishes as the lead time of prediction extends.The spatial distribution of the actual prediction skill closely resembles the corresponding persistence skill,indicating that the persistence of OHC serves as the primary predictive signal for its predictability.The decline in actual prediction skill is more pronounced in the Indian and Atlantic oceans than in the Pacific Ocean,particularly within tropical regions.Additionally,notable seasonal variations in the actual prediction skills across different oceans align well with the phase-locking features of OHC variability.The potential predictability of OHC generally surpasses the actual prediction skill at all lead times,highlighting significant room for improvement in current OHC predictions,especially for the North Indian Ocean and the Atlantic Ocean.Achieving such improvements necessitates a collaborative effort to enhance the quality of ocean observations,develop effective data assimilation methods,and reduce model bias.

Rotating tank experiments for the study of geophysical fluid dynamics

Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD employs various research approaches including in-situ observations,satellite measurements,numerical simulations,theoretical analysis,artificial intelligence,and physical model experiments in laboratory.Among these approaches,rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories.With proportional scaling and proper techniques,scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system,which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans.In this review,rotating tanks of various scales in the world are introduced,as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics.To illustrate the GFD experiments,three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments:mesoscale eddies in the ocean,convection processes,and plume dynamics.Detailed references for the experimental procedures are provided.Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods.This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.

Twenty years of ocean observations with China Argo

The international Argo program,a global observational array of nearly 4000 autonomous profiling floats initiated in the late 1990s,which measures the water temperature and salinity of the upper 2000 m of the global ocean,has revolutionized oceanography.It has been recognized one of the most successful ocean observation systems in the world.Today,the proposed decade action“OneArgo”for building an integrated global,full-depth,and multidisciplinary ocean observing array for beyond 2020 has been endorsed.In the past two decades since 2002,with more than 500 Argo deployments and 80 operational floats currently,China has become an important partner of the Argo program.Two DACs have been established to process the data reported from all Chinese floats and deliver these data to the GDACs in real time,adhering to the unified quality control procedures proposed by the Argo Data Management Team.Several Argo products have been developed and released,allowing accurate estimations of global ocean warming,sea level change and the hydrological cycle,at interannual to decadal scales.In addition,Deep and BGC-Argo floats have been deployed,and time series observations from these floats have proven to be extremely useful,particularly in the analysis of synoptic-scale to decadal-scale dynamics.The future aim of China Argo is to build and maintain a regional Argo fleet comprising approximately 400 floats in the northwestern Pacific,South China Sea,and Indian Ocean,accounting for 9%of the global fleet,in addition to maintaining 300 Deep Argo floats in the global ocean(25%of the global Deep Argo fleet).A regional BGC-Argo array in the western Pacific also needs to be established and maintained.

Epipelagic mesozooplankton communities in the northeastern Indian Ocean off Myanmar during the winter monsoon

The northern Andaman Sea off Myanmar is one of the relatively high productive regions in the Indian Ocean.The abundance,biomass and species composition of mesozooplankton and their relationships with environmental variables in the epipelagic zone(~200 m)were studied for the first time during the Sino-Myanmar joint cruise(February 2020).The mean abundance and biomass of mesozooplankton were(1916.7±1192.9)ind./m3and(17.8±7.9)mg/m3,respectively.A total of 213 species(taxa)were identified from all samples.The omnivorous Cyclopoida Oncaea venusta and Oithona spp.were the top two dominant taxa.Three mesozooplankton communities were determined via cluster analysis:the open ocean in the Andaman Sea and the Bay of Bengal(Group A),the transition zone across the Preparis Channel(Group B),and nearshore water off the Ayeyarwady Delta and along the Tanintharyi Coast(Group C).Variation partitioning analysis revealed that the interaction of physical and biological factors explained 98.8%of mesozooplankton community spatial variation,and redundancy analysis revealed that column mean chlorophyll a concentration(CMCHLA)was the most important explanatory variable(43.1%).The abundance and biomass were significantly higher in Group C,the same as CMCHLA and column mean temperature(CMT)and in contrast to salinity,and CMT was the dominant factor.Significant taxon spatial variations were controlled by CMCHLA,salinity and temperature.This study suggested that mesozooplankton spatial variation was mainly regulated by physical processes through their effects on CMCHLA.The physical processes were simultaneously affected by heat loss differences,freshwater influx,eddies and depth.

The first quantitative remote sensing of ocean internal waves by Chinese GF-3 SAR satellite

Quantitative analysis and retrieval is given by the State Key Laboratory of Satellite Ocean Environment Dynamics（SOED）,Second Institute of Oceanography（SIO）,State Oceanic Administration（SOA）,China,from the first batch of GF-3 synthetic aperture radar（SAR）data with ocean internal wave features in the Yellow Sea.

Comparisons of OCO-2 satellite derived XCO_(2)with in situ and modeled data over global ocean

Atmospheric CO_(2)is one of key parameters to estimate air-sea CO_(2)flux.The Orbiting Carbon Observatory-2(OCO-2)satellite has observed the column-averaged dry-air mole fractions of global atmospheric carbon dioxide(XCO_(2))since 2014.In this study,the OCO-2 XCO_(2)products were compared between in-situ data from the Total Carbon Column Network(TCCON)and Global Monitoring Division(GMD),and modeling data from CarbonTracker2019 over global ocean and land.Results showed that the OCO-2 XCO_(2)data are consistent with the TCCON and GMD in situ XCO_(2)data,with mean absolute biases of 0.25×10^(-6)and 0.67×10^(-6),respectively.Moreover,the OCO-2 XCO_(2)data are also consistent with the CarbonTracker2019 modeling XCO_(2)data,with mean absolute biases of 0.78×10^(-6)over ocean and 1.02×10^(-6)over land.The results indicated the high accuracy of the OCO-2 XCO_(2)product over global ocean which could be applied to estimate the air-sea CO_(2)flux.

Impacts of channel dredging on hydrodynamics and sediment dynamics in the main channels of the Jiaojiang River Estuary in China

Channel dredging in estuaries increases water depth and subsequently impacts sediment dynamics and morphology. The Jiaojiang River Estuary is dredged frequently owing to heavy shipping demands. In this study,the effects of different dredging schemes on siltation were assessed through numerical modeling. The sediment model of the Jiaojiang River Estuary utilized an optimized bottom boundary layer model that considered the bed sediment grain size and fluid mud, and this model was calibrated using field data. Result reveal that channel dredging modifies the flow velocity inside and around the channel by changing the bathymetry;subsequently, this affects the residual current, bed stress, suspended sediment concentration, and sediment fluxes. Increasing the dredging depth and width increases the net sediment fluxes into the channel and dredging depth has a greater influence on the channel siltation thickness. When the dredging depth is 8.4 m or11.4 m, the average siltation thickness of the channel is 0.07 m or 0.15 m per mouth respectively. The parallel movement of the channel has small effects on the siltation volume during the simulation period. The sediment deposits in the channel primarily originates from the tidal flats, through bottom sediment fluxes. Vertical net circulation has a dominant impact on siltation because the difference of horizontal current of each layer on the longitudinal section of the channel increases, which intensifies the lateral sediment transport between the shoal and channel. The influence of vertical frictional dissipation on the lateral circulation at the feature points accounts for more than 50% before dredging, while the non-linear advective term is dominant after dredging. Tidal pumping mainly affects the longitudinal sediment fluxes in the channel. These results can be used for channel management and planning for similar estuaries worldwide.

Study of coexisting upstream solitary wave packet and downstream wakes induced by Diaoyu Dao and its affiliated islands detected by satellite sun glitter

Taking the advantage of sun glitter(SG)observed from high-resolution satellites Gaofen-1(GF-1)and Gaofen-6(GF-6),a new method named Shield and Vortex 1-2(SAV1-2)for extracting spatial texture information from sun glitter was established.Sea surface texture detail information around Diaoyu Dao and its affiliated islands was extracted using SAV1-2.Meanwhile,the dynamic characteristics of the water environment were analyzed by combining the water color,temperature and dynamic data.The results show the following information.(1)Stable westward shield effect and eastward Karman vortex streets,extracted from SG,appear upstream(westward)and downstream(eastward)of the Diaoyu Dao and its affiliated islands respectively.(2)The dominant direction of the Kuroshio Current in the Diaoyu Dao and its affiliated islands area is east,the Diaoyu Dao and its affiliated islands interacting with Kuroshio,inducing western shield and eastern shelter and wake.Furthermore,wave intervals of the shield in front of the island range from hundreds to thousands of metres,and extend wider than the island itself.(3)Combining with high-resolution sea surface temperature(SST)and chlorophyll a(Chl a)concentration,the directional changes of water color elements are mutually supported and proved with the stable shield(wave packet)effect in the west and vortex street effect in the east.The change of SST upstream of the island(western shield area)is not significant,the temperature in the downstream shelter area decreases slightly,and the SST in the downstream wake area shows a general trend of obvious decrease.The wake area is dominated by Karman vortex streets in shape,supplementing by vortices.The concentration of Chl a in the west shield of island is as low as that in downstream shelter area,while it increases significantly in the downstream wake area with shape in eddy or ribbon.(4)The SAV methods of extracting sea surface texture detail using SG can be widely used in different sea areas and water quality.This paper can provide reference for the protection and development of Diaoyu Dao and its affiliated islands and its surrounding waters.It is suggested that some kind of current buffer,such as marine wind farm,should be established in the western waters of Diaoyu Dao and its affiliated islands to protect the islands,and marine pasture should be developed in the downstream of eastern waters of Diaoyu Dao and its affiliated islands.

Satellite remote sensing of ultraviolet irradiance on the ocean surface

Ultraviolet （UV） radiation has a significant influence on marine biological processes and primary productivity; however, the existing ocean color satellite sensors seldom contain UV bands. A look-up table of wavelength- integrated UV irradiance （280-400 nm） on the sea surface is established using the coupled ocean atmosphere radiative transfer （COART） model. On the basis of the look-up table, the distributions of the UV irradiance at middle and low latitudes are inversed by using the satellite-derived atmospheric products from the Aqua satellite, including aerosol optical thickness at 550 nm, ozone content, liquid water path, and the total precipitable water. The validation results show that the mean relative difference of the 10 d rolling averaged UV irradiance between the satellite retrieval and field observations is 8.20% at the time of satellite passing and 13.95% for the daily dose of UV. The monthly-averaged UV irradiance and daily dose of UV retrieved by satellite data show a good correlation with the in situ data, with mean relative differences of 6.87% and 8.43%, respectively. The sensitivity analysis of satellite inputs is conducted. The liquid water path representing the condition of cloud has the highest effect on the retrieval of the UV irradiance, while ozone and aerosol have relatively lesser effect. The influence of the total precipitable water is not significant. On the basis of the satellite-derived UV irradiance on the sea surface, a preliminary simple estimation of ultraviolet radiation＇s effects on the global marine primary productivity is presented, and the results reveal that ultraviolet radiation has a non-negligible effect on the estimation of the marine primary productivity.

Tracing nitrate sources in one of the world's largest eutrophicated bays(Hangzhou Bay):insights from nitrogen and oxygen isotopes

Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well understood.In this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B ay.Spatial distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the bay.Based on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and sewage.End-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head area.In the lower half of the bay,DIN was sourced mainly from strongly intruding coastal water.DIN coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.

Spatiotemporal characteristics of water exchange between the Andaman Sea and the Bay of Bengal

A high-resolution customized numerical model is used to analyze the water transport in the three major water passages between the Andaman Sea(AS)and the Bay of Bengal,i.e.,the Preparis Channel(PC),the Ten Degree Channel(TDC),and the Great Channel(GC),based on the daily averaged simulation results ranging from 2010 to 2019.Spectral analysis and Empirical Orthogonal Function(EOF)methods are employed to investigate the spatiotemporal variability of the water exchange and controlling mechanisms.The results of model simulation indicate that the net average transports of the PC and GC,as well as their linear trend,are opposite to that of the TDC.This indicates that the PC and the GC are the main inflow channels of the AS,while the TDC is the main outflow channel of the AS.The transport variability is most pronounced at surface levels and between 100 m and 200 m depth,likely affected by monsoons and circulation.A 182.4-d semiannual variability is consistently seen in all three channels,which is also evident in their second principal components.Based on sea level anomalies and EOF analysis results,this is primarily due to equatorial winds during the monsoon transition period,causing eastward movement of Kelvin waves along the AS coast,thereby affecting the spatiotemporal characteristics of the flow in the AS.The first EOF of the PC flow field section shows a split at 100 m deep,likely due to topography.The first EOF of the TDC flow field section is steady but has potent seasonal oscillations in its time series.Meanwhile,the first EOF of the GC flow field section indicates a stable surface inflow,probably influenced by the equatorial Indian Ocean’s eastward current.

Noise‐tolerant matched filter scheme supplemented with neural dynamics algorithm for sea island extraction

Achieving high‐precision extraction of sea islands from high‐resolution satellite remote sensing images is crucial for effective resource development and sustainable management.Unfortunately,achieving such accuracy for sea island extraction presents significant challenges due to the presence of extensive background interference.A more widely applicable noise‐tolerant matched filter(NTMF)scheme is proposed for sea island extraction based on the MF scheme.The NTMF scheme effectively suppresses the background interference,leading to more accurate and robust sea island extraction.To further enhance the accuracy and robustness of the NTMF scheme,a neural dynamics algorithm is supplemented that adds an error integration feedback term to counter noise interference during internal computer operations in practical applications.Several comparative experiments were conducted on various remote sensing images of sea islands under different noisy working conditions to demonstrate the superiority of the proposed neural dynamics algorithm‐assisted NTMF scheme.These experiments confirm the ad-vantages of using the NTMF scheme for sea island extraction with the assistance of neural dynamics algorithm.

Inter-annual variations of dissolved oxygen and hypoxia off the northern Changjiang River(Yangtze River) Estuary in summer from 1997 to 2014

Hypoxia off the Changjiang River Estuary has been the subject of much attention,yet systematic observations have been lacking,resulting in a lack of knowledge regarding its long-term change and drivers.By revisiting the repeated surveys of dissolved oxygen(DO) and other relevant hydrographic parameters along the section from the Changjiang River Estuary to the Jeju-do in the summer from 1997 to 2014,rather different trends were revealed for the dual low-DO cores.The nearshore low-DO core,located close to the river mouth and relatively stable,shows that hypoxia has become more severe with the lowest DO descen ding at a rate of -0.07 mg/(L·a) and the thickness of low-DO zone rising at a rate of 0.43 m/a.The offshore core,centered around 40-m isobath but moving back and forth between 123.5°-125°E,shows large fluctuations in the minimum DO concentration,with the thickness of low-DO zone falling at a rate of -1.55 m/a.The probable factors affecting the minimum DO concentration in the two regions also vary.In the nearshore region,the decreasing minimum DO is driven by the increase in both stratification and primary productivity,with the enhanced extension of the Changjiang River Diluted Water(CDW) strengthening stratification.In the offshore region,the fluctuating trend of the minimum DO concentration indicates that both DO loss and DO supplement are distinct.The DO loss is primarily attributed to bottom apparent oxygen utilization caused by the organic matter decay and is also relevant to the advection of low-DO water from the nearshore region.The DO supplement is primarily due to weakened stratification.Our analysis also shows that the minimum DO concentration in the nearshore region was extremely low in 1998,2003,2007 and 2010,related to El Ni?o signal in these summers.

Effects of phosphorus limitation on sinking velocities of phytoplankton during summer in the Changjiang River Estuary

The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.

Coastal hypoxia response to the coupling of catastrophic flood,extreme marine heatwave and typhoon:a case study off the Changjiang River Estuary in summer 2020

Massive bodies of low-oxygen bottom waters are found in coastal areas worldwide,which are detrimental to coastal ecosystems.In summer 2020,the response of coastal hypoxia to extreme weather events,including a catastrophic flooding,an extreme marine heatwave,and Typhoon Bavi,is investigated based on multiple satellite,four cruises,and mooring observations.The extensive fan-shaped hypoxia zone presents significant northward extension during July-September 2020,and is estimated as large as 13 000 km^(2) with rather low oxygen minimum(0.42 mg/L) during its peak in 28-30 August.This severe hypoxia is attributed to the persistent strong stratification,which is indicated by flood-induced larger amount of riverine freshwater input and subsequent marine heatwave off the Changjiang River Estuary.Moreover,the Typhoon Bavi has limited effect on the marine heatwave and coastal hypoxia in summer 2020.

The largest CPIES array in the marginal sea:abundant dynamics in the northeast South China Sea

The South China Sea(SCS)is a marginal sea connecting the Pacific and Indian oceans and has gained much attention in recent decades.The dynamics in the northeast SCS are considerably influenced by topography,monsoons,tropical cyclones,the Kuroshio intrusion,and water exchange through the Luzon Strait(LS).

Study of the propagation direction of the internal waves in the South China Sea using satellite images

Internal wave propagation carries considerable vertical shear which can lead to turbulence and mixing. Based on the analysis of more than 2 500 synthetic aperture radar （SAR） and optical satellite images, the in- ternal wave propagation in the whole South China Sea was investigated systematically. The results show that （1） in the northeastern South China Sea, most internal waves propagate westward from the Luzon Strait and are diffracted by coral reefs near the Dongsha Islands. Some impinge onto the shelf and a few are reflected; （2） in the northwestern South China Sea, most internal waves are generated at the shelf and propagate northwestward or westward to the coast; （3） in the western South China Sea, most internal waves propagate westward to the Vietnamese coast, except a few propagate southward to the deep sea; and （4） in the southern South China Sea, most internal waves propagate southwestward to the coast. Some prop- agate southeastward to the coast of Kalimantan Island, and a few propagate southeastward because of the influence of the Mekon~ River.

A New Hybrid Vertical Coordinate Ocean Model and Its Application in the Simulation of the Changjiang Diluted Water

Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ coordinate for current and σ-z coordinate for salinity. To combine the current and salinity, the Eulerian-Lagrangian method is used for the salinity calculation, and the baroclinic pressure gradient （BPG） is calculated on the salinity sited layers. The new hybrid vertical coordinate is introduced to the widely used model of POM （Princeton Ocean Model） to make a new model of POM-σ-z. The BPG calculations of an ideal case show that POM-σ-z model brings smaller error than POM model does. The simulations of CDW also show that POM-σ-z model is better than POM model on simulating the salinity and its front.

Environmental control of mesozooplankton community structure in the Hangzhou Bay, China

A quarterly study of mesozooplankton community structure and environmental variables in the Hangzhou Bay was conducted to examine the response of mesozooplankton community to the variation of water mass and environmental condition. The southeast coast of China is a typical region under the intensive influence of Asia monsoon and freshwater discharge from rivers. The water mass and environmental condition of the Hangzhou Bay, which were influenced by the interaction of currents, freshwater discharge of the Qiantang River and Changjiang River Plume, showed significant seasonal variation. Our results showed that both biomass and abundance were significantly higher in summer（（247.7±148.8） mg/m^3 and（350.9±215.6） ind./m^3, respectively）than those in other seasons. Four eco-geographical regions were divided based on the cluster analysis of zooplankton community of the Hangzhou Bay throughout the year, except for winter. Monsoon and the dissolved inorganic nitrogen（DIN） input from freshwater discharge of the Qiantang River and Changjiang River resulted in temporal and spatial variations of environmental gradient in the Hangzhou Bay, which significantly influenced the structure of mesozooplankton community. Redundancy analysis（RDA） indicated that the mesozooplankton community structure was strictly correlated with the DIN gradient, while salinity gradient showed a weak influence in the Hangzhou Bay.

Variation of Indo-Pacific upper ocean heat content during 2001–2012 revealed by Argo

Understanding of the temporal variation of oceanic heat content （OHC） is of fundamental importance to the prediction of climate change and associated global meteorological phenomena. However, OHC characteristics in the Pacific and Indian oceans are not well understood. Based on in situ ocean temperature and salinity profiles mainly from the Argo program, we estimated the upper layer （0-750 m） OHC in the Indo-Pacific Ocean （40°S-40°N, 30°E-80°W）. Spatial and temporal variability of OHC and its likely physical mechanisms are also analyzed. Climatic distributions of upper-layer OHC in the Indian and Pacific oceans have a similar saddle pattern in the subtropics, and the highest OHC value was in the northern Arabian Sea. However, OHC variabilities in the two oceans were different. OHC in the Pacific has an east-west see-saw pattern, which does not appear in the Indian Ocean. In the Indian Ocean, the largest change was around 10°S. The most interesting phenomenon is that, there was a long-term shift of OHC in the Indo-Pacific Ocean during 2001-2012. Such variation coincided with modulation of subsurface temperature/salinity. During 2001-2007, there was subsurface cooling （freshening） nearly the entire upper 400 m layer in the western Pacific and warming （salting） in the eastern Pacific. During 2008-2012, the thermocline deepened in the western Pacific but shoaled in the east. In the Indian Ocean, there was only cooling （upper 150 m only） and freshening （almost the entire upper 400 m） during 2001-2007. The thermocline deepened during 2008-2012 in the Indian Ocean. Such change appeared from the equator to off the equator and even to the subtropics （about 20°N/S） in the two oceans. This long-term change of subsurface temperature/salinity may have been caused by change of the wind field over the two oceans during 2001-2012, in turn modifying OHC.