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Characteristics and mechanisms of the intraseasonal variability of sea surface salinity in the southeastern Arabian Sea during 2015-2020

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Acta Oceanologica Sinica 2023年第5期42卷 25-34页

作者： Hui Teng Yun Qiu Xinyu Lin Xiwu Zhou Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQingdao 266237China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519082China Fujian Provincial Key laboratory of Marine Physical and Geological Processes Xiamen 361005China

Based on Soil Moisture Active Passive sea surface salinity(SSS)data from April 2015 to August 2020,combined with Objectively Analyzed Air-Sea Heat Flux and other observational data and Hybrid Coordinate Ocean Model(HYCOM)data,this work explores the characteristics and mechanisms of the intraseasonal variability of SSS in the southeastern Arabian Sea(SEAS).The results show that the intraseasonal variability of SSS in the SEAS is very significant,especially the strongest intraseasonal signal in SSS,which is located along the northeast monsoon current(NMC)path south of the Indian *** are remarkable seasonal differences in intraseasonal SSS variability,which is very weak in spring and summer and much stronger in autumn and *** strong intraseasonal variability in autumn and winter is closely related to the Madden-Julian Oscillation(MJO)event during this *** northeast wind anomaly in the Bay of Bengal(BOB)associated with the active MJO phase strengthens the East India Coastal Current and NMC and consequently induces more BOB low-salinity water to enter the SEAS,causing strong SSS *** addition,MJO-related precipitation further amplifies the intraseasonal variability of SSS in *** on budget analysis of the mixed layer salinity using HYCOM data,it is shown that horizontal salinity advection(especially zonal advection)dominates the intraseasonal variability of mixed layer salinity and that surface freshwater flux has a secondary role.

关键词： southeastern Arabian Sea sea surface salinity intraseasonal variability air-sea interaction

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Validation and error analysis of wave-modifi ed ocean surface currents in the northwestern Pacifi c Ocean

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Journal of Oceanology and Limnology 2022年第4期40卷 1289-1303页

作者： Zhenli HUI Ying LI Jia SUN Long YU Xia JU Xuejun XIONG First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Shandong Key laboratory of Marine Science and Numerical Modeling Qingdao 266061China

By incorporating the wave-induced Coriolis-Stokes forcing into the classical Ekman layer,the wave-modifi ed ocean surface currents in the northwestern Pacifi c Ocean were ***,the ocean surface currents are the combination of classical Ekman current from the cross-calibrated multi-platform(CCMP)wind speed,geostrophic current from the mean absolute dynamic topography(MADT),and wave-induced current based on the European Centre for Medium-Range Weather Forecasts(ECMWF)Interim Re-Analysis(ERA-Interim)surface wave *** functions are introduced in the Ekman current formulation as *** with in-situ data from Lagrangian drifters in the study area and Kuroshio Extension Observatory(KEO)observations at 32.3°N,144.6°E,and 15-m depth indicate that wave-modifi ed ocean surface currents provide accurate time means of zonal and meridional currents in the northwestern Pacifi c *** shows that the wave-modifi ed currents are quite consistent with the Lagrangian drifter observations for the period 1993-2017 in the deep *** correlation(root mean square error,RMSE)is 0.96(1.45 cm/s)for the zonal component and 0.90(1.07 cm/s)for the meridional ***,wave-modifi ed currents underestimate the Lagrangian drifter velocity in strong current and some off shore regions,especially in the regions along the Japan coast and the southeastern ***’s more,the wave-modifi ed currents overestimate the pure Eulerian KEO current which does not consider the impact of waves,and the zonal(meridional)correlation and RMSE are 0.95(0.90)and 11.25 cm/s(12.05 cm/s)*** comparisons demonstrate that our wave-modifi ed ocean surface currents have high precision and can describe the real-world ocean in the northwestern Pacifi c Ocean accurately and intuitively,which can provide important routes to calculate ocean surface currents on large spatial scales.

关键词： ocean surface current Ekman current geostrophic current Stokes drift

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Decadal variation of thermocline-sea surface temperature feedback in the tropical Indian Ocean and the underlying mechanisms

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Acta Oceanologica Sinica 2021年第11期40卷 31-38页

作者： Meiqi Zhang Shuangwen Sun Lin Liu Yongcan Zu Lin Feng First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao 266061China laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China Shandong Key laboratory of Marine Science and Numerical Modeling Qingdao 266061China

The thermocline-sea surface temperature(SST)feedback is the most important component of the Bjerknes feedback,which plays an important role in the development of the air-sea coupling modes of the Indian *** thermocline-SST feedback in the Indian Ocean has experienced significant decadal variations over the last40 *** feedback intensified in the late twentieth century and then weakened during the hiatus in global warming at the early twenty-first *** thermocline-SST feedback is most prominent in the southeastern and southwestern Indian *** the decadal variations of feedback are similar in these two regions,there are still differences in the underlying *** decadal variations of feedback in the southeastern Indian Ocean are dominated by variations in the depth of the thermocline,which are modulated by equatorial zonal wind *** the decadal variation of feedback in the southwestern Indian Ocean is mainly controlled by the intensity of upwelling and thermocline depth in winter and spring,*** upwelling and thermocline depth are both affected by wind stress curl anomalies over the southeastern Indian Ocean,which excite anomalous Ekman pumping and influence the southwestern Indian Ocean through westward propagating Rossby waves.

关键词： Indian Ocean thermocline-SST feedback decadal variation upwelling thermocline depth

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Spatial Distribution and Seasonal Variation of Hypoxic Zone in the Eastern Equatorial Indian Ocean

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Journal of Ocean University of China 2023年第4期22卷 918-929页

作者： XIE Linping WANG Baodong XIN Ming WANG Ying SUN Xia WEI Qinsheng LIU Lin YUAN Chao Key laboratory of Marine Eco-Environmental Science and Technology First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China

The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to *** showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 *** southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer *** hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of *** hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate *** new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.

关键词： hypoxic zone spatial distribution vertical structure seasonal variation eastern equatorial Indian Ocean

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Nonlinearity and Finite-Time Instability in a T21L3 Quasigeostrophic Model

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Acta meteorologica Sinica 2011年第4期25卷 419-429页

作者：姜智娜王东海 State Key laboratory of Severe Weather Chinese Academy of Meteorological Sciences

In this paper, a nonlinear optimization method is used to explore the finite-time instability of the atmospheric circulation with a three-level quasigeostrophic model under the framework of the conditional nonlinear optimal perturbation （CNOP）. As a natural generalization of linear singular vector （SV）, CNOP is defined as an initial perturbation that makes the cost function the maximum at a prescribed forecast time under certain physical constraint conditions. Special attentions are paid to the different structures and energy evolutions of the optimal perturbations. The results show that the most instable region of the global atmospheric circulation lies in the midlatitude Eurasian continent. More specially, SV and CNOP in the total energy norm with an optimization time of 2 days both present localness： they are mainly located in the midlatitude Asian continent and its east coast. With extension of the optimization time, SVs are more upstream and less localized in the zonal direction, and CNOPs differ essentially from SVs with broader zonal and meridional coverages; as a result, CNOPs acquire larger kinetic and available potential energy amplifications than SVs in the nonlinear model at the corresponding optimization time. For the climatological wintertime flow, it is seen that the baroclinic terms remain small over the entire time evolution, and the energy production comes essentially from the eddy kinetic energy, which is induced by the horizontal shear of the basic flow. In addition, the effects of SVs and CNOPs on the Eurasian atmospheric circulation are explored. The results show that the weather systems over the Eurasian continent in the perturbed fields by CNOPs are stronger than those by SVs at the optimization time. This reveals that the CNOP method is better in evaluating the instability of the atmospheric circulation while the SV method underestimates the possibility of extreme weather events.

关键词： nonlinearity finite-time instability barotropic baroclinic

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Shock-produced akimotoite in the Suizhou L6 chondrite

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Science China Earth Sciences 2015年第6期58卷 876-880页

作者： CHEN Ming XIE XianDe State Key laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Key laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Shock-produced akimotoite was identified in the Suizhou chondritic meteorite, which occurs in two kinds of occurrence. The first is the irregular layers of akimotoite up to 4 ?m in thickness occurring in fractures and cracks of low-Ca pyroxene enclosed in the shock veins. The second is the zonal polycrystalline aggregates of akimotoite in shocked pyroxene grains close to the shock vein, where akimotoite occurs in a zonal area in between pyroxene and Mg Si O3-glass as irregular small clumps up to 5 ?m in size. This investigation suggests a solid-state transformation mechanism of pyroxene to akimotoite, and that akimotoite should have nucleated and grew in the area with abundant defects caused by shock deformation because the defect significantly enhances the solid-state reactivity and the kinetics of nucleation of high-pressure phase. The spatial relationship among the composed grains of pyroxene, akimotoite and Mg Si O3-glass(possibly vitrified perovskite) demonstrates a temperature gradient from the vein wall to the unmelted chondritic meteorite.

关键词： pyroxene akimotoite perovskite shock vein Suizhou meteorite

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Simulating multiple urban land use changes by integrating transportation accessibility and a vector-based cellular automata:a case study on city of Toronto

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Geo-Spatial Information Science 2022年第3期25卷 439-456页

作者： Xiaocong Xu Dachuan Zhang Xiaoping Liu Jinpei Ou Xinxin Wu School of Geography and Planning Guangdong Key Laboratory for Urbanization and Geo-simulationSun Yat-Sen UniversityGuangzhouChina Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) ZhuhaiChina

The accessibility provided by the transportation system plays an essential role in driving urban growth and urban functional land use *** studies on land use simulation usually simplified the accessibility as proximities and adopted the grid-based simulation strategy,leading to the insufficiencies of characterizing spatial geometry of land parcels and simulating subtle land use changes among urban functional *** overcome these limita-tions,an Accessibility-interacted Vector-based Cellular Automata(A-VCA)model was proposed for the better simulation of realistic land use change among different urban functional *** accessibility at both local and zonal scales derived from actual travel time data was considered as a key driver of fine-scale urban land use changes and was integrated into the vector-based CA simulation *** proposed A-VCA model was tested through the simulation of urban land use changes in the City of Toronto,Canada,during 2012-2016.A vector-based CA without considering the driving factor of accessibility(VCA)and a popular grid-based CA model(Future Land Use Simulation,FLUS)were also implemented for *** simulation results reveal that the proposed A-VCA model is capable of simulating fine-scale urban land use changes with satisfactory accuracy and good morphological feature(kappa=0.907,figure of merit=0.283,and cumulative producer’s accuracy=72.83%±1.535%).The comparison also shows significant outperformance of the A-VCA model against the VCA and FLUS models,suggesting the effectiveness of the accessibility-interactive mechanism and vector-based simulation *** proposed model provides new tools for a better simula-tion of fine-scale land use changes and can be used in assisting the formulation of urban and transportation planning.

关键词： Urban land use change simulation transportation accessibility Vector-based cellular automata(VCA)

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An Analysis of the Steric Sea Level Change by Introducing Sea Surface Temperature

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Journal of Ocean University of China 2013年第1期12卷 37-44页

作者： SUN Ruili LI Lei LI Peiliang Physical Oceanography laboratory Ocean University of China

In this paper, we use the optimum interpolation sea surface temperature (OISST) provided by the National Center for Environmental Prediction (NCEP) to replace the temperature in the top three layers in the ISHII data, and make use of the modified ISHII temperature data to calculate the thermosteric sea level (called modified steric sea level (SSL) hereafter). We subtract the modified SSL and the steric sea level (called ordinary SSL hereafter) derived from the ISHII temperature and salinity from the steric sea level (SSL) provided by the Gravity Recovery and Climate Experiment (GRACE), respectively, and find that the rms error of the difference of the former is obviously smaller than that of the latter. Therefore we reach the conclusion that under the assumption that the GRACE SSL is accurate, the modified SSL can reflect the true steric sea level more accurately. Making use of the modified SSL, we can find that the modified SSL in sea areas of different spatial scales shows an obvious rising trend in the upper 0-700 m layer for the period 1982-2006. The global mean SSL rises with a rate of 0.6 mm year-1 .The modified SSLs in sea areas of different spatial scales all show obvious oscillations with period of one year. There are oscillations with periods of 4-8 years in global oceans and with periods of 2-7 years in the Pacific. The Empirical Orthogonal Function method is applied to the sea areas of different spatial scales and we find that the first modes all have obvious 1-year period oscillations, the first mode of the global ocean has 4-8 year period oscillations, and that of the Pacific has 2-6 year period oscillations. The spatial distribution of the linear rising trend of the global modified SSL in the upper 0-700 m layer is inhomogeneous with intense regional characteristics. The modified SSL linear trend indicates a zonal dipole in the tropical Pacific, rising in the west and descending in the east. In the North Atlantic, the modified SSL indicates a meridion

关键词： GRACE ISHII OISST steric sea level

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Does Glacial-Interglacial Transition Affect Sediment Accumulation in Monsoon-Dominated Regions?

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1079-1094页

作者： Dharmendra Pratap SINGH Rajeev SARASWAT Dinesh K.NAIK Micropaleontology laboratory Geological Oceanography DivisionNational Institute of Oceanography

The spatio-temporal changes in sedimentation rate along the continental margin of the monsoon-dominated eastern Arabian Sea during the last 24 kyr have been estimated from a compilation of 58 radiocarbon dated cores, in order to understand the effect of glacial-interglacial variation on sedimentation. The sedimentation rate has been computed for four-time slices, viz. the last glacial maximum, glacial-interglacial transition, early Holocene and late Holocene. We report that the average sedimentation rate in the slope to the abyssal region of the entire eastern Arabian Sea, although higher during the Holocene as compared with that during the last glacial maximum and glacial-interglacial transition, does not significantly vary during all four-time intervals. The sedimentation rate during any particular time interval, however, varies from core to core, thus indicating zonal changes. We report four zones of relatively high sedimentation rate, viz. the northeastern Arabian Sea, the region off the Gulf of Khambhat, the region off Goa and Mangalore, and off the southern tip of India. We suggest that a complex interaction of land-ocean-atmospheric processes controlled sedimentation rate in the eastern Arabian Sea during the last 24 kyr in such a way that the average sedimentation rate does not vary significantly, even during highly contrasting climatic conditions.

关键词： Sedimentation rate monsoon glacial Holocene Arabian Sea

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Role of Horizontal Density Advection in Seasonal Deepening of the Mixed Layer in the Subtropical Southeast Pacific

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Advances in Atmospheric Sciences 2016年第4期33卷 442-451页

作者： Qinyu LIU Yiqun LU Physical Oceanography laboratory Qingdao Collaborative Innovation Center of Marine Science and TechnologyKey Laboratory of Ocean–Atmosphere Interaction and Climate in Universities of ShandongOcean University of China

The mechanisms behind the seasonal deepening of the mixed layer （ML） in the subtropical Southeast Pacific were investigated using the monthly Argo data from 2004 to 2012. The region with a deep ML （more than 175 m） was found in the region of （22°-30°S, 105°-90°W）, reaching its maximum depth （-200 m） near （27°-28°S, 100°W） in September. The relative importance of horizontal density advection in determining the maximum ML location is discussed qualitatively. Downward Ekman pumping is key to determining the eastern boundary of the deep ML region. In addition, zonal density advection by the subtropical countercurrent （STCC） in the subtropical Southwest Pacific determines its western boundary, by carrying lighter water to strengthen the stratification and form a ＂shallow tongue＂ of ML depth to block the westward extension of the deep ML in the STCC region. The temperature advection by the STCC is the main source for large heat loss from the subtropical Southwest Pacific. Finally, the combined effect of net surface heat flux and meridional density advection by the subtropical gyre determines the northern and southern boundaries of the deep ML region： the ocean heat loss at the surface gradually increases from 22~S to 35~S, while the meridional density advection by the subtropical gyre strengthens the strat- ification south of the maximum ML depth and weakens the stratification to the north. The freshwater flux contribution to deepening the ML during austral winter is limited. The results are useful for understanding the role of ocean dynamics in the ML formation in the subtropical Southeast Pacific.

关键词： mixed layer seasonal deepening Southeast Pacific heat flux density advection

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