Efficient and accurate prediction of ocean surface latent heat fluxes is essential for understanding and modeling climate dynamics.Conventional estimation methods have low resolution and lack accuracy.The transformer ...Efficient and accurate prediction of ocean surface latent heat fluxes is essential for understanding and modeling climate dynamics.Conventional estimation methods have low resolution and lack accuracy.The transformer model,with its self-attention mechanism,effectively captures long-range dependencies,leading to a degradation of accuracy over time.Due to the non-linearity and uncertainty of physical processes,the transformer model encounters the problem of error accumulation,leading to a degradation of accuracy over time.To solve this problem,we combine the Data Assimilation(DA)technique with the transformer model and continuously modify the model state to make it closer to the actual observations.In this paper,we propose a deep learning model called TransNetDA,which integrates transformer,convolutional neural network and DA methods.By combining data-driven and DA methods for spatiotemporal prediction,TransNetDA effectively extracts multi-scale spatial features and significantly improves prediction accuracy.The experimental results indicate that the TransNetDA method surpasses traditional techniques in terms of root mean square error and R2 metrics,showcasing its superior performance in predicting latent heat fluxes at the ocean surface.展开更多
The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting t...The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting two simulations that include and exclude the OSC in the calculation of the ice-ocean stress(IOS), using an eddy-permitting coupled ocean-sea ice global model. By comparing the results of these two experiments, significant increases of 5%, 27%, and 24%, were found in the subpolar Southern Ocean when excluding the OSC in the IOS calculation for the ocean surface stress,upwelling, and downwelling, respectively. Excluding the OSC in the IOS calculation also visibly strengthens the total mechanical energy input to the OSC by about 16%, and increases the eddy kinetic energy and mean kinetic energy by about38% and 12%, respectively. Moreover, the response of the meridional overturning circulation in the Southern Ocean yields respective increases of about 16% and 15% for the upper and lower branches;and the subpolar gyres are also found to considerably intensify, by about 12%, 11%, and 11% in the Weddell Gyre, the Ross Gyre, and the Australian-Antarctic Gyre, respectively. The strengthened ocean circulations and Ekman pumping result in a warmer sea surface temperature(SST), and hence an incremental surface heat loss. The increased sea ice drift and warm SST lead to an expansion of the sea ice area and a reduction of sea ice volume. These results emphasize the importance of OSCs in the air-sea-ice interactions on the global ocean circulations and the mass balance of Antarctic ice shelves, and this component may become more significant as the rapid change of Antarctic sea ice.展开更多
A new method is proposed to produce gas from oceanic gas hydrate reservoir by combining the ocean surface warm water flooding with depressurization which can efficiently utilize the synthetic effects of thermal, salt ...A new method is proposed to produce gas from oceanic gas hydrate reservoir by combining the ocean surface warm water flooding with depressurization which can efficiently utilize the synthetic effects of thermal, salt and depressurization on gas hydrate dissociation. The method has the advantage of high efficiency, low cost and enhanced safety. Based on the proposed conceptual method, the physical and mathematical models are established, in which the effects of the flow of multiphase fluid, the kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, salt inhibition, dispersion, convection and conduction on the hydrate disso- ciation and gas and water production are considered. The gas and water rates, formation pressure for the combination method are compared with that of the single depressurization, which is referred to the method in which only depres- surization is used. The results show that the combination method can remedy the deficiency of individual producing methods. It has the advantage of longer stable period of high gas rate than the single depressurization. It can also reduce the geologic hazard caused by the formation defor- mation due to the maintaining of the formation pressure by injected ocean warm water.展开更多
As an important physical process at the air-sea interface, wave movement and breaking have a significant effect on the ocean surface mixed layer (OSML). When breaking waves occur at the ocean surface, turbulent kineti...As an important physical process at the air-sea interface, wave movement and breaking have a significant effect on the ocean surface mixed layer (OSML). When breaking waves occur at the ocean surface, turbulent kinetic energy (TKE) is input downwards, and a sublayer is formed near the surface and turbulence vertical mixing is intensively enhanced. A one-dimensional ocean model including the Mellor-Yamada level 2.5 turbulence closure equations was employed in our research on variations in turbulent energy budget within OSML. The influence of wave breaking could be introduced into the model by modifying an existing surface boundary condition of the TKE equation and specifying its input. The vertical diffusion and dissipation of TKE were effectively enhanced in the sublayer when wave breaking was considered. Turbulent energy dissipated in the sublayer was about 92.0% of the total depth-integrated dissipated TKE, which is twice higher than that of non-wave breaking. The shear production of TKE decreased by 3.5% because the mean flow fields tended to be uniform due to wave-enhanced turbulent mixing. As a result, a new local equilibrium between diffusion and dissipation of TKE was reached in the wave-enhanced layer. Below the sublayer, the local equilibrium between shear production and dissipation of TKE agreed with the conclusion drawn from the classical law-of-the-wall (Craig and Banner, 1994).展开更多
This study uses a large eddy simulation （LES） model to investigate the turbulence processes in the ocean surface boundary layer at Zhangzi Island offshore. Field measurements at Zhangzi Island （39°N, 122°...This study uses a large eddy simulation （LES） model to investigate the turbulence processes in the ocean surface boundary layer at Zhangzi Island offshore. Field measurements at Zhangzi Island （39°N, 122°E） during July 2009 are used to drive the LES model. The LES results capture a clear diurnal cycle in the oceanic turbulence boundary layer. The process of the heat penetration and heat distribution characteristics are analyzed through the heat flux results from the LES and their differences between two diurnal cycles are discussed as well. Energy balance and other dynamics are investigated which show that the tide-induced shear production is the main source of the turbulence energy that balanced dissipation. Momentum flux near the surface shows better agreement with atmospheric data computed by the eddy correlation method than those computed by bulk formula.展开更多
To investigate the annual and interaunual variability of ocean surface wind over the South China Sea （SCS）, the vector empirical orthogonal function （VEOF） method and the Hilbert-Huang transform （HHT） method wer...To investigate the annual and interaunual variability of ocean surface wind over the South China Sea （SCS）, the vector empirical orthogonal function （VEOF） method and the Hilbert-Huang transform （HHT） method were employed to analyze a set of combined satellite scatterometer wind data during the period from December 1992 to October 2009. The merged wind data were generated from European Remote Sensing Satellite （ERS）-1/2 Scatterometer, NASA Scatterometer （NSCAT） and NASA＇s Quick Scatterometer （QuikSCAT） wind products. The first VEOF mode corresponds to a winter-summer mode which accounts for 87.3% of the total variance and represents the East Asian monsoon features. The second mode of VEOF corresponds to a spring-autumn oscil- lation which accounts for 8.3% of the total variance. To analyze the interannual variability, the annual signal was removed from the wind data set and the VEOFs of the residuals were calculated. The temporal mode of the ftrst intcrannual VEOF is correlated with the Southern Oscillation Index （SOI） with a four-month lag. The second temporal interannual VEOF mode is correlated with the SOI with no time lag. The time series of the two interannual VEOFs were decomposed using the HI-IT method and the results also show a correlation between the interannual variability and El Nino-Southern Oscillation （ENSO） events.展开更多
The inflow angle of tropical cyclones （TC） is generally neglected in numerical studies of ocean surface waves induced by TC. In this study, the impacts of TC inflow angle on ocean surface waves were investigated usi...The inflow angle of tropical cyclones （TC） is generally neglected in numerical studies of ocean surface waves induced by TC. In this study, the impacts of TC inflow angle on ocean surface waves were investigated using a high-resolution wave model. Six numerical experiments were conducted to examine, in detail, thc effects of inflow angle on mean wave parameters and the spectrum of wave directions. A comparison of the waves simulated in these experiments shows that inflow angle significantly modifies TC-induced ocean surface waves. As the inflow angle increases, the asymmetric axis of the significant wave height （SWH） field shifts 30° clockwise, and the maximum SWH moves from the front-right to the rear-right quadrant. Inflow angle also affects other mean wave parameters, especially in the rear-left quadrant, such as the mean wave direction, the mean wavelength, and the peak direction. Inflow angle is a key factor in wave models for the reproduction of double-peak or multi-peak patterns in the spectrum of wave directions. Sensitivity experiments also show that the simulation with a 40° inflow angle is the closest to that of the NOAA statistical SLOSH inflow angle. This suggests that 40° can be used as the inflow angle in future TC-induced ocean surface wave simulations when SLOSH or observed inflow angles are not available.展开更多
Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forc...Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forcing, tides and storm surges on the waves are investigated using a wave model, a high-resolution atmospheric mesoscale model and a hydrodynamic ocean circulation model. Five month-long wave model simulations are inducted to examine the sensitivity of ocean waves to various wind forcing fields, tides and storm surges during January 1997. Compared with observed mean wave parameters, results indicate that the high frequency variability in the surface wind filed has very great effect on wave simulation. Tides and storm surges have a significant impact on the waves in nearshores of the Tsushima-kaihyS, but not for other regions in the Sea of Japan. High spatial and temporal resolution and good quality surface wind products will be crucial for the prediction of surface waves in the JES and other marginal seas, especially near the coastal regions.展开更多
A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any ...A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any position of ocean surface under any ocean floor conditions using wave num decomposition.LOD scheme is proposed based on quad-tree block,which simplifies the ocean surface regular mesh and realizes the real-time rendering of large-scale ocean surface.Experimental results show that these methods can get realistic effect and fast rendering speed,which are appropriated to the applications of 3D games and battlefield simulation.展开更多
Understanding the sea surface scattering process is very important in the development of models to detect the target above or under the surface. In this paper, both the analytical and the numerical methods applied in ...Understanding the sea surface scattering process is very important in the development of models to detect the target above or under the surface. In this paper, both the analytical and the numerical methods applied in sea surface scattering are summarized. Some important problems concerned in this field are discussed. For numerical study, edge effect brings artificial nonrealistic scattering and therefore must be suppressed. Different edge treatment methods are compared in this paper. Scattering of breaking wave surface at very low grazing angle always needs more attentions than other scattering problems. Some numerical results show the existence of the special phenomena at very low grazing angle, for example, the ＂sea spikes＂ and the Doppler splitting.展开更多
The ocean surface wind(OSW)data retrieved from microwave scatterometers have high spatial accuracy and represent the only wind data assimilated by global numerical models on the ocean surface,thus playing an important...The ocean surface wind(OSW)data retrieved from microwave scatterometers have high spatial accuracy and represent the only wind data assimilated by global numerical models on the ocean surface,thus playing an important role in improving the forecast skills of global medium-range weather prediction models.To improve the forecast skills of the Global/Regional Assimilation and Prediction System Global Forecast System(GRAPES_GFS),the HY-2B OSW data is assimilated into the GRAPES_GFS four-dimensional variational assimilation(4DVAR)system.Then,the impacts of the HY-2B OSW data assimilation on the analyses and forecasts of GRAPES_GFS are analyzed based on one-month assimilation cycle experiments.The results show that after assimilating the HY-2B OSW data,the analysis errors of the wind fields in the lower-middle troposphere(1000-600 hPa)of the tropics and the southern hemisphere(SH)are significantly reduced by an average rate of about 5%.The impacts of the HY-2B OSW data assimilation on the analysis fields of wind,geopotential height,and temperature are not solely limited to the boundary layer but also extend throughout the entire troposphere after about two days of cycling assimilation.Furthermore,assimilating the HY-2B OSW data can significantly improve the forecast skill of wind,geopotential height,and temperature in the troposphere of the tropics and SH.展开更多
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 estimated.Thus,the ocean surface currents are ...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 estimated.Thus,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 datasets.Weight functions are introduced in the Ekman current formulation as well.Comparisons 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 Ocean.Result shows that the wave-modifi ed currents are quite consistent with the Lagrangian drifter observations for the period 1993-2017 in the deep ocean.The 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 component.However,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 Mindanao.What’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)respectively.These 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.展开更多
Currently,numerical models based on idealized assumptions,complex algorithms and high computational costs are unsatisfactory for ocean surface current prediction.Moreover,the complex temporal and spatial variability o...Currently,numerical models based on idealized assumptions,complex algorithms and high computational costs are unsatisfactory for ocean surface current prediction.Moreover,the complex temporal and spatial variability of ocean currents also makes the prediction methods based on time series data challenging.The deep network model can automatically learn and extract complex features hidden in large amount of complex data,so it is a promising method for high quality prediction of ocean currents.In this paper,we propose a spatiotemporal coupled attention deep network model STCANet that can extract abundant temporal and spatial coupling information on the behavior characteristics of ocean currents for improving the prediction accuracy.Firstly,Spatial Module is designed and implemented to extract the spatiotemporal coupling characteristics of ocean currents,and meanwhile the spatial correlations and dependencies among adjacent sea areas are obtained through Spatial Channel Attention Module(SCAM).Secondly,we use the GatedRecurrent-Unit(GRU)to extract temporal relationships of ocean currents,and design and implement the nearest neighbor time attention module to extract the interdependences of ocean currents between adjacent times,which can further improve the accuracy of ocean current prediction.Finally,a series of comparative experiments on the MediSea_Dataset and EastSea_Dataset showed that the prediction quality of our model greatly outperforms those of other benchmark models such as History Average(HA),Autoregressive Integrated Moving Average Model(ARIMA),Long Short-term Memory(LSTM),Gate Recurrent Unit(GRU)and CNN_GRU.展开更多
This paper proposes a multifunction radar that can not only measure sea currents but also perform sea-surface imaging.The fundamental aspect of the proposed radar comprises transmitting time-shifted up-and-down contin...This paper proposes a multifunction radar that can not only measure sea currents but also perform sea-surface imaging.The fundamental aspect of the proposed radar comprises transmitting time-shifted up-and-down continuous wave linear frequency modulated signals that allow for the offset of two one-dimensional range images of the sea surface that respectively correspond to the upward linear frequency modulated(LFM)signal and the downward LFM signal.Owing to the Doppler frequency shift from the sea surface,a range offset,which is proportional to the radial velocity of the sea surface,occurs between the upward and downward LFM signals.By using the least-squares linear fitting method in the transformed domain,the range offset can be measured and the current velocity can be retrieved.Finally,we verify the accuracy of current measurement with simulation results.展开更多
A necessary big step up in the modern water wave theories and their widespread application in ocean engineering is how to obtain 6-wave resonance conditions and to prove it. In the light of the existing forms and char...A necessary big step up in the modern water wave theories and their widespread application in ocean engineering is how to obtain 6-wave resonance conditions and to prove it. In the light of the existing forms and characteristics of 3-wave, 4-wave and 5-wave resonance conditions, the 6-wave resonance conditions are proposed and proved for currently a maximum wave-wave resonance interactions of the ocean surface gravity waves in deep water, which will be indispensable to both the Kolmogorov spectrum of the corresponding universal wave turbulence and a synthetic 4-5-6-wave resonant model for the ocean surface gravity waves.展开更多
A cloud-ocean planetary boundary layer (OPBL) feedback mechanism is presented and tested in this paper. Water vapor, evaporated from the ocean surface or transported by the large-scale air flow, often forms convective...A cloud-ocean planetary boundary layer (OPBL) feedback mechanism is presented and tested in this paper. Water vapor, evaporated from the ocean surface or transported by the large-scale air flow, often forms convective clouds under a conditionally unstable lapse rate. The variable cloud cover and rainfall may have positive and negative feedback with the ocean mixed layer temperature and salinity structure. The coupling of the simplified Kuo's (1965) cumulus cloud model to the Kraus-Turner's (1967) ocean mixed layer model shows the existence of this feedback mechanism. The theory also predicts the generation of low frequency oscillation in the atmosphere and oceans.展开更多
A polarized bidirectional reflectance distribution function(pBRDF)matrix is developed from two-scale roughness theory with the aim of providing more accurate simulations of microwave emissions and scattering required ...A polarized bidirectional reflectance distribution function(pBRDF)matrix is developed from two-scale roughness theory with the aim of providing more accurate simulations of microwave emissions and scattering required for ocean-atmosphere coupled radiative transfer models.The potential of the pBRDF matrix is explored for simu-lating the ocean backscatter at Ku-band.The effects of ocean wave spectra including the modified Durden and Vesecky(DV2),Elfouhaily,and Kudryavtsev spectra on the pBRDF matrix backscatter simulations are investi-gated.Additionally,the differences in backscattering normalized radar cross-section(NRCS)simulations between the Ku-band geophysical model function and pBRDF matrix are analyzed.The results show that the pBRDF matrix can reasonably reproduce the spatial distribution of ocean surface backscattering energy,but the distribution pat-tern and numerical values are influenced by ocean wave spectra.The DV2 spectrum is the best one for the pBRDF matrix to simulate horizontally polarized NRCSs,with the exception of scenarios where the incidence angle is below 35°,the wind speed is less than 10 m s^(−1),and in the cross-wind direction.Also,the DV2 spectrum effec-tively characterizes the wind speed and relative azimuth angle dependence for vertically polarized NRCSs.The Elfouhaily spectrum is suitable for simulating vertically polarized NRCSs under conditions of low wind speed(be-low 5 m s^(−1))and incidence angles under 40°.The Kudryavtsev spectrum excels in simulating vertically polarized NRCSs at high incidence angles(>40°)and horizontally polarized NRCSs at low incidence angles(<35°).展开更多
Internal solitary waves(ISW),characterized by large amplitude and long propagation distance,are widespread in global oceans.While remote sensing images have played an essential role in studying ISWs,they mainly exploi...Internal solitary waves(ISW),characterized by large amplitude and long propagation distance,are widespread in global oceans.While remote sensing images have played an essential role in studying ISWs,they mainly exploit two-dimensional image information.However,with the launch of the surface water ocean topography(SWOT)satellite on December 16,2022,a unique opportunity has emerged to capture wide-swath three-dimensional ISW-induced sea surface information.In this study,we examine ISWs in the Andaman Sea using data from the Ka-band Radar Interferometer(KaRIN),a crucial sensor onboard SWOT.KaRIN not only provides backscattering satellite images but also employs synthetic aperture interferometry techniques to retrieve wide-swath two-dimensional sea surface height measurements.Our observations in the Andaman Sea revealed the presence of ISWs characterized by dark-bright strips and surface elevation solitons.The surface soliton has an amplitude of 0.32 m,resulting in an estimation of ISW amplitude of approximately 60 m.In contrast to traditional two-dimensional satellite images or nadir-looking altimetry data,the SWOT mission’s capability to capture threedimensional sea surface information represents a significant advancement.This breakthrough holds substantial promise for ISW studies,particularly in the context of ISW amplitude inversion.展开更多
A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform infor...A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform information from SAR images,in order to generate elevation maps of topography for land surfaces.Here,in order to retrieve ocean wave characteristics,we apply the SFS methodology,together with a method to orient the angular measurements of the azimuth slope and range slope,in the measurement of ocean surface waves.This method is applied to high resolution fine-quad polarization mode(HH,VV,VH and HV)C-band RADARSAT-2 SAR imagery,in order to retrieve ocean wave spectra and extract wave parameters.Collocated in situ buoy measurements are used to validate the reliability of this method.Results show that the method can reliably estimate wave height,dominant wave period,dominant wave length and dominant wave direction from C-band SAR images.The advantage of this method is that it does not depend on modulation transfer functions(MTFs),in order to measure ocean surface waves.This method can be used in monitoring ocean surface wave propagation through open water areas into ice-covered areas,especially the marginal ice zone(MIZ)in polar oceans.展开更多
A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition...A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat fluxQ to air/sea temperature difference ΔT by a relaxation coefficientk. The model was initiated from the National Centers for Environmental Prediction (NCEP) atmospheric observations for 1 December 1977, and from the National Ocean Data Center (NODC) global climatological mean December temperature and salinity fields at 1°x 1° resolution. The time step is 7.5 minutes. We integrated the model for 450 days and obtained a complete model-generated global data set of daily mean downward net surface fluxQ, surface air temperatureT A, and sea surface temperatureT O. Then, we calculated the cross-correlation coefficients (CCC) betweenQ and ΔT. The ensemble mean CCC fields show (a) no correlation betweenQ and ΔT in the equatiorial regions, and (b) evident correlation (CCC≥0.7) betweenQ and ΔT in the middle and high latitudes. Additionally, we did the variance analysis and found that whenk=120 W m?2K?1, the two standard deviations, σQ and σκδT , are quite close in the middle and high latitudes. These results agree quite well with a previous research (Chu et al., 1998) on analyzing the NCEP re-analyzed surface data, except that a smaller value ofk (80 W m?2K?1) was found in the previous study. Key words Air-sea coupled system - Ocean surface fluxes - Surface thermal boundary condition展开更多
基金The National Natural Science Foundation of China under contract Nos 42176011 and 61931025the Fundamental Research Funds for the Central Universities of China under contract No.24CX03001A.
文摘Efficient and accurate prediction of ocean surface latent heat fluxes is essential for understanding and modeling climate dynamics.Conventional estimation methods have low resolution and lack accuracy.The transformer model,with its self-attention mechanism,effectively captures long-range dependencies,leading to a degradation of accuracy over time.Due to the non-linearity and uncertainty of physical processes,the transformer model encounters the problem of error accumulation,leading to a degradation of accuracy over time.To solve this problem,we combine the Data Assimilation(DA)technique with the transformer model and continuously modify the model state to make it closer to the actual observations.In this paper,we propose a deep learning model called TransNetDA,which integrates transformer,convolutional neural network and DA methods.By combining data-driven and DA methods for spatiotemporal prediction,TransNetDA effectively extracts multi-scale spatial features and significantly improves prediction accuracy.The experimental results indicate that the TransNetDA method surpasses traditional techniques in terms of root mean square error and R2 metrics,showcasing its superior performance in predicting latent heat fluxes at the ocean surface.
基金supported by the Independent Research Foundation of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant No. SML2021SP306)National Natural Science Foundation of China (Grant Nos. 41941007, 41806216, 41876220, and 62177028)+2 种基金Natural Science Foundation of Jiangsu Province (Grant No. BK20211015)China Postdoctoral Science Foundation (Grant Nos. 2019T120379 and 2018M630499)the Talent start-up fund of Nanjing Xiaozhuang University (Grant No. 4172111)。
文摘The mechanical influences involved in the interaction between the Antarctic sea ice and ocean surface current(OSC)on the subpolar Southern Ocean have been systematically investigated for the first time by conducting two simulations that include and exclude the OSC in the calculation of the ice-ocean stress(IOS), using an eddy-permitting coupled ocean-sea ice global model. By comparing the results of these two experiments, significant increases of 5%, 27%, and 24%, were found in the subpolar Southern Ocean when excluding the OSC in the IOS calculation for the ocean surface stress,upwelling, and downwelling, respectively. Excluding the OSC in the IOS calculation also visibly strengthens the total mechanical energy input to the OSC by about 16%, and increases the eddy kinetic energy and mean kinetic energy by about38% and 12%, respectively. Moreover, the response of the meridional overturning circulation in the Southern Ocean yields respective increases of about 16% and 15% for the upper and lower branches;and the subpolar gyres are also found to considerably intensify, by about 12%, 11%, and 11% in the Weddell Gyre, the Ross Gyre, and the Australian-Antarctic Gyre, respectively. The strengthened ocean circulations and Ekman pumping result in a warmer sea surface temperature(SST), and hence an incremental surface heat loss. The increased sea ice drift and warm SST lead to an expansion of the sea ice area and a reduction of sea ice volume. These results emphasize the importance of OSCs in the air-sea-ice interactions on the global ocean circulations and the mass balance of Antarctic ice shelves, and this component may become more significant as the rapid change of Antarctic sea ice.
文摘A new method is proposed to produce gas from oceanic gas hydrate reservoir by combining the ocean surface warm water flooding with depressurization which can efficiently utilize the synthetic effects of thermal, salt and depressurization on gas hydrate dissociation. The method has the advantage of high efficiency, low cost and enhanced safety. Based on the proposed conceptual method, the physical and mathematical models are established, in which the effects of the flow of multiphase fluid, the kinetic process of hydrate dissociation, the endothermic process of hydrate dissociation, ice-water phase equilibrium, salt inhibition, dispersion, convection and conduction on the hydrate disso- ciation and gas and water production are considered. The gas and water rates, formation pressure for the combination method are compared with that of the single depressurization, which is referred to the method in which only depres- surization is used. The results show that the combination method can remedy the deficiency of individual producing methods. It has the advantage of longer stable period of high gas rate than the single depressurization. It can also reduce the geologic hazard caused by the formation defor- mation due to the maintaining of the formation pressure by injected ocean warm water.
基金Supported by the NSFC (No. 40476008)Knowledge Innovation Programs of the Chinese Academy of Sciences (No. KZCX3-SW-222)the NSFDYS (No. 40425015)
文摘As an important physical process at the air-sea interface, wave movement and breaking have a significant effect on the ocean surface mixed layer (OSML). When breaking waves occur at the ocean surface, turbulent kinetic energy (TKE) is input downwards, and a sublayer is formed near the surface and turbulence vertical mixing is intensively enhanced. A one-dimensional ocean model including the Mellor-Yamada level 2.5 turbulence closure equations was employed in our research on variations in turbulent energy budget within OSML. The influence of wave breaking could be introduced into the model by modifying an existing surface boundary condition of the TKE equation and specifying its input. The vertical diffusion and dissipation of TKE were effectively enhanced in the sublayer when wave breaking was considered. Turbulent energy dissipated in the sublayer was about 92.0% of the total depth-integrated dissipated TKE, which is twice higher than that of non-wave breaking. The shear production of TKE decreased by 3.5% because the mean flow fields tended to be uniform due to wave-enhanced turbulent mixing. As a result, a new local equilibrium between diffusion and dissipation of TKE was reached in the wave-enhanced layer. Below the sublayer, the local equilibrium between shear production and dissipation of TKE agreed with the conclusion drawn from the classical law-of-the-wall (Craig and Banner, 1994).
基金The National Basic Research Program of China under contract Nos 201 1CB403501 and 2012CB417402the Fund for Creative Research Groups by the National Natural Science Foundation of China under contract No.41121064+1 种基金the National Natural Science Foundation of China under contract Nos 41206015 and 41176016the Open Research Foundation for the State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,State Oceanic Administration under contract No.SOED1210
文摘This study uses a large eddy simulation （LES） model to investigate the turbulence processes in the ocean surface boundary layer at Zhangzi Island offshore. Field measurements at Zhangzi Island （39°N, 122°E） during July 2009 are used to drive the LES model. The LES results capture a clear diurnal cycle in the oceanic turbulence boundary layer. The process of the heat penetration and heat distribution characteristics are analyzed through the heat flux results from the LES and their differences between two diurnal cycles are discussed as well. Energy balance and other dynamics are investigated which show that the tide-induced shear production is the main source of the turbulence energy that balanced dissipation. Momentum flux near the surface shows better agreement with atmospheric data computed by the eddy correlation method than those computed by bulk formula.
基金supported by the National Natural Science Foundation of China through G41006108the Open Research Fund of the Shandong Provincial Key Laboratory of Marine Ecology and Environment & Disaster Prevention and Mitigation through G2011001+1 种基金the Laboratory of Data Analysis and Application, State Oceanic Administration through LDAA-2013-02the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering through G2009586812
文摘To investigate the annual and interaunual variability of ocean surface wind over the South China Sea （SCS）, the vector empirical orthogonal function （VEOF） method and the Hilbert-Huang transform （HHT） method were employed to analyze a set of combined satellite scatterometer wind data during the period from December 1992 to October 2009. The merged wind data were generated from European Remote Sensing Satellite （ERS）-1/2 Scatterometer, NASA Scatterometer （NSCAT） and NASA＇s Quick Scatterometer （QuikSCAT） wind products. The first VEOF mode corresponds to a winter-summer mode which accounts for 87.3% of the total variance and represents the East Asian monsoon features. The second mode of VEOF corresponds to a spring-autumn oscil- lation which accounts for 8.3% of the total variance. To analyze the interannual variability, the annual signal was removed from the wind data set and the VEOFs of the residuals were calculated. The temporal mode of the ftrst intcrannual VEOF is correlated with the Southern Oscillation Index （SOI） with a four-month lag. The second temporal interannual VEOF mode is correlated with the SOI with no time lag. The time series of the two interannual VEOFs were decomposed using the HI-IT method and the results also show a correlation between the interannual variability and El Nino-Southern Oscillation （ENSO） events.
基金Supported by the National Natural Science Foundation of China(No. 40706008)the Open Research Program of the Chinese Academy Sciences Key Laboratory of Tropical Marine Environmental Dynamics (No. LED0606)+1 种基金the Shandong Province Natural Science Foundation (No. Z2008E02)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘The inflow angle of tropical cyclones （TC） is generally neglected in numerical studies of ocean surface waves induced by TC. In this study, the impacts of TC inflow angle on ocean surface waves were investigated using a high-resolution wave model. Six numerical experiments were conducted to examine, in detail, thc effects of inflow angle on mean wave parameters and the spectrum of wave directions. A comparison of the waves simulated in these experiments shows that inflow angle significantly modifies TC-induced ocean surface waves. As the inflow angle increases, the asymmetric axis of the significant wave height （SWH） field shifts 30° clockwise, and the maximum SWH moves from the front-right to the rear-right quadrant. Inflow angle also affects other mean wave parameters, especially in the rear-left quadrant, such as the mean wave direction, the mean wavelength, and the peak direction. Inflow angle is a key factor in wave models for the reproduction of double-peak or multi-peak patterns in the spectrum of wave directions. Sensitivity experiments also show that the simulation with a 40° inflow angle is the closest to that of the NOAA statistical SLOSH inflow angle. This suggests that 40° can be used as the inflow angle in future TC-induced ocean surface wave simulations when SLOSH or observed inflow angles are not available.
基金This research was supported by a grant from the 0ffice of Naval Research of United States under the Sea of Japan Departmental Research Initiatite of N00014-98-1-0236a project from the National Natural Science Foundation of China under contract No.40506006.
文摘Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forcing, tides and storm surges on the waves are investigated using a wave model, a high-resolution atmospheric mesoscale model and a hydrodynamic ocean circulation model. Five month-long wave model simulations are inducted to examine the sensitivity of ocean waves to various wind forcing fields, tides and storm surges during January 1997. Compared with observed mean wave parameters, results indicate that the high frequency variability in the surface wind filed has very great effect on wave simulation. Tides and storm surges have a significant impact on the waves in nearshores of the Tsushima-kaihyS, but not for other regions in the Sea of Japan. High spatial and temporal resolution and good quality surface wind products will be crucial for the prediction of surface waves in the JES and other marginal seas, especially near the coastal regions.
文摘A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any position of ocean surface under any ocean floor conditions using wave num decomposition.LOD scheme is proposed based on quad-tree block,which simplifies the ocean surface regular mesh and realizes the real-time rendering of large-scale ocean surface.Experimental results show that these methods can get realistic effect and fast rendering speed,which are appropriated to the applications of 3D games and battlefield simulation.
文摘Understanding the sea surface scattering process is very important in the development of models to detect the target above or under the surface. In this paper, both the analytical and the numerical methods applied in sea surface scattering are summarized. Some important problems concerned in this field are discussed. For numerical study, edge effect brings artificial nonrealistic scattering and therefore must be suppressed. Different edge treatment methods are compared in this paper. Scattering of breaking wave surface at very low grazing angle always needs more attentions than other scattering problems. Some numerical results show the existence of the special phenomena at very low grazing angle, for example, the ＂sea spikes＂ and the Doppler splitting.
基金supported by the Key Special Project for the Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (Grant No. GML2019ZD0302)the National Key R&D Program of China (Grant No. 2018YFC1506205)
文摘The ocean surface wind(OSW)data retrieved from microwave scatterometers have high spatial accuracy and represent the only wind data assimilated by global numerical models on the ocean surface,thus playing an important role in improving the forecast skills of global medium-range weather prediction models.To improve the forecast skills of the Global/Regional Assimilation and Prediction System Global Forecast System(GRAPES_GFS),the HY-2B OSW data is assimilated into the GRAPES_GFS four-dimensional variational assimilation(4DVAR)system.Then,the impacts of the HY-2B OSW data assimilation on the analyses and forecasts of GRAPES_GFS are analyzed based on one-month assimilation cycle experiments.The results show that after assimilating the HY-2B OSW data,the analysis errors of the wind fields in the lower-middle troposphere(1000-600 hPa)of the tropics and the southern hemisphere(SH)are significantly reduced by an average rate of about 5%.The impacts of the HY-2B OSW data assimilation on the analysis fields of wind,geopotential height,and temperature are not solely limited to the boundary layer but also extend throughout the entire troposphere after about two days of cycling assimilation.Furthermore,assimilating the HY-2B OSW data can significantly improve the forecast skill of wind,geopotential height,and temperature in the troposphere of the tropics and SH.
基金Supported by the National Natural Science Foundation of China(No.42106034)the Laboratory for Regional Oceanography and Numerical Modeling,Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2019A02)+1 种基金the Basic Scientifi c Fund for National Public Research Institutes of China(No.2020Q05)the National Natural Science Foundation of China(Nos.41706034,41706225,41906003)。
文摘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 estimated.Thus,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 datasets.Weight functions are introduced in the Ekman current formulation as well.Comparisons 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 Ocean.Result shows that the wave-modifi ed currents are quite consistent with the Lagrangian drifter observations for the period 1993-2017 in the deep ocean.The 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 component.However,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 Mindanao.What’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)respectively.These 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.
基金The authors would like to thank the financial support from the National Key Research and Development Program of China(Nos.2020YFE0201200,2019YFC1509100)the partial support by the Youth Program of Natural Science Foundation of China(No.41706010)the Fundamental Research Funds for the Central Universities(No.202264002).
文摘Currently,numerical models based on idealized assumptions,complex algorithms and high computational costs are unsatisfactory for ocean surface current prediction.Moreover,the complex temporal and spatial variability of ocean currents also makes the prediction methods based on time series data challenging.The deep network model can automatically learn and extract complex features hidden in large amount of complex data,so it is a promising method for high quality prediction of ocean currents.In this paper,we propose a spatiotemporal coupled attention deep network model STCANet that can extract abundant temporal and spatial coupling information on the behavior characteristics of ocean currents for improving the prediction accuracy.Firstly,Spatial Module is designed and implemented to extract the spatiotemporal coupling characteristics of ocean currents,and meanwhile the spatial correlations and dependencies among adjacent sea areas are obtained through Spatial Channel Attention Module(SCAM).Secondly,we use the GatedRecurrent-Unit(GRU)to extract temporal relationships of ocean currents,and design and implement the nearest neighbor time attention module to extract the interdependences of ocean currents between adjacent times,which can further improve the accuracy of ocean current prediction.Finally,a series of comparative experiments on the MediSea_Dataset and EastSea_Dataset showed that the prediction quality of our model greatly outperforms those of other benchmark models such as History Average(HA),Autoregressive Integrated Moving Average Model(ARIMA),Long Short-term Memory(LSTM),Gate Recurrent Unit(GRU)and CNN_GRU.
基金The National Key Research and Development Program under contract No.2016YFC1401002the National Natural Science Foundation of China under contract Nos 41606201,41576173,41620104003 and 41706202.
文摘This paper proposes a multifunction radar that can not only measure sea currents but also perform sea-surface imaging.The fundamental aspect of the proposed radar comprises transmitting time-shifted up-and-down continuous wave linear frequency modulated signals that allow for the offset of two one-dimensional range images of the sea surface that respectively correspond to the upward linear frequency modulated(LFM)signal and the downward LFM signal.Owing to the Doppler frequency shift from the sea surface,a range offset,which is proportional to the radial velocity of the sea surface,occurs between the upward and downward LFM signals.By using the least-squares linear fitting method in the transformed domain,the range offset can be measured and the current velocity can be retrieved.Finally,we verify the accuracy of current measurement with simulation results.
基金Project supported by the National Natural Science Foundation of China(Grant No.11772180)the State Key Laboratory of Ocean Engineering of China(Grant No.1503)
文摘A necessary big step up in the modern water wave theories and their widespread application in ocean engineering is how to obtain 6-wave resonance conditions and to prove it. In the light of the existing forms and characteristics of 3-wave, 4-wave and 5-wave resonance conditions, the 6-wave resonance conditions are proposed and proved for currently a maximum wave-wave resonance interactions of the ocean surface gravity waves in deep water, which will be indispensable to both the Kolmogorov spectrum of the corresponding universal wave turbulence and a synthetic 4-5-6-wave resonant model for the ocean surface gravity waves.
文摘A cloud-ocean planetary boundary layer (OPBL) feedback mechanism is presented and tested in this paper. Water vapor, evaporated from the ocean surface or transported by the large-scale air flow, often forms convective clouds under a conditionally unstable lapse rate. The variable cloud cover and rainfall may have positive and negative feedback with the ocean mixed layer temperature and salinity structure. The coupling of the simplified Kuo's (1965) cumulus cloud model to the Kraus-Turner's (1967) ocean mixed layer model shows the existence of this feedback mechanism. The theory also predicts the generation of low frequency oscillation in the atmosphere and oceans.
基金funded by the National Key Research and Development Program[grant number 2022YFC3004200]the National Natural Science Foundation of China[grant number U2142212]the Hunan Provincial Natural Science Foundation of China[grant number 2021JC0009]。
文摘A polarized bidirectional reflectance distribution function(pBRDF)matrix is developed from two-scale roughness theory with the aim of providing more accurate simulations of microwave emissions and scattering required for ocean-atmosphere coupled radiative transfer models.The potential of the pBRDF matrix is explored for simu-lating the ocean backscatter at Ku-band.The effects of ocean wave spectra including the modified Durden and Vesecky(DV2),Elfouhaily,and Kudryavtsev spectra on the pBRDF matrix backscatter simulations are investi-gated.Additionally,the differences in backscattering normalized radar cross-section(NRCS)simulations between the Ku-band geophysical model function and pBRDF matrix are analyzed.The results show that the pBRDF matrix can reasonably reproduce the spatial distribution of ocean surface backscattering energy,but the distribution pat-tern and numerical values are influenced by ocean wave spectra.The DV2 spectrum is the best one for the pBRDF matrix to simulate horizontally polarized NRCSs,with the exception of scenarios where the incidence angle is below 35°,the wind speed is less than 10 m s^(−1),and in the cross-wind direction.Also,the DV2 spectrum effec-tively characterizes the wind speed and relative azimuth angle dependence for vertically polarized NRCSs.The Elfouhaily spectrum is suitable for simulating vertically polarized NRCSs under conditions of low wind speed(be-low 5 m s^(−1))and incidence angles under 40°.The Kudryavtsev spectrum excels in simulating vertically polarized NRCSs at high incidence angles(>40°)and horizontally polarized NRCSs at low incidence angles(<35°).
基金Supported by the National Key Research and Development Program of China(No.2022YFE0204600)the National Natural Science Foundation for Young Scientists of China(No.41906157)。
文摘Internal solitary waves(ISW),characterized by large amplitude and long propagation distance,are widespread in global oceans.While remote sensing images have played an essential role in studying ISWs,they mainly exploit two-dimensional image information.However,with the launch of the surface water ocean topography(SWOT)satellite on December 16,2022,a unique opportunity has emerged to capture wide-swath three-dimensional ISW-induced sea surface information.In this study,we examine ISWs in the Andaman Sea using data from the Ka-band Radar Interferometer(KaRIN),a crucial sensor onboard SWOT.KaRIN not only provides backscattering satellite images but also employs synthetic aperture interferometry techniques to retrieve wide-swath two-dimensional sea surface height measurements.Our observations in the Andaman Sea revealed the presence of ISWs characterized by dark-bright strips and surface elevation solitons.The surface soliton has an amplitude of 0.32 m,resulting in an estimation of ISW amplitude of approximately 60 m.In contrast to traditional two-dimensional satellite images or nadir-looking altimetry data,the SWOT mission’s capability to capture threedimensional sea surface information represents a significant advancement.This breakthrough holds substantial promise for ISW studies,particularly in the context of ISW amplitude inversion.
基金This work was supported by the National Natural Science Foundation of China(Grant NO.41276187)the Global Change Research Program of China(Grant No.2015CB953901)+3 种基金the Startup Foundation for Introducing Talent of NUIST(Grant No.20110310)Program for Innovation Research and Entrepreneurship Team in Jiangsu Provincethe CFOSAT project,the Canadian Program on Energy Research and Developmentthe Canadian Space Agency GRIP program funding for wave-ice interactions
文摘A new method for the retrieval of ocean wave parameters from SAR imagery is developed,based on the shape-from-shading(SFS)technique.Previously,the SFS technique has been used in the reconstruction of 3D landform information from SAR images,in order to generate elevation maps of topography for land surfaces.Here,in order to retrieve ocean wave characteristics,we apply the SFS methodology,together with a method to orient the angular measurements of the azimuth slope and range slope,in the measurement of ocean surface waves.This method is applied to high resolution fine-quad polarization mode(HH,VV,VH and HV)C-band RADARSAT-2 SAR imagery,in order to retrieve ocean wave spectra and extract wave parameters.Collocated in situ buoy measurements are used to validate the reliability of this method.Results show that the method can reliably estimate wave height,dominant wave period,dominant wave length and dominant wave direction from C-band SAR images.The advantage of this method is that it does not depend on modulation transfer functions(MTFs),in order to measure ocean surface waves.This method can be used in monitoring ocean surface wave propagation through open water areas into ice-covered areas,especially the marginal ice zone(MIZ)in polar oceans.
文摘A coupled atmosphere-ocean model developed at the Institute for Space Studies at NASA Goddard Space Flight Center (Russell et al., 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat fluxQ to air/sea temperature difference ΔT by a relaxation coefficientk. The model was initiated from the National Centers for Environmental Prediction (NCEP) atmospheric observations for 1 December 1977, and from the National Ocean Data Center (NODC) global climatological mean December temperature and salinity fields at 1°x 1° resolution. The time step is 7.5 minutes. We integrated the model for 450 days and obtained a complete model-generated global data set of daily mean downward net surface fluxQ, surface air temperatureT A, and sea surface temperatureT O. Then, we calculated the cross-correlation coefficients (CCC) betweenQ and ΔT. The ensemble mean CCC fields show (a) no correlation betweenQ and ΔT in the equatiorial regions, and (b) evident correlation (CCC≥0.7) betweenQ and ΔT in the middle and high latitudes. Additionally, we did the variance analysis and found that whenk=120 W m?2K?1, the two standard deviations, σQ and σκδT , are quite close in the middle and high latitudes. These results agree quite well with a previous research (Chu et al., 1998) on analyzing the NCEP re-analyzed surface data, except that a smaller value ofk (80 W m?2K?1) was found in the previous study. Key words Air-sea coupled system - Ocean surface fluxes - Surface thermal boundary condition
