Xuefeng Zhang

• PhD
• Professor at Tianjin University

The inversion of ocean subsurface temperature and salinity (TS) is a hot topic and challenging problem in the oceanic sciences. In this study, a new method for the inversion of underwater TS in the South China Sea is proposed based on an improved generative adversarial network (GAN). The proposed model can derive the underwater TS from sea surface...

Accurately identifying ocean fronts is essential for advancing marine science and effectively managing aquatic resources. Traditional identification methods and certain deep learning approaches often struggle to capture the dynamic complexity of oceanic phenomena due to the limitations in identification efficiency, detail sensitivity, and real-worl...

Generally, sea ice prediction skills can be improved by assimilating available observations of the sea ice concentration (SIC) and sea ice thickness (SIT) into a numerical forecast model to update the initial conditions. However, due to inadequate daily SIT satellite observations in the Arctic melting season, the SIC fields in forecast models are u...

The sea surface temperature (SST) is one of the most important parameters that characterize the thermal state of the ocean surface, directly affecting the heat exchange between the ocean and the atmosphere, climate change, and weather generation. Generally, due to factors such as the weather, satellite scanning orbit range, and satellite sensor mal...

Dehazing individual remote sensing (RS) images is an effective approach to enhance the quality of hazy remote sensing imagery. However, current dehazing methods exhibit substantial systemic and computational complexity. Such complexity not only hampers the straightforward analysis and comparison of these methods but also undermines their practical...

Significant Wave Height (SWH) is a crucial parameter in ocean wave dynamics, impacting coastal safety, maritime transportation, and meteorological research. Building upon the TimesNet neural network, a recent advancement in the realm of time series prediction in deep learning, this study proposes an integrated approach combining Empirical Mode Deco...

To effectively extract multi-scale information from observation data and improve computational efficiency, a multi-scale second-order autoregressive recursive filter (MSRF) method is designed. The second-order autoregressive filter used in this study has been attempted to replace the traditional first-order recursive filter used in spatial multi-sc...

The Array for Real-time Geostrophic Oceanography (Argo) program provides valuable data for maritime research and rescue operations. This paper is based on Argo historical and satellite observations, and inverted sea surface and submarine drift trajectories. A neural network method was developed to predict the position of Argo buoys, improving targe...

Based on the high-resolution remote sensing images and deep learning models, more and more detailed spatial information around the coastlines can be extracted automatically nowadays. As so far, most of the sea-land segmentation networks choose batch normalization (BN) as the normalization layer. However, the accuracy of segmentation results is easi...

The northern part of the South China Sea is a complex ocean environment with a large range of tidal waves and the stable Luzon cold eddy, which significantly influence the sound propagation characteristics through their impact on sound speed. This study uses a 3D ocean-acoustic framework consisting of MITgcm and BELLHOP ray model to investigate the...

Acoustic tracking of whales’ underwater cruises is essential for protecting marine ecosystems. For cetacean conservationists, fewer hydrophones will provide more convenience in capturing high-mobility whale positions. Currently, it has been possible to use two hydrophones individually to accomplish direction finding or ranging. However, traditional...

Plain Language Summary Accurate sea ice forecasting is critical to understanding the risks of Arctic maritime activity and to improving climate forecasting in the mid‐high latitudes of the Northern Hemisphere. Data assimilation of sea ice observations is an effective way to improve the numerical model forecast results, and its effect is related to...

Deep learning has been acknowledged as an increasingly important technology for ENSO forecasts. The most cutting-edge deep learning algorithm is developed based on Convolutional Neural Network (CNN), which can achieve a multi-year (about 17-month-lead) forecast and has conquered the ‘spring forecast barrier’ problem. However, this group of methods...

Plain Language Summary Generative adversarial networks (GANs) are undoubtedly one of the most creative advances in deep learning due to their excellent generation performances, but they are not widely used for interior ocean variables' deriving. Deriving sea subsurface temperature fields from satellite remote sensing data using deep learning method...

Seawater temperature and salinity are basic marine environmental parameters, which can be used to calculate other marine environmental parameters. However, most of the on-site observation data have the problems of uneven spatial distribution and time discontinuity, and it is difficult for remote sensing observation methods to obtain subsurface info...

The sea surface temperature anomaly (SSTA) plays a key role in climate change and extreme weather processes. Usually, SSTA forecast methods consist of numerical and conventional statistical models, the former can be seriously influenced by the uncertainty of physical parameterization schemes, the nonlinearity of ocean dynamic processes, and the non...

Ocean mesoscale eddy is a special mesoscale phenomenon in the ocean, which widely exists in all oceans and marginal seas around the world. Compared with ordinary ocean circulation, mesoscale eddy has high rotating speed, strong current velocity, and average vertical depths of several kilometres, which play an important role in ocean circulation and...

Sea surface temperature anomalies (SSTAs) and sea surface height anomalies (SSHAs) are indispensable parts of scientific research, such as mesoscale eddy, current, ocean-atmosphere interaction and so on. Nowadays, extended-range predictions of ocean dynamics, especially in SSTA and SSHA, can provide daily prediction services in the range of 30 days...

The varies of ice floe thickness (IFH) is a very influential research content in the Earth system academic research, it is closely related to the distribution of underwater acoustic fields. However, the discontinuous physical parameters of ice floes make it difficult to clear this relationship with conventional acoustic propagation models or measur...

To predict tidal current movement accurately is essential in the process of tidal energy development. However, the existing methods have limits to meet the need for accuracy. Recently, artificial intelligence technology has been widely applied to solve this problem. In this paper, a tidal current prediction model combining numerical simulation with...

A three-dimensional and complete adjoint model of the Princeton Ocean Model with a generalized coordinate system (POMgcs) is developed to construct the 4D-Variational data assimilation (4D-Var) algorithm in this study. Uncertain parameters in the Mellor-Yamada 2.5 turbulence submodel (MY-2.5) which is enclosed in POMgcs, are tentatively estimated v...

The United Nations Convention on the Law of the Sea provides only basic legal principles for maritime delimitation disputes among coastal states. The implementation of maritime delimitation requires the comprehensive use of legal, political, and technical means by relevant states to generate the expected equitable results. Accurate calculation of t...

The benthic structure of seamounts is critical for understanding the ecological environment and for assessing the influence of resource exploitation. However, the characteristics of the benthic structure of the seamount, especially for guyot, are still far from being clearly understood. For the first time, we carried out detailed hydroacoustic mapp...

Using observational information to tune uncertain physical parameters in an ocean model via a robust data assimilation method has great potential to reduce model bias and improve the quality of sea temperature analysis and prediction. However, how observational information should be used to optimize geographic-dependent parameters through four-dime...

Deep learning has been acknowledged as an increasingly important technology for ENSO forecasts. The most cutting-edge deep learning algorithm is developed based on Convolutional Neural Network (CNN), which can achieve a multi-year (about 17-month-lead) forecast and has conquered the ‘spring forecast barrier’ problem. However, this group of methods...

Generally, the sea ice prediction skills can be improved via assimilating available observations of the sea ice concentration (SIC) and the sea ice thickness (SIT) into a numerical forecast model to update the initial fields of the model. However, due to the lack of SIT satellite observations in the melting season, only SIC fields in the forecast m...

With the development and deployment of observation systems in the ocean, more precise passive and active microwave data are becoming available for the weather forecasting and the climate monitoring. Due to the complicated variability of the sea ice concentration (SIC) in the marginal ice zone and the scarcity of high-precision sea ice data, how to...

Harmful algal blooms (HABs) events have a serious impact on marine fisheries and marine management. They occur globally with high frequency and are characterized by a long duration and difficult governance. HABs incidents have occurred in the South China Sea (SCS), and the frequency of occurrence has been on the rise in recent decades. Predicting t...

Due to the model and sampling errors of the finite ensemble, the background ensemble spread becomes small and the error covariance is underestimated during filtering for data assimilation. Because of the constraint of computational resources, it is difficult to use a large ensemble size to reduce sampling errors in high-dimensional real atmospheric...

Global warming has intensified the rise in sea levels and has caused severe ecological disasters in shallow coastal waters such as the Northeastern China's Bohai Sea. The prediction of the sea surface height anomaly (SSHA) has great significance in the context of monitoring changes in sea levels. However, the non-linearity of SSHA due to the occurr...

This paper proposes a two-dimensional underwater sound propagation model using the Discontinuous Galerkin Finite Element Method (DG-FEM) to investigate the influence of current on sound propagation. The acoustic field is calculated by the convected wave equation with the current speed parameter. Based on the current speed data from an assimilation...

Sound Speed Profile (SSP) affecting underwater acoustics is closely related to the temperature and the salinity fields. It is of great value to obtain the temperature and the salinity information through the high-precision sound speed profiles. In this paper, a data assimilation scheme by introducing sound speed profiles as a new constraint is prop...

A coupled ocean-wave-sea spray model system is used to investigate the impacts of sea spray and sea surface roughness on the response of the upper ocean to the passage of the super typhoon Haitang. Sea spray mediated heat and momentum fluxes are derived from an improved version of Fairall’s heat fluxes formulation (Zhang et al., 2017) and Andreas’s...

Abstract The usage of four‐dimensional variational (4DVar) scheme is limited by the static background error covariance and the adjoint model. In a hybrid frame of the four‐dimensional ensemble‐variational data assimilation scheme (4DEnVar), being able to avoid the tangent linear and adjoint models in the 4DVar and nowadays developed into a cutting‐...

In order to understand the wave–turbulence interaction under non-hydrostatic conditions to prepare future advanced very-high-resolution ocean reanalysis data, an σ-coordinate ocean model—namely, the Marine Environment Research and Forecasting (MERF) model—with an idealized supercritical slope topography is applied to conduct a series of high-resolu...

The sea ice concentration observation from satellite remote sensing includes the spatial multi-scale information. However, traditional data assimilation methods cannot better extract the valuable information due to the complicated variability of the sea ice concentration in the marginal ice zone. A successive corrections analysis using variational...

The effect of wave-enhanced mixing on the upper mixing in the YS is investigated preliminarily using wave model and POMgcs jointly. The process of WB is able to dissipate most of energy brought by wind. Stokes dissipation of wave energy is small comparing with wave breaking in the YS in summer. Coriolis term is balanced mainly by barotropic term in...

Tidal characteristics in the well-known Coastal Marine Proving Ground near Chudao Island located in Shandong Province, China, are firstly investigated based on Princeton Ocean Model (POM) with a generalized coordinate system. Numerical results having been validated by available observations, the ensemble transform–based sensitivity method that calc...

Recent studies have started to explore coupled data assimilation (CDA) in coupled ocean–atmosphere models because of the great potential of CDA to improve climate analysis and seamless weather–climate prediction on weekly-to-decadal time scales in advanced high-resolution coupled models. In this review article, we briefly introduce the concept of C...

Uncertainties of the wave state parameters in a sea spray parameterization scheme can be a major source of errors for air-sea turbulent (momentum, sensible and latent) fluxes parameterizations resulting in biases in numerical ocean simulations and forecasts. In this study, we explore applications of the ensemble adjustment Kalman filter (EAKF) data...

The “Two Oceans and One Sea” area (West Pacific, Indian Ocean, and South China Sea; 15°S–60°N, 39°–178°E) is a core strategic area for the “21st Century Maritime Silk Road” project, as well as national defense. With the increasing demand for disaster prevention and mitigation, the importance of 10–30-day extended range prediction, between the conve...

Langmuir turbulence (LT) due to the Craik-Leibovich vortex force had a clear impact on the thermal response of the ocean mixed layer to Supertyphoon Haitang (2005) east of the Luzon Strait. This impact is investigated using a 3D wave-current coupled framework consisting of the Princeton Ocean Model with the generalized coordinate system (POMgcs) an...

Parametric uncertainty in convection parameterization is one major source of model errors that cause model climate drift. Convection parameter tuning has been widely studied in atmospheric models to help mitigate the problem. However, in a fully coupled general circulation model (CGCM), convection parameters which impact the ocean as well as the cl...

Effects of longitudinal shifts of centre of gravity with respect to the designed one on the ship resistance are studied utilizing computational fluid dynamics (CFD). Such a shift of centre of gravity has been frequently observed in practice. This can occur, for example, due to inaccuracies in size and weight estimations of the ship components in th...

Crew and passengers’ comfort is one of the main objectives in the design of a ferry. A parameter quantifying it is the so-called motion sickness incidence (MSI). In this study, the comfort level of a roro ferry design is assessed for which the vessel’s vertical acceleration and the MSI were used as quantitative parameters. The voyage area is the se...

This study addresses how to maintain oceanic mixing along potential density surface in ocean data assimilation (ODA). It is well known that the oceanic mixing across the potential density surface is much weaker than that along the potential density surface. However, traditional ODA schemes allow the mixing across the potential density surface and t...

Observing System Simulation Experiments (OSSEs) have been conducted to evaluate the effect of Argo data assimilation on ocean reanalysis in the Pacific region. The “truth” is obtained from a 5-year model integration from 2003 to 2007 based on the MIT general circulation model with the truly varying atmospheric forcing. The “observations” are the pr...

Strong winds lead to large amounts of sea spray in the lowest part of the atmospheric boundary layer. The spray droplets affect the air-sea heat fluxes due to their evaporation and the momentum due to the change of sea surface, and in turn change the upper ocean thermal structure. In this study, impact of sea spray on upper ocean temperatures in th...

An ocean state monitor and analysis radar (OSMAR), developed by Wuhan University in China, have been mounted at six stations along the coasts of East China Sea (ECS) to measure velocities (currents, waves and winds) at the sea surface. Radar-observed surface current is taken as an example to illustrate the operational high-frequency (HF) radar obse...

Imperfect physical parameterization schemes are an important source of model bias in a coupled model and adversely impact the performance of model simulation. With a coupled ocean-atmosphere-land model of intermediate complexity, the impact of imperfect parameter estimation on model simulation with biased physics has been studied. Here, the biased...

Sequential, adaptive, and gradient diffusion filters are implemented into spatial multiscale three-dimensional variational data assimilation (3DVAR) as alternative schemes to model background error covariance matrix for the commonly used correction scale method, recursive filter method, and sequential 3DVAR. The gradient diffusion filter (GDF) is v...

A variational method is used to estimate wave-affected parameters in a two-equation turbulence model with assimilation of temperature data into an ocean boundary layer model. Enhancement of turbulent kinetic energy dissipation due to breaking waves is considered. The Mellor-Yamada level 2.5 turbulence closure scheme (MY2.5) with the two uncertain w...

Imperfect physical parameterization schemes in a coupled climate model are an important source of model biases that adversely impact climate prediction. However, how observational information should be used to optimize physical parameterizations through parameter estimation has not been fully studied. Using an intermediate coupled ocean-atmospherem...

At the interface between the lower atmosphere and sea surface, sea spray might significantly influence air-sea heat fluxes and subsequently, modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model, to investigate the effects of se...

This study systematically investigated the ocean mixed layer responses to tropical cyclone (TC) using available Argo profiles during the period of 1998-2011 in the Northwest Pacific. Results reveal that isothermal layer (IL) deepening and isothermal layer (IL) cooling with evident rightward biases induced by strong TCs are clearer compared to the w...

Based on the statistics of surface drifter data of 1979–2011 and the simulation of nuclear pollutant particulate movements simulated using high quality ocean reanalysis surface current dataset, the transport pathways and impact strength of Fukushima nuclear pollutants in the North Pacific have been estimated. The particulates are used to increase t...

Imperfect dynamical core is an important source of model biases that adversely impact on the model simulation and predictability of a coupled system. With a simple pycnocline prediction model, in this study, we show the mitigation of model biases through parameter optimization when the assimilation model consists of a "biased" time-differencing. He...

A two-dimensional numerical model, which is configured on the basis of Princeton ocean model (POM), is used to study the effect of Stokes production (SP) of the turbulent kinetic energy on a density profile and Ekman transport in an idealized shelf region in summer. The energy input from SP is parameterized and included into the Mellor-Yamada turbu...

The first version of a global ocean reanalysis over multiple decades (1979–2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data as...

A salinity sensor drift in the Array for Real-time Geostrophic Oceanography (Argo) float has been identified. In the present study the salinity calibration results for global Argo floats indicate that an upper 900 dbar averaged-positive salinity drift appears during the floats' operating period from January 2001 to December 2010. These offsets are...

A new regional ocean reanalysis over multiple decades (1958{2008) for the coastal waters of China and adjacent seas has been completed by the National Marine Data and Information Service (NMDIS) under the CORA (China Ocean ReAnalysis) project. Evaluations were performed on three aspects: (1) the improvement of general reanalysis quality; (2) eddy s...

The impact of assimilating Argo data into an initial field on the short-term forecasting accuracy of temperature and salinity is quantitatively estimated by using a forecasting system of the western North Pacific, on the base of the Princeton ocean model with a generalized coordinate system (POMgcs). This system uses a sequential multigrid three-di...

Anew, fully conservedminimal adjustment schemewith temperature and salinity (T, S) coherency is presented for eliminating false static instability generated fromanalyzing and assimilating stable ocean (T, S) profiles data, that is, from generalized averaging over purely observed data (data analysis) or over modeled/observed data (data assimilation)...

Based on the statistics of all surface drifting buoys of 1978–2011 and Lagrangian tracers simulated from high quality ocean reanalysis currents, the impact times and strength of Fukushima nuclear pollution to the east coast of China and the west coast of America have been estimated. Under the circumstances of the radioactive pollutants drifting in...

The Princeton Ocean Model (POM) with generalized coordinate system (POMgcs) is used to study the summer surface-layer thermal response to surface gravity waves in the Yellow Sea (YS). The parameterization schemes of wave breaking developed by Mellor and Blumberg (J Phys Oceanogr 34:693–698, 2004) and Kantha and Clayson (Ocean Model 6:101–124, 2004)...

Based on the statistics of all surface drifting buoys of 1979-2011, the transport paths and times of Fukushima nuclear pollutants in the North Pacific surface have been studied. We examined the trajectories of surface drifting buoys that passed by the pre-defined source region of nuclear pollutants (totally 176 buoys) one by one to identify typical...

We investigated the Stokes drift-driven ocean currents and Stokes drift-induced wind energy input into the upper ocean using a two-way coupled wave-current modeling system that consists of the Princeton Ocean Model generalized coordinate system (POMgcs), Simulating WAves Nearshore (SWAN) wave model, and the Model Coupling Toolkit (MCT). The Corioli...

A regional ocean reanalysis system for the coastal waters of China and adjacent seas has been developed by the National Marine Data and Information Service (NMDIS). It produces a dataset package called CORA (China ocean reanalysis). The regional ocean model used is based on the Princeton Ocean Model with a generalized coordinate system (POMgcs). Th...

The Stokes drift-induced ocean currents and wind energy input into the upper ocean have been investigated using a fully coupled wave-current model consisting of the Princeton Ocean Model (POMgcs), Simulating WAves Nearshore (SWAN) wave model and the Model Coupling Toolkit (MCT). The Coriolis-Stokes forcing (CSF), which is computed using the wave pa...

A regional ocean reanalysis system in the China seas and the adjacent sea area has been developed recently. The regional ocean model used is a parallel version of Princeton Ocean Model with generalized coordinate system (POMgcs) with a domain covering an area extending from 10˚S to 52˚N in latitude and from 99˚E to 150˚E in long...