Yijun He

Nanjing University of Information Science and Technology · School of Marine Sciences

Introduction to Geophysical Fluid Dynamics provides an introductory-level exploration of geophysical fluid dynamics (GFD), the principles governing air and water flows on large terrestrial scales. Physical principles are illustrated with the aid of the simplest existing models, and the computer methods are shown in juxtaposition with the equations...

Effects of marine environment and climate changes on phytoplankton dynamics in global oceans have received increasing attention but remain a mystery. This study used a comprehensive approach combining correlation and information flow to explore relationships among phytoplankton biomass, marine environment, and climate forcing based on global observ...

Ocean waves are essential elements across the air‐sea interface, regulating momentum and energy transfer. The mixture of wind sea and ocean swell coupled with surface winds results in diverse sea state conditions that modify the local air‐sea interaction. Previous classifications of wind waves and swells are mostly binary that are insufficient to r...

A long-term time series of 319 Sentinel-1 SAR Imagery with Interferometric Wide Swath (IW) mode was used to study the characteristics of submesoscale eddies over Japanese coastal regions from 2015 to 2021, including spatiotemporal eddy properties and possible mechanisms of their formation. The results showed that around 98% of the 1499 eddies ident...

本书主要介绍了微波遥感理论、系统和应用方面的内容，包括电磁波的传播和反射、雷达散射、微波辐射测量和辐射传输、大气辐射探测、散射模型与陆地观测、辐射模型与陆地探测、雷达观测和卫星散射计、真实孔径与合成孔径机载侧视雷达、干涉合成孔径雷达、雷达遥感海洋原理和方法、星载高度计和辐射计海洋遥感等内容。

To obtain new information about surface waves, it is proposed to use an underwater acoustic wave gauge, and an assessment of its effectiveness can be performed using a numerical simulation and field experiment. A new device, an underwater acoustic wave gauge named “Kalmar”, was developed by the Institute of Applied Physics of the Russian Academy of...

This paper presents a new simulator able to generate raw data for ocean wave radar spectrometer (OWRS). Data simulation involves three key procedures: Generating two-dimensional (2-D) sea wave height, velocity, and acceleration fields by use of a prescribed ocean wave height spectrum; calculating the 2-D sea surface normalized radar cross section f...

This study investigates the impact of eddy-induced sea surface temperature (SST) anomalies on the overlying atmosphere in the South China Sea, utilizing observational and reanalysis datasets. The results reveal that SST anomalies caused by anticyclonic or cyclonic eddies have a significant impact on the acceleration or deceleration of surface winds...

The purpose of this study is to analyze the applicability conditions for the significant wave height (SWH) measurement approach based on measuring the cross-correlation function of two signals with similar frequencies reflected by the sea surface in the bistatic problem statement (the transmitting antenna and the receiving antenna are separated in...

Marine phytoplankton fuel the oceanic biotic chain, determine the carbon sequestration levels, and are crucial for the global carbon cycle and climate change. In the present study, we show a near-two-decadal (2002-2022) spatiotemporal distribution of global phytoplankton abundance, proxy as dominant phytoplankton taxonomic groups (PTGs), with a new...

Since launch, the Ku-band rotating fan-beam scatterometer onboard the China–France Oceanography Satellite (CFOSAT) has provided valuable sea surface wind measurements for more than four years. The performance of CFOSAT scatterometer (CSCAT)-derived wind vectors is generally good in terms of root-mean-square error, while the absolute calibration err...

Two-dimensional (2D) wave spectra describe the distribution of wave energy in terms of frequency and direction. For unimodal seas (i.e. single peaked), wave spectra can describe the wave component accurately. However, they fail to describe wave components properly in more complex situations. The simultaneous existence of wind-sea and one or more sw...

This study aims to explore the joint usage of multisource scatterometer measurements in polar sea water and ice discrimination. All radar backscatter measurements from current operating satellite scatterometers are considered, including the C-band ASCAT scatterometer on board the MetOp series satellites, the Ku-band scatterometer on board the HY-2B...

The internal energy distribution of waves can be described using ocean-wave spectra. In many ways, obtaining wave spectra on a global scale is critical. Surface waves investigation and monitoring onboard the Chinese-French oceanography satellite is the first space-borne instrument for detecting wave spectra specially, which was launched on October...

The particle composition of suspended matter provides crucial information for a deeper understanding of marine biogeochemical processes and environmental changes. Particulate backscattering efficiency (Qbbe(λ)) is critical to understand particle composition, and a Qbbe(λ)-based model for classifying particle types was proposed. In this study, we ev...

The Ku-band scatterometer onboard China France Oceanography Satellite (CFOSAT) observes the sea surface with two conically scanning fan beams. Compared to the prior Ku-band pencil beam scatterometers, this innovative observing mechanism provides more independent backscatter measurements at varying incidence and azimuth angles, as such it brings cha...

This study is aimed at expanding the number of measured parameters to analyze the features of the formation of surface waves under the influence of wind. The paper develops an original approach to obtaining information on the variability of the short-wavelength part of the wave spectrum (examples are given for wavelengths from about 50 cm to 2 cm i...

In this study, the interaction between the packaging effect (Qa⁎) and total chlorophyll-a concentration (Ct) or total size index (SIt) was investigated to explore the potential bio-optical mechanism in phytoplankton cells in the global oceans. In addition, the long-term spatiotemporal characteristics of these interactions were necessary for graspin...

Knowledge of the marine phytoplankton communities is vital for understanding the carbon cycle, ecological and biogeochemical processes, and climate change. Phytoplankton assemblages contain multiple pigments that play a significant role in describing the phytoplankton communities. Thus, detecting the concentrations of phytoplankton pigments is of g...

By using a Lagrangian-Averaged Vorticity Deviation (LAVD)-based vortex detection scheme, rotationally coherent Lagrangian vortices in the South Atlantic Ocean are detected. These vortices act as agents for water transport and can stay coherent in a limited time scale. Our study starts from the life cycle of several long-lived Agulhas rings detected...

Tropical cyclones (TC) transfer kinetic energy to the upper ocean and thus accelerate the ocean mixed layer (OML) currents. However, the quantitative link between near‐surface currents and high wind speeds, under extreme weather conditions, remains poorly understood. In this study, we use multi‐mission satellites and drifting‐buoy observations to i...

The total mean square slope (mss) of large-scale (in comparison with the scale of radar wavelengths) ocean waves can describe the roughness of the ocean surface. This important parameter has found many applications and can be determined by the dependence of large-scale mss on azimuthal angles. The Surface Waves Investigation and Monitoring instrume...

A three-component model is often used to invert the phytoplankton size class (PSC) concentration globally, especially in open oceans. Limited by the assumption of this three-component model, new efforts have been made to explore PSCs in different bathymetric regions. Mass global cruise datasets were gathered and classified into coastal, mixed, and...

For current direction retrieval

Surface waves play an essential role in modifying the momentum fluxes across the air‐sea interface, especially under tropical cyclone (TC) conditions. A coupled wave‐ocean circulation model system, taking into consideration the surface wave effects on momentum fluxes, is applied to investigate the generation of near‐inertial motions (NIMs) under TC...

The present climate simulation and future projection of the mixed layer depth (MLD) and subduction process in the subtropical Southeast Pacific are investigated based on the geophysical fluid dynamics laboratory earth system model (GFDL-ESM2M). The MLD deepens from May and reaches its maximum (>160 m) near (24°S, 104°W) in September in the historic...

The Chinese HY-2D satellite was launched on 19 May 2021, carrying a Ku-band scatterometer. Together with the operating scatterometers onboard the HY-2B and HY-2C satellites, the HY-2 series scatterometer constellation was built, constituting different satellite orbits and hence opportunity for mutual intercomparison and intercalibration. To achieve...

Accurate and rapid monitoring of green macroalgae blooms (GMB; also known as green tide) provide valuable information in decision making for mitigating its environmental impacts and economic losses. Plenty of spectral-based algorithms mainly rely on Rayleigh-corrected or atmospherically-corrected reflectance. However, this inherently requires addit...

Wave mode of spaceborne synthetic aperture radar (SAR) is designed for the global ocean wave observations. Despite the fact that the significant wave height inferred from SAR measurements has been validated against model output and in-situ data, SAR's primary and unique capability for operational 2-dimensional spectral description of sea state rema...

The spatial distribution of eddy diffusivity, basic characteristics of coherent mesoscale eddies and their relationship are analyzed from numerical model outputs in the Southern Ocean. Mesoscale fluctuation information is obtained by a temporal-spatial filtering method, and the eddy diffusivity is calculated using a linear regression analysis betwe...

Ocean waves can affect the roughness of the ocean surface, and the waves generated by tropical cyclones impact the momentum and energy fluxes across the air-sea interface. In this study, the impacts of ocean waves on the momentum and energy fluxes under tropical cyclones is examined by using the tropical cyclone observation dataset IBTrACS (Interna...

We aim to directly invert wave parameters by using the data of a compact polarimetric synthetic aperture radar (CP SAR) and validate the effectiveness of ocean wave parameter retrieval from the circular transmit/linear receive mode and π/4 compact polarimetric mode. Relevant data from the RADARSAT-2 fully polarimetric SAR on the C-band were used to...

The surface wave investigation and monitoring (SWIM) aboard the China-France Oceanography Satellite (CFOSAT), a pioneer conically scanning wave spectrometer, was successfully launched on October 29, 2018. Its innovative configuration composed of one nadir and five rotating near-nadir beams is designed to simultaneously observe the directional wave...

The Chinese HY-2C satellite was launched on Sep. 21, 2020, carrying the new Ku-band scatterometer (HSCAT-C). Different from the other currently operating scatterometers, the HSCAT-C is in a non-sun-synchronous orbit and as such it will be useful for the cross-calibration of sea surface wind products from current space-borne scatterometers and radio...

A novel remote sensing algorithm was developed based on Landsat 8 Operational Land Imager (OLI) data to separately recognize concurrent Sargassum and Ulva prolifera in the South Yellow Sea. This algorithm has three main steps: 1) classification of macroalgae-containing pixels from normal seawater pixels by means of a mature floating algae index (FA...

Accurate and rapid monitoring of green macroalgae blooms (GMB; also known as green tide) provide valuable information in decision making for mitigating its environmental impacts and economic losses. Plenty of spectralbased algorithms mainly rely on Rayleigh-corrected or atmospherically-corrected reflectance. However, this inherently requires additi...

A sharp decline in the Sediment load at the seaward most Datong station (DTS) of the Yangtze River occurred at an average rate of 7.22 × 10⁶ t/yr since 1956, and this drop had a staircase pattern that can be divided into five distinct periods (1956–1968, 1969–1991, 1992–2002, 2003–2012, and 2013–2017). In this study, a new holistic basin-wide Sedim...

Marine phytoplankton absorption plays an important role in oceanic biological productivity and ecological environmental dynamics. Understanding the optical absorption variability associated with phytoplanktonic groups still remains a challenge. In this study, samples (n = 206) were collected for the marginal seas of the northwest Pacific Ocean from...

Sea surface winds derived from the spaceborne rotating pencil-beam scatterometers, such as the current Chinese Haiyang-2 (HY-2) scatterometers and the Indian SCATSAT-1 scatterometer, are used in a wide range of atmospheric and oceanic applications. One key problem of the pencil-beam scatterometers is the relatively low wind quality in the nadir reg...

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 r...

The China France Oceanography Satellite (CFOSAT) and Haiyang‐2B (HY‐2B) satellites were successively launched in China on the 29th and 25th of October 2018, respectively. HY‐2 B carries the second Chinese radar altimeter along with three other microwave sensors, whereas CFOSAT contains the first Surface Waves Investigation and Monitoring (SWIM) ins...

As a second-order expression of the phytoplankton absorption coefficient (a ph (λ)), the specific absorption coefficient of phytoplankton (a ph *(λ)) is an essential optical parameter that refines the a ph (λ) normalized by phytoplankton pigment concentration. Based on the in-situ samples collected in the Bohai Sea, Yellow Sea, and the East China S...

The packaging effect (Qa*) of phytoplankton pigments can account for over half of the variability in the phytoplankton absorption coefficient (aph) in oceanic waters. Given the significance of aph in many marine biogeochemical and environmental processes, exploring the packaging effect on absorption properties is a crucial task. In the present stud...

Measurements of ocean surface currents in coastal waters are crucial for improving our understanding of tidal atlases, as well as for ecosystem and water pollution monitoring. This paper proposes an improved method for estimating the baseline-to-platform speed ratio (BPSR) for improving the current line-of-sight (LOS) velocity measurement accuracy...

We investigated the interaction between mesoscale eddies and the Kuroshio Current east of Taiwan, China, using a fine-resolution regional general circulation model. Mesoscale eddies are injected into a region east of Taiwan, China, according to the quasi-geostrophic theory of stratified fluids. Modeled eddies propagated westward at the velocity of...

With continuing sea ice reductions in the Arctic, dynamic physical and ecological processes have more active roles compared to the ice-locked, isolated Arctic Ocean of previous decades. To better understand these changes, observations of high-resolution sea ice conditions are needed. Remote sensing is a useful tool for observations in the harsh Arc...

The first rotating fan beam scatterometer onboard China-France Oceanography Satellite (CFOSAT) was successfully launched on October 29, 2018. CFOSAT SCATterometer (CSCAT) is dedicated to the monitoring of sea surface wind vectors but also provides valuable data for the applications over land and Polar Regions. This article provides an overview of t...

Synthetic aperture radar (SAR) has proven to be an important tool for the retrieval of ocean surface currents. However, existing spaceborne SAR systems can usually measure only one component of an ocean current vector. In this article, we propose a new concept of dual-look spaceborne SAR system for ocean surface motion remote sensing. The key of th...

Colored dissolved organic matter (CDOM) is the main constituent of dissolved organic matter (DOM), also a key indicator of water quality conditions. Accurate estimation of CDOM is essential for understanding biogeochemical processes and ecosystems in marine waters. The use of remote sensing to derive the changes in CDOM is vital technology that can...

The temporal and spatial variation in submesoscale eddies in the coastal region of Lianyungang (China) is studied over a period of nearly two years with high-resolution (0.03°, about 3 km) observations of surface currents derived from high-frequency coastal radars (HFRs). The centers and boundaries of submesoscale eddies are identified based on a v...

: Microstructure and corrosion behavior of the solution-treated Mg-1.8Zn-1.74Gd-0.5Y-0.4Zr (wt%) alloy were studied. The results of microstructure indicated that the second phases of as-cast alloy was mainly comprised of Mg12Zn(Gd,Y) phase, Mg3Zn3(Gd,Y)2 phase and (Mg,Zn)3(Gd,Y) phase. After solution treatment process, the second phase gradually di...

Twenty 9O-substituted palmatine derivatives were prepared and tested for their biological effect against collagen α1 (I) (COL1A1) promotor in human hepatic stellate LX-2 cells. The structure−activity relationship (SAR) indicated that the introduction of a benzyl motif on the 9O atom was favorable for activity. Among them, compound 6c provided the h...

Abrupt-chilling events threaten the survival of alfalfa plants, the ability to cope with such condition should be considered during cultivar selection in the production. To assess biochemical and molecular responses of alfalfa to abrupt chilling, the cultivars “WL440HQ” (WL) and “ZhaoDong” (ZD) were subjected to a five-phase experimental regime tha...

The Data Interpolating Empirical Orthogonal Functions (DINEOF) method has demonstrated usability and accuracy for filling spatial gaps in remote sensing datasets. In this study, we conducted the reconstruction of the chlorophyll-a concentration (Chl-a) data using a convolutional neural networks model called Data-Interpolating Convolutional Auto-Enc...

To reduce the smoke and nitrogen oxide (NOx) emissions; a detailed study concerned with exhaust gas recirculation (EGR) and diesel injection strategy was conducted on a two-stage series turbocharging diesel engine under transient operating condition. One transient process based on the constant speed of 1650 r/min and load increases linearly from 10...

Background: Head and neck squamous cell carcinoma (HNSCC) is one of the leading causes of cancer-related deaths and calls for new druggable targets. We have previously highlighted the critical role of ADP-ribosylation factor-1 (Arf1) activation in HNSCC. In the present study, we address the question whether targeting Arf1 could be proposed as a va...

Although many studies have recently investigated how the product quality impacts on economic and environment performance under remanufacturing, all of them assume that remanufacturing operations are undertaken by the original equipment manufacturers (OEMs) or independent remanufacturers (IRs). However, many OEMs such as Lexmark, Canon, and Epson fi...

In this work, the hypolipidemic activities of two pentapeptides (VIAPW and IRWWW) from miiuy croaker (Miichthys miiuy) muscle on oleic acid (OA)-induced lipid accumulation in HepG2 cells were investigated. VIAPW and IRWWW could significantly inhibit lipid accumulation induced by OA and decreased intracellular levels of intracellular triglyceride (T...

Surface finishing and polishing are important quality assurance processes in many manufacturing industries. A polished surface (low surface roughness) is linked with many useful properties other than providing an appealing gloss to the product, such as surface friction, electrical and chemical resistance, thermal conductivity, reflection, and produ...