Yanlei Du

Yanlei Du
Tsinghua University | TH · Department of Electronic Engineering

Doctor of Philosophy

About

40
Publications
2,236
Reads
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89
Citations
Introduction
Yanlei Du currently works at the Department of Electronic Engineering, Tsinghua University. Yanlei does research in Remote Sensing and Oceanography. Their most recent publication is 'An Improved Spectrum Model for Sea Surface Radar Backscattering at L-Band'.
Additional affiliations
July 2019 - July 2021
Tsinghua University
Position
  • PostDoc Position
Description
  • Computational electromagnetics in applications of ocean remote sensing and satellite oceanography.
October 2017 - May 2019
University of Michigan
Position
  • Visiting Scholar
Description
  • Computational Electromagnetic; Radar and radiometric remote sensing of Ocean.
Education
September 2014 - June 2019
Chinese Academy of Sciences
Field of study
  • Ocean Remote Sensing
September 2010 - July 2014
Chang'an University
Field of study
  • Remote Sensing

Publications

Publications (40)
Article
Radio spectrum bands allocated to spaceborne synthetic aperture radar (SAR) imagery are shared by multiple missions. In practical radio spectrum environment, these bands are also used by some ground radars, e.g., C-band weather radar. Due to this fact, radio frequency interference (RFI) may occur for a spaceborne SAR when its received signals conta...
Article
Synthetic aperture radar (SAR) plays an essential role in earth observation and projection due to its capability to penetrate clouds, which makes it possible to monitor terrestrial surfaces under all weather conditions. Multiplicative noise often occurs in the SAR signal, hampering the retrieval of information from SAR imagery. Convolutional neural...
Article
The wind direction dependence of the fully polarimetric ocean emissivity at L-band is studied using a semi-theoretical approach. The model, which is tuned and validated against Aquarius and Soil Moisture Active-Passive (SMAP) mission observations, incorporates the two-scale polarimetric ocean emission model, an improved directional wave spectrum, t...
Conference Paper
Full-text available
Launched on June 5 th , 2019, Bufeng-1 twin satellites that carry the Chinese first generation spaceborne GNSS-R instruments started using reflected GNSS signals to perform earth observation. By utilizing the Bufeng-1 Normalized Bistatic Radar Cross Section (NBRCS), the preliminary results show that BuFeng-1 has a high agreement compared with ECMWF...
Conference Paper
The effects of ocean spectrum truncation on the sea clutter distribution properties in numerical simulations are studied using a recently developed full-wave method, i.e., the multi-level steepest decent – sparse matrix canonical grid (MLSD-SMCG) method and the KHCC03 spectrum. Two types of ocean surface profiles are generated for Monte Carlo simul...
Conference Paper
The wind direction asymmetries of the fully polarimetric ocean emissivity at L-band are studied using a semi-theoretical approach. The model is tuned and validated against Aquarius and SMAP observations, which incorporates the two-scale polarimetric ocean emission model, an improved directional wave spectrum, the AG13 foam emissivity model and a no...
Conference Paper
In a recent work, a neighborhood polarimetric covariance matrix [N] was proposed to detect ships from polarimetric SAR(PolSAR) imagery. However, its computational complexity is extremely high. Besides, the heterogeneity surrounding ship edges is also not well considered in [N]. To cure these drawbacks, we construct a novel superpixels-based neighbo...
Article
Radio signals emitted by various sources, such as ground radars and broadcast/communication devices, can unintentionally cause radio frequency interference (RFI) to spaceborne synthetic aperture radar (SAR), degrading SAR image qualities to various degrees. Most existing methods tackle this problem by applying specially designed preprocessing steps...
Article
In order to detect ships from the imagery of polarimetric synthetic aperture radar (PolSAR), a neighborhood polarimetric covariance matrix (for simplicity, we call it [N] hereinafter) was recently constructed. However, its calculation process is time-consuming and the backscattering heterogeneity near ship edges is also not well considered. For cu...
Article
Full-text available
In order to verify the technology of the membrane diffractive imaging system for Chinese next generation geo-stationary earth orbit (GEO) satellite, a series of ground experiments have been carried out using a membrane optical camera with 80 mm aperture (Φ80) lens. The inherent chromatic aberration due to diffractive imaging appears in the obtained...
Article
Full-text available
The comprehensive utilization of images from various satellite sensors can significantly increase the performance of remote sensing applications and has therefore attracted extensive research attention. One of the essential challenges that researches encounter comes from multisource image registration. This paper proposes a novel region-based image...
Article
Roughness-induced emission from ocean surfaces is one of the main issues that affects the retrieval accuracy of sea surface salinity remote sensing. In previous studies, the correction of roughness effect mainly depended on wind speeds retrieved from scatterometers or those provided by other means, which necessitates a high requirement for accuracy...
Article
Full-text available
Superpixel segmentation approaches for polarimetric synthetic aperture radar (SAR) images have only been studied in recent years. Simple linear iterative clustering (SLIC) is a simple and efficient superpixel segmentation method, first proposed for optical images. It basically includes three implementation steps, i.e., initialization, local k-means...
Article
Full-text available
Synthetic Aperture Radar (SAR) has been proven to be a useful tool in monitoring hurricane structure and intensity. By far, SAR is the most promising spaceborne sensor to obtain high resolution hurricane wind field on the ocean surface. In this paper, an improved asymmetric hurricane parametric (IMAHP) model has been proposed to reconstruct the asy...
Conference Paper
The effects of roughness scale on bistatic radar scattering from an ocean surface at L-band are studied using the second order small slope approximation (SSA-II) and the method of moments (MoM). Ocean roughness is represented and varied using different ranges of the KHCC03 spectrum. The criteria of full spectrum truncation are also given. Numerical...
Conference Paper
Full-text available
To achieve the demand of earth observation with high spatiotemporal resolution and large scale, a novel optical imaging system is planning to equip on Chinese next generation geo-stationary earth orbit (GEO) satellite. The primary mirror of camera is made of a set of thin films and adopts the diffraction imaging mechanism. A series of ground experi...
Conference Paper
Accurate calculations of electromagnetic scattering and emission from ocean surfaces with large sizes and root-mean-square (RMS) heights are still a challenge for the full-wave numerical methods. The widely used sparse matrix canonical grid (SMCG) method is only efficient for small and moderate roughness surfaces. This is because of the limitation...
Conference Paper
The effects of sea surface temperature (SST) on ocean radar backscattering and wind retrieval are investigated using the second-order small slope approximation (SSA-II) model. Impact factors are parameterized and built into an SST-enhanced KHCC03 spectrum. By employing the Monin-Obukhov similarity theory (MOST), the air-sea interaction is considere...
Conference Paper
We employ the second-order small slope approximation (SSA-II) and the method of moment (MoM) to investigate the roughness scale effect on ocean radar scattering in both three- (3-D) and two-dimensional (2-D) cases. Various roughness scales of the ocean surface are represented by truncating the Kudryavtsev wave spectrum. Criteria of full spectrum tr...
Article
Full-text available
Ship detection using polarimetric synthetic radar (PolSAR) imagery attracts a lot of attention in recent years. Most notably, the detector polarimetric notch filter (PNF) has been demonstrated to be effective for ship detection in PolSAR imagery, which gives excellent performances. In this work, a mathematical form of one new PNF (NPNF) based on ph...
Article
The effects of sea surface temperature (SST) on ocean radar backscattering are investigated under both neutral and non-neutral atmospheric conditions for the applications of wind retrieval. Impact factors are parameterized as functions of the SST. The SST effects on the variations of ocean scattering and the wind retrieval are evaluated using an an...
Article
The roughness scale effects on ocean radar scattering are studied using the second order small slope approximation (SSA-II) and the method of moments (MoM). The KHCC03 spectrum is employed to represent 2D and 1D sea surfaces in above two scattering methods, respectively. Criteria of full spectrum truncation are proposed for the numerical simulation...
Conference Paper
Sea surface salinity (SSS) is an important ocean dynamic parameter, which plays a crucial role in the studies of global climate change, global water cycle forecast, marine environment monitoring, etc.[1-3]. Especially in polar region, SSS becomes a sensitive indicator of climate change. However, the accuracies of retrieved SSS using the popular L-b...
Article
We use full wave simulations of rough surfaces to calculate the emissivities of polar ocean between 0.5 GHz to 2 GHz for applications in ocean salinity. High accuracy is required because the emissivity variations between flat and rough surfaces are at the order of magnitude of 10-3. In addition, the changes of emissivity due to salinity change are...
Article
为了解各向异性随机粗糙海面的微波双站散射机制及其特性,本文利用解析近似的积分方程模型以及一种改进的半经验海浪谱模型实现了对各向异性随机粗糙海面的全极化微波散射仿真模拟,并与卫星观测数据、经验的地球物理模式函数及已有的解析近似散射模型仿真结果进行了对比,验证了仿真结果的可行性和准确性。利用该模型分析了入射波频率、入射角、极化方式、海面风速及风向等参数对各向异性海面双站散射的影响。模拟结果表明,在不同的入射角、散射角及方位角等观测几何条件下,海面不同波段的双站散射表现出不同的空间散射特性,且对风速、风向等海面动力学参数表现出不同的敏感性,以L波段为例,海面向后半球双站散射在各个极化方式下都对风速较为敏感,而在同极化方式下,其对风向的响应在中低风速和高风速条件下相反,整体而言,低风速下海面双站散射...
Conference Paper
The studies of electromagnetic scattering and emission by ocean surfaces are crucial for remote sensing of ocean dynamic parameters, e.g., sea surface wind (SSW) and sea surface salinity (SSS). Analytic approximation models have been proposed to simulate the ocean scattering and emission [1-5]. Numerical methods using surface integral equations imp...
Article
The offshore wind energy industry has surged in recent years as a main source of clear energy. Meanwhile, remote sensing can retrieve sea surface wind data and provide valuable information to locate suitable offshore wind power plants. Published studies mostly focus on the retrieval of average wind speed and average wind power density. However, win...
Article
Full-text available
In order to have the required accuracies in method of moments (MoM) for numerical simulations of ocean scattering at microwave frequencies, we need to account for the much larger wavenumber of sea water relative to that of air. This paper presents simulation results of 2D ocean surface scattering with the required accuracies and that energy conserv...
Article
Full-text available
L-band active microwave remote sensing is one of the most important technical methods of ocean environmental monitoring and dynamic parameter retrieval. Recently, a unique negative upwind-crosswind (NUC) asymmetry of L-band ocean backscatter over a low wind speed range was observed. To study the directional features of L-band ocean surface backscat...
Article
Full-text available
Atmospheric correction is very important to the accurate retrieval of geophysical parameters from spaceborne L-band radiometers. In this paper, the L-band upwelling and downwelling radiation brightness temperature and transmittance above sea surface are calculated using the atmospheric radiation transfer model based on NCEP temperature and humidity...

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