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A comparison of multiplatform wind products in the South China Sea during summer and autumn in 2019

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Journal of Oceanology and Limnology 2021年第6期39卷 2181-2194页

作者： Yuxin LIU mingsen lin Xingwei JIANG Xiujun SUN Xiangzhou SONG Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China National Satellite Ocean Application Service Beijing 100081China Key Laboratory of Space Ocean Remote Sensing and Application Ministry of Natural ResourcesBeijing 100081China Physical Oceanography Laboratory Ocean University of ChinaQingdao 266100China College of Oceanography Hohai UniversityNanjing 210098China

Sea surface wind(SSW)observations from a newly developed“Black Pearl”wave glider,the Chinese-French Oceanography Satellite(CFOSAT),the HY-2A microwave scatterometer,and a recently released high-resolution atmospheric reanalysis(ERA5)are evaluated with respect to in-situ buoy observations(115.46°E,19.85°N)from the South China *** observations from June to November 2019 are used to evaluate the wind estimates from the different *** comparisons show that the HY-2A and CFOSAT scatterometer wind speeds have mean root mean square errors(RMSEs)of approximately 1.6 and 1.6 m/s,respectively,and the corresponding mean wind direction RMSEs are approximately 19°and 17°,which indicates that these satellite retrievals meet the requirements of design engineering *** wind speed and wind direction RMSEs of ERA5 are approximately 1.9 m/s and 33°,*** correlation coefficients between the HY-2A,CFOSAT,and ERA5 wind speeds and the buoy observations are 0.86,0.85,and 0.84,respectively,and the corresponding coefficients of the wind direction are 0.98,0.98,and 0.93,respectively,at a 95%confidence ***,the wind sensor in the wave glider provides relatively poor-quality observations compared with the buoy measurements and has higher wind speed and wind direction RMSEs of 2.9 m/s and 50.1°,*** diagrams are utilized to illustrate comprehensive wind comparisons between the multiplatform observations and buoy *** results help identify the basic biases in SSWs among different products and enhance confidence in the future use of SSW data for studies of upper ocean dynamics and climate *** are also off ered to help improve the design of next-generation wave gliders.

关键词： sea surface wind(SSW) calibration South China Sea(SCS) wave glider fi fth European Centre for Medium-Range Weather Forecasts reanalysis(ERA5) HY-2A Chinese-French Oceanography Satellite(CFOSAT)

Results About Ocean Satellite Observation

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空间科学学报 2010年第5期30卷 474-485页

作者： Jiang Xingwei lin mingsen National Satellite Ocean Application Service Beijing 100081

Ocean observing satellites have become an important part of the China's three-dimensional marine observation *** have played more and more important roles in marine pollution monitoring,marine environment and marine disaster monitor and forecasting,marine resource investigation and marine scientific *** this paper,the author will give a brief review of China's operational and scientific activities in satellites ocean observation during 2008 to *** activities include the application of the HY-1B for red tide and green tide detecting and monitoring,sea ice monitoring,fishery resources assessment at coastal zone and ocean,marine water quality assessment,sea surface temperature monitoring and forecasting,ocean primary productivity and carbon cycle research,and the development in the ocean dynamic environment parameter application technology before launch of *** achievements we have made in the ocean observation and monitoring during the past 3 years indicate that,the development of the ocean satellite series and the application of the ocean satellite can greatly promote the development of China's three-dimensional marine observation system and earth-observation system from space,accordingly we can improve the ability of acquiring the marine environmental parameter to sustain the marine economy development and the sea defense construction.

关键词：海洋观测系统卫星观测海洋环境参数海洋观测卫星海洋初级生产力灾害监测海洋资源调查卫星应用

A study of sea level variability and its long-term trend in the South China Sea

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Acta Oceanologica Sinica 2016年第9期35卷 22-33页

作者： XU Ying lin mingsen ZHENG Quan'an SONG Qingtao YE Xiaomin College of Information Science and Engineering Ocean University of China National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of Space Ocean Remote Sensing and Application State Oceanic Administration Department of Atmospheric and Oceanic Science University of MarylandCollege Park

On the basis of the satellite maps of sea level anomaly（MSLA） data and in situ tidal gauge sea level data,correlation analysis and empirical mode decomposition（EMD） are employed to investigate the applicability of MSLA data,sea level correlation,long-term sea level variability（SLV） trend,sea level rise（SLR） rate and its geographic distribution in the South China Sea（SCS）.The findings show that for Dongfang Station,Haikou Station,Shanwei Station and Zhapo Station,the minimum correlation coefficient between the closest MSLA grid point and tidal station is *** suggests that the satellite altimeter MSLA data are effective to observe the coastal SLV in the *** the monthly scale,coastal SLV in the western and northern part of SCS are highly associated with coastal *** the seasonal scale,SLV of the coastal area in the western part of the SCS is still strongly influenced by the coastal current system in summer and *** Pacific change can affect the SCS mainly in winter rather than summer and the affected area mostly concentrated in the northeastern and eastern parts of the ***,the average SLR in the SCS is 90.8 mm with a rising rate of（5.0±0.4） mm/a during1993–*** SLR rate from the southern Luzon Strait through the Huangyan Seamount area to the Xisha Islands area is higher than that of other areas of the SCS.

关键词： South China Sea sea level variability correlation analysis empirical mode decomposition

A routine operational backscattering coefficient regrouping algorithm for a HY-2A scatterometer

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Acta Oceanologica Sinica 2018年第3期37卷 111-116页

作者： ZOU Juhong lin mingsen ZOU Bin GUO Maohua ZHANG Yi Key Laboratory of Space Ocean Remote Sensing and Application State Oceanic Administration National Satellite Ocean Application Sevice State Oceanic Administration

The routine operational sigma0 regrouping method is proposed for a HY-2 A scatterometer（HSCAT） that maps time-ordered sigma0 s and related parameters into a subtrack aligned grid of wind vector cells（WVCs）. The regrouping method consists of two critical steps： ground grid generation and sigma0 resampling. The HSCAT uses subtrack swath coordinates, in which the nadir track of the satellite represents the center and the designated positions are specified in terms of a pair of along-track and cross-track coordinates. To calculate the subtrack coordinates for each sigma0, a ＂triangle marking＂ resampling method is developed. Three points, including the point of intersection, the center of a pulse footprint, and the origin of the subtrack coordinate system, form a right triangle; the length of the two right-angled sides is used to represent the cross-track and the along-track coordinates in the subtrack coordinate system. In addition, a nadir point interpolation correction is used to ensure the operation of the regrouping algorithm when the nadir point positional information is missing. To illustrate the ability of the proposed regrouping algorithm, the distribution of the WVC positions and wind vector retrieval results are analyzed, which show that the proposed regrouping algorithm meets the requirements for high-quality sea surface wind field retrieval.

关键词： regrouping HY-2A scatterometer backscattering coefficient

Coastal wind field retrieval from polarimetric synthetic aperture radar

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Acta Oceanologica Sinica 2014年第5期33卷 54-61页

作者： ZHANG Yi JIANG Xingwei SONG Qingtao lin mingsen XIE Xuetong National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of Space Ocean Remote Sensing and Applications State Oceanic Administration

Coastal winds are strongly influenced by topology and discontinuity between land and sea surfaces. Wind assessment from remote sensing in such a complex area remains a challenge. Space-borne scatterometer does not provide any information about the coastal wind field, as the coarse spatial resolution hampers the radar backscattering. Synthetic aperture radar （SAR） with a high spatial resolution and all-weather observation abilities has become one of the most important tools for ocean wind retrieval, especially in the coastal area. Conventional methods of wind field retrieval from SAR, however, require wind direction as initial information, such as the wind direction from numerical weather prediction models （NWP）, which may not match the time of SAR image acquiring. Fortunately, the polarimetric observations of SAR enable independent wind retrieval from SAR images alone. In order to accurately measure coastal wind fields, this paper proposes a new method of using co-polarization backscattering coefficients from polarimetric SAR observations up to polarimetric correlation backscattering coefficients, which are acquired from the conjugate product of co-polarization backscatter and cross-polarization backscatter. Co-polarization backscattering coefficients and polarimetric correlation backscattering coefficients are obtained form Radarsat-2 single-look complex （SLC） *** maximum likelihood estimation is used to gain the initial results followed by the coarse spatial filtering and fine spatial filtering. Wind direction accuracy of the final inversion results is 10.67 with a wind speed accuracy of 0.32 m/s. Unlike previous methods, the methods described in this article utilize the SAR data itself to obtain the wind vectors and do not need external wind directional information. High spatial resolution and high accuracy are the most important features of the method described herein since the use of full polarimetric observations contains more information about the space

关键词： polarimetric synthetic aperture radar coastalwind field polarimetric correlation backscattering coefficients

Nonparametric estimations of the sea state bias for a radar altimeter

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Acta Oceanologica Sinica 2017年第9期36卷 108-113页

作者： MIAO Hongli JING Yujie JIA Yongjun lin mingsen ZHANG Guoshou WANG Guizhong College of Information Science and Engineering Ocean University of China National Satellite Ocean Application Service State Oceanic Administration

To estimate the sea state bias（SSB） for radar altimeter, two nonparametric models, including a Nadaraya-Watson（NW） kernel estimator and a local linear regression（LLR） estimator, are studied based on the Jason-2 altimeter data. Selecting from different combinations of the Gaussian kernel function, spherical Epanechnikov kernel function, a fixed bandwidth and a local adjustable bandwidth, it is observed that the LLR method with the spherical Epanechnikov kernel function and the local adjustable bandwidth is the optimal nonparametric model for the SSB estimation. The comparisons between the nonparametric and parametric models are conducted and the results show that the nonparametric model performs relatively better at high-latitudes of the Northern Hemisphere. This method has been applied to the HY-2A altimeter as well and the same conclusion can be obtained.

关键词： radar altimeter sea state bias significant wave height wind speed nonparametric model parametric model

A study of long-term sea level variability in the East China Sea

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Acta Oceanologica Sinica 2015年第11期34卷 109-117页

作者： XU Ying lin mingsen ZHENG Quanan YE Xiaomin LI Junyi ZHU Benlu College of Information Science and Engineering Ocean University of China National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of Space Ocean Remote Sensing and Application State Oceanic Administration Department of Atmospheric and Oceanic Science University of Maryland College Park State Key Laboratory of Marine Environmental Science College of Ocean & Earth Sciences Xiamen University Fujian Marine Forecasts

From the analyses of the satellite altimeter Maps of Sea Level Anomaly （MSLA） data, tidal gauge sea level data and historical sea level data, this paper investigates the long-term sea level variability in the East China Sea （ECS）. Based on the correlation analysis, we calculate the correlation coefficient between tidal gauge and the closest MSLA grid point, then generate the map of correlation coefficient of the entire ECS. The results show that the satellite altimeter MSLA data is effective to observe coastal sea level variability. An important finding is that from map of correlation coefficient we can identify the Kuroshio. The existence of Kuroshio decreases the correlation between coastal and the Pacific sea level. Kurishio likes a barrier or a wall, which blocks the effect of the Pacific and the global change. Moreover, coastal sea level in the ECS is mainly associated with local systems rather than global change. In order to calculate the long-term sea level variability trend, the empirical mode decomposition （EMD） method is applied to derive the trend on each MSLA grid point in the entire ECS. According to the 2-D distribution of the trend and rising rate, the sea level on the right side of the axis of Kuroshio rise faster than in its left side. This result supports the barrier effect of Kuroshio in the ECS. For the entire ECS, the average sea level rose 45.0 mm between 1993 and 2010, with a rising rate of （2.5_＋0.4） mm/a which is slower than global average. The relatively slower sea level rising rate further proves that sea level rise in the ECS has less response to global change due to its own local system effect.

关键词： East China Sea sea level variability correlation analysis empirical mode decomposition

An improved method of absolute calibration to satellite altimeter: A case study in the Yellow Sea, China

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Acta Oceanologica Sinica 2014年第5期33卷 103-112页

作者： LIU Yalong TANG Junwu ZHU Jianhua lin mingsen ZHAI Wanlin CHEN Chuntao Ocean University of China National Ocean Technological Center State Oceanic Administration National Satellite Ocean Application Service State Oceanic Administration

An improved absolute calibration technology based on indirect measurements was developed through two probative experiments, the performance of which was evaluated by applying the approach to in situ sea surface height （SSH） at the Tianheng Island （tidal gauge） and the satellite nadir （GPS buoy）. Using Geoid/MSS （mean sea surface） data, which accounted for a constant offset between nadir and onshore tidal gauge water levels, and TMD （tidal model driver）, which canceled out the time-varying offsets, nadir SSH （sea surface height） could be indirectly acquired at an onshore tidal gauge instead of from direct offshore observation. The approach extrapolated the onshore SSH out to the offshore nadir with an accuracy of （1.88±0.20） cm and a standard deviation of 3,3 cm, which suggested that the approach presented was feasible in absolute altimeter calibration/validation （Cal/Val）, and the approach enormously facilitated the obtaining SSH from the offshore nadir.

关键词： radar altimeter absolute calibration Yellow Sea

A unified C-band and Ku-band geophysical model function determined by neural network approach

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Acta Oceanologica Sinica 2008年第6期27卷 33-39页

作者： ZOU Juhong lin mingsen PAN Delu CHEN Zhenghua YANG Le State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administra-tion Hangzhou 310012 China Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China National Satellite Ocean Application Center National Marine Environmental Forecasting Center State Oceanic Administra-tion Beijing 100081 China

The geophysical model function （GMF） describes the relationship between backscattering and sea surface wind, so that wind vec- tors can be retrieved from backscattering measurement. The GMF plays an important role in ocean wind vector retrievals, its performance will directly influence the accuracy of the retrieved wind vector. Neural network （NN） approach is used to develop a unified GMF for C-band and Ku-band （NN-GMF）. Empirical GMF CMOIM and QSCAT-1 are used to generate the simulated training data-set, and Gaussian noise at a signal noise ratio of 30 dB is added to the data-set to simulate the noise in the backscat- tering measurement. The NN-GMF employs radio frequency as an additional parameter, so it can be applied for both C-band and Ku-band. Analyses show that the %predicted by the NN-GMF is comparable with the σpredicted by CMOIM and QSCAT-1. Also the wind vectors retrieved from the NN-GMF and empirical GMF CMOIM and QSCAT-1 are comparable, indicating that the NN-GMF is as effective as the empirical GMF, and has the advantages of the universal form.

关键词： GMF neural network CMOD4 QSCAT-1