A New Retracking Technique for Brown Peaky Altimetric Waveforms     

Fukai Peng 《Marine Geodesy》2018,41(2):99-125

A new Brown-Peaky (BP) retracker has been developed for peaky waveforms that usually appear within ～10 km to the coastline. The main feature of the BP is that it fits peaky waveforms using the Brown model without introducing a peak function. The retracking strategy first detects the peak location and width of a waveform using an adaptive peak detection method, and then estimates retracking parameters using a weighted least squares (WLS) estimator. The WLS assigns a downsized weight to corrupted waveform gates, but an equal weight to other normal waveform gates. The BP retracker has been applied to 4-year Jason-1 waveform (2002–2006) in two Australian coastal zones. The results retracked by BP, MLE4 and ALES retrackers have been validated against tide-gauge observations located at Burnie, Lorne and Broome. The comparison results show that three retrackers have similar performance over open oceans with the correlation coefficient (～0.7) and RMSE (～13 cm) between altimetric and tide-gauge sea levels for distance >7 km offshore. The main improvement of BP retracker occurs for distance ≤7 km to the coastline, where validation results indicate that data retracked by BP are more accurate (15–21 cm) than those by ALES (16–24 cm) and MLE4 (19–37 cm).  相似文献   

Boussinesq相位解析的海岸水动力学数学模型研究进展     

张尧  谢欣  陶爱峰  王岗  陈新平  郑金海 《海洋通报》2018,(5):481-493

由于在平衡计算效率和精度上具有优势,Boussinesq相位解析数学模型研究不断取得突破,已成为波浪和水流精细化模拟的较优解析方式,为海岸工程、环境、地质等问题提供了实用和高效的研究手段。本文对已有Boussinesq类模型的研究进行了评述,深入探讨其重要发展、实际应用和理论瓶颈,从高阶非静压修正、GPU准三维高性能算法编译、波浪破碎和泥沙运移沉积等4个方面提出未来可能的科学突破方向。  相似文献   

In situ measurements of wind‐driven salt fluxes through constructed channels in a coastal wetland ecosystem          下载免费PDF全文

Alex K. Manda  Enrique Reyes  James M. Pitt 《水文研究》2018,32(5):636-643

A suite of instruments was deployed in a coastal wetland ecosystem in the Albemarle estuarine system, North Carolina (USA), to characterize wind‐driven transport of saltwater through a constructed (man‐made) channel. Flow velocity, electrical conductivity, and stage were measured in a representative channel over a 2‐month period from May to July 2014, during which 4 wind tides were observed. Collected data show that thousands of metric tons of salt were advected through the channel into coastal wetlands during each event, which lasted up to 4 days. The results reveal that as much as 36% of advected salts accumulated in the wetlands, suggesting that the cumulative effects of these events on the health of coastal wetlands in the Albemarle system may be substantial due to the abundance of constructed channels and the frequency of wind‐driven tidal events. This study is the first to quantify wind‐driven salt fluxes through constructed channels in coastal wetland settings.  相似文献   

湿地土壤和沉积物异化铁还原过程研究进展     

朱晓艳  袁宇翔  宋长春  姜明 《湿地科学》2020,18(1):122-128

异化铁还原是湿地土壤和沉积物中重要的生物地球化学过程,也是有机质矿化的主要途径之一。湿地干湿交替等过程会使土壤的氧化还原状态发生改变,影响铁元素及与其相关的元素的迁移和转化。总结了湿地土壤和沉积物中异化铁还原过程及其与碳、磷、硫等元素在生物地球化学循环关键过程中的相互作用,阐述了湿地土壤和沉积物中异化铁还原过程对微量金属元素迁移和转化的影响,分析了影响湿地土壤和沉积物异化铁还原过程的主要环境因子。未来相关研究应集中于湿地土壤和沉积物中异化铁还原微生物分析和纯化、不同有机质形式对异化铁还原过程的影响以及异化铁还原对土壤有机质矿化的贡献。  相似文献   

天津沿海赤潮发生的基本特征研究     

张琪  孙家伟  冯延竹  李希彬  王鲁宁  崔健 《海洋预报》2020,37(1):62-66

使用《天津市海洋环境状况公报》中的数据,分析天津沿海赤潮发生的特征。通过分析发现2005-2017年天津海域共发生赤潮30次,累计发生面积4 695 km2。天津沿海赤潮发生主要集中在夏季,又以8月最多,占赤潮发生总数的30%。通过赤潮优势种的分析发现近年来天津海域赤潮生物的优势种类有不断增加的趋势。同时本文从水文气象条件诱发赤潮的角度分析得出了天津沿海最易发生赤潮的天气形势,天津沿海25~27℃水温范围内赤潮发生较多,最适宜赤潮发生的风速为3、4级风,风向为东南风、西南风。  相似文献   

Remote sensing for wetland classification: a comprehensive review     

Sahel Mahdavi  Bahram Salehi  Jean Granger  Meisam Amani  Brian Brisco  Weimin Huang 《地理信息系统科学与遥感》2018,55(5):623-658

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The Synergism between Methanogens and Methanotrophs and the Nature of their Contributions to the Seasonal Variation of Methane Fluxes in a Wetland: The Case of Dajiuhu Subalpine Peatland     

Luwen WANG  Jiwen GE  Liang FENG  Yaoyao LIU  Yu LI  Jiumei WANG  Xiang XIAO  Zhiqi ZHANG 《大气科学进展》2022,39(8):1375-1385

Wetland ecosystems are the most important natural methane (CH₄) sources, whose fluxes periodically fluctuate. Methanogens (methane producers) and methanotrophs (methane consumers) are considered key factors affecting CH₄ fluxes in wetlands. However, the symbiotic relationship between methanogens and methanotrophs remains unclear. To help close this research gap, we collected and analyzed samples from four soil depths in the Dajiuhu subalpine peatland in January, April, July, and October 2019 and acquired seasonal methane flux data from an eddy covariance (EC) system, and investigated relationships. A phylogenetic molecular ecological networks (pMENs) analysis was used to identify keystone species and the seasonal variations of the co-occurrence patterns of methanogenic and methanotrophic communities. The results indicate that the seasonal variations of the interactions between methanogenic and methanotrophic communities contributed to CH₄ emissions in wetlands. The keystone species discerned by the network analysis also showed their importance in mediating CH₄ fluxes. Methane (CH₄) emissions in wetlands were lowest in spring; during this period, the most complex interactions between microbes were observed, with intense competition among methanogens while methanotrophs demonstrated better cooperation. Reverse patterns manifested themselves in summer when the highest CH₄ flux was observed. Methanoregula formicica was negatively correlated with CH₄ fluxes and occupied the largest ecological niches in the spring network. In contrast, both Methanocella arvoryzae and Methylocystaceae demonstrated positive correlations with CH₄ fluxes and were better adapted to the microbial community in the summer. In addition, soil temperature and nitrogen were regarded as significant environmental factors to CH₄ fluxes. This study was successful in explaining the seasonal patterns and microbial driving mechanisms of CH₄ emissions in wetlands.  相似文献   

华南西部滨海湿地调查及主要成果   总被引：1，自引：1，他引：0  

何海军  甘华阳  夏真  万荣胜  陈太浩 《中国地质调查》2018,5(6):75-82

通过遥感、单波束测量、地质取样、海水取样、钻探、地下水采集与监测等多种调查手段及工作方法,首次在我国华南西部开展1∶10万滨海湿地地质调查与生态环境评价工作,对滨海湿地类型及分布、滨海海域地形地貌、沉积物环境质量、海水环境质量、生态地质演化、地下水化学要素进行综合分析与研究。项目系统查明了该区滨海湿地类型、分布、生态环境现状及其主要影响因素,对湿地生态地质环境质量进行了综合评价,构建了华南西部滨海湿地地质调查技术方法体系和生态地质环境综合评价体系,提出了滨海湿地保护和恢复的建议,为后续我国南方滨海湿地调查提供了示范。  相似文献   

Evaluation of the Bioavailability of Metals in Sediment from the Southern Coastal Wetland of the Qiantang Estuary by Using Diffusive Gradients in Thin Films Technique     

FENG Weihua  WANG Zhifu  ZHU Wenzhuo  ZHENG Fangqin  ZHANG Dongrong  XU Hengtao 《中国海洋大学学报(英文版)》2022,21(2):375-387

Metal pollution has become an major issue governing the wetland ecosystem health.The southern coastal wetland of the Qiangtang Estuary are facing unusual perturbation due to rapid development along the embayment in recent decades.This study evaluated the bioavailability of metals(Cu,Pb,Cd,Cr and Zn)in the sediment of the southern coastal wetland of the Qiangtang Es-tuary using diffusive gradients in thin films(DGT)techniques and compared with several methods based on total metal content.The results showed that the contents of Cr,Pb,Cd and Cu in sediment,as detected using DGT,were considerably correlated with the exchangeable fraction and the content in Phragmites australis roots,while a weak correlation was observed for Zn.Therefore,DGT analysis could be used to evaluate the bioavailability and potential risk of Cr,Cd,Pb and Cu for P.australis.Quantitative indices,such as DGT concentration,bioaccumulation in P.australis,geoaccumulation index(Igeo)and potential ecological risk index(RI),revealed that Cd was a major potential ecological risk factor along the southern coast wetland of the Qiantang Estuary,especially in the upstream region,which is potentially more vulnerable to the anthropogenic pollution.  相似文献   

中国海岸带专用地图投影设计   总被引：3，自引：0，他引：3  

韩雪培  李满春  傅小毛 《测绘学报》2006,35(4):395-399

地图投影是各类海岸带信息的空间定位框架要素之一。通过对目前我国海岸带常用的各种地图投影现状分析,设计并实现全国海岸带专用投影———斜轴等角圆锥投影,该投影不仅使得整个中国海岸带实现无缝的一体化表达,而且使变形达到最小。文中详细阐述该投影的设计思想和设计原理,并将结果与其他各种海岸带投影进行详细的分析比较。  相似文献