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   

珠江口淇澳岛滨海湿地沉积环境演化及其对人类活动的响应   总被引：1，自引：1，他引：0  

叶翔  李靖  王爱军 《海洋学报》2018,40(7):79-89

滨海湿地作为人类活动和全球变化反应最为敏感的区域，其沉积记录可以反映出周边地区环境变化及人类活动信息。珠江口淇澳岛滨海湿地钻孔分析结果表明，在中全新世期间淇澳岛附近海域为河口湾环境，在风化层以上开始出现淤积，但在4 200 a BP前后受极冷气候的影响，沉积物粗化；自2 500 a BP以来，沉积环境相对稳定，在小冰期期间略有变化。沉积速率计算结果显示:淇澳岛附近海域自中全新世高海面以来的平均沉积速率为0.29 cm/a，4 160~2 500 a BP、2 500 a BP-1488年、1488-1893年、1893-1986年、1990-2007年期间的平均沉积速率分别为:0.17 cm/a、0.23 cm/a、0.35 cm/a、1.37 cm/a和5.94 cm/a，沉积速率逐渐增大，反映了珠江三角洲演化过程中沉积相与沉积环境的变化；1986-1990年期间的海堤建造极大地扰动了该钻孔上部的沉积过程，在工程施工期间共沉积了厚度约112 cm的沉积层，而在海堤建成后，沉积速率也显著增大。沉积物总有机碳、总氮和C/N值的垂向分布表明，在4 160~2 500 a BP期间受海洋环境影响较大，沉积物中有机碳以海源为主，2 500 a BP以来沉积物中碳、氮含量明显增大，C/N也相应变大，有机碳主要来源于陆源输入，但在小冰期期间海源有机碳贡献略有所增大；近百年来由于受人类活动影响显著，陆源有机碳的贡献快速增加。  相似文献   

浙南近海虾类群落结构及其多样性分析   总被引：1，自引：0，他引：1  

陈伟峰  彭欣  叶深  谢起浪  陈少波  汪振华  陈骁 《海洋科学》2018,42(3):37-45

作者根据2015年11月(秋季)、2016年2月(冬季)、2016年5月(春季)和2016年8月(夏季)对浙南近海进行的渔业资源调查数据,用生物量作为虾类资源分布的数量指标,对该海域虾类的组成、数量分布以及季节变化进行分析。结果显示:该区域共鉴定出虾类30种,隶属于10科21属,以对虾科(Penaeidae)虾类最多,其次为管鞭虾科(Solenoceridae),长臂虾科(Palaemonida)位居第3位。按季节来看,秋季共鉴定虾类27种,各站位平均生物量为6.97 kg/km2,优势种为凹陷管鞭虾(Solenocera koelbeli)、中国毛虾(Acetes chinensis)和中华管鞭虾(Solenocera crassicornis)等3种;冬季鉴定出虾类25种,平均生物量为1.65 kg/km2,优势种为凹陷管鞭虾、扁足异对虾(Atypopenaeus stenodactylus)、日本鼓虾(Alpheus japonicus)、鲜明鼓虾(Alpheus digitalis)、中国毛虾、中华管鞭虾和周氏新对虾(Metapenaeus joyneri)等7种;春季20种,平均生物量为2.22 kg/km2,优势种为戴氏赤虾(Metapenaeopsis dalei)、东海红虾(Metapenaeopsis dalei)和中华管鞭虾等3种;夏季16种,平均生物量为10.36 kg/km2,优势种有鹰爪虾(Trachysalambria curvirostris)和中华管鞭虾等2种。Margalef丰富度指数(D)、Shannon-Wiener多样性指数(H′)和Pielou均匀度指数(J′)秋季均低于冬季。秋冬季受到浙闽沿岸流影响,温度、盐度相对较低,夏季受到台湾暖流外侧影响,温度、盐度相对较高,且各季节间由于瓯江、椒江、飞云江、鳌江等陆源性冲淡水的影响,盐度、温度变化相对较大,使得该区域的物种不得不适应一个跨度较大的温盐范围,广温广盐性种类为主。  相似文献   

解郁安神法联合体外反搏对PCI术后气滞血瘀型胸痹患者的临床疗效观察          下载免费PDF全文

王敏  徐新利  姜光萍 《应用海洋学学报》2020,36(12):1

目的：观察解郁安神法联合体外反搏（EECP）对经皮冠状动脉介入治疗（PCI）术后气滞血瘀型胸痹患者的临床疗效。方法：将80例冠心病PCI术后气滞血瘀型胸痹患者随机分为治疗组和对照组,每组各40例。对照组采用PCI术后规范化治疗,同时联合EECP治疗;治疗组在对照组基础上加服解郁安神方治疗,随访观察7周,比较2组临床证候疗效、Zung焦虑自评量表（SAS）评分、抑郁自评量表（SDS）评分、西雅图心绞痛调查量表（SAQ）评分。结果：总有效率治疗组为82.5%（33/40）,高于对照组的60.0%（24/40）,2组比较,差异有统计学意义（P<0.05）;2组SAS、SDS、SAQ评分治疗前后组内比较及治疗后组间比较,差异均有统计学意义（P<0.05）。结论：解郁安神法联合EECP治疗可明显改善PCI术后气滞血瘀型胸痹患者的临床症状,缓解焦虑抑郁程度,提高患者生活质量,值得临床推广应用。  相似文献   

滨海城市竖向避难场所选址可靠性评价与若干问题探讨     

张威涛  任利剑  运迎霞 《地理科学》2020,40(11):1899-1908

关注滨海城市竖向避难场所的选址可靠性问题，首先深化确立“竖向避难场所”概念；然后构建竖向避难场所选址可靠性评价模型，综合自然地理要素和建成环境要素，从与灾害直接作用相关的选址暴露性、与应急交通相关的选址敏感性、与应急服务相关的选址适应性3个维度展开，搭建3级评价指标体系；再以天津滨海新区为例、聚焦滨海城市潮洪灾害和人口安全矛盾的集核——临港城区展开实证研究，借助ArcGIS分类与可视化发现：高低可靠性选址之间具有明显的空间分异，可以分解为灾害暴露性的“近岸高?远岸低”分异、交通敏感性的“外围高?中心低”分异、服务适应性的“中心与沿河高?外围低”兼“近港高?远港低”分异。同时发现：商业设施用地选址价值较高，在高可靠性选址中占比第一；中小学和社会福利设施用地选址价值最高，在高可靠性选址中占比第二；文化科研和娱乐康体设施用地在高可靠性选址中占比最小。针对临港城区实证研究结果，提出滨海城市竖向避难场所选址及可靠性提升对策。  相似文献   

Multiple longshore sand bars in the upper Chesapeake Bay     

Thomas J. Dolan  Robert G. Dean 《Estuarine, Coastal and Shelf Science》1985,21(5):727-743

In the upper Chesapeake Bay (Maryland, U.S.A.) field surveys were conducted at 18 multiple longshore sand bar sites. The multiple bar systems were found in water depths less than approximately 2 m (mean sea level), and exhibited mild bottom slopes of 0·0052 or less. The number of bars composing each system ranged from four to 17 and the spacing between the crests typically increased in the offshore direction, ranging from 12 to 70 m. Bar height also typically increased with distance offshore and ranged from 0·03 to 0·61 m. A grain size analysis of crest and trough sediment did not reveal any significant differences and the sediment was categorized as ‘fine sand’. A review of the literature data indicated that the Chesapeake Bay multiple bars possessed similar characteristics to those found in Gelding Bay (Baltic Sea); similarities in fetch, wave height and tidal range between the two bays may account for this finding. The surf-scaling parameter indicated that the multiple bar systems were extremely dissipative with regard to wave energy, and wave height appeared to be an important factor in controlling bar spacing and bar height. A multiple wave break point hypothesis was discussed as a possible mechanism for the formation of Chesapeake Bay multiple longshore bars, and limited observational evidence appeared to support such a mechanism.  相似文献   

Particulate organic matter in the coastal and estuarine waters of Goa and its relationship with phytoplankton production     

X.N. Verlencar  S.Z. Qasim 《Estuarine, Coastal and Shelf Science》1985,21(2):235-243

In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l^?1 and from 0.28 to 5.24 mg l^?1 and particulate phosphorus (PP) varied from 0.71 to 5.18 μg l^?1 and from 0.78 to 20.34 μg l^?1, respectively. The mean values of chlorophyll and primary productivity were 1.94 mg m^?3 and 938.1 mg C m^?2 day^?1 in the coastal waters and 4.3 mg m^?3 and 636.5 mg C m^?1 day^?1 in the estuarine waters, respectively.$\text{POC}\text{chl}$ ratios were low in June and October even when POC values were quite high. The POC in surface waters was linearly correlated with the chlorophyll content. Also PP increased when chlorophyll and primary productivity remained high. The results suggest that the phytoplankton was sharply increasing and contributed to POC and PP content. The percentage of detritus calculated from the intercept values of chlorophyll on POC varied from 46 to 76% depending on season. Results indicate that the major portion of POC and PP during postmonsoon (October–January) is derived from phytoplankton production while the allochthonous matter predominate during monsoon (June–September).  相似文献   

Contribution of storms to groundwater recharge in the semi‐arid region of Karnataka,India     

K. Shivanna  U. P. Kulkarni  T. B. Joseph  S. V. Navada 《水文研究》2004,18(3):473-485

This paper describes the application of environmental isotopes and injected tracer techniques in estimating the contribution of storms as well as annual precipitation to groundwater recharge and its circulation, in the semi‐arid region of Bagepalli, Kolar district, Karnataka. Environmental isotopes ²H, ¹⁸O and ³H were used to study the effect of storms on the hydrological system, and an isotope balance was used to compute the contribution of a storm component to the groundwater. Some of the groundwater samples collected during the post‐storm periods were highly depleted in stable isotope content with higher deuterium excess relative to groundwater from the pre‐storm periods. Significant variation in deuterium excess in groundwater from the same area, collected in two different periods, indicates the different origin of air masses. The estimated recharge component of a storm event of 600 mm to the groundwater was found to be in the range of 117–165 mm. There was no significant variation in environmental tritium content of post‐storm and pre‐storm groundwater, indicating the fast circulation of groundwater in the system. After completion of the environmental isotope work, an injected radiotracer ³H technique was applied to estimate the direct recharge of total precipitation to the groundwater. The estimated recharge to the groundwater is 33 mm of the 550 mm annual precipitation during 1992. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Galileo系统及其在中国的应用   总被引：9，自引：0，他引：9  

韩玲  朱文耀 《天文学进展》2005,23(1):10-28

较详细地介绍了Galileo系统的全面体系结构、频率设计、服务内容及其广泛的应用范围，指出了它与GPS系统相比的优点，并对开发和增强Galileo系统在我国多层次、全方位的应用提出了建议。  相似文献   

Effects of Different Diets on the Dietary Attractability and Selectivity of Chinese Shrimp, Fenneropenaeus chinensis     

HUANGGuoqiang DONGShuanglin WANGFang 《中国海洋大学学报(英文版)》2005,4(1):56-60

Attractabilities of different diets and dietary selectivity of Chinese shrimp, Fenneropenaeus chinensis were studied through behavior observation and feeding experiment, respectively. The five diets used in the experiment are: Fish Flesh (FF), Shrimp Flesh (SF), Clam Foot (CF), Polychaete Worm (PW), and Formulated Diet (FD). No significant differences of attractability exist between any two different diets when every two natural diets or all five diets are provided simultaneously. On the other hand, significant differences of attractability exist between FD and every single natural diet when they are provided simultaneously. Results of behavioral observation indicate that natural diets are more attractive than FD. In feeding experiment, Chinese shrimp has distinct selectivity on different diets. It positively selects CF and PW, negatively selects FF and SF, and excludes FD absolutely. The results of the present studies indicate that the dietary selectivity of shrimp was based not only on the attractabilities of the diets, but also on the responses such as growth and food conversion.  相似文献