基于浮标观测的长江口外海流特征分析     

李鹏  史本伟  汪亚平  秦渭华  李延刚  陈健 《海洋学报(英文版)》2017,36(4):13-20

为了揭示长江口外海域海流的特征及其季节和垂向变化规律,于2006年8月1日-2007年7月31日在长江口外海域（平均水深约46.0m）利用大型浮标进行了1年的分层海流流速流向观测。结果表明：（1）该海域海流为顺时针方向的旋转流,在垂向上流向较一致,季节变化不显著。（2）长江口外海域水平流速总体较大,夏季表层最大流速为128.5cm/s,冬季最大表层流速为105.5cm/s;垂线平均流速相近（差异<8.0 cm/s）,夏季流速最大为47.0cm/s,冬季为40.8cm/s。小潮的平均流速为26.5cm/s,大潮平均流速为小潮的2倍。（3）剖面各层流速垂向差异明显,最大流速出现在表层（春季和冬季）或次表层（夏季和秋季）,最小流速均出现在底层;各层的最大平均流速为57.9cm/s,出现在夏季的18m层。（4）垂线平均余流为7.5~11.3 cm/s,春季最强冬季最弱;春季和冬季各层余流均为东向,夏季和秋季基本为东北向或北向。（5）观测海域海流受长江冲淡水、台湾暖流、季风、潮汐等动力作用的共同制约。  相似文献   

Quality evaluation and calibration of the SWIM significant wave height product with buoy data     

Jing Ye  Yong Wan  Yongshou Dai 《海洋学报(英文版)》2021,40(10):187-196

The significant wave height (SWH) is one of the main parameters that describe wave characteristics and is widely used in wave research fields. Wave parameters measured by radar are influenced by the offshore distance and sea state. Validation and calibration are of great significance for radar data applications. The nadir beam of surface wave investigation and monitoring (SWIM) detects the global-ocean-surface SWH. To determine the product quality of SWIM SWH, this paper carried out time-space matching between SWIM and buoy data. The data qualities were evaluated under different offshore distances and sea states. An improved calibration method was proposed based on sea state segmentation, which considered the distribution of the point collocation numbers in various sea states. The results indicate that (1) the SWIM SWH accuracy at offshore distances greater than 50 km is higher than that at distances less than 50 km, with an root mean squared error (RMSE) of 0.244 4 m, scatter index (SI) of 0.115 6 and relative error (RE) of 9.97% at distances greater than 50 km and those of 0.446 0 m, 0.223 0 and 18.66% at distances less than 50 km. (2) SWIM SWH qualities are better in moderate and rough sea states with RMSEs of 0.284 8 m and 0.316 9 m but are worse in slight and very rough sea states. (3) The effect of the improved calibration method is superior to the traditional method in each sea state and overall data, and the RMSE of SWIM SWH is reduced from the raw 0.313 5 m to 0.285 9 m by the traditional method and 0.198 2 m by the improved method. The influence of spatiotemporal window selection on data quality evaluation was analyzed in this paper. This paper provides references for SWIM SWH product applications.  相似文献   

Capture Performance of A Multi-Freedom Wave Energy Converter with Different Power Take-off Systems     

Huang  Shu-ting  Shi  Hong-da  Dong  Xiao-chen 《中国海洋工程》2019,33(3):288-296

Among the wave energy converters (WECs), oscillating buoy is a promising type for wave energy development in offshore area. Conventional single-freedom oscillating buoy WECs with linear power take-off (PTO) system are less efficient under off-resonance conditions and have a narrow power capture bandwidth. Thus, a multi-freedom WEC with a nonlinear PTO system is proposed. This study examines a multi-freedom WEC with 3 degrees of freedom: surge, heave and pitch. Three different PTO systems (velocity-square, snap through, and constant PTO systems) and a traditional linear PTO system are applied to the WEC. A time-domain model is established using linear potential theory and Cummins equation. The kinematic equation is numerically calculated with the fourth-order Runge–Kutta method. The optimal average output power of the PTO systems in all degrees of freedom are obtained and compared. Other parameters of snap through PTO are also discussed in detail. Results show that according to the power capture performance, the order of the PTO systems from the best to worst is snap through PTO, constant PTO, linear PTO and velocity-square PTO. The resonant frequency of the WEC can be adjusted to the incident wave frequency by choosing specific parameters of the snap through PTO. Adding more DOFs can make the WEC get a better power performance in more wave frequencies. Both the above two methods can raise the WEC’s power capture performance significantly.  相似文献   

ERA-Interim和NCEP/NCAR再分析资料在我国东南近海适用性分析     

申华羽  吕劲文  涂小萍  方艳莹 《海洋预报》2019,36(2):9-20

利用我国东南近海5个浮标站观测资料,对2012—2016年ERA-Interim和NCEP/NCAR再分析资料10 m风、2 m气温、海平面气压的适用性进行了评估。结果表明:NCEP/NCAR的再分析10 m风适用性更好,ERA-Interim的2 m气温适用性更好,海平面气压两者差异不大。风速再分析值与观测值具有较好的一致性,相关系数达0.8～0.9,但再分析风速总体上有偏小的趋势,平均偏差在-1.3～0 m/s之间,均方根误差在1.5～3 m/s。再分析资料的平均风向有顺时针偏差的趋势,温州浮标偏右达14°以上,均方根误差大多在40°～50°。不管风速还是风向,5个浮标站中均以舟山浮标的再分析值与观测值最为接近;分析还表明,再分析资料的冬季风代表性相对较差,这是造成风速和风向系统性偏差的主要原因。再分析资料与观测2 m气温相关系数均在0.95以上,且有偏高的趋势,NCEP偏高更为明显,有4个浮标站平均偏差达1～2℃,而ERA-I仅1个浮标站偏差1～2℃,4个在1℃以内。春季和冬季气温偏高最为明显,春季升温过程存在异常偏高的可能,秋季气温与观测值最为接近。海平面气压适用性较好,总体优于10 m风和2 m气温,且季节间差异也不大。  相似文献   

Absolute calibration of HY-2A and Jason-2 altimeters for sea surface height using GPS buoy in Qinglan,China     

CHEN Chuntao  ZHU Jianhua  ZHAI Wanlin  YAN Longhao  ZHAO Yili  HUANG Xiaoqi  YANG Weiwei 《海洋湖沼学报（英文）》2019,(5):1533-1541

GPS buoy methodology is one of the main calibration methodologies for altimeter sea surface height calibration. This study introduces the results of the Qinglan calibration campaign for the HY-2A and Jason-2 altimeters. It took place in two time slices;one was from August to September 2014, and the other was in July 2015. One GPS buoy and two GPS reference stations were used in this campaign. The GPS data were processed using the real-time kinematic (RTK) technique. The fi nal error budget estimate when measuring the sea surface height (SSH) with a GPS buoy was better than 3.5 cm. Using the GPS buoy, the altimeter bias estimate was about -2.3 cm for the Jason-2 Geophysical Data Record (GDR) Version ‘D' and from -53.5 cm to -75.6 cm for the HY-2A Interim Geophysical Data Record (IGDR). The bias estimates for Jason-2 GDR-D are similar to the estimates from dedicated calibration sites such as the Harvest Platform, the Crete Site and the Bass Strait site. The bias estimates for HY-2A IGDR agree well with the results from the Crete calibration site. The results for the HY-2A altimeter bias estimated by the GPS buoy were verifi ed by cross-calibration, and they agreed well with the results from the global analysis method.  相似文献   

基于RT-P P P技术的船体及浮标定位系统     

张昊楠  胡广浩  樊贞  马鸿燕  王振波  孙青 《测绘科学技术学报》2019,36(3):233-237

高精度GNSS定位是海上勘探作业质量保障的核心技术之一。随着海洋石油勘探作业逐步走向深海领域,传统的岸基差分定位,由于需要依靠岸台基准站向船上发送差分信号,已无法满足远海定位的需求。本文通过对中海油田服务股份有限公司自主研发的"海星"船体以及浮标定位系统进行研究,提出了一种基于实时精密单点定位RT-PPP技术的坐标解算方法;并进行了陆地静态试验及海上拖缆地震勘探作业动态试生产实验。实验结果表明,系统的定位精度均优于1 m,系统的定位精度及可靠性能够满足海上拖缆地震勘探作业需要。  相似文献   

冰区四季通用灯浮标的二阶波浪力计算     

邓祝森 《海洋技术学报》2018,(2):107-109

冰区四季通用灯浮标是一种为满足北方冬季冰冻港口一年四季的助航服务需求研制的新型灯浮标,二阶波浪力对其漂浮姿态和漂移运动有较大影响。文中研究了浮标受到的二阶波浪力的数值计算方法,计算了不同流速下罐形和锥形灯浮标的二阶波浪力。研究结果显示,罐形和锥形灯浮标受到的一阶波浪力相差不大,罐形的二阶波浪力明显小于锥形,具有一定的外形优势。  相似文献   

水质监测浮标数据采集和接收系统设计及其应用   总被引：1，自引：0，他引：1  

曹文熙  孙兆华  李彩  邹国旺 《热带海洋学报》2018,37(5):1-6

1)文章设计了水质监测浮标数据采集系统, 该数据采集系统包括CPU模块、控制保障模块、通讯定位模块以及接口扩展模块; 采用CF2主板为CPU模块, 辅助以单片机为核心的多功能板, 主要用于完成采集数据、保存数据、通讯等工作; 控制保障模块设计有双“看门狗”, 实现了无人值守、全天候、全过程安全工作。2)文章还设计了水质监测数据远程接收系统, 该远程接收系统主要包括数据接收模块、数据处理模块、系统预警模块和数据显示模块等四个部分, 具有操作简便、自动化程度高、图形显示直观简洁易读等特点, 实现了数据接收、存储、显示及预警等功能。  相似文献   

水质监测浮标及其传感器的防污染措施     

曹文熙  孙兆华  李彩  邹国旺 《热带海洋学报》2018,37(5):7-12

近岸、河口和海湾水质浮标监测越来越受到关注, 但目前有关水质监测传感器的防污染技术的报道还很少。文章介绍了在珠江口水质监测浮标中使用的几种防污染方法。对于有光学窗口的监测仪器, 采用自动防污染装置可以清除窗口表面的污染物。对于不便于采用自动防污染刷的传感器, 根据情况分别采用防污染材料包络, 或者海水注入管路的防污染过滤头等方式, 也可以达到一定的防污染效果。对于长期水下观测仪器, 每隔一段时间还应进行舱体污染物的人工清洗, 以保证设备的正常使用。  相似文献   

基于MEMS加速度计空投浮标的波浪测量方法试验研究     

刘宁  魏晓辉  王斌  董涛 《海洋科学》2020,44(9):146-153

针对基于MEMS加速度传感器的空投波浪浮标存在采样频率与测波精度低的问题,根据频域衰减积分算法,提出一种相应的波浪测量算法,为了验证该算法测波的准确性,开展了多功能水槽试验研究。该算法旨在将MEMS加速度传感器输出的加速度与姿态角转化为浮标运动的波形,首先将加速度与姿态角信号进行竖向处理获得竖直方向的加速度,再利用离散傅里叶变换将竖向加速度转化为频域内的加速度复数序列,然后引入控制函数减弱低频噪声,经过频域积分、离散傅里叶逆变换、时域积分获得竖直方向的位移,最后通过后处理得到最终的波形。多功能水槽试验采取10中不同波高和周期的工况,对比空投波浪测量浮标与波高仪的测量结果,试验结果表明,浮标的测量误差在10%以内,达到测波标准。  相似文献