Coupling of life cycles of the copepods Calanus chilensis and Centropages brachiatus to upwelling induced variability in the central-southern region of Chile     

Pamela Hidalgo  Ruben Escribano 《Progress in Oceanography》2007,75(3):501-517

A time series of zooplankton sampling carried out at Station 18 off Concepción (36°S, 73°W) from August 2002 to December 2003 allowed the study of annual life cycles of the copepods Calanus chilensis and Centropages brachiatus in association with environmental variability in the coastal upwelling zone. Changes in the abundance of eggs, nauplii, and copepodids were assessed from samples taken at a mean time interval of ca. 20 days. Upwelling variability in near-surface waters was reflected in seasonal changes in salinity, water column stratification, and oxycline depth, as well as a weak seasonal signal in sea surface temperature (1-2 °C). Both copepods exhibited similar life cycles, characterized by continuous reproduction throughout the year. Estimates of generation times, as a function of temperature, were 25-30 days for C. chilensis and 27-35 days for C. brachiatus, predicting about 12 and 10 generations a year, respectively. These estimates were consistent with reproduction pulses observed in the field. It was thus suggested that copepods may grow under non-limiting food conditions in this upwelling area. However, despite continuous reproduction, there were abrupt changes in population sizes along with the disappearance of early naupliar and copepodid stages taking place even during the upwelling season (spring/summer). These changes were attributed to sudden increases in mortality taking place in spring or early summer, after which the populations remained at low levels through the fall and winter. It is thus suggested that, in addition to variability in the physical environment, biological interactions modulating changes in copepod mortality should be considered for understanding copepod life cycles in highly productive upwelling systems.  相似文献   

Adjustment time of the first baroclinic Rossby wave in the global oceans     

FAN Haimei  LI Bingrui  XU Ren  ZHANG Zhenglong  LI Yihong 《海洋学报(英文版)》2006,25(6):15-21

1Introduction Planetary waves involve the main processes bywhich perturbation signal in one part of the ocean istransferred to another part.In the1970s,mostof theprevious theoretical studies focus on the local Ekmanpumping and the nondispersive long baroc…  相似文献   

High Precision Geoid Models HKGEOID-2000 for Hong Kong and SZGEOID-2000 for Shenzhen, China     

Zhicai Luo  Jinsheng Ning  Yongqi Chen  Zhanji Yang 《Marine Geodesy》2005,28(2):191-200

High precision geoid models HKGEOID-2000 for Hong Kong and SZGEOID-2000 for Shenzhen, China, have been developed with a hybrid approach of so-called sequential processing, using high precision GPS/leveling data, land and sea gravity anomalies, and digital terrain models. These two local geoid models have the same 1-km resolution. The estimated accuracy (external accuracy) is better than 1.7 cm for HKGEOID-2000 and 1.4 cm for SZGEOID-2000. Some common areas are covered by HKGEOID-2000 and SZGEOID-2000. So these two geoid models, along with high quality GPS/leveling data collected on the overlapping areas, can be used to detect the systematic bias between HKGEOID-2000 and SZGEOID-2000, as well as the difference between Hong Kong Principal Datum and 1956 yellow sea height datum of China, yielding RMS errors of 1.011 m and 1,003 m, respectively. Moreover, HKGEOID-2000, along with GPS ellipsoidal heights, is employed to determine the errors of the “orthometric heights” from purely trigonometric heighting, yielding an RMS error of 0.102 m. The combination of SZGEOID-2000 and GPS ellipsoidal heights has been used to replace the traditional spirit leveling and mapping, called GPS mapping.  相似文献   

基于GIS的无人机地面监控系统的设计与实现   总被引：3，自引：0，他引：3  

熊自明  葛文 《海洋测绘》2007,27(4):54-56

在分析无人机领域飞行数据特征的基础上,设计实现了一套功能较为完善的无人机地面监控系统。该系统主要完成了无人机飞行状态实时显示、航线规划和航线回放等功能模块。系统借助于G IS技术,导入矢量形式的电子地图,利用丰富的地理信息来辅助实现无人机的地面监控,在V isual C 6.0开发环境下利用基于异步方式和事件驱动方式的串口通信实现了系统与地面控制站的通信,利用地图控制文件实现了地图数据的调度,利用显示缓存实现了视图实时刷新。经过实际联调,系统运行良好,实用性较好。  相似文献   

Toward a generic method for studying water renewal, with application to the epilimnion of Lake Tanganyika   总被引：3，自引：0，他引：3  

Olivier Gourgue  Eric Deleersnijder  Laurent White   《Estuarine, Coastal and Shelf Science》2007,74(4):628

We present a method, based on the concept of age and residence time, to study the water renewal in a semi-enclosed domain. We split the water of this domain into different water types. The initial water is the water initially present in the semi-enclosed domain. The renewing water is defined as the water entering the domain of interest. Several renewing water types may be considered depending on their origin. We present the equations for computing the age and the residence time of a certain water type. These timescales are of use to understand the rate at which the water renewal takes place. Computing these timescales can be achieved at an acceptable extra computer cost.The above-mentioned method is applied to study the renewal of epilimnion (i.e. the surface layer) water in Lake Tanganyika. We have built a finite element reduced-gravity model modified to take into account the water exchange between the epilimnion and the hypolimnion (i.e. the bottom layer), the water supply from precipitation and incoming rivers, and the water loss from evaporation and the only outgoing river. With our water renewal diagnoses, we show that the only significant process in the renewal of epilimnion water in Lake Tanganyika is the water exchange between the epilimnion and the hypolimnion, other phenomena being negligible.  相似文献   

GPS数据采集技术及其在海洋调查中的应用   总被引：1，自引：0，他引：1  

邱雨生  陈敏  刘广山 《台湾海峡》2003,22(3):354-359

本文应用VB6．0开发了智能化的GPS数据采集软件．对该软件的功能进行了简单的介绍，同时对一些关键技术作了较详细的描述。利用该软件、GPS接收机及PC机的组合，可对走航式测量仪器(或移动设备)进行实时定位并保存定位记录，且大大减少一些不必要的数据，使得软件更为实用。  相似文献   

海洋遥感四维测量应用     

张兆瑛  李铜基 《海洋技术学报》1997,16(3):1-11

机载成象光谱仪遥感海洋是在轨星载海洋传感器定标校验的一种方法。本文研究了海洋航空遥感的四维测量方法，以及实现卫星、飞行遥感和船舶同步测量的重要意义。  相似文献   

底部浮泥表层推移速度分布的ADCP—GPS估测方法   总被引：3，自引：0，他引：3  

吴中  陈力平等 《海洋工程》2002,20(4):85-88

ADCP对底跟踪走航观测的流速数据中包含水体底部浮泥、底沙运动信息,对比GPS定位方法算出的水体流速数据可以分离出浮泥相对于GPS定位的运动信号,从而达到对底质推移观测的目的。  相似文献   

使用GAMIT进行高精度基线向量解算的方法与实践   总被引：2，自引：0，他引：2  

徐杰  任超  孟黎 《海洋测绘》2007,27(6):29-32

GAM IT是国际上常用的GPS定位定轨软件,但由于其安装的平台(UN IX/LINUX)与我们通用的W indow s平台有所差异,使得GAM IT的入门较难。因此本文结合具体实例,介绍GAM IT的安装、基本操作以及应用GAM IT进行高精度基线向量解算,供初学者参考。  相似文献   

A phase-averaged Boussinesq model with effective description of carrier wave group and associated long wave evolution     

K. Nadaoka  K. Raveenthiran 《Ocean Engineering》2002,29(1):21-37

From the phase-resolving improved Boussinesq equations (Beji and Nadaoka, Ocean Engineering 23 (1996) 691), a phase-averaged Boussinesq model for water waves is derived by more effectively describing carrier wave groups and accompanying long wave evolution with less CPU time. Linear shoaling characteristics of carrier wave equations are investigated and found to agree exactly with the analytical expression obtained from the constancy of energy flux for the improved Boussinesq equations themselves, showing that the present model equations are the results of a consistent derivation procedure regarding energy considerations. Numerical simulations of the derived equations for the single wave group and narrow-banded random waves show the validity of the present model and its high performance, especially on the CPU time.  相似文献