Characteristics of Kd （490） around Nansha Islands in the South China Sea

The diffusion attenuation coefficient for downwelling irradiance, Ka(490), is an important optical parameter of seawater. The optical property, Kd(490), around Nansha Islands in the South China Sea was analyzed based on optical data profiles measured with SPMR (SeaWiFS Profiling Multichannel Radiometer) and SMSR ( SeaWiFS Multichannel Surface Reference ) instrument in April and May, 1999. The results show that Kd(490) is closely correlated with chlorophyll-a concentration, Ccgka, and that the vertical distribution of Kd(490) shows the strong stratification of the water column in this area. Kd(490) has a similar vertical co-variation as KL(490), the diffusive attenuation coefficient for upwelling radiance.Both coefficients increase with depth in the upper layer, where KL(490) is greater than Kd(490); and after a depth, approximatively at the chlorophyll maximum, they decrease with depth, with the former being smaller than the latter.     

Current Measurements of the Japan Sea Proper Water and the Intermediate Water by ALACE Floats

The subsurface current of the Japan Sea was observed by two Autonomous Lagrangian Circulation Explorer (ALACE) floats. One float, having a 20-day cycle, was deployed on 29 July 1995 in the eastern Japan Basin and drifted in the northeastern part of the basin until 15 September 2000. The other float, with a 10-day cycle, was deployed on 4 August 1995 in the western Japan Basin and drifted in the western Japan Basin, in the Yamato Basin and around the Yamato Rise until it reached its life limit in mid-May 2000. An anticlockwise circulation in the eastern Japan Basin was observed and it was assumed to be in the upper portion of the Japan Sea Proper Water (UJSPW) or in the intermediate water. The spatial scale of the circulation increased as the depth decreased. A clockwise circulation was observed around the Yamato Rise in the UJSPW. Smaller clockwise and anticlockwise rotations were observed in the western Japan Sea, where a seasonal variation was seen in drift speed with different phase by depth. The correlation coefficient between drift speeds of two floats indicated little coherence among the subsurface circulation between the east and the west of the Japan Basin, or between the north and the south of the subpolar front. This revised version was published online in August 2006 with corrections to the Cover Date.     

Image processing for video images of buoy motion

In this paper, image processing technique that reduces video images of buoy motion to yield time series of image coordinates of buoy objects will be investigated. The buoy motion images are noisy due to time-varying brightness as well as non-uniform background illumination. The occurrence of boats, wakes, and wind-induced white caps interferes significantly in recognition of buoy objects. Thus, semiautomated procedures consisting of object recognition and image measurement aspects will be conducted. These offer more satisfactory results than a manual process. Spectral analysis shows that the image coordinates of buoy objects represent wave motion well, indicating its usefulness in the analysis of wave characteristics.     

Deep-circulation flow at mid-latitude in the western North Pacific

Direct current measurements with five moorings at 27–35°N, 165°E from 1991 to 1993 and with one mooring at 27°N, 167°E from 1989 to 1991 revealed temporal variations of deep flow at mid-latitude in the western North Pacific. The deep-circulation flow carrying the Lower Circumpolar Deep Water from the Southern Ocean passed 33°N, 165°E northwestward with a high mean velocity of 7.8 cm s⁻¹ near the bottom and was stable enough to continue for 4–6 months between interruptions of 1- or 2-months duration. The deep-circulation flow expanded or shifted intermittently to the mooring at 31°N, 165°E but did not reach 35°N, 165°E although it shifted northward. The deep-circulation flow was not detected at the other four moorings, whereas meso-scale eddy variations were prominent at all the moorings, particularly at 35°N and 29°N, 165°E. The characteristics of current velocity and dissolved oxygen distributions led us to conclude that the deep-circulation flow takes a cyclonic pathway after passing through Wake Island Passage, passing 24°N, 169.5–173°E and 30°N, 168–169°E northward, proceeds northwestward around 33°N, 165°E, and goes westward through the south of the Shatsky Rise. We did not find that the deep-circulation flow proceeded westward along the northern side of the Mid-Pacific Seamounts and eastward between the Hess Rise and the Hawaiian Ridge toward the Northeast Pacific Basin.     

台站用百叶箱内外气温比对与分析

用双通道自动测温表对台站用的百叶箱内外气温进行了同步比对测量与分析。指出自然通风时，百叶箱对箱内气温变化产生一定程度的滞后和热辐射作用。滞后作用较明显。     

岩样孔隙汞渗入量超声法精密测定

采用声学方法精密测定汞被高压强压入储油岩样的渗入体积，对岩芯孔隙结构测定中的汞体积计量方法作了重要改进。本方法以无水酒精作为计量工作介质，在其中发射声波，通过对汞界面反射声波的识别，进行非接触的声学测量，从根本上解决了当前国内外采用的电阻法，电容法无法避免的由于汞腐蚀或油污染而要求经常进行与有毒汞接触的清洗，并且确保了计量系统工作性能的长期稳定与准确可靠。在０．０１ＭＰａ至５０ＭＰａ压强范围内连续计量，量程０～１０ｍｌ，准确度０．０１ｍｌ。     

灰色系统在电敏感区法粒度分析曲线外推技术中的应用

根据TAI型库尔特计数器单管粒度分析结果,利用灰色系统建立GM(1,1)预测模型,对样品频率曲线进行外推处理,可获得小于仪器基线通道阈值颗粒的体积百分比含量,并将结果与入重-出重法测定结果进行对比,精度较高。为电敏感区法粒度分析资料的外推处理提供了新的方法。     

声相关海流剖面(ACCP)测量的流速估值方法

声相关海流剖面（ACCP）测量技术对水体回波信号进行空间相关处理来估计流速值，与声学多普勒海流剖面仪（ADCP）相比ACCP的工作频工，更适合深海测流应用，ACCP测量系统对回波信号进行时空相关处理，根据相关函数的位置来估计被测水团的流速值，ACCP从信号中提取流速值要运用参数估计技术，本文介绍了采用极大似然法和最小二乘法进行流速参数的处理方法，给出一些典型流速情形的数值计算结果。