Reproductive Biology of Yeilowfin Tuna T. albacares in the West-Central Indian Ocean

Survey of yellowfin tuna in the west-central Indian Ocean was conducted on board of Chinese Iongliners during 2003, 2004 and 2005, which is a part of Chinese Tuna Fishery Scientific Observer Program (CTFSOP). The reproductive biology has been investigated. A total of 1023 samples are collected including 417 ovaries and 606 testes. Spawning activities of yellowfin tuna have been studied for both male and female from January to June. The data showed that the average monthly sex ratio is 0.59, and the minimum length at sexual maturity is 101 cm for female and 110 cm for male respectively. Length at 50% sexual maturity is esti- mated at 113.77 cm for female and 120.20 cm for male, whereas maturation rate is 0.066 cm-1 for female and 0.091 cm-1 for male. Sex ratio by length class indicates that the proportion of male is higher than female's along with size increasing; for instance, in the group of the body length longer than 145 cm, some females have their body length from 145 to 160 cm and males have their body length at 160 cm and even longer. Statistically, yellowfin tuna has a significant seasonal reproduction.     

基于Barnes滤波原理的降水场客观分析及尺度分离

基于Barnes滤波原理（又称高斯加权客观分析）,在进行网格点插值的同时,通过选择适当的滤波参数C、G滤去原始场中的短波噪音,使分析结果平稳光滑;另外可通过它构成一带通滤波器,根据实际需要分离出影响天气过程的各种次天气尺度,达到尺度分离的目的。以全国160个国家基准代表站1954—2006年共53a的年平均降水场为例作实例分析,并同用Grads内插函数（Oacres函数）、九点平滑函数（Smth9函数）的绘图结果进行对比分析,结果表明客观分析结果同Grads内插平滑分析结果基本相似,都能反映出我国53a年平均降水场从东南向西北逐渐递减的趋势且与实际情况相符,降水场高值中心位于长江流域及以南的华南等地区,低值中心位于黄河流域以北的广大西部地区。取不同的参数C和G得到的尺度分离后的带通滤波值,既抑止了长波,又抑制了短波,达到较好的尺度分离效果。     

Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water

This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations. The model, with no flux adjustment, reproduces well the Atlantic Water core temperature （AWCT） in the Arctic Ocean and shows that four largest decadalscale warming episodes occurred in the 1930s, 70s, 80s, and 90s, in agreement with the hydrographic observational data. The difference is that there was no pre-warming prior to the 1930s episode, while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s, leading the 1990s into the largest and prolonged warming in the 20th century. Over the last century, the simulated heat transport via Fram Strait and the Barents Sea was estimated to be, on average, 31.32 TW and 14.82 TW, respectively, while the Bering Strait also provides 15.94 TW heat into the west- ern Arctic Ocean. Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT （ C = 0.75 ） at 0- lag. The modeled North Atlantic Oscillation （NAO） index has a significant correlation with the heat transport （ C = 0.37 ）. The observed AWCT has a significant correlation with both the modeled AWCT （ C =0.49） and the heat transport （ C =0.41 ）. However, the modeled NAO index does not significantly correlate with either the observed AWCT （ C = 0.03 ） or modeled AWCT （ C = 0.16 ） at a zero-lag, indicating that the Arctic climate system is far more complex than expected.     

Contribution of a pathway through the Arctic Ocean to the re cent reduction in the ice cover

The sea ice cover in the Arctic Ocean has been reducing and hit the low record in the summer of 2007. The anomaly was extremely large in the Pacific sector. The sea level height in the Bering Sea vs. the Greenland Sea has been analyzed and compared with the current meter data through the Bering Strait. A recent peak existed as a consequence of atmospheric circulation and is considered to contribute to inflow of the Pacific Water into the Arctic Basin. The timing of the Pacific Water inflow matched with the sea ice reduction in the Pacific sector and suggests a significant increase in heat flux. This component should be included in the model prediction for answering the question when the Arctic sea ice becomes a seasonal ice cover.     

An estimation of internal soliton forces on a pile in the ocean

Internal soliton forces on oil-platform piles in the ocean are estimated with the Morison Formula. Different from sur- face wave forces, which change only in magnitude along a pile, internal soliton forces can be distributed over the entire pile in the water and they change not only in magnitude but also in direction with depth. Our calculations show that the maximum total force caused by a soliton with its associated current of 2.1 m s-1 is nearly equal to the maximum total force exerted by a surface wave with a wavelength of 300 m and a wave-height of 18 m. The total internal soliton force is large enough to affect the operations of marine oil platforms and other facilities. Therefore, the influence of internal solitons should not be neglected in the design of oil platforms.     

A sub-surface eddy at inertial current layer in the Canada Basin,Arctic Ocean

An Arctic Ocean eddy in sub-surface layer is analyzed in this paper by use of temperature,salinity and current profiles data obtained at an ice camp in the Canada Basin during the second Chinese Arctic Expedition in summer of 2003.In the vertical temperature section,the eddy shows itself as an isolated cold water block at depth of 60 m with a minimum temperature of-1.5℃,about 0.5℃ colder than the ambient water.Isopycnals in the eddy form a pattern of convex,which indicates the eddy is anticyclonic.Although maximum velocity near 0.4 m s-1 occurs in the current records observed synchronously,the current pattern is far away from a typical eddy.By further analysis,inertial frequency oscillations with amplitudes comparable with the eddy velocity are found in the sub-surface layer currents.After filter the inertial current and mean current,an axisymmetric current pattern of an eddy with maximum velocity radius of 5 km is obtained.The analysis of the T-S characteristics of the eddy core water and its ambient waters supports the conclusion that the eddy was formed on the Chukchi Shelf and migrated northeastward into the northern Canada Basin.     

Zircon U-Pb geochronology and geochemistry of syenogranites in western Niubiziliang,northwestern Qaidam,Qinghai

The study presents the results of U-Pb dating of zircons and whole-rock geochemical analyses of a syenogranite located in the western Niubiziliang area,China with the aim of determining its formation time,petrogenesis and the regional tectonic setting. Zircons within the syenogranite are euhedral-subhedral and display rhythmic growth zoning,indicating a magmatic origin. Zircon U-Pb data obtained by LA-ICP-MS indicate the syenogranite formed in the Late Permian (260.7±1.5 Ma). The w(SiO_2) of syenogranites is 70.82%--73.59%,w(Al_2O_3) is 13.49%--14.82%,and w(Na_2O + K_2O) is 7.85%--8.52%,and yield K_2O/Na_2O ratios of 1.06--1.26. Therefore,the syenogranites belong to the high-K calc-alkaline and metaluminous (A/CNK 1,A/NK 1) series which display I-type granites similarly. The syenogranites also show the geochemical characteristics of volcanic arc rocks,being enriched in large-ion lithophile elements (LILEs; K,Rb) and light rare-earth elements (LREEs; La,Ce,Sm,Nd),but depleted in high field strength elements( HFSEs; Ta,Nb,P,Ti). On the whole,trace element ratios are close to the mean of the Earth's crust,indicating a lowercrust magma source. The low Sr (161--214) ×10~(-6) and Yb (1.08--1.80)×10~(-6) concentrations indicate that plagioclase and hornblende are residual mineral phases in the source. The regional geology and whole-rock geochemistry suggest that the formation of the syenogranites was related to subduction of the Zongwulong Ocean crust,and the north margin of Qaidam Block during the Late Permian was in an active continental margin tectonic setting.     

Prediction of application scope of vertical fracture strike based on scattered wave fracture orientation function

Fracture system plays a very important role in the enrichment and accumulation of oil and gas in the reservoirs. Based on scattering wave information,Fracture Orientation Function( FOF) was built,which can be used to predict the fracture orientations. However,this method has only been verified by physical experiments without studies on the application scope. In this study,based on the linear sliding theory,FOF of the scattering wave was applied to the numerical simulation and the application scope was further studied according to fracture flexibility tensor. According to the fractures filled with gas and liquid,numerical simulation was conducted on the models with various fracture flexibilities. Numerical simulation results were used to inverse fracture orientation with the aid of the FOF of the scattering wave. The results show that it is workable to predict the vertical fracture orientation with the FOF of the scattering wave. Application of this method is more effective when the fractures are filled with gas than liquid. Moreover,the application scope can be predicted by the fracture flexibility.     

Empirical formula for wave length of ocean wave in finite depth water

In this paper, function characteristics of dispersion of ocean wave in finite depth water were analyzed systematically. The functional form of the fitting function is reasonably proposed, in which the parameters are optimally determined by the least square method （LSM）. For infinitely deep and extremely shallow water,the fitting function fits strictly the dispersion to be fitted. A new technique is presented in application of LSM.An empirical formula with maximum error of less than 0.5% for computing wavelength in finite depth water is presented for practical applications.     

弹性反射波频谱分析对比法检测浆砌片石挡墙质量

大量的浆砌片石挡墙需要作快速质量检测,作者比较了利用弹性波速、瑞利面波和弹性波频谱分析法后,认为后者分辨率高,方法简单,并作了几百个点的检测,得到了成功。