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991.
We utilized 234Th, a naturally occurring radionuclide, to quantify the particulate organic carbon (POC) export rates in the northern South
China Sea (SCS) based on data collected in July 2000 (summer), May 2001 (spring) and November 2002 (autumn). Th-234 deficit
was enhanced with depth in the euphotic zone, reaching a subsurface maximum at the Chl-a maximum in most cases, as commonly
observed in many oceanic regimes. Th-234 was in general in equilibrium with 238U at a depth of ∼100 m, the bottom of the euphotic zone. In this study the 234Th deficit appeared to be less significant in November than in July and May. A surface excess of 234Th relative to 238U was found in the summer over the shelf of the northern SCS, most likely due to the accumulation of suspended particles entrapped
by a salinity front. Comparison of the 234Th fluxes from the upper 10 m water column between 2-D and traditional 1-D models revealed agreement within the errors of
estimation, suggesting the applicability of the 1-D model to this particular shelf region. 1-D model-based 234Th fluxes were converted to POC export rates using the ratios of bottle POC to 234Th. The values ranged from 5.3 to 26.6 mmol C m−2d−1 and were slightly higher than those in the southern SCS and other oligotrophic areas. POC export overall showed larger values
in spring and summer than in autumn, the seasonality of which was, however, not significant. The highest POC export rate (26.6
mmol C m−2d−1) appeared at the shelf break in spring (May), when Chl-a increased and the community structure changed from pico-phytoplankton
(<2 μm) dominated to nano-phytoplankton (2–20 μm) and micro-phytoplankton (20–200 μm) dominated. 相似文献
992.
珠江口盆地白云凹陷陆坡区10.5Ma以来的沉积体系 总被引:2,自引:0,他引:2
通过对珠江口盆地白云凹陷陆坡区10.5Ma以来的地震相分析,共识别出席状平行亚平行地震相、透镜状前积地震相、深切河谷地震相、帚状地震相和杂乱地震相,不同的地震相分别代表不同的沉积体系类型。综合所识别的地震相类型,分析了陆架边缘下切谷、浊积扇和陆架边缘三角洲3种主要的沉积体系及其配置关系。物源供给是影响陆坡区沉积体系发育的最重要因素,是沉积体系发育的物质基础,海平面变化和构造运动为沉积体系发育提供了可容纳空间,3种影响因素共同影响了陆坡区沉积体系的发育。 相似文献
993.
994.
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996.
通过能量色散X荧光衍射仪(EDXRF)对3种南海潮间带海绵:细薄星芒海绵Stelletta tenui(Lindgren)、澳大利亚厚皮海绵Craniella australiensis (Carter)和多皱软海绵Halichondria hugosa (Ridley&Dendy)的元素组成和含量进行了研究,并与两种黄海潮间带海绵进行了比较。结果表明,海绵体内的元素组成受种属差异的影响较大,溴元素的含量可能同一定的活性物质产生相关。另外,不同海绵具有骨针形态的多样性,为深入研究内部合成机制提供了材料。 相似文献
997.
Aim to linking the variability of drought in northwest China to the oceanic influence of North Atlantic SSTs at the background of global warming and at the regional climate change shifting stages, year aridity index variations in northwest China and summer North Atlantic sea surface temperature (SST) variations are examined for the 44 a period of 1961-2004 using singular value decomposition (SVD) analysis. Results show that the SST anomalies (SSTA)in the North Atlantic in summer reflected three basic models. The first SVD mode of SST pattern shows a dipole - like variation with the positive center located at southwest and negative center at northeast of extratropical North Atlantic. And it strongly relates to the positive trend in AI variation in northwest China. The second coupled modes display the coherent positive anomalies in extratropical North Atlantic SST and the marked opposite trend of AI variability between north and south of Xinjiang. In addition, the lag correlation analysis of the first mode of SSTA and geopotential heights at 500 hPa variations also shows that the indication of the former influencing the latter configuration, which result in higher air temperature and less precipitation when the SSTA in the North Atlantic Ocean in summer motivated Eurasian circulation of EA pattern, further to influence the wet - dry variations in northwest China by the ocean-to - atmosphere forcing. 相似文献
998.
2006年夏季在珠江口外海域进行了143个站位的海气通量船基观测.设计了一个剔除船速的滤波器及资料处理程序,对观测资料进行了处理.通过对垂向观测风速的平均值、湍流功率谱、观测通量值的计算,得出该次观测方法是不可取的.设备安置在船舷外,气流绕过船体时形成上升气流并干扰了湍流场,测得的垂向平均风速不为零,一般存在0.2-1.0m·s-1的垂向平均风速,无量纲湍流功率谱在惯性次区不符合f-2/3次律,通过涡动相关法计算的动量通量远大于块体动力学公式的计算结果.今后的船基通量观测需要选取好设备安装位置及安装高度. 相似文献
999.
Li-Chung Wu Dong-Jiing Doong Beng-Chun Lee Laurence Zsu-Hsin Chuang Chia Chuen Kao 《Marine Geophysical Researches》2008,29(1):43-50
The purpose of this study is to discuss the influence of signal nonlinearity upon X-band radar observations. A method for
estimating the degree of nonlinearity by bispectral analysis was applied and discussed. We found that bispectral analyses
from spatial radar backscatter series are similar to results obtained from water level time series. In addition, the average
nonlinear degree from radar backscatter is related to wind speed. The accuracy of wave observations derived by consideration
of the nonlinear effect from radar backscatter was also investigated. The estimated error in wave height from the radar data
is also related to the degree of nonlinearity. In order to improve accuracy, the modulation transfer function method was applied
in order to eliminate the influence of nonlinearity. 相似文献
1000.
文中利用加拿大环境部气候研究中心研发的惩罚最大t检验方法,选取均一的邻近气象站为参考站,结合元数据信息,对1960-2017年成山头海洋站海表温度序列进行了均一性检验与订正。利用订正后的海表温度序列对成山头海温气候变化特征进行分析。结果表明,订正前后年平均海表温度趋势发生了明显改变,表现出海温上升趋势较订正前加强的特征,增暖趋势由订正前的0.04℃/10 a上升到0.15℃/10 a,其中最暖的5个年份多发生在1980年以后,分别为1973年、1989年、2002年、2007年和2017年。海表温度总体呈显著上升趋势和明显的年代际波动,20世纪60年代至80年代末为偏冷阶段,之后开始增暖,20世纪90年代至今为偏暖阶段。1960-2017年,成山头的海温突变点在1987年,是一次增暖性突变,与中国大陆的气温突变特征和气温变化阶段性特征非常一致。 相似文献