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251.
日本海洋科学技术中心最近发表观测报告宣布,在日本列岛东部海域发现见了过去未曾观测到的强大海流。 报告说,这股海流的位置在流经日本列岛南部的暖流以北250公里处,由东向西,与暖流呈相反方向,流速达3.5节(1.852公里)每小时。据悉,这股暖流是科学家们于本月初通过观测浮标的位移而发现的。该中心认为这一发现颇有意义,并表示将进一步研究这股海流对渔业资源及二氧化碳吸收量等的影响。 相似文献
252.
The upper layer (above 140 m depth) temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring
buoy (CMB) with 15 attached thermistors during July 28–August 7, 2005. The data were collected every 10 min at 1, 3, 5, 10,
15, and 20 m using the CMB sensors, and every 15 sec at 15 different depths between 25 m and 140 m. Internal waves and solitons
were identified from the time-depth plot of the temperature field. Without the internal waves and solitons, the power spectra,
structure functions, and singular measures (representing the intermittency) of temperature field satisfy the power law with
multi-scale characteristics at all depths. The internal waves do not change the basic characteristics of the multifractal
structure. However, the internal solitons change the power exponent of the power spectra drastically, especially in the low
wave number domain; they also break down the power law of the structure function and increase the intermittency parameter.
The physical mechanisms causing these different effects need to be explored further. 相似文献
253.
Mesoscale features in the eastward extension of the Kuroshio were investigated using assimilation of TOPEX/POSEIDON (T/P)
data into a three-layer quasi-geostrophic model. The T/P data exhibited an elongated state of the southern recirculation gyre
in 1993–95 and 1997, between whose two periods the gyre had a contracted state in 1995–96. A few stationary eddies were located
in the southern gyre during the contracted state. The baroclinic instability, which was indicated by the phase shift from
the uppermost-to the lowest-layer anomalies toward the downstream side, was evident near the Kuroshio Extension (KE) path.
Since the instability never appeared in the artificial model without bottom topography, the topographic barrier for the eastward
flow in the lowest layer was a necessary condition for the instability. The instability synchronized with the transition in
the western region of the KE axis from the elongated to the contracted states. This evolution was interpreted as if the baroclinic
instability played some part in the KE states and was a trigger for the transition from the elongated to the contracted states. 相似文献
254.
255.
Following our previous study (Sugimoto and Hanawa, 2005b), we further investigate the reason why reemergence of winter sea
surface temperature anomalies does not occur in the North Pacific eastern subtropical mode water (NPESTMW) area, despite its
occurrence in the North Pacific subtropical mode water and North Pacific central mode water areas. We use vertical temperature
and salinity profiles of the World Ocean Circulation Experiment Hydrographic Program and Argo floats with high vertical and
temporal resolution, together with heat flux data through the sea surface. We point out first that one of the causes for non-occurrence
of reemergence is that the thickness of NPESTMW is very thin. In addition to this basic cause, two major reasons are found:
a vigorous mixing in the lower portion of NPESTMW and less heat input from the atmosphere in the warming season. Since, in
the lower portion of NPESTMW and deeper, the stratification is favorable for salt-finger type convection to occur compared
with the other mode water areas, vigorous mixing takes place. This is confirmed by both a large Turner Angle there and the
existence of staircase structures in vertical temperature and salinity profiles. From the viewpoint of heat input, the NPESTMW
area gradually gains heat in the warming season compared with other mode water areas. As a result, NPESTMW cannot be capped
so quickly by the shallow summer mixed layer, and water properties of NPESTMW are to be gradually modified, even in the upper
portion. 相似文献
256.
A geomorphological and statistical analysis of slope canyons from the northern KwaZulu-Natal continental margin is documented
and compared with submarine canyons from the Atlantic margin of the USA. The northern KwaZulu-Natal margin is characterized
by increasing upslope relief, concave slope-gradient profiles and features related to upslope growth of the canyon forms.
Discounting slope-gradient profile, this morphology is strikingly similar to canyon systems of the New Jersey slope. Several
phases of canyon incision indicate that downslope erosion is also an important factor in the evolution of the northern KwaZulu-Natal
canyon systems. Despite the strong similarities between the northern KwaZulu-Natal and New Jersey slope-canyon systems, key
differences are evident: (1) the concavity of the northern KwaZulu-Natal slope, contrasting with the ∼linear New Jersey slope;
(2) the relative isolation of the northern KwaZulu-Natal canyons, rather than the dense clustering of the New Jersey canyons;
and (3) the absence of strongly shelf-breaching canyons along the northern KwaZulu-Natal margin. In comparison with the New
Jersey margin, we surmise a more youthful stage of canyon evolution, a result of either the canyons themselves being younger
or the formative processes being less active. Less complicated patterns of erosion resulting from reduced sediment availability
have developed in northern KwaZulu-Natal. The reduction in slope concavity on the New Jersey margin may be the result of grading
of the upper slope by intensive headward erosion, a process more subdued—or less evident—on the KwaZulu-Natal margin. 相似文献
257.
作者引入 I(L)值完全下半连续映射 ,研究其性质。利用 I(L)值完全下半连续映射定义I(L)值完全诱导空间 ,给出 I(L)值完全诱导空间的拓扑基的表达形式 ,证得两个 I(L)值完全诱导空间的映射是连续映射的充分必要条件 ,并建立了乘积空间的 I(L)值完全诱导空间与 I(L)值完全诱导空间的乘积空间的联系 相似文献
258.
讨论了~936)Cl的成因、~(36)Cl断代法的原理及测试方法。自1987年以来,应用该方法测得柴达木盆地尕斯库勒湖和大浪滩湖石盐的沉积年龄,并与~(14)C,~(230)Th和古地磁测年法所测得的年龄数据进行对比,结果均在误差(1δ)范围内相吻合,表明石盐的~(36)Cl断代法是可行的,获得的年龄数据是可靠的。 相似文献
259.
本文选择酒石酸消除海水基体对铜信号的干扰,用塞曼石墨炉原子吸收法直接测定海水中的铜。从Cu的原子化曲线可知,加入酒石酸后,背景值减小,Cu原子吸收信号增强,且出现时间提前,表明酒石酸是有效的海水基体改进剂。用P.E.Z3030光谱仪测得双蒸水及海水中的元素Cu的特征质量(m。)分别为12.5pg及12.7pg;检测限分别为0.18μg/L和0.19μg/L,表明基体效应已消除,符合海洋监测要求。可用纯Cu标准溶液作校正曲线,以国家海洋局的两个标准海水样品中的Cu评定本法的准确度,相对偏差为0及-4.6%,与经典的经富集后的FAAS法的结果相比,相对偏差在3.0—6.5%范围内。用不同类型的光谱仪测定了30个海水样品,回收率在89—104%范围内。本法操作简便、快速。 相似文献
260.
Robert D. Moore Leroy M. Dorman Chin-Yen Huang David L. Berliner 《Marine Geophysical Researches》1981,4(4):451-477
We describe the design and construction of an ocean bottom seismometer configured as a computer, based on an Intersil IM6100 microprocessor plus appropriate peripheral devices. The sensors consist of triaxial 1 Hz seismometers and a hydrophone, each sensor channel being filtered prior to digitizing so that typical noise spectra are whitened. Digital data are recorded serially on magnetic tape. The instrument is placed on the ocean bottom by allowing it to fall freely from just below the surface. An acoustic system allows precise determination of instrument position, acoustic recall, and transmission of operational information to the surface. Release from an expendable anchor is accomplished by redundant pyrotechnic bolts which can be fired by acoustic command or by precision timers.The operational flexibility provided by the micro-computer, which executes the DEC PDP8/E instruction set, enables optimum use of the 6-hr recording capacity (at 128 samples/second/channel) in the context of the particular experiment being performed.
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