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991.
Dissolved Organic Matter in Oceanic Waters 总被引:13,自引:0,他引:13
The amount of information on oceanic dissolved organic matter (DOM) has increased dramatically in the last decade thanks to
the advances in chemical characterization. This information has supported the development of some novel and important ideas
for DOM dynamics in the ocean. Consequently, we have a better understanding of the importance of DOM in oceanic biogeochemical
cycles. Here we review studies published mainly during 1995–2001, synthesize them and discuss unsolved problems and future
challenges. The measurement, distribution and turnover of dissolved organic carbon (DOC) are presented as the bulk dynamics
of the oceanic DOM. The size spectrum, elemental composition, and chemical compositions at molecular and functional group
levels are described. The mechanisms proposed for the survival of biomolecules in DOM are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
992.
太平洋西北海域海水中钇与稀土元素的地球化学 总被引:1,自引:0,他引:1
海水样品是在东京大学海洋研究所科学考察船(淡青丸KT)93-14次航海期间,于1993年9月12日在日本伊豆-小笠原海沟海域(29°05′N,142°51′E,水深9500m)采集的。采用化学萃取-反萃取分离法并结合等离子质谱仪,对样品进行分析研究。结果表明,海水中重稀土相对于轻稀土富集,相对于重稀土和轻稀土来说,中稀土有一定程度的亏损。钇浓度从海水表面随深度的增加而逐渐增加,与稀土元素一样在海水断面上呈营养盐型分布。同时还发现Ho是稀土中与Y相关性最好的元素,并指出Ho/Y的浓度比同样可以用来示踪海洋中水团的移动。 相似文献
993.
By measuring the maximum water level of the traces attained by the Japan Sea Tsunami on 26 May 1983, we obtained the distribution along the west coast of the northeast Japan. The level reaches a maximum at the coast eastward of the epicenter and decreases with the relationship 8.6e
–0.017x
(m) with distancex (km) measured from the coast nearest to the epicenter. A small increase of levels was observed at coasts to the south of the tsunami source having distance larger than 200 km. With the aid of tide gauge records we revealed an excitation of edge wave which brought about the small increase of levels at the southern coast. In comparison with the decrease with distance obtained on the coasts of the main islands of Japan, some noticeable peaks were observed at several small islands. It is suggested that the reason why a short period component is predominant for the initial wave motion of tsunami is that the source region has depth of 3, 000 meters. The feature of wave period is discussed in comparison with that of the 1964 Niigata Tsunami. 相似文献
994.
Evaluation of the Diurnal Warming of Sea Surface Temperature Using Satellite-Derived Marine Meteorological Data 总被引:2,自引:0,他引:2
In order to produce a high-quality sea surface temperature (SST) data set, the daily amplitude of SST (ΔSST) should be accurately
known. The purpose of this study was to evaluate the diurnal variation of sea surface temperature in a simple manner. The
authors first simulated ΔSST with a one-dimensional numerical model using buoy-observed meteorological data and satellite-derived
solar radiation data. When insolation is strong, the model-simulated 1-m-depth ΔSST becomes much smaller than the in situ
value as wind speed decreases. By forcibly mixing the sea surface layer, the model ΔSST becomes closer to the in situ value.
It can be considered that part of this difference is due to the turbulence induced by the buoy hull. Then, on the assumption
that the model results were reliable, the authors derived a regression equation to evaluate ΔSST at the skin and 1-m depth
from daily mean wind speed (U) and daily peak solar radiation (PS). ΔSST is approximately proportional to In(U) and (PS)2, and the skin ΔSST estimated by the equation is not inconsistent with in situ observation results reported in past studies.
The authors prepared maps of PS and U using only satellite data, and demonstrated the ΔSST evaluation over a wide area. The result showed that some wide patchy
areas where the skin ΔSST exceeds 3.0 K can appear in the tropics and the mid-latitudes in summer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
995.
Hiroshi Takeda 《Journal of Oceanography》1985,41(4):199-206
Transmission and reflection problems when kissing≓ occurs among planetary and topographic Rossby waves in a two-layer ocean are studied. The slope parameterS(=dh
2/dx, whereh
2is the thickness of the lower layer) is assumed to have constant values in the regionsx 0 andxL and to vary linearly with the increase ofx in the region0xL (refer to Fig. 2 in the text). Furthermore, a wave is entered fromx=– and kissing is assumed to occur in the region (0<)x
axxb(<L).It is found that a wave of the same type as the incident wave is mainly transmitted when the width of the region in which kissing occurs,L
kiss(=tx
b–xa), is smaller than
kiss=2/(¦K¦+
y/2), whereK is a representative wavenumber in the regionx
ab, y is they-component of , and is the frequency. WhenL
kiss is larger than
kiss, on the other hand, the main wave transmitted is of a different type to the incident wave. As an application, transmission and reflection problems of planetary Rossby waves are considered, and it is shown that when an external (internal) planetary Rossby wave is entered, an internal (external) one can be transmitted due to the effect of kissing. 相似文献
996.
Masayuki Takahashi Hiroko Nagai Yukuya Yamaguchi Shun-ei Ichimura 《Journal of Oceanography》1974,30(3):137-150
Chla, protein, RNA and DNA were measured in 400 samples taken from the surface down to 5,000 m at 27 oceanographical stations in the North Pacific Ocean. Two section diagrams of these cellular constituents were given along 155°E and 155°W meridians, and several vertical profiles of the four constituents were also given at some stations near Japan. The average concentration ranges of Chla, protein, RNA and DNA obtained in this study area were 0.025–0.862, 11.4–88.1, 1.36–35.3 and 0.13–5.24g/l, respectively. Chla was distributed mostly in the photic zone as we would expect. However protein, RNA were in high concentrations within the photic zone and sometimes extremely high concentrations in the deep aphotic zone. 相似文献
997.
Hiroshi Takeda 《Journal of Oceanography》1984,40(5):349-366
General characteristics of topographically trapped subinertia waves are discussed from the viewpoint of an eigenvalue problem and ray theory. Special attention is paid to the slope parameterS(x) (=(dh/dx)/h, wherex denotes the coordinate perpendicular to the shoreline, increasing seaward, andh(x) is the depth) which is a measure of the strength of the restoring force of the waves. Three cases for theS distribution are considered, in whichS is assumed to be positive at the coast and to tend to zero far from the coast. The first is whereS(x) decreases monotonically towards the open ocean. It is found in this case that waves are trapped near the coast. The second is whereS(x) does not decrease monotonically, but has a maximum. It is concluded that this case may contain two types of waves, i.e., those trapped near the coast and those trapped near the maximum, and the dispersion curves corresponding to different types may nearly intersect, namely, result in “kissing”. The third is whereS(x) has a negative region (corresponding to the presence of a trench). It is found in this case that an infinite sequence of waves is trapped in the negativeS region which propagate with the coast to their left (right) in the northern (southern) hemisphere besides the waves trapped near the coast. The topography in the second case corresponds to a typical continental shelf and a typical continental slope. It is shown by model calculation that trapped waves are present over the continental slope as well as over the continental shelf. Almost the same results are obtained for superinertia waves ifS is replaced by 1/h which is a measure of the restoring force of superinertia waves. 相似文献
998.
Shun-ei Ichimura Timothy R. Parsons Masayuki Takahashi Humitake Seki 《Journal of Oceanography》1980,36(5):259-262
Four methods were compared for the integration of14C-primary productivity per m2; (1) thein situ method at 0, 2.5, 5, 7.5, 10 and 12.5 m (standard depths 1); (2) thein situ method at 0, 5, 10 and 12.5 m (standard depths 2); (3) thein situ method at 2.5, 7.5 and 11.5 m for each sample pumped over depth intervals 0 to 5 m, 5 to 10 m, and 10 to 12.5 m, respectively (integrated depths); and (4) the simulatedin situ method for samples collected from light standard depths. The method which appeared to give the most reliable results was that (3) in which samples were averaged by pumping water over the euphotic depth followed by incubation of integrated samples at the middle of each depth interval. 相似文献
999.
Toru Kobari Kazuaki Tadokoro Hiroya Sugisaki Hiroshi Itoh 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2748
To evaluate their response to oceanographic conditions, interannual variations in seasonal abundance of Eucalanus bungii were investigated in zooplankton samples collected from the Oyashio Current system from 1960 to 2002. Large decadal changes were observed in seasonal timing and population age-structure. During the early 1970s and 1990s, E. bungii were abundant until mid-summer, but during the late 1970s and early 1980s, the season of maximum abundance was limited to spring and early summer. From the late 1970s to early 1980s, spring–summer abundance of newly recruited young copepodites (C1–C2) declined significantly, and an even more pronounced decline was observed for the abundance of the late copepodite stages (C3–C5). Monthly population structure showed that young of the year stopped development at C3 during the late 1970s to early 1980s, but molted into late copepodite stages in the other decades. Seasonal weakening of the Aleutian Low Pressure System estimated from North Pacific Index (NPI) was rapid during the late 1970s to early 1980s, and the NPI was positively correlated with phosphate concentrations at sea surface, spring–summer abundance of the young copepodites stages, and the extended duration of the season of high abundance. These results suggest that the decadal decline of copepod abundance originated at the early life stages, and was associated with a shift of atmospheric and oceanographic conditions. As possible biological mechanisms, we propose reduced egg production, lower survival for the portion of the annual cohort with late birth date, and overwintering of the survivors at younger stages. 相似文献
1000.
Hiroshi Ichikawa 《Journal of Oceanography》1978,34(4):117-128
The wave-induced fluctuations of wind velocity over wind-waves measured in the wind tunnel experiment (Ichikawa andImasato, 1976) are compared with the numerical results estimated by a linear model (Model II) on the turbulent wind field over a dominant component of wind-waves. In the Model II, the undulation of mean air flow is introduced by adopting the curvilinear co-ordinates, and the existence of viscous sublayer and the influence of underlying wind-waves to background atmospheric turbulence are taken into account. The numerical results estimated by the Model II are in good agreement with the experimental results. The good agreement, which was not obtained from the previous model (Model I) in the Cartesian co-ordinates, is shown to be attributed to the undulating mean flow introduced in the Model II. 相似文献