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1.
Diel patterns in the chlorophyll a specific absorption coefficient of surface picoplankton, a*pico (γ) (m2·[mg chlorophyll a]−1), were studied at 7 stations under daily cycle of in situ light condition in the western subarctic Pacific and Japan Sea. All the data were normalized by dividing the anomaly with daily averaged a*pico (γ). Opposite diel patterns were observed for the normalized a*pico (443) and a*pico (675) with maximum toward dawn or dusk and minimum toward midday at 4 stations under low-irradiance (LI) conditions and vice versa at 3 stations under high-irradiance (HI) conditions. The absorption efficiency factors at red absorption peak, Q
a (675), were determined by reconstruction with intracellular chlorophyll a concentration and cell diameter. The normalized Q
a (675) also showed diel pattern with maximum toward midday and minimum toward dawn or dusk under LI. The diel pattern in a*pico (675) and Q
a (675) were primarily caused by changes in intracellular chlorophyll a concentration due to photoadaptation under LI. The diel pattern in a*pico (443) was influenced by pigmentation, as recognized by blue to red ratio [a*pico (443)/a*pico (675)] under HI. This study proposed that the opposite diel pattern in a*pico (γ) might occur for a wide range of algal species. The results presented here have important consequences for the interpretation of diel variations in optical properties observed in the open ocean. 相似文献
2.
The Fukuoka Prefectural Fisheries Experimental Station has been carrying out oceanographic observations on a fixed line in
the East Tsushima Strait since 1913. Seasonal and secular changes in water temperature were investigated based on these data
from 1919 to 1979. The deviations from the mean water temperature were large in summer, especially in the thermocline layer
at 50 m. Abnormally high temperatures appear from spring to autumn whereas abnormally low temperature appears from autumn
to spring. The secular variation of water temperature in the East Tsushima Strait shows a 6- or 8-year periodicity from 1919
to 1943 and a 6-year periodicity after 1948. 相似文献
3.
Tetsuo Yanagi Satoru Takahashi Akira Hoshika Terumi Tanimoto 《Journal of Oceanography》1996,52(5):539-552
Seasonal variation in the transport of suspended matter across the East China Sea is investigated with the use of results of field observations and diagnostic numerical experiments. Suspended matter is transported from the shelf edge to the inner shelf in summer and from the inner shelf to the shelf edge in autumn and winter due to the vertical circulation mainly induced by the monsoon wind. The maximum transport of suspended matter from the inner shelf to the shelf edge occurs in autumn. 相似文献
4.
Shinya Magome Tomohiro Yamashita Takeshi Kohama Atsushi Kaneda Yuichi Hayami Satoru Takahashi Hidetaka Takeoka 《Journal of Oceanography》2007,63(5):761-773
Jellyfish patch formation is investigated by conducting a drifter experiment combined with aerial photography of a sustained
patch of the moon jellyfish in Hokezu Bay, Japan. Jellyfish patches are aggregations of individuals that are caused by a combination
of swimming (active influence) and advection by currents (passive influence). The drifter experiment involved the injection
of 49 drifters around a distinct surface patch of jellyfish within an area of approximately 300 m × 300 m. The drifters’ motion,
caused only by the passive influence, was recorded in a series of 38 aerial photographs taken over approximately 1 h. The
ambient uniform current field larger than the patch scale was estimated from the movement of the centroid position of drifters,
while the distribution of horizontal divergence and relative vorticity around the patch was estimated from the time-derivative
in areas of triangles formed by the drifters. The centroid positions of both drifters and patches moved stably toward the
bay head at different speeds. The difference vector between the patch and drifter centroids was directed to the sun, and was
opposite to the ambient current. The distributions of vorticity and divergence around patches exhibited inhomogeneity within
the patch scale, and the drifters in this nonuniform current field aggregated near the convergence area within 1 h. The results
suggest that horizontal patch formation is predominantly influenced by passive factors at the surface of Hokezu Bay. Furthermore,
the upward swimming against downwelling may make sustained patch in surface layer. 相似文献
5.
6.
Sliding of natural and artificial slopes generally occurs during or following strong earthquakes. Such sliding is greatly affected by a combination of geological conditions and earthquake loading. Earthquake-induced landslides often cause more damage to infrastructure and human lives than the earthquake itself. Pseudo-static analysis is widely implemented as one of several design methods used in engineering practice to assess the seismic stability of natural and artificial slopes. However, the most important issue of pseudo-static analysis is to select the most appropriate method for measuring seismic coefficient. In order to investigate this, back analysis was conducted for surficial slides subjected to strong ground motion during the 2004 Mid-Niigata prefecture earthquake in Japan. This paper surveyed the stochastic properties of earthquake-induced surficial slides and clearly showed that the obtained results were applicable to back analysis of shear strength and seismic coefficient. In back analysis, soil properties such as soil strength and density and sliding depth were assumed as random variables owing to their uncertainties. Seismic coefficient is also assumed to be a random variable and varies with distance from the epicenter fault line. The analysis of 4504 recorded surficial slides clearly shows a unique relationship of landslide occurrence ratio with slope angle and distance from the epicenter fault line. This study’s results enhance the calculation of the shear strength of weathered soil covering slopes and the horizontal seismic coefficient through back analysis procedure. By considering possible stochastic properties of variables, some case studies were implemented in the back analysis. 相似文献
7.
Nondimensionalization of variables enables us to treat experiment data much more simply and efficiently by decreasing the
number of variables. In some cases, trivial conclusions (which Kenney, 1982, called spurious self-correlation) result from
a formal application of dimensional analyses. In contrast, in some cases fully significant conclusions can be derived. We
first discuss how to construct nondimensional variables retaining the physical meanings of variables. We then propose simple
and efficient methods, especially the use of “spurious triangle (SpT)”, to discriminate between significant conclusions and
spurious self-correlations in the analysis of nondimensionalized variables. 相似文献
8.
Seasonal variation of the water circulations in the East China Sea and the Yellow Sea is investigated with use of a robust diagnostic numerical model. Water circulations in four season are calculated diagnostically from the observed water temperature and salinity data from JODC (Japan Oceanographic Data Center) and wind data from COADS (Comprehensive Ocean-Atmosphere Data Set). Counter-clockwise circulations are developed at the upper and middle layers and a clockwise one at the lower layer in the central part of he Yellow Sea in summer. On the other hand, a clockwise circualtion is developed from the surface to the bottom in the Yellow Sea and a counter-clockwise one in, the northern part of the East China Sea in winter. 相似文献
9.
Microbial degradation and utilization of proteins derived from bacterial detritus were investigated in a microcosm experiment
using Pseudomonas aeruginosa detritus as a substrate. To assess the effects of natural marine microbial communities on degradation and utilization of
protein derived from P. aeruginosa cells, four microcosms were prepared: natural seawater (containing the natural microbial community) with P. aeruginosa detritus (N+Pa), autoclaved seawater with P. aeruginosa detritus (A+Pa), natural seawater (N) and autoclaved seawater (A) without adding anything as a control. The numbers of total
and growing bacterial cells, protease activity, and transition of P. aeruginosa proteins were monitored in the four microcosms. Changes in the numbers of total and growing bacterial cells and protease
activities indicated that bacterial detritus significantly stimulated the microbial community in the microcosms. Both the
surviving P. aeruginosa in A+Pa and natural microbial community in N+Pa microcosms were able to degrade and utilize P. aeruginosa detritus; however, the community in N+Pa including various microbes maintained high activity longer, indicating that diversity
is an important factor in keeping the community active. Even under the very high protease activity in N+Pa, 39-kDa and 48-kDa
proteins from P. aeruginosa remained in the microcosm during the entire experiment (150 days). Immunoblotting suggested the 48-kDa protein was an intact
molecule of OprP, which had been detected from the dissolved fraction of natural seawater in previous studies. This result
suggests that the protein molecules that had been detected from natural seawater actually had a high tolerance to microbial
degradation. 相似文献
10.
Richard A. Staff Takeshi Nakagawa Gordon Schlolaut Michael H. Marshall Achim Brauer Henry F. Lamb Christopher Bronk Ramsey Charlotte L. Bryant Fiona Brock Hiroyuki Kitagawa Johannes van der Plicht Rebecca L. Payne Victoria C. Smith Darren F. Mark Alison Macleod Simon P. E. Blockley Jean‐Luc Schwenninger Pavel E. Tarasov Tsuyoshi Haraguchi Katsuya Gotanda Hitoshi Yonenobu Yusuke Yokoyama Suigetsu Project Members 《Boreas: An International Journal of Quaternary Research》2013,42(2):259-266
The varved sediment of Lake Suigetsu (central Japan) provides a valuable opportunity to obtain high‐resolution, multi‐proxy palaeoenvironmental data across the last glacial/interglacial cycle. In order to maximize the potential of this archive, a well‐constrained chronology is required. This paper outlines the multiple geochronological techniques being applied – namely varve counting, radiocarbon dating, tephrochronology (including argon–argon dating) and optically stimulated luminescence (OSL) – and the approaches by which these techniques are being integrated to form a single, coherent, robust chronology. Importantly, we also describe here the linkage of the floating Lake Suigetsu (SG06) varve chronology and the absolute (IntCal09 tree‐ring) time scale, as derived using radiocarbon data from the uppermost (non‐varved) portion of the core. This tie‐point, defined as a distinct (flood) marker horizon in SG06 (event layer B‐07–08 at 1397.4 cm composite depth), is thus derived to be 11 255 to 11 222 IntCal09 cal. years BP (68.2% probability range). 相似文献