Isotope fractionation of neon during stepheating extraction?: a comment on ‘Re‐interpretation of the existence of a primitive plume under Australia based on neon isotope fractionation during step heating’ by Gautheron and Moreira (2003)     

Takuya Matsumoto  Masahiko Honda  Ian McDougall  Igor Yatsevich  Suzanne Y. O'Reilly 《地学学报》2004,16(1):23-26

Using a Rayleigh distillation fractionation model, we calculate that the maximum isotope fractionation potentially achievable is less than 5% during the early stages of gas release from a sample. Our calculation corrects the erroneous conclusions of Gautheron and Moreira (2003), who re‐interpreted the plume‐like neon isotopic compositions found in metasomatic apatite from a south‐eastern Australian xenolith (Matsumoto et al., 1997) to be the result of Rayleigh‐type isotope fractionation of originally MORB‐type neon during stepheating gas extraction. We stress that the modelling of neon isotopic fractionation by Gautheron and Moreira (2003) is incorrect, and that the finding of a plume‐like neon isotopic composition in the apatite by Matsumoto et al. (1997) remains a quite valid and robust conclusion.  相似文献   

Real-time difference imaging analysis of MOA Galactic bulge observations during 2000     

I.A. Bond  F. Abe  R.J. Dodd  J.B. Hearnshaw  M. Honda  J. Jugaku  P.M. Kilmartin  A. Marles  K. Masuda  Y. Matsubara  Y. Muraki  T. Nakamura  G. Nankivell  S. Noda  C. Noguchi  K. Ohnishi  N.J. Rattenbury  M. Reid  To. Saito  H. Sato  M. Sekiguchi  J. Skuljan  D.J. Sullivan  T. Sumi  M. Takeuti  Y. Watase  S. Wilkinson  R. Yamada  T. Yanagisawa  P.C.M. Yock 《Monthly notices of the Royal Astronomical Society》2001,327(3):868-880

We describe observations carried out by the MOA group of the Galactic bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These events are particularly useful for studies of extrasolar planets and faint stars. Approximately 17 deg² were monitored at a sampling rate of up to six times per night. The images were analysed in real time using a difference imaging technique. 20 microlensing candidates were detected, of which eight were alerted to the microlensing community whilst in progress. Approximately half of the candidates had high magnifications (≳10), at least one had very high magnification (≳50), and one exhibited a clear parallax effect. The details of these events are reported here, together with details of the on-line difference imaging technique. Some nova-like events were also observed and these are described, together with one asteroid.  相似文献   

Diel Patterns in Chlorophyll <Emphasis Type="Italic">a</Emphasis> Specific Absorption Coefficient and Absorption Efficiency Factor of Picoplankton     

Nobuaki?OhiEmail author  Hiroaki?Saito  Satoru?Taguchi 《Journal of Oceanography》2005,61(3):379-388

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   

Seasonal and secular variations of water temperature in the East Tsushima Strait     

Tsunehiro Miita  Satoru Tawara 《Journal of Oceanography》1984,40(2):91-97

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   

Seasonal variation in the transport of suspended matter in the East China Sea   总被引：8，自引：0，他引：8  

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   

Excess CO2 and pHexcess in the Intermediate Water Layer of the Northwestern Pacific     

Andrey Andreev  Makio Honda  Yuichiro Kumamoto  Masashi Kusakabe  Akihiko Murata 《Journal of Oceanography》2001,57(2):177-188

Excess CO₂ and pH_excess showing an increase in dissolved inorganic carbon and a decrease in pH from the beginning of the industrial epoch (middle of the 19th century) until the present time have been calculated in the intermediate water layer of the northwestern Pacific and the Okhotsk Sea. It is concluded that: (1) The Kuril Basin (Okhotsk Sea) and the Bussol' Strait areas are characterized by the greatest concentrations of excess CO₂ at isopycnal surfaces due to the processes of formation and transformation of intermediate water mass. (2) The largest difference in excess CO₂ concentration between the Okhotsk Sea and the western subarctic Pacific (about 8 µmol/kg) is found at the = 27.0. (3) The difference in excess CO₂ between the western subarctic Pacific and subtropical regions is significant only in the upper part of the intermediate water layer ( = 26.7–27.0). (4) About 10% of the excess CO₂ accumulation in the subtropical north Pacific is determined by water exchange with the subarctic Pacific and the Okhotsk Sea.  相似文献   

Seasonal variation of circulations in the East China Sea and the Yellow Sea   总被引：2，自引：0，他引：2  

Tetsuo Yanagi  Satoru Takahashi 《Journal of Oceanography》1993,49(5):503-520

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   

Nankai Trough: A hot trench?     

M. Yamano  S. Honda  S. Uyeda 《Marine Geophysical Researches》1984,6(2):187-203

Heat flow estimated from the gas hydrate layers on the landward slope of the Nankai Trough reveals that heat flow increases downslope toward the trench floor. This data plus six new heat flow values obtained by a conventional probe and two values available from DSDP drill holes give a fairly detailed heat flow distribution in the Nankai Trough area, when combined with the already existing data set. There appears to be a zonal pattern parallel to the trough axis, with a high heat flow zone on the floor of the trough that is quite anomalous for a subduction zone. It might be explained as a result of subduction of the hot portion of the Philippine Sea plate, i.e. the Shikoku Basin, and/or of more local effects such as heating due to intrusion of hot water from subducted sediments to shallow depth beneath the trough floor. Surface heat flow patterns landward of the trough were calculated for a simple thermal model of subduction. Perfect reproduction of the observed zonal pattern is difficult to achieve by the simple model, suggesting the necessity for further heat flow and other observations.  相似文献   

Jellyfish patch formation investigated by aerial photography and drifter experiment     

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   

Effects of a soft surface layer on near-fault static and dynamic displacements     

Ryou Honda  Kiyoshi Yomogida 《Geophysical Journal International》2003,154(2):441-462

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