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91.
92.
Abstract

The propagation of Rossby-gravity waves, which are of astronomical interest near the critical level (or corotation point), is considered in a linear-shear, exponentially stratified flow by means of a ray tracing method. It is shown, using the analytic solutions for the stream function, that for a Richardson number J > 1/4 a wave-packet can cross the critical level in a finite time. In the unstable stratified case (J < 0), it cannot cross the critical level for large |J| (J < 0), but may do so for some intermediate |J| values.

Based on the above results, the possible existence of the regular normal mode with a discrete point eigenvalue in the continuous spectrum is discussed for bounded systems.  相似文献   
93.
94.
Diurnal Sea Surface Temperature (SST) variations and the near-surface thermal structure of the tropical hot event (HE) have been investigated using advanced in-situ equatorial observations with hourly temporal resolution. The information on the HE area defined by the satellite cloud-free SSTs is used to sample the in-situ observations. The in-situ SSTs sampled for the HE conditions show that a maximum (minimum) SST has a histogram mode at 30.8°C (29.0°C), and frequently appears at 15:00 (07:00) local time. The amplitude of the diurnal SST variation (DSST) is defined by the difference between the maximum and minimum SSTs. The mean DSST during HEs is greater than 0.5°C, and has a maximum of about 0.75°C at the HE peak. The time series of mean DSST gradually increases (rapidly decreases) before (after) the peak. The satellite SST has a systematic positive bias against the corresponding daytime SST measured by the Triangle Trans-Ocean buoy Network. This bias is enhanced under conditions of large in-situ DSST. One-dimensional numerical model simulation suggests that the systematic bias is caused by the sharp vertical temperature gradient in the surface layer of HE. The near-surface thermal structure is generated by conditions of high insolation and low wind speed, which is the typical HE condition.  相似文献   
95.
Ocean Dynamics - Although the different aspects of wave-mud interaction have been studied by many researchers, few studies have been conducted on the effect of solitary wave on the particle...  相似文献   
96.
Analytical data for five GSJ (Geological Survey of Japan) reference samples, the "Instrumental analysis series" received by October 1998, are compiled. The data reported in publications and personal communications were evaluated statistically, taking into account the analytical method and sample preparation. Based on the selected available data, recommended and preferred values for fourteen major and fifty one minor and trace elements are proposed.  相似文献   
97.
Two steps have been taken to decide at what place and altitude to set up the JNLT on Mauna Kea. First, the wind tunnel experiment has been made in collaboration with the Institute of Meteorology using the two models of summit area with the reduced scales of 1/1000 and 1/5000. This study tells us that the north-west cone is suitable for JNLT. Secondly, we have done the measurement of the microthermal activities in this area with a 30 m tower, which was continued for about 4 months in collaboration with the University of Hawaii. This experiment has given the mean vertical profile ofC T 2 over 4 months and its scale height in the boundayr layer on our site. By use of these measurements, the contribution of the boundary layer to seeing is estimated. The behaviour ofC T 2 under strong winds can be explained very well by topographic effects, which is in fairly good agreement with the results of our wind tunnel experiment.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.  相似文献   
98.
Masataka Ando 《Island Arc》2001,10(3-4):206-214
Abstract The Nojima Fault Zone Probe was designed to study the properties and recovery processes of the Nojima Fault, which moved during the Hyogo-ken Nanbu earthquake ( M JMA7.2) of 1995. Three holes, 500 m, 800 m and 1800 m deep, were drilled into or near the fault zone by the Disaster Prevention Research Institute, Kyoto University. The 500 m and 800 m holes were drilled in November 1995, and in December 1996 the last hole reached its final depth of 1760 m. The significant results are: (i) Geological and geophysical reconstruction of the structure and evolution of the Nojima Fault was obtained; (ii) the maximum compression axis was found to be perpendicular to the fault, approximately 45° to the regional compression stress axis; (iii) micro-earthquakes (m = –2 to +1) were induced by water injections 1–3 km from the injection points in the 1800 m hole; (iv) the fault zone was measured to be 30 m wide from microscopic studies of core samples. Instruments such as three-component seismometers, crustal deformation instruments, and thermometers were installed in the holes.  相似文献   
99.
To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg− 1 (average 199 μg kg− 1, n = 22) and 23–100 μg kg− 1 (average 55 μg kg− 1, n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter.  相似文献   
100.
Hydrographic measurements by CTD were made in the western-central Equatorial Pacific (160°W–147°E) during the Japanese Pacific Climate Study cruise in January–February 1991. InT-S diagram, three water masses are seen in the layer of kg/m3: salinity water corresponding to the Tropical Water of eastern South Pacific origin, less saline water in the North Pacific, and water with salinity between the above two, found on the equator. In three meridional sections (160°W–160°E), the Tropical Water of eastern South Pacific origin extends further equatorward than the climatological data of Levitus (1982).  相似文献   
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