Underwater Acoustic Telemetry for Oceanographical and Limnological Research (Part II)

The acoustic telemetry system described in this paper is designed for measuring depth, water temperature and turbidity in a reservoir. This instrument is self-contained and transmits a modulated super sonic F-M signal to a hydrophone near the shore or the surface of the reservoir. The transmitted signal is received and then demodulated to recover the original information for depth, water temperature and turbidity by a specially designed F-M receiver, and recorded on a D. C. recorder. The system is completely acoustical and eliminates the need for electrical cables or other connecting devices. This can be also used for oceanographical observations in deep sea

SOME EXPERIMENTS ON THE SEDIMENTATION IN ESTUARIES WITH DENSITY STRATIFICATION

For the study of coloid chemical and hydrodynamic effects on estuarine sedimentation, the settling processes in salt wedges were investigated by flume experiments. The results of experiments show that strong turbulence in a thin layer on the interface between fresh and salt waters controls the settling process and cations can not directly increase the settling rate owing to weak mixing between solid particles and cations across the stable interface

Internal Waves in Lake Biwa (H) -Numerical experiments with a two layer model-

Surface and internal elevations and velocities in two layer Lake Biwa have been calculated numerically using a constant depth model with 25×62 square mesches of 1 km intervals. Linear hydrodynamic equations for the equivalent volume transports and the equivalent elevations were integrated by means of an implicit method, taking into account wind stress, bottom stress and Colioris force. In the present experiment, the case of duration time of 450 minutes for a NW-wind of 5 m/sec and of interface position of 17.5 m at the equilibrium and density difference of 2.5×10^-3 g/cm^3 between upper and lower layers was treated. From the results of Fourier spectrum analysis for the calculated time series of elevation and velocity at various sampling positions in the model lake, the long period internal Kelvin waves and internal Poincare waves were distinguished

Underwater Acoustic Telemetry for Oceanographical and Limnological Research (Part I)

This paper describes the underwater acoustic telemetry system and some results of the field operation of this system. The system consists of two units ; the one is the underwater unit (transmitter) and the other is the deck unit (receiver). The underwater unit is self-contained and can measure water temperature, and transmits the temperature information as a modulated supersonic F-M signal to a hydrophone connected to the deck unit. The received signal is demodulated to recover the original information through the deck unit which is a specially designed F-M discriminater and is then recorded on a D. C. recorder

Internal Waves in Lake Biwa (I) -The Responses of the Thermocline to the Wind Action-

In the recent preliminary observation of the internal waves in Lake Biwa, the longitudinal inclination of the thermocline due to the wind with the north component and the initial stage of the free oscillation after the wind has ceased, are observed. The period of the first swing was about 56 hours and this period just coincides with the one calculated for a simplified two layer lake. Another small periodic change with the period of 10 hr was also observed. And it is concluded that this oscillation corresponds to the transverse internal seiches under geostrophic effects

Errata to "Internal Waves in Lake Biwa (I) -The Responses of the Thermocline to the Wind Action-"

In the recent preliminary observation of the internal waves in Lake Biwa, the longitudinal inclination of the thermocline due to the wind with the north component and the initial stage of the free oscillation after the wind has ceased, are observed. The period of the first swing was about 56 hours and this period just coincides with the one calculated for a simplified two layer lake. Another small periodic change with the period of 10 hr was also observed. And it is concluded that this oscillation corresponds to the transverse internal seiches under geostrophic effects

ビワコニオケルチョウシュウキナイブセイシンノケンキュウ

京都大学0048新制・論文博士理学博士乙第2478号論理博第464号新制||理||193(附属図書館)3964UT51-49-B44(主査)教授 国司 秀明, 教授 奥田 節夫, 教授 中島 暢太郎学位規則第5条第2項該当Kyoto UniversityDA

Internal Wave Rolls Observed with the TSP, and their Contribution to Turbulent Energy Transfer

In order to investigate the role of wave breaking in mixing processes, we observe finestructures of temperature in a coastal region, by using a towed thermister chain, which referred to as Towed temperature Structure Profiler (TSP). Internal wave rolls with a wave length of about 15 m, which may be caused by the K-H instability, were captured by the TSP. The temperature field obtained by the TSP enable us to analyze turbulent processes due to internal wave breaking. Spatial scales of mixing patches associated with the internal wave rolls are estimated as about 300 m in horizontal and 2-3 m in vertical by examining the spatial distribution of wave number spectra. The radiative loss of energy from the mixing patch by internal waves are also estimated. An importance of 'pressure-velocity correlation divergence ' term in the equation of turbulent kinetic energy budget in the coastal region was discussed. 1