Harmonic coefficients of site displacements due to the solid earth tide and the ocean loading are estimated for 50 observation sites of space geodetic techniques in Japan. Mean amplitudes of the solid earth tide and the ocean loading are 15cm and 1-2cm, respectively. Variations of 1000km baselines due to the solid earth tide are 1 cm and 2 cm in baseline length and vertical component, respectively. Variations of domestic baselines due to the ocean loading are several mm and 1 cm in baseline length and vertical component, respectively. This model gives better precision in the satellite laser ranging (SLR) analysis of the Titi Sima-Simosato baseline.

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We have successfully developed application technologies of GPS in the Oceans. The progress of technologies in our company based on continuous investigations with some manufactures.
Firstly, we have introduced high-precision D-GPS to survey system of ocean depth. Secondly, we have constructed RTK- OTF-GPS to manage data automatically. This system is applied to constructions in the oceans.
Hitherto, GPS surveying required an initialization of "rover" receivers before use. If satellites signals are blocked, then the surveyor must go to a known point to re-initialize the system. However, our new GPS can re-initialize while you're moving-"on the fly" (OTF).
Key Features:
·GPS provide gains on projects when line-of-sight is a problem, such as sties rolling terrain, large equipment, rain and fog problems, and so forth.
·Centimeter-accuracy in real-time,
·Multiple rovers form one base instrument station,
·Automatic initialization while stationary or while moving,
·GPS observations and positions are available directly from the field.

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A new versatile deep-sea three-component magnetometer has been developed in order to investigate fine magnetic structures of the oceanic crust. The system includes a tri-axis fluxgate magnetometer, an attitude detection meter and a depth meter. The system is operated with an AC or battery power supply. The magnetometer and the attitude detection meter measure the magnetic field vectors and the roll and pitch of the system every 0.5 or 1 sec. Vector geomagnetic anomalies are calculated from these data and yaw data measured by an external gyro system. Observations with the battery power supply can be made continuously for as long as 18 hours for 0.5 sec sampling and 36 hours for 1 sec sampling. The depth meter provides the pressure data and the temperature data every 3.5 sec. This system operates to a maximum depth of 6,500 m. In addition to the above performance, it has versatile usage which enables us to make the following three types of observations using the same instruments: a stand-alone observation; a cooperative observation with another deep-sea system; an on-board observation. We successfully measured the geomagnetic field near the ocean bottom around the Mid-Atlantic Ridge and the west Kane Transform Fault using our magnetometer system mounted on the submersible "Shinkai 6500" in 1994. We will here explain the present system and show some of the results obtained in 15 dives by the "Shinkai 6500".

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