Chapter 7 Oceanographic Surveys and Provision of Oceanographic Information
I. Oceanographic Surveys and Provision of Information to Ensure Navigational Safety
1. Oceanographic Surveys to Ensure Navigational Safety
JMSA conducts hydrographic and oceanographic surveys to ensure navigational safety, and compiles and publishes the results in hydrographic charts and publications. It also provides Notices to Mariners on ship traffic and other information.
In addition, the results of these surveys are also used as the basic data for the prediction of the drifting of objects during maritime distress, earthquake prediction, and the various types of marine development in coastal areas.
(1) Surveys of Ports and Coastlines and Surveys to Update Charts
JMSA conducts surveys of ports and coastlines and surveys to update charts, to publish new or revised nautical charts in order to ensure navigational safety in coastal areas, by incorporating changes in the status quo that result from harbor renovations and other changes.
(2) Oceanographic Surveys
Large hydrographic survey vessels conduct hydrographic and oceanographic surveys to prepare navigational charts used by ships navigating on the high seas.
(3) Geomagnetic Surveys
Precise magnetic variations and annual variations must be noted on sea and aviation charts to ensure the safety of ships and aircraft using magnetic compasses.
It is for this reason that, the Hachijo Hydrographic Observatory conducts regular geomagnetic observations, as well as conducts magnetic measurements by aircraft of the waters surrounding Japan and annual variation measurements at land-based points along the coast, every five years for two years at a time.
(4) Port and Harbor Investigation
Because sailing directions note the current state of harbors, in FY 1995, JMSA investigated 110 harbors such as Niigata Harbor. During FY 1996, it is investigating harbors such as Otaru Harbor.
