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Robotic deep sea observation, named Deep NINJA 2021.07.21

Deep sea profiling float


Global warming refers to the disruption of the thermal balance of climate systems and the buildup of heat on Earth. Over 90% of that heat is said to be in the seas, and even a small change in the sea can have a profound impact on our living environments. This is why data regarding the sea is essential to understanding the Earth’s climate system.

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and Tsurumi-Seiki have jointly developed Deep NINJA, a robotic measuring system that can operate at depths of 4,000 meters, to gain a greater understanding of the changes global warming is causing on the surfaces and depths of the seas.


A robotic deep sea observation project aimed at gaining a greater understanding of global warming

Argo is a large-scale international program launched in the year 2000 that aims to observe changes in the world’s seas in real time. The observation devices at the heart of the Argo program are robots called “Argo Floats.” They automatically submerge to depths of 2,000 meters and float to the surface, measuring water temperatures, salinity, and the like.

This makes it possible to perform measurements in sea areas where observation vessels cannot operate and during periods when observation activities are impossible due to harsh conditions. Argo Floats can also measure data between the sea surface and deep sea areas, something that cannot be achieved with observation systems such as ship and satellite systems.

OceanObs09, an international marine science conference held in 2009, called for deep sea observation activities to be enhanced over the decade-long period ending in 2019. The construction of a new deep sea observation network using deep sea floats was proposed. Achieving this would require observation technologies that could be used in deep sea areas at depths of over 4,000 meters, a challenge that had never been taken on before.

Robotic observation systems

With support from JAMSTEC’s “Practical Implementation Promotion Program” (FY2010 to FY2012), in 2011, Tsurumi-Seiki and JAMSTEC jointly developed Deep NINJA, a profiling float for use at depths of 4,000 meters.

Tsurumi-Seiki was involved in the development of the electrical mechanism used by Deep NINJA’s functions for controlling buoyancy to submerge, float, and surface, functions for profile measurement of water temperatures, salinity, and pressure, and functions for identifying the float’s own location on the sea’s surface and transmitting data. In 2012, four Deep NINJAs were deployed in the South Pacific Ocean. In 2013, they succeeded for the first time ever in performing overwintering and a full year of continuous profile observation in the Antarctic Ocean.

In 2018, observation by Deep NINJA found that the amount of Antarctic Bottom Water was rapidly decreasing. Taiyo Kobayashi, Senior Researcher at JAMSTEC, reported on the changes to deep ocean water masses and circulation through a report that was the world’s first to use actual observation data regarding the phenomenon. Deep NINJA floats are continuing to be used in observation in the Antarctic. The operating status of the Deep NINJA devices can be viewed by anyone on the Ocean-ops website.


Deep NINJA can be used to perform deep sea observation at depths of up to 4,000 meters in all of the world’s oceans except areas that are frozen over year-round (some portions of the Arctic Ocean).


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