Ocean Circulation Research Group

The goal of this group is to enhance understandings of ocean circulation and mid-to-long-term global-scale changes of ocean climate.

1. Ocean observations with Argo profiling floats

We take advantage of the mobility of Argo floats to strategically deploy them at times and places best suited to elucidate changes in the properties of the ocean.

2. Data synthesis by using a 4-dimensional (time and space) variational data assimilation (4D-VAR) approach:

Application of sophisticated data assimilation methods allows us to estimate global ocean states over a 50-year time period with the Earth Simulator. Our forte is our ability to assimilate data synthesis techniques into climate research.

3. Data management for climate research:

The Pacific Argo Regional Center (PARC) has developed a highly sophisticated data management system for climate research and contributes to the quality control of a wide variety of ocean observations, including Argo float data.

Approach and vision

  • We strategically deploy and control Argo profiling floats. Use of global Argo float data along with high-quality hydrographic observations, remote sensing products, and ocean general circulation models, allows us to carry out data synthesis experiments that produce a comprehensive estimation of the state of the ocean.
  • Our products (up-to-date Argo float data and improved ocean state estimation) facilitate ocean circulation research. The feedback between data and models enables us to clarify ocean climate changes, optimize observations, and provide information that can be used to improve general circulation models.
Argo float
  • In carrying out this work, we hope to reveal the structure of subsurface ocean properties/circulation and to quantify the influence of changes in this structure on variations in climate and the global changes in the heat content of the ocean and the oceanic freshwater budgets.

Research activity for fiscal year 2014

1. Ocean observations with Argo profiling floats:

We are focusing on the properties of water masses in the North Pacific and Southern Ocean, which play a key role in global climate change. The PARC is supporting scientific activity related to Argo float data. Part of this research contributes to the Global Argo Project, an international research effort.

2. Data synthesis by using a 4D-VAR approach:

The Estimated State of the Ocean for Climate Research (ESTOC) is being produced with our ocean data synthesis system on the Earth Simulator. The synthesis system is being updated to enhance the quality of the ESTOC. We will conduct global change research with the synthesis dataset.

3. Surveys with a research vessel:

We use the JAMSTEC research vessel Kaiyo to elucidate the formation and transformation of subtropical mode water.

Global Distribution of Argo Floats
Global Distribution of Argo Floats
Simulated rapid warming of abyssal North Pacific Waters: One example of how climate change research takes advantage of the data synthesis system.
Simulated rapid warming of abyssal North Pacific Waters: One example of how climate change research takes advantage of the data synthesis system.

Goal: discover characteristics of subsurface water masses and ocean circulation and the relationship between variations in these physical properties and changes in the characteristics of the ocean such as heat content and fresh water budgets relevant to mid-to-long-term climate change.