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Island Arc Turbulent Eddy Regional Exchange (ARCTERX)

The western Pacific region between the Luzon and Marianas Island Arcs is known for its rich eddy field. The combination of the Kuroshio Current, the monsoon, strong tides, and the dramatic topography lead to a rich physical forcing environment. The focus will be on the turbulent eddy exchange throughout this region, and on the class of oceanographic variability that is poorly constrained in models including eddies, rings, vortices and filaments, and their interactions with smaller-scale phenomena. The work will pursue in-situ sampling with a heavy emphasis on autonomous instrument platforms, which have the ability to follow features of interest over weeks to months over vast regions. Remote sensing, and ocean modeling, both from large-scale assimilative models, and finer-scale process resolving models, will also play a central role in the study.


The objectives of the proposed study are to understand the nature of the ARCTERX sub-mesoscale cascade. This topic has outstanding potential to produce new understanding of small-scale and rapidly evolving variability in the region. Specific questions include:

  • What are the dynamic and thermodynamic characteristics of the sub-mesoscale features (e.g. meanders, rings, vortices, filaments) in this region that distinguish it from other regions?
  • Do numerical models have the correct parameterizations to characterize the sub-mesoscale cascade?
  • What time and space scales characterize the sub-mesoscale cascade in this region?

Awards for the ARCTERX study will begin FY21. Following a year of planning, the primary study period will occur FY22-24, with a dedicated year of analysis in FY25. As such, 5-year plans are welcome.

Outcomes are expected on fundamental principles:

  • Improve our physical understanding of sub-mesoscale variations in ARCTERX region.
  • Testing of hypotheses related to questions of evolution scales of the sub-mesoscale cascade.
  • Production of a dataset suitable for model validations, leading to improvement of the forecast skills of high-resolution coupled models.

Request for Planning Letters

The first step in the DRI process is for prospective investigators to prepare planning letters. The purpose of the planning letters is to allow investigators to submit a short (three pages maximum) summary of their ideas on this topic for ONR to evaluate, provide technical feedback and indicate whether a full proposal would have a reasonable chance of success.

Important Dates

October 15, 2020: Last date to submit planning letters (submit by email)

November 15, 2020: Last date ONR will respond to all submitted planning letters and requests for proposals

January, 2021: Earliest anticipated commencement of awards made with FY21 funding - dependent on USG budgetary process

All planning letters should be submitted by email to:

Dr. Scott Harper ( and Dr. Lou St. Laurent (

Please note "ARCTERX planning letter and 'Your Name'" in your email subject line. If you do not receive a thank you note within 10 days, please follow-up with a resend.