Flow Encountering Abrupt Topography (FLEAT)

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The scientific goal of the FLEAT research initiative is to determine the effects (process-wise) when major current systems encounter topography. Little is known about the interaction dynamics and the consequent results. Preliminary data, theory indicate that these topographic interactions influence the structure of major current systems, internal wave climates and highly-energetic down-slope flows. There are indications that ocean current interactions with major ocean ridges and island archipelagos are not properly represented in large scale models and the modeling science of “downscaling” need to be used to achieve realistic results. Multiple papers have been written on implementing the “island rule” but this concept has only ever been tested in quasi-geostrophic models and never has been evaluated with an appropriate data set.

An integrated modeling and observational program is proposed to first map and determine the dynamic response of flows to abrupt topography and second, to test ocean models nested across a wide range of scales in the context of a western Pacific, low latitude system. The goal of the proposed program is to develop the understanding necessary to quantify and predict the correct circulation in the western Pacific and its vertical structure. The critical study area follows a major subsurface ridge (the west Mariana Ridge –extending from Guam, past the Micronesian Islands, to the Mariana Trench). Few studies have been conducted in this area and the projected circulation is largely from large scale ocean models. The program will jointly address, through observation and models, circulation dynamics on scales ranging from the vertical and horizontal structure of the topographic ridge (3000m high, 10-100 km width, to 1000’s miles long) to flows near island boundaries. Establishing the linkage between these scales, which have traditionally been studied separately, will lead to fundamental advances in the science of island circulation, boundary layers, and downscaling, and subsequently, will advance our ability to accurately model the relevant processes.


  1. Understand and quantify large-scale and meso-scale processes that govern the low-latitude current interactions with topography
  2. Evaluate the need and methods for down-scaling in models of this region

The DRI is expected to run for five years (FY15-FY19). In years one, the chosen investigators will focus on planning the modeling and field deployments; we anticipate field work to be intensive in FY16-F17 and the remaining years will examine data and evaluate the modeling and simulation; some initial deployments may occur early if affordable.

We are looking for white papers addressing:

  • Modeling: process, forecast, addressing the island rule, evaluating the skill of representing flow encountering topography
  • Ship-borne studies and autonomous studies of meso-fine scale circulation
  • Data analysis as well as data assimilation

The overall effort will require integration of theory, observation and modeling to accelerate the discovery and understanding of both fine scale and basin scale processes.

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