Program Managers

Scott Harper

ONR

Martin Jeffries

ONR

SODA INVESTIGATORS:

Science Steering Team

Sylvia Cole

Woods Hole Oceanographic Institution

Craig Lee, Chair

APL-UW

Jennifer MacKinnon

Scripps Institution of Oceanography

Tim Stanton

Naval Postgraduate School

Jeremy Wilkinson

British Antarctic Survey

_______

Matthew Alford

Scripps Institution of Oceanography

Dale Chayes

University of New Hampshire

Kyoung-Ho Cho

Korean Polar Research Institute

Martin Doble

Polar Scientific Ltd.

Lee Freitag

Woods Hole Oceanographic Institution

John Guthrie

APL-UW

Steve Jayne

Woods Hole Oceanographic Institution

Joo-Hong Kim

Korean Polar Research Institute

James Morison

APL-UW

Ruth Musgrave

Massachusetts Institute
of Technology

Jae-Hun Park

Inha University

Tom Peacock

Massachusetts Institute
of Technology

Luc Rainville

APL-UW

Bill Shaw

Naval Postgraduate School

Harper Simmons

University of Alaska, Fairbanks

Oliver Sun

Naval Oceanographic Laboratory, Stennis Space Center

Jim Thomson

APL-UW

John Toole

Woods Hole Oceanographic Institution

Dan Torres

Woods Hole Oceanographic Institution

Lovro Valcic

Bruncin d.o.o.

Research Sponsor

ONR

Stratified Ocean Dynamics of the Arctic (SODA)

Science & Experiment Plan – Office of Naval Research Departmental Research Initiative

Overview

Vertical and lateral water properties and density structure within the Arctic Ocean are intimately related to the ocean circulation, and have profound consequences for sea ice growth and retreat as well as for propagation of acoustic energy at all scales.

Recently, there has been significant arctic warming, accompanied by changes in the extent, thickness distribution, and properties of the arctic sea ice cover. Summertime sea ice extent has been declining since at least 1979.

Sea ice has become younger alongside the decreases in extent. Sea ice thickness typically increases with age, such that the combined trends toward decreasing extent and younger mean age point to a persistent loss of sea ice volume. Thinner, younger ice tends to be weaker, more subject to deformation and fracturing, and thus more mobile and more likely to provide efficient coupling between the atmosphere and upper ocean. Furthermore, the growing summertime expanses of open water provide periods when the dynamics might more closely resemble those that govern the upper ocean at lower latitudes.

The need to understand these changes and their impact on arctic stratification and circulation, sea ice evolution, and the acoustic environment motivate the Office of Naval Research (ONR) Stratified Ocean Dynamics of the Arctic Departmental Research Initiative (SODA DRI).

Objectives

SODA focuses on understanding how the upper Beaufort Sea responds to changes in inflow and surface forcing. Specific science questions address three oceanographic properties: buoyancy, momentum, and heat.

Buoyancy

Momentum

Heat

What are the causes and consequences of the changing upper ocean stratification (mixed layer and Pacific Water)?

Vertical: What is the interplay among wind entrainment, convection, solar heating, and buoyancy input?

  • On synoptic, seasonal, and year-long integral timescales?
  • How does this balance vary with sea ice conditions?

Lateral: What is the importance of heterogeneity in mesoscale and submesocale processes?

  • On synoptic, seasonal, and year-long integral timescales?
  • How spatially variable is this balance? (Is it more important at some locations, e.g., ice edge, mesoscale fronts, etc.?

How is the wind stress partitioned within the ice–ocean system (depth and frequency; surface waves; ice motions; mixed layer and deeper acceleration; internal waves)?

  • How do sea ice properties affect this partition?
  • How do the buoyancy flux and stratification affect the partition?
  • How do lateral contrasts in forcing or ocean structure affect the partition and create secondary circulations?
  • How does the phenology of the air–ice–ocean system affect the partition?

What is the fate and impact of the significant increase in upper ocean heat (and the associated sound channel)?

What processes control the near surface temperature maximum formation and release?

  • How does it impact the fall sea ice freeze-up?
  • How does it vary with sea ice conditions?

How difficult is it for the mixed layer to entrain and access heat carried in the Pacific Water, and how does it vary with sea ice conditions?

Time series of Northern Hemisphere sea ice extent anomalies in March (the month of maximum ice extent) and September (the month of minimum ice extent). The anomaly value for each year is the difference (in %) in ice extent relative to the mean values for the period 1981–2010. The black and red dashed lines are least squares linear regression lines. The slopes of these lines indicate ice losses of –2.6% and –13.4% per decade in March and September, respectively. Both trends are significant at the 99% confidence level. From Perovich et al. (2015).

A time series of sea ice age in March from 1985 to the present (top) and maps of sea ice age in March 1985 (lower left) and March 2015 (lower right). From Perovich et al. (2015).

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