Collaborative Research: Sampling the Ocean-Sea Ice Interaction in the Pacific Center of the Antarctic Dipole

PI: Xiaojun Yuan, Lamont-Doherty Earth Observatory of Columbia University

PI: Janet Sprintall, Scripps Institution of Oceanography

Program Description

The Antarctic Dipole (ADP) presents the strongest tropical-polar teleconnection climate signal in the Southern Ocean, with poles centered within the Ross Gyre of the Pacific sector and the central Weddell Gyre of the Atlantic sector. The ADP is a standing mode pattern characterized by out-of-phase relationships in the surface air temperature, sea surface temperature, and sea ice fields. The opposing large-scale spatial patterns of the ADP within the Pacific and Atlantic centers are clearly associated with both positive and negative phases of ENSO. Outside these sectors the anomalies are not coherent or distinct. Furthermore, the anomalous signals persist in the subpolar waters for nearly a year after the demise of the ENSO event in the tropics. While the atmospheric and sea surface signatures of the ADP have received much recent attention, little is known about the role of the upper ocean in maintaining and reinforcing the ADP climate anomalies in the Southern Ocean. Clearly the upper ocean has a longer memory and larger heat capacity than the atmosphere to store anomalous climate signals.

The key component of the project is a deep sea subsurface mooring that reach to the mixed layer in winter. The project directly monitors the upper ocean in the regional centers of the strongest climate signal in the Southern Ocean, and investigate the role of the ocean in the highly coupled air-sea-ice system that maintains this signal. Our over-riding objective is to document and investigate the processes of ocean-sea ice interaction that amplify and maintain the strong ADP signal in the subpolar ocean. The multi-year, high vertical resolution mooring data will provide unique measurements of the upper ocean temperature and salinity characteristics in the Pacific ADP center, from the mixed layer through the thermocline, from synoptic to interannual time scales. sampling effort.


        National Science Foundation, Office of Polar Program
        United States of America


Supported by Chief Scientist James Swift from SIO and Co-chief scientist Alex Orsi from TAMU, the ADP mooring was successfully deployed on April 3, 2011 during CLIVAR S04P (NBP11-02) cruise. Mooring specialist, James Ryder of WHOI, led the deployment effort. The mooring team used the Palmer's multi-beam bathymetric mapping system (managed by Chris Linden, RPSC) to map the ocean floor searching for a relatively flat bottom, then conducted a CTD cast at the chosen site to measure the water characteristics and verify the bottom depth.During the first year of the mooring deployment, no alarm beacon signal has been received, indicating that the mooring currently still stays under the surface. Scientists on board of NBP conducted all five planned CTD stations for the mooring project, three of them were part of the S04P transect. All S04P CTD data have been processed by the Scripps team and posted on the web site of CCHDO ( Numbers of XBTs were also deployed in the adjacent area of the mooring. Four ice-avoidance APEX floats were deployed in the vicinity of the mooring site during austral summer of 2010. These floats went under sea ice cover between mid March to early May 2010, stayed under the ice for 6-8 months. All four floats survived the first winter and re-appeared in austral summer 2011.

The mooring recovry is scheduled on NBP13-02, Feb. 2013.

The mooring consists an Ice Profiler Sonar (IPS) at the 100m depth and a series of discrete temperture, conductivity and pressure sensors, as well as a current meter between 100m and 200m. The design allows the MMP to travel from 204 to 1206m on a stiff mooring line, measuring the stratification through the temperature maximum. A temperature and pressure sensor is isntalled near the bootom. In addition, the mooring has two alarm beacons, in case of a premature surface of the mooring.

ADP mooring design.


S04P cruise track with ADP mooring location at 66.6612S and 136.0593W.

The mooring team assampled the mooring prior to the deployme. (photo credit: Juan Botella)

Jim Ryder (WHOI) led the mooring deployment. (photo credit: Chris Measures)



McKee, D. C; X. Yuan; A. L. Gordon; B. A. Huber; Z. Dong. Climate Impact on Interannual Variability of Weddell Sea Bottom Water. J. Geophys. Res. - Oceans. VOL. 116, C05020, doi:10.1029/2010JC006484, 2011. Nuncio, M.; A. J. Luis; and X. Yuan. Topographic Meandering of Antarctic Circumpolar Current and Antarctic Circumpolar Wave in the ice-ocean-atmosphere system. Geophys. Res. Lett., VOL. 38, L13708, doi:10.1029/2011GL046898, 2011. Yuan, X., and E. Yonekura, Decadal variability in the Southern Hemisphere, J. Geophys. Res-Atmospheres., 116, D19115, doi:10.1029/2011JD015673, 2011. Montes-Hugo, M. and X. Yuan, Climate patterns and phytoplankton dynamics in Antarctic latent heat polynyas. J. Goephys. Res.-Oceans., in press, 2012.

This page is maintained by Xiaojun Yuan ( The last update was on 6/13/2012