U.S./Chinese Collaborative Study: Investigation of Bottom Water Formation in Prydz Bay, Antarctica

The field program will be carried out on board of R/V Xuelong during her annual trip to service Chinese Antarctic Stations.

Program Description

Supported by National Science Foundation of United States and Chinese Arctic and Antarctic Administration, scientists from Lamont-Doherty Earth Observatory of Columbia University (Lamont), First Institute of Oceanography (FIO) and Polar Research Institute of China (PRIC) will collaboratively conduct three seasons of physical oceanography surveys in Prydz Bay, Antarctica to investigate the bottom water formation processes.


    National Science Foundation
    United States of America

    Chinese Arctic and Antarctic Administraiton
    State Ocean Administration
    People's Republic of China

Principal Investigators

    Xiaojun Yuan
    Lamont Associate Research Professor
    Lamont-Doherty Earth Observatory of Columbia University
    The United States

    Libao Gao
    First Institute of Oceanography
    State Ocean Administration
    People's Republic of China

    Bingrui Li
    Director of Physical Oceanography division
    Polar Research Institute Of China
    State Ocean Administration
    People's Republic of China

Field Work

Figure 1. Summary of hydrographic surveys by US/Chinese collaborative research in the Prydz Bay region. Mooring M1 to M4 were originally deployed in 2/2012. M1 and M3 mooring were recovered and redeployed in 2/2013. M9 and MA were deployed in 3/2014.

Lamont Mooring M1

Preliminary Results

Dense shelf water exists on the Prydz Bay shelf region even in austral summer. The lower water column (approximately 200m thick) has potential density higher than 27.80 kg/m3 with maximum density of 27.84 kg/m3 near the shelf break (figure 2). If it were exported off the shelf, it would be dense enough to descend along the slope. Figure 4 shows the spatial distribution of the dense shelf water in February 2013.

Figure 3. Potential temperature (a), salinity (b) and potential density (c) at 272m on M1 from 2/12/2012 to 2/12/2013 with a sampling rate of 15-minute. The vertical lines separate measurements into 4 periods according to their characteristics. The mean values of temperature, salinity and density in each period are marked in each panel.

It is mainly concentrated in the Amery Depression, where the topography is 800-900m deep. Temperature is close to the surface freezing point, while salinity reaches 34.6 in the depression, consistent with winter elephant seal data (Ohshima et al., 2013),. Oxygen near the bottom is above 6.6 ml/l in most of shelf region, suggesting that the bottom layer is well ventilated in winter. The bottom density is mostly higher than 27.80 with a maximum of 27.86 kg/m3 along the west limb of the depression. Although the bottom salinity in the Prydz Bay shelf region is not as high as that in the Cape Darnley polynya in winter, the density of shelf water is higher than the density on the slope and would sink down the slope upon being exported.

The circulation in the bay also favors export at Prydz Channel. M1 current meter at 347m (figure 1) recorded an annual mean speed of 7+/- 4 cm/s and mean direction of 10+/- 21 degree from north. The current does not have a clear seasonal cycle but the maximum speed can reach 31cm/s. The volume of dense shelf water is determined by amounts of mCDW intrusion and sea ice production. Estimates of salt injection from ice formation and salt fluxes delivered by mCDW are currently being constructed for the period of 2/2012 to 2/2013 using data from M1 and M3 moorings, surface winds from reanalysis and sea ice observations (Yuan et al., in preparation).

Figure 5 Schematic AABW flow pattern. AABW originated from the Weddell Sea (blue arrows), from Ross Sea/Aledie Land coastal region (red arrows) and from Cape Darnley (yellow arrows) are color-coded. Proposed subsurface moorings (MS1,MS2,M1,M3 and M10) are marked in red stars, while black and green dached lines indicate proposed CTD/LADCP sections.


CTD Data

2013 - in progress
2014 - in progress


Sun, Y., X. Yuan, J. Shi, L. Gao, Changes of Antarctic Bottom Water Properties in the Prydz Bay Region, Poster presentation, The Ocean Science Meeting, Honolulu, 2014.

Gao, L., W. Guy, X. Yuan. Variability of Deep Circumpolar Deep Water inflow onto the Prydz Bay shelf region. In preparation.

Yuan, X. L. Gao, Y. Sun, et al., Spatial and Temporal variability of shelf water in Prydz Bay. In preparation.

This page is maintained by Xiaojun Yuan (xyuan@ldeo.columbia.edu). The last update was on 5/18/2012