1 Interaction of the Subtropical Front with topography around 1 southern New Zealand 2 3 Robert O. Smith a,1 Ross Vennell a Helen C. Bostock b Michael J. M. Williams b 4 a Ocean Physics Group, Department of Marine Science, University of Otago, PO Box 56, Dunedin 5 9054, New Zealand. 6 b National Institute of Water and Atmospheric Research, 301 Evans Bay Parade, Wellington 6021, 7 New Zealand. 8 1 Email address: smiro528@student.otago.ac.nz (Robert Smith). Corresponding author. 9 10 Abstract 11 The Subtropical Front Zone (STFZ) is a fundamental feature of the southwest Pacific Ocean. It separates waters in the 12 subtropical gyres from subantarctic waters. In this study we examine a section of the global STFZ that passes around 13 southern New Zealand, using hydrographic sections and remotely sensed sea surface temperature (SST) data collected 14 during the austral autumns of 2007, 2008 and 2011. The STFZ was composed of a single southern Subtropical Front (S- 15 STF) that marked the poleward edge of the STFZ, while the region north of the S-STF was characterised by a series of 16 shallow fronts (< 50 m depth) and a freshwater-induced neritic front. The S-STF around southern New Zealand is also 17 distinguished by moderate-to-weak density compensation, in contrast to the strong density compensation to the west 18 and east of New Zealand. We find strong coupling between the surface and subsurface expressions of the S-STF and 19 demonstrate the practicality of tracing the pathway of the front using its surface expression from remotely sensed 20 images. The S-STF is steered by topography as it crosses the Macquarie Ridge close to 49.6°S and to the east of 166°E 21 as it turns equatorward following the upper continental slope. This is contrary to some previous descriptions that placed 22 the S-STF lying across the Snares Shelf close to 47.5°S. Topographic interactions between the S-STF and sharply 23 defined bathymetry around southern New Zealand appear to strongly influence the position of the front in this region. 24 Cross-frontal temperature and salinity gradients at the S-STF were also found to be intensified in regions of shallow 25 bathymetry. Both results are attributed to topographic steering of the front by bathymetry at approximately 500 m depth. 26 27 Keywords: Subtropical Front, STFZ, Topographic steering, Macquarie Ridge, New Zealand, Density compensation 28 In press: Deep Sea Research Part I, March 2013, Uncorrected proof http://dx.doi.org/10.1016/j.dsr.2013.02.007