We seek to utilize satellite estimates of sea level height, sea surface temperature, and winds, together with NCEP air-sea fluxes of heat, momentum, and kinetic energy, to understand ocean-atmosphere coupling physics of the Antarctic Circumpolar Wave in the Southern Ocean.
We diagnose atmospheric-driven heat and vorticity budgets in the upper ocean associated with the Antarctic Circumpolar Wave (ACW) [White and Peterson, 1996; Peterson and White, 1998; White et al., 1998; White, 2000; Gloersen and White, 2001] along its path around the Southern Ocean utilizing TOPEX/POSEIDON sea level height (SLH) anomalies and National Centers for Climate Prediction (NCEP) sea surface temperature (SST), sea level pressure (SLP), air-sea heat flux (Q), and air-sea momentum flux (t) anomalies from 1993 to 1999.
We find the anomalous SLH tendency in the ACW balanced almost exclusively by Ekman pumping, with meridional advection of planetary vorticity offset by the zonal advection of potential vorticity by the Antarctic Circumpolar Current (ACC). We find the anomalous SST tendency in the ACW balanced by the sum of anomalous zonal heat advection by the ACC and by surface air temperature induced sensible-plus-latent heat flux anomalies, the latter displaced to the east of SST anomalies and explaining their eastward phase propagation.
The correspondence of SLH and SST anomalies arises because anomalous SLH and SST tendencies are both associated with high (low) SLP anomalies, the former linked to anticyclonic (cyclonic) wind stress curl and the latter linked to warm (cool) air temperature anomalies, both occurring simulteneously in the warm (cold) core high (low) sea level pressure anomaly patterns associated with the ACW.
Over this next year, we shall adress two questions; how deep the ACW extends, and its coupling with the overlying atmosphere. Preliminary results indicate that the ACW does not follow the core of the Antarctic Circumpolar Current, but rather follows the path of the principal storm track across the Southern Ocean, along which coupling is maximized, the latter needed to maintain the ACW against dissipation. Moreover, we find the ACW in the western Pacific sector of the Southern Ocean forced by meridional teleconnections from the tropics, but thereafter its propagation over the remainder of the Southern Ocean arises from the air-sea coupling [White, Chen, and Allan, 2000]. We will examine these coupling physics by linking the vorticity and heat budgets of the upper ocean to those in the lower atmosphere.
White W.B., R. Peterson, 1996: An Antarctic Circumpolar Wave in surface pressure, wind, temperature, and sea ice extent. Nature, 380, 699-702.
Peterson R.G., W.B. White, 1998: Slow oceanic teleconnections linking the Antarctic Circumpolar Wave with tropical ENSO. J. Geophys. Res.,103, 24,573-24,583.
White W.B., S.C. Chen, R. Peterson, 1998: The Antarctic Circumpolar Wave: A beta-effect in ocean-atmosphere coupling over the Southern Ocean. J. Phys. Oceanogr., 28, 2345-2361.
White W.B., N.J. Cherry, 1999: Influence of the Antarctic Circumpolar Wave upon New Zealand temperature and precipitation during Autumn-Winter. J. Clim. 12, 960-976.
White W.B., 2000: Influence of the Antarctic Circumpolar Wave on Australian precipitation from 1958 to 1997, J. Clim., 13, 2125-2141.
Gloersen P., W.B. White, 2001: Reestablishing the circumpolar wave in sea ice around Antarctica from one winter to the next. J. Geophys. Res., (in press).
White W.B., S.C. Chen, R.J. Allan, 2001: Positive feedbacks between the Antarctic Circumpolar Wave and the El Niño-Southern Oscillation. J. Geophys. Res. (in review).
Oceanic heat and vorticity budgets of the Antarctic circumpolar wave