Oceanic transports of heat and salt from a global model and data

Abstract

A state estimate produced by ECCO-GODAE from a global one-degree model and data spanning the years 1992-2005 is analyzed in terms of transports of volume, temperature, and freshwater. The estimate is assessed to be sufficiently close to observations to merit analysis. The methods of analysis are similar to those of Stammer et al. (2003). The longer time period allows trends to be measured with greater confidence. Time mean flow characteristics demonstrate agreement with previous estimates. The strength of the ACC (146±5Sv) is larger than in the Stammer et al. (2003) state estimate, but is within the range of other estimates. A twelve-year decreasing trend is observed in the strength of the ACC of approximately 0.88Sv/year. The Indonesian throughflow transport of 1 l±2Sv is within the expected range. There is also a decreasing twelve year trend in the strength of the ITF of 0.065Sv/year. The ITF is stronger in boreal summer than boreal winter by approximately 4Sv. A strong annual cycle is present in the transport record on most sections, but higher frequency variability is also present. Most temperature transport variability results from velocity fluctuations, except in the Southern Ocean where temperature fluctuations are more important. Recommended further work includes a more detailed analysis of variability in this state estimate.