A paper published August 20th in Geophysical Research Letters finds from newly deployed observation systems that the Southern Oceans show an annual net heat loss of -10 Wm-2.
- Southern Ocean air-sea fluxes are under-observed, leading to large uncertainty
- The first year-long air-sea flux observations quantify an annual cycle
- Shows seasonal cycle, small annual net ocean heat loss and extreme events
Due to a previous “paucity of reference observations”, this paper is the first to study annual heat flux between the atmosphere and the Southern Oceans, a “key component of the global climate system: insulating the Antarctic polar region from the subtropics, transferring climate signals throughout the world’s oceans and forming the southern component of the global overturning circulation.”
That finding contradicts claims that the oceans are gaining ‘missing heat’ due to an increase in greenhouse gases. For example, The figure below from Bob Tisdale compares the ARGO-era Ocean Heat Content observations to the model projection, which is an extension of the linear trend determined by Hansen et al (2005), for the period of 1993 to 2003. Over that period, the modeled OHC rose at 0.6 watt-years per year. With the recent seasonal declines in Global Ocean Heat Content anomalies, the model projection is rising at a rate that’s more than 10 times higher than the observations since 2003. 10 times higher. Yet the southern ocean has just been demonstrated to be losing heat.
Here is the paper:
GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L16606, 8 PP., 2012
doi:10.1029/2012GL052290 E. W. Schulz, S. A. Josey, and R. Verein
The Southern Ocean is a key component of the global climate system: insulating the Antarctic polar region from the subtropics, transferring climate signals throughout the world’s oceans and forming the southern component of the global overturning circulation. However, the air-sea fluxes that drive these processes are severely under-observed due to the harsh and remote location. This paucity of reference observations has resulted in large uncertainties in ship-based, numerical weather prediction, satellite and derived flux products. Here, we report observations from the Southern Ocean Flux Station (SOFS); the first successful air-sea flux mooring deployment in this ocean. The mooring was deployed at 47°S, 142°E for March 2010 to March 2011 and returned measurements of near surface meteorological variables and radiative components of the heat exchange. These observations enable the first accurate quantification of the annual cycle of net air-sea heat exchange and wind stress from a Southern Ocean location. They reveal a high degree of variability in the net heat flux with extreme turbulent heat loss events, reaching −470 Wm−2 in the daily mean, associated with cold air flowing from higher southern latitudes. The observed annual mean net air-sea heat flux is a small net ocean heat loss of −10 Wm−2, with seasonal extrema of 139 Wm−2 in January and −79 Wm−2 in July. The novel observations made with the SOFS mooring provide a key point of reference for addressing the high level of uncertainty that currently exists in Southern Ocean air-sea flux datasets.
Here are two additional figures from the paper: wind speed
Surface variables and heat flux:
h/t to The Hockey Schtick