Internal Waves for Ocean Heat Transport Hypothesis

I am not convinced that we know anything from this particular item.  To start with, the necessary measurements are few enough to be largely early days for this science. A simple shifting back and forth along a channel of movement will provide vast ranges of variation and that as yet can not be discounted without a massive investment in data collection that we are nowhere near having.


I have already argued for a millennial long cycle in the impact of the North Atlantic on global climate.  The implied variation supports a modest increase in heat flow brought about by a modest change in flow rate of the currents.  The gulf Stream is a perfectly good suspect but that does not exclude other deeper flows we barely know exist.  Again, during the Bronze Age, the North Atlantic was an amazing two degrees warmer for a long time.


In short, this paper is at best a guess.  The trouble with all this, besides the lack of data is the lack of perspective drawn from centuries of such observations.  I sometimes wish science would hold off on speculation where the data is scant or at least say as much.  Even my interpretation of a millennial cycle is based on some good evidence and a best interpretation of truly ancient sources that supports the proposition past three data points.  I went looking and found support when I asked the question suggested by the key data points.


Internal heat waves are a nice idea.  So are quarks.  The messy part comes in demonstration.  We already know that we have a discernable forty year cycle related to hurricanes and climate change generally.  So we can not go too far wrong there.   Transporting that heat cycle through a subsea mechanism that is not a slow moving current is helpful.  Having such a device ex machina makes simulation almost work.


So prove it exists!



Internal waves transport oceanic heat within 40 years

Jun 29, 2010

Measurements show that the deep waters of the world's major oceans have warmed over the last few decades. But the mechanism for this heating has not been clear. Now, using a simulation, researchers from Japan and the UK have found that an increase in heat transport from the atmosphere into the ocean off Antarctica can warm deep waters in the North Pacific within 40 years. They believe that the heat is moved by the action of internal waves.
"This means that changes in the heat content of the deep ocean, which is an important part of the three-dimensional global heat distribution, are far more sensitive to air–sea thermal interchanges [than previously believed]," Shuhei Masuda of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) told environmentalresearchweb. "Our findings require a re-assessment of the role of the Southern Ocean in determining the impact of atmospheric warming on deep ocean waters."

Ice formation and heat exchange with the atmosphere around Antarctica create particularly dense water masses. These sink to the depths to form Antarctic Bottom Water. The northwards spread of this water over much of the world's ocean floor helps to drive the global thermohaline circulation.
Bottom waters in the Pacific Ocean warmed 0.003–0.01 °C from 1985 to 1999, according, in part, to measurements taken during the World Ocean Circulation Experiment.
Scientists have estimated that heat transport via mass movement through the ocean would take several centuries. For example, an abyssal current flowing at 0.001 m/s would take more than 350 years to travel 12,000 km. The new mechanism proposed by the team sees a reduction in the formation of Antarctic Bottom Water, due to the input of more heat from the atmosphere, alter isopycnal surfaces in the deep ocean. These isopycnal changes are transmitted as internal oceanic waves and affect deep waters in the whole North Pacific. The resultant weaker deep water current reduces abyssal cooling and enables geothermal heating to warm the bottom waters.
"Although I am not sure at this stage how this teleconnection puts an impact on future climate (e.g. whether it accelerates or decelerates global warming), these findings should be a steady forward step to resolve these issues," said Masuda.
Together with colleagues from JAMSTEC; Kyoto University, Japan; and Environmental Satellite Applications, UK, Masuda used an ocean data assimilation system based on a 4-dimensional variational (4D-VAR) adjoint approach, to examine the effect of changes in heat flux off the Adélie Coast of Antarctica on bottom water temperature at 47° N–170 ° E.
"I think the 4D-VAR data synthesis approach is nowadays the only way to resolve the difficulties evolving in the sporadic ocean observations/imperfect model simulations to represent the deep ocean properties," said Masuda. "An adjoint sensitivity analysis, which can be employed by using a part of the 4D-VAR system, has great advantages for pursuing the possible physical mechanism of any climate changes based on the primitive equations for ocean representation."
According to Masuda, the findings are the first step in revealing the changes in properties of the global deep ocean. Now the team plans to investigate the Atlantic and Indian oceans, where bottom-water warming has also been observed, as well as to work on discovering the impact of this rapid teleconnection on future climate.
The researchers reported their work in Sciencexpress.

No comments:

Post a Comment