Where does overturning collide?

In physical oceanography, overturning is the slow vertical-and-horizontal loop by which surface water sinks at high latitudes, flows along the deep ocean, and rises again elsewhere, carrying heat and dissolved gases around the planet; the Atlantic limb of this loop is the meridional overturning circulation. Kuhlbrodt and colleagues' 2007 On the driving processes of the Atlantic meridional overturning circulation reviews how surface buoyancy loss and wind- and tide-driven mixing together sustain the loop. The referent is a mass-transport circulation measured in sverdrups, and it has nothing to do with a toppling torque on a structure beyond the shared image of water turning over.[1]

Unit

The volume transport of the sinking-and-rising loop, in sverdrups

Recovery means

Not applicable

Measured by

Estimated from transoceanic moored arrays, hydrographic sections, and the resulting streamfunction of north–south volume transport by depth

In structural and geotechnical engineering, the overturning moment is the turning effect of lateral loads (wind, waves, seismic shaking, or an eccentric weight) about the base edge of a structure, which if it exceeds the stabilising moment from the structure's own weight and foundation will tip it over. Kolios, Chahardehi, and Brennan's 2011 Experimental determination of the overturning moment and net lateral force generated by a novel vertical axis wind turbine shows how such a moment is measured and designed against under load uncertainty. The referent is a torque with units of force times distance, compared against a resisting moment through a factor of safety, and it is a different construct from a basin-scale water loop despite sharing the word.[2]

Unit

The destabilising torque about a base edge, in newton-metres

Recovery means

Not applicable

Measured by

Computed from lateral load magnitude and its lever arm, or measured on test rigs, then checked against the stabilising moment as a safety factor