Hypercane

Abstract: K. Emanuel et al. [see Geophys. Res., vol. 100, no. D7, pp. 13,755-13,765 (1995)] believe that neither bolide (exploding meteor) impacts nor large-scale volcanism alone have the force to inject enough material into the stratosphere for sufficient time to cause mass extinctions. They propose that one of the suspects may have created a massive storm called a hypercane. Theoretically, hypercanes are extremely intense hurricanes formed when the air-sea thermodynamic equilibrium exceeds a threshold, i.e. the bolide impact or volcanism heats the ocean so much that a massive hurricane forms. A hypercane could inject enormous quantities of water vapor, condensed water and ash into the stratosphere, with potentially disastrous results. To determine the possibility of hypercanes, Emanuel modified a numerical hurricane model and executed it on the National Center for Atmospheric Research's Cray Y-MP. They added a sea surface temperature anomaly to represent the abnormal increase in temperature caused by bolide impact or undersea volcanism. To trigger the hypercane, they used an initial vortex with wind speeds of 12 m/s. Emanuel and his colleagues conclude that the simulation works well for the period of the storm's transition to a hypercane, but it does not fully explain mature hypercane behavior. However, they believe the model's success shows that hypercanes are possible. >