92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 9:00 AM
The Cyclonic Low-Level Jet in a Warmer Climate
Room 354 (New Orleans Convention Center )
G. M. Lackmann, North Carolina State Univ., Raleigh, NC

The influence of latent heat release in extratropical cyclones has been quantified in past studies via potential vorticity (PV) techniques. For cyclones that are accompanied by heavy precipitation, the diabatic contribution to the cyclonic circulation can be 50% or more. Additionally, latent heat release contributes to the strength of the low-level jet (LLJ) often found near the border of the cyclonic warm sector. The LLJ contributes significantly to poleward moisture transport and can be associated with straight-line windstorms.

Future climate projections consistently reveal increased precipitation, a consequence of enhanced vapor content. What are the dynamical consequences of potentially heavier precipitation on extratropical cyclones? How are the precipitation increases distributed within cyclones? We hypothesize that heavier rainfall leads to increased diabatic PV generation and a stronger LLJ, which in turn increases poleward moisture transport.

Simulations of current and future flooding events are undertaken using the “pseudo global warming” method. The Tennessee flood of May, 2010 is simulated for current and future conditions. A PV budget and PV inversion are used to ascertain whether a previously documented positive feedback mechanism is enhanced in future climates.

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