Atmospheric Sciences Seminar

Interactions between water vapor, potential vorticity, and vertical wind shear in rotational tropical disturbances: Insights from a simple model

Dr. Angel F. Adames-Corraliza
Assistant Professor
Department of Atmospheric and Oceanic Sciences
University of Wisconsin-Madison

Date: Wednesday, October 21, 2020
Time: 3:30 p.m. HST
Zoom Meeting: https://hawaii.zoom.us/j/97454168193
Meeting ID: 974 5416 8193
Passcode: 207183

Abstract:
A linear two-layermodel is used to elucidate the role of prognostic moisture on quasi-geostrophic(QG) motions in the presence of a mean thermal wind. Solutions to the basicequations reveal two instabilities.  The well-documentedbaroclinic instability is characterized by growth at the synoptic scale(horizontal scale of?1000 km) and systems that grow from this instability tilt against theshear.  Moisture-vortex instability —aninstability that occurs when moisture and lower-tropospheric vorticity exhibitan in-phase component— exists only when moisture is prognostic.  The instability is also strongest at thesynoptic scale, but systems that grow from it exhibit a vertically-stacked structure.  When moisture is prognostic, baroclinicinstability exhibits a pronounced weakening when the thermal wind is easterly.On the other hand, moisture-vortex instability is strongest in this mean state.Based on these results, it is hypothesized that moisture-vortex instability isthe dominant instability in humid regions of easterly thermal wind such as theSouth Asian and African monsoons.

Event Sponsor
SOEST Atmospheric Sciences, Mānoa Campus

More Information
808-956-8775, SEE FLYER (PDF)

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