[A-AS03] Large-scale moisture and organized cloud systems

[AAS03-01] The importance of water vapor in convectively-coupled tropical motions

★Invited Papers

*Ángel Francisco Adames-Corraliza¹ (1.University of Wisconsin Madison)

Keywords:water vapor, convection, tropical waves

Two realizations that have contributed significantly to our understanding of the tropical motions will be reviewed: (1) Free tropospheric water vapor plays an important role in the occurrence and organization of tropical deep convection. (2) The latent heat released in convection is quickly transported around the tropics by gravity waves, the physical mechanism underpinning the weak temperature gradient (WTG) approximation. Simple models of the tropics that include (1) and (2) revealed the existence of moisture modes, waves in which water vapor plays a dominant role in their evolution. In these waves, cloud-radiation interactions play a key role in the maintenance of the convection while moisture advection governs their propagation. Through scale analysis, it is revealed that waves that exhibit slow propagation (~5 m/s) can be characterized as moisture modes. Extension of this theory to off-equatorial motions reveals that the large-scale flow in off-equatorial vortices can interact with water vapor in such a way that it can lead to growth, a process referred to as “moisture-vortex instability”. While including moisture as an integral part of tropical motions, there are still many unresolved questions and opportunities to apply the theory to answer important questions about tropical weather and climate.