What is it about?

Using the QG-omega equation, we show that the vertical velocities associated with precipitation extremes increase overall in climate model simulations. This overall increase can be explained by the increased latent-heat release by water vapor from a dry perspective; it can also be explained by a decrease in the stableness of atmosphere with respect to moist convection from a moist perspective.

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Why is it important?

This work first clarifies a misconception from previous works that the changes in vertical velocity is mainly related to changes in the horizontal length scales of extreme events. We also demonstrated that the QG-omega equation is a useful tool for understanding the physical processes influencing the dynamical aspect (vertical velocities) in precipitation extremes, and we provided a moist perspective to link changes in vertical velocities and changes in moist static stability.


Useful as the QG-omega equation is, it still has drawbacks in explaining power when used on the extreme precipitation events. For example, the QG-omega equation states that the horizontal and vertical length scales of extreme events can in principle influence the strength of omega at a particular location, but such scales are intrinsic to the omega itself.

Ziwei Li
Massachusetts Institute of Technology

Read the Original

This page is a summary of: Response of Vertical Velocities in Extratropical Precipitation Extremes to Climate Change, Journal of Climate, July 2020, American Meteorological Society,
DOI: 10.1175/jcli-d-19-0766.1.
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