MASS: Caroline Muller - MIT - Relationship between tropical precipitation and water vapor in current climate and under warming
Date Time Location
May 3rd, 2010 2:00pm-3:00pm 54-915
**Note special time** Caroline Muller || MIT || Title: Relationship between tropical precipitation and water vapor in current climate and under warming ||

Abstract: There is a tight relationship between precipitation and column-integrated water vapor in the tropics, as has been shown by several observational studies. In the first part of the talk, we will show that a simple analytical physically-based model for the onset of precipitation can reproduce the main features of this relationship. In the second part of the talk, we will investigate the response of precipitation extremes in the tropics to climate change. It has been argued that precipitation extremes should increase following the atmospheric water vapor content, assuming that the most intense rainfall occurs when all the atmospheric moisture precipitates out, and that vertical velocities in updrafts stay approximately constant. If vertical velocities do not stay constant but rather increase, as has been suggested should be the case due to increased latent heat release favoring upward motion, precipitation extremes will increase faster than atmospheric water vapor with warming. Using a high-resolution cloud resolving model, we find that increases in precipitation extremes are actually smaller than increases in atmospheric water vapor content. We will derive a scaling that relates the changes in precipitation extremes to changes in thermodynamic and dynamic variables. Such a scaling is particularly attractive since it provides a predictive tool for the response of precipitation extremes to a change in climate. ||

Host: Brian Tang