Environmental Science and Engineering Seminar

Projected changes to precipitation in a warming climate vary considerably from region to region and between precipitation intensities. While it is well recognized that increases in atmospheric water vapor content in a warmer climate will lead to hydrological cycle intensification, changes in atmospheric circulation play an important role in shaping the spatial distribution of precipitation intensity and frequency. In this talk, I will present a moisture budget perspective of regional precipitation responses to climate warming for the full probability distribution of precipitation in a large ensemble of climate simulations. This approach attributes changes in precipitation to different moisture budget processes from region to region and percentile by percentile. It is shown that the thermodynamic effect, due to increased atmospheric moisture, is relatively uniform spatially and across the probability distribution of precipitation events. In contrast, the dynamical effect, due to changes in intensity and location of weather systems, varies spatially and between intensities. In particular, the upward motion associated with heaviest precipitation events (e.g., a 10-year event) in the subtropics will increase more than the ascent for less intense events, indicating a dynamical amplification of subtropical precipitation that would bring more challenges to water resource managements in a drying subtropical climate.