Atmosphere Ocean Science Colloquium

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Global Simulations of Atmospheric Rivers: Past, Present & Future

Speaker: Jeff Kiehl, NCAR

Location: Warren Weaver Hall 1302

Date: Wednesday, May 6, 2015, 3:30 p.m.

Synopsis:

In the early 1990s, Newell and colleagues first identified narrow filamentary structures of tropospheric water vapor that they termed atmospheric rivers.These narrow bands of water vapor account for approximately 90% of the moisture transport from the tropics to the extra-tropics. More recently, atmospheric rivers have been linked to extreme precipitation events in the western United States, the United Kingdom and Europe. Over the past decade many studies based on observations and reanalysis products have provided great insight into the dynamical and thermodynamic processes leading to atmospheric rivers and their connections to extreme precipitation. In this presentation, I consider how well high-resolution global climate models can simulate atmospheric rivers and their connections to extreme precipitation events. I also consider how modes of natural variability affect the characteristics of these rivers. Given their importance to the global water cycle, I also consider how the statistical characteristics of atmospheric rivers may change as the world continues to warm due to increased levels of atmospheric carbon dioxide. This model analysis employs global simulations from the Community Earth System Model (CESM) run at atmospheric horizontal resolutions of 50 and 25 kilometers.