Oceans at MIT

Striving to understand, harness and sustain Earth's defining frontier.

http://oceans.mit.edu

America/New_York

20171105T020000 -0400 -0500 20181104T020000 EST 20180311T020000 -0500 -0400 EDT 20170213T120000-8ccmb0ifths3ko79iorelr6vsk@google.com 20180503T093957Z Title: Monsoon circulations and tropical heterogeneous chlorine chemistry in the stratosphere Abstract: This seminar presents novel findings that expand the range of latitudes over which heterogeneous chemistry operates in the stratosphere. It has long been thought that heterogeneous chlorine chemistry would only be important in the Antarctic and Arctic. Our new work shows that tropical heterogeneous chemistry is also important. Transport processes associated with the summer monsoons bring increased abundances of hydrochloric acid into contact with liquid sulfate aerosols in the cold tropical lowermost stratosphere, leading to heterogeneous chemical activation of chlorine species. The calculations indicate that the spatial and seasonal distributions of chlorine monoxide and chlorine nitrate near the monsoon regions of the northern hemisphere tropical and subtropical lowermost stratosphere could provide indicators of heterogeneous chlorine processing. In the model, these processes impact the local ozone budget and decrease ozoneabundances, implying a chemical contribution to longer-term northern tropical ozone profile changes at 16-19 km. 20170213T120000 20170213T130000 Ida Green Lounge (9th Floor), Building 54, Cambridge, MA, United States 0

**CANCELLED** PAOC Colloquium: Susan Solomon, MIT