[Crib-list] VIRTUAL Event...SPEAKER: Justin Finkel (Univ. of Chicago) / CRIBB Seminar / 12:00 PM - 1:00 PM / Friday, March 4, 2022

[Shirley Entzminger]

    VIRTUAL...

 	      COMPUTATIONAL RESEARCH in BOSTON and BEYOND SEMINAR
 				 (CRIBB)


   ZOOM meeting info...

 	https://mit.zoom.us/j/96155042770

 	Meeting ID: 961 5504 2770

====================================

DATE:	Friday, March 4, 2022

TIME:	12:00 PM - 1:00 PM


TITLE:	Short weather forecasts inform long-term climatology of sudden
 	stratospheric warming



SPEAKER:   Justin Finkel  (University of Chicago)


ABSTRACT:

In some physical systems such as the Earth's atmosphere, the most extreme 
and rare events matter a great deal, both for their human impact and for 
their dynamical consequences. A prototypical example is sudden 
stratospheric warming (SSW), a rapid breakdown of the winter stratospheric 
polar vortex, which causes extreme mid-latitude cold spells and alters 
surface weather for months. The historical scarcity of observations, and 
an unusually SSW-rich 2000's decade, lead to uncertain SSW climatology: 
when do they occur, how often, and how predictably? Long, expensive model 
runs could answer these statistical questions, but with a tradeoff between 
cost and bias. We instead utilize weather forecast ensembles that are 
high-resolution, but short (subseasonal) in duration. A simple 
coarse-graining procedure chains them together to estimate key climate 
statistics, such as annual frequencies and timing distributions of SSW 
events, as formulated in Transition Path Theory. Using forecast ensembles 
initialized between 1996 and 2018, we find that the SSW statistics match 
well with 20th-century reanalysis. Our method extrapolates the climatology 
well beyond what is possible with the short observational dataset that 
initialized the forecasts, yielding accurate estimates of 1 in a century 
events. This suggests exciting new uses for ensemble forecasts in rare 
event analysis


=======================================

For information about the "Computational Research in Boston and Beyond Seminar"
(CRIBB), please visit:

 		https://math.mit.edu/sites/crib/


=================

Shirley A. Entzminger
Administrative Assistant II
Department of Mathematics
Massachusetts Institute of Technology
77 Massachusetts Avenue
Building 2, Room 350A
Cambridge, MA 02139
PHONE: 	(617) 253-4994
E-mail:	daisymae at math.mit.edu
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