“Sticky” Winter Weather: Does It Take Two to Tango?

Jennifer'Francis'Department)of)Marine)and)Coastal)Sciences)

Rutgers)University)

California drought 2014-2015 U.S. Eastern freeze 2014-2015

Nov)2014)

A Tale of Two Winters

Nov)2007)

Sea ice cover: differences from normal Air temperature differences

from%NSIDC% from%ESRL.NOAA%

-PDO

+PDO

The

“It Takes Two to Tango”

hypothesis

Extra heating intensifies ridge, making it more persistent.

Two necessary factors, neither sufficient alone!!

Ice loss has no effect

The good old days…

O U

D

-PDO +PDO

Evidence from the Real World

Lee)et)al,))GRL))2015)

Height)in)meters)

Layer Heights:

OBS

Model with Pac SSTs AND

Sea Ice

Model with Pac SSTs

Model with

Sea Ice

Winter)2013/14)

Mercury%Press%&%Media%Ltd.%

2 To

Tango?

francis@imcs.rutgers.edu%