An altered atmospheric circulation regime during Last Glacial Maximum

Camille Li, Aaron DonohoeDavid Battisti

University of Washington

poleward heat flux 850mb (Km/s)

Coupled modelwinter jet and storminess

poleward heat flux 850mb (Km/s)

Coupled modelwinter jet and storminess

Compared to today’s climate, the ice age climate simulated by the coupled model exhibits• a stronger, steadier Atlantic jet• reduced storminess

poleward heat flux 850mb (Km/s)

Coupled modelwinter jet and storminess

Coupled modelwinter jet and storminess

poleward heat flux 850mb (Km/s)

Laurentide elevation (km)

ICE-5G

ICE-4G

CAM Model Run with ICE 5G Vertically Integrated JFM Eddy Heat Transport

Contours are the jet speed at 400 hPa

K m/s

LGM

Modern

LGM- Modern

Possible Causes of Reduced LGM Atlantic StorminessI.) Narrow LGM jet inhibits storm growth

Jet Speed Cross Sections LGM jet is narrow

NOT Strong enough effect

II.) High LGM Static stability inhibits storm growthStrong LGM Baroclinicity still predicts stronger storm Growth

III.) LGM Storms are not seeded efficiently

MagnitudeGeopotential Height Perturbation (meters)

00 4 8 12

50

16Days Since Storm Entered Atlantic Domain

LGMModern