simulating the extratropical response to the madden-julian oscillation

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Simulating the extratropical response to the Madden-Julian Oscillation Hai Lin RPN-A, Environment Canada International S2S Conference, College Park February 10-13, 2014

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Simulating the extratropical response to the Madden-Julian Oscillation. Hai Lin RPN-A, Environment Canada International S2S Conference, College Park February 10-13, 2014. Introduction. MJO Global impact (boreal winter): NAO (Lin et al 2009); PNA (Mori and Watanabe 2008) - PowerPoint PPT Presentation

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Page 1: Simulating the extratropical response to the Madden-Julian Oscillation

Simulating the extratropical response to the Madden-Julian Oscillation

Hai Lin

RPN-A, Environment Canada

International S2S Conference, College Park

February 10-13, 2014

Page 2: Simulating the extratropical response to the Madden-Julian Oscillation

Introduction

o MJO

o Global impact (boreal winter):

NAO (Lin et al 2009); PNA (Mori and Watanabe 2008)

AO (L’Heureux and Higgins 2008)

Canadian temperature (Lin and Brunet 2010)

Canadian precipitation (Lin et al 2010)

• Atmospheric response to MJO forcing:

Matthews et al. (2004)

Lin et al. (2010)

Seo and Son (2012)

Page 3: Simulating the extratropical response to the Madden-Julian Oscillation

Outlines

o Introduction

o Numerical experiments: Dependence on heating location

Nonlinearity

Dependence on initial condition

o Summary

Page 4: Simulating the extratropical response to the Madden-Julian Oscillation

Correlation when PC2 leads PC1 by 2 pentads: 0.66

Lin et al. (2010)

Page 5: Simulating the extratropical response to the Madden-Julian Oscillation

Normalized Z500 regression to PC2

Lin et al. (2010)

Page 6: Simulating the extratropical response to the Madden-Julian Oscillation

Model and experiment

• Primitive equation AGCM (Hall 2000) – similar configuration of model forcing as the Marshall-Molteni model, but not Q-G.

• T31, 10 levels

• Time-independent forcing to maintain the winter climate

• Linear integration, winter basic state

Page 7: Simulating the extratropical response to the Madden-Julian Oscillation

Thermal forcing

Exp1 forcing Exp2 forcing

Lin et al. (2010)

Page 8: Simulating the extratropical response to the Madden-Julian Oscillation

Z500 response

Exp1

Exp2

Lin et al. (2010)

Page 9: Simulating the extratropical response to the Madden-Julian Oscillation

• Linear integration, winter basic state

• with a single center heating source

• Heating at different longitudes along the equator from 60E to 150W at a 10 degree interval, 16 experiments

• Z500 response at day 10

Why the response to a dipole heating is the strongest ?

Page 10: Simulating the extratropical response to the Madden-Julian Oscillation

Day 10 Z500 linear response

80E

110E

150E

Similar pattern for heating 60-100E

Similar pattern for heating 120-150W

Page 11: Simulating the extratropical response to the Madden-Julian Oscillation

• Are the responses to opposite signs of MJO forcing mirror images? (nonlinearity)

• Which response is less sensitive to initial condition and background flow? with less spread?

• How does the response depend on extratropical jet initial condition?

Questions:

Page 12: Simulating the extratropical response to the Madden-Julian Oscillation

• 3 sets of experiments:

1) Control

2) +MJO forcing

3) –MJO forcing

• From 360 different initial conditions

• 30-day nonlinear integrations

Nonlinearity

Page 13: Simulating the extratropical response to the Madden-Julian Oscillation

Thermal forcing

Exp1 forcing Exp2 forcing

Lin et al. (2010)

+MJO thermal forcing

Page 14: Simulating the extratropical response to the Madden-Julian Oscillation

NonlinearityZ500 response

Page 15: Simulating the extratropical response to the Madden-Julian Oscillation

spread

+MJO response has less spread, less sensitive to initial condition

Page 16: Simulating the extratropical response to the Madden-Julian Oscillation

EOF

Downstream shift Intensify

of 360 Z500 day 6-10 responses to the same +MJO

Page 17: Simulating the extratropical response to the Madden-Julian Oscillation

Dependence on initial condition U200

Jet intensifies

Jet moves southward

Page 18: Simulating the extratropical response to the Madden-Julian Oscillation

Summary

• There is significant nonlinearity in response in mean response and spread

• Response to –MJO is more sensitive to initial condition (when the heating is over central Pacific)

• Response sensitive to the strength and position of East Asian jet

• Implication to subseasonal forecasting: MJO phase and jet initial condition

Page 19: Simulating the extratropical response to the Madden-Julian Oscillation