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

2. Introduction MJO 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)
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

3. Outlines Introduction Numerical experiments: Summary
Dependence on heating location
Nonlinearity
Dependence on initial condition
Summary
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

4. Correlation when PC2 leads PC1 by 2 pentads: 0.66
Lin et al. (2010)

5. Normalized Z500 regression to PC2
Lin et al. (2010)

6. 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

7. Thermal forcing
Exp1 forcing
Exp2 forcing
Lin et al. (2010)

8. Z500 response
Exp1
Exp2
Lin et al. (2010)

9. Why the response to a dipole heating is the strongest ?
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
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

10. 80E
Day 10 Z500 linear response
Similar pattern for heating E
110E
150E
Similar pattern for heating W

11. Questions:
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?
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

12. Nonlinearity 3 sets of experiments: 1) Control 2) +MJO forcing
From 360 different initial conditions
30-day nonlinear integrations
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

13. Thermal forcing +MJO thermal forcing Exp1 forcing Exp2 forcing
Lin et al. (2010)

14. Nonlinearity Z500 response
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO

15. spread
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO
+MJO response has less spread, less sensitive to initial condition

16. EOF of 360 Z500 day 6-10 responses to the same +MJO Downstream shift
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO
Downstream shift
Intensify

17. Dependence on initial condition U200
Jet intensifies
To assess the contribution of moisture and convections to LFV, especially the MJO.
Does tropical intraseasonal variability (TIV) exist in a dry model?
Global view of the intraseasonal variability.
Implication to the MJO
Jet moves southward

18. 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