1 / 19

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. Introduction. MJO Global impact (boreal winter): NAO (Lin et al 2009); PNA (Mori and Watanabe 2008)

hettie
Télécharger la présentation

Simulating the extratropical response to the Madden-Julian Oscillation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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)

  3. Outlines • Introduction • Numerical experiments: Dependence on heating location Nonlinearity Dependence on initial condition • Summary

  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

  10. 80E Day 10 Z500 linear response Similar pattern for heating 60-100E 110E 150E Similar pattern for heating 120-150W

  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?

  12. Nonlinearity • 3 sets of experiments: 1) Control 2) +MJO forcing 3) –MJO forcing • From 360 different initial conditions • 30-day nonlinear integrations

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

  14. Nonlinearity Z500 response

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

  16. EOF of 360 Z500 day 6-10responses to the same +MJO Downstream shift Intensify

  17. Dependence on initial condition U200 Jet intensifies 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

More Related