1 / 32

The Modulation of Tropopause-level Wave Breaking by the Madden Julian Oscillation

The Modulation of Tropopause-level Wave Breaking by the Madden Julian Oscillation. Richard Moore 1 , Olivia Martius 2 , Thomas Spengler 2 & Huw Davies 2. Motivation. 250 hPa Wind Velocity. 500 hPa Height. Average MJO Phase. Shading: anomaly from DJF average.

fweeks
Download Presentation

The Modulation of Tropopause-level Wave Breaking by 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. The Modulation of Tropopause-level Wave Breaking by the Madden Julian Oscillation Richard Moore1, Olivia Martius2, Thomas Spengler2 & Huw Davies2

  2. Motivation 250 hPa Wind Velocity 500 hPa Height Average MJO Phase Shading: anomaly from DJF average Quantitatively assess the behavior of wave breaking that accompanies the observed flow anomalies

  3. Roadmap • Ingredients of analysis • Briefly outline the climatological response of WB to MJO forcing • Combine climatological and case study viewpoints to gain further insight • Simplify and summarize via a ‘Cartoon’ interpretation of observed evolution

  4. Data & Methodology • ERA-40 Re-Analysis Data for NH Winter from 1979-2002: • Wave breaking (Wernli & Sprenger 2007; Martius et al. 2007) • Surface cyclone frequency (Wernli et al. 2006) • Atmospheric blocking frequency (Croci-Maspoli et al. 2007) • 10 MJO Indices (Climate Prediction Center) • Combine a climatological and case-study analysis of the response to MJO forcing

  5. Extratropical Wave Breaking “The basic criterion for saying whether a wave of any kind is breaking is whether material contours and surfaces are being irreversibly deformed rather than simply undulating back and forth as is assumed in linear wave theory” McIntyre and Palmer 83

  6. Synoptic Scale Rossby Wave Breaking stratosphere, high PV troposphere, low PV PV on 325K January 2007

  7. ‘Lifecycle’ Separation of Wave Breaking (WB) Events Thorncroft et al. 93 LC1, AC anticyclonic life-cycle in anti- cyclonic shear jet Dynamical Tropopause cyclonic life-cycle in cyclonic shear jet LC2, C LC1/LC2 wave breaking in ERA-40: Martius et al. 2007

  8. Wave Breaking Frequency: 1979-2002 DJF Cyclonic (LC2) on 310 K Anticyclonic (LC1) on 330 K

  9. Links to Severe Weather Floods in Algeria November 2001 strong convective activity along eastern flank PV on 320K SLP IR meteosat L formation of low pressure systems cyclonic windfield which can reach the surface wind on 850hPa precipitation

  10. Links to Severe Weather Gondo October 2000 PV-streamer tropopause Alps sea sea wind field Massacand et al. 98, 01

  11. Atmospheric Blocking A disruption in the midlatitude westerlies due to the presence of a quasi-stationary high pressure system Z - PV Anomaly TP

  12. Cyclonic WB on 310 K Cyclonic WB Anomalies MJO INDEX 3 (120E) MJO INDEX 7 (40W) Average for MJO Phase Shading: anomaly from DJF average

  13. WB Anomalies: Overview Cyclonic WB on 310 K • Statistically significant anomalies are prevalent • Dynamical distinction between baroclinic lifecycles is instructive • Strong anti-correlation, fairly rapid transition between anomalies of opposite sign Anticyclonic WB on 340 K

  14. Outstanding Questions What is the relationship between the tropical convection and the observed jet – wave breaking anomalies? Might wave breaking be integral to the observed evolution?

  15. Direct Impact of MJO Convection January 16, 1993 Streamfunction Anomaly POS NEG Shading: Daily Mean OLR • upper-level anticyclone: shifts jet to the north; • local jet intensification

  16. Jet / WB Structure 12Z January 16, 1993 + • Predisposition to anticyclonic lifecycle • Weak waveguide in central Pacific coincides with anticyclonic WB • WB locally shifts jet north + - + - Shading: instantaneous 250 hPa velocity Anticyclonic WB 250 hPa Velocity 2 PVU on 310 K 2 PVU on 330 K 2 PVU on 350 K

  17. Jet / WB Structure 12Z January 28, 1993 • Cyclonic WB in west-central Pacific on northside of locally-enhanced jet • baroclinic instability? + - Cyclonic WB 250 hPa Velocity

  18. Jet / WB Structure: Index 7 (40W) 12Z February 5, 1993 • Eastward extended, zonal jet – strong waveguide • Southward shift over Asia – cyclonic lifecyle • WB shifts jet southward - - + + -

  19. WB and PNA-like signal 3 (120E) 4 (140E) 5 (160E) 6 (120W) MJO Index: 7 (40W) 500 hPa Height Cyclonic WB on 310 K Average MJO Phase Shading: anomaly from DJF average

  20. Anticyclonic WB Anomalies MJO INDEX 3 (120E) MJO INDEX 7 (40W) Average for MJO Phase Shading: anomaly from DJF average

  21. modulation of sub & extratropics • Northward shifted jet over Asia • Anticyclonic WB in central Pacific • Double jet structure • Enhanced blocking frequency in central Pacific

  22. modulation of sub & extratropics • Pattern shifts east • Cyclonic WB ensues on northside of zonally, locally-strong jet • Surface cyclone often co-located in time and space with cyclonic wave breaking event • LC2 wave breaking leads to quick transition of PNA

  23. modulation of sub & extratropics • Single jet extended to the east, southward shift over Asia • Cyclonic WB (surface cyclones) eastern Pacific in jet exit region • Subsequent to this time, in absence of MJO convection the jet breaks down and retreats westward

  24. Questions? http://www.met.reading.ac.uk/~pete/

  25. MJO Indices based on 200 hPa velocity potential http://www.cpc.noaa.gov/products/precip/CWlink/daily_mjo_index/mjo_index.html

  26. Anticyclonic WB Anomalies MJO INDEX 3 (120E) MJO INDEX 7 (40W) Average for MJO Phase Shading: anomaly from DJF average

  27. LC1,AC instantaneous field Shading: anomaly from DJF average

  28. LC2,C instantaneous field Shading: anomaly from DJF average

  29. + anomaly - anomaly Jet Structure MJO forcing changes jet strength, meridional & longitudinal location 250 hPa Jet:

  30. Surface Cyclone Frequency MJO Index 3 MJO Index 7 @ @ - anomaly + anomaly

  31. What is the MJO? • Dominant source of tropical intraseasonal variability • Large-scale coupled patterns in deep convection & atmospheric circulation • Characteristics: • Zonal scale ~ 12-20K km • Eastward propagation ~ 5 m/s • Lifecycle ~ 48 days http://www.met.reading.ac.uk/~pete/

  32. Wave Breaking Frequency: 1979-2002 DJF Cyclonic (LC2) on 310 K Anticyclonic (LC1) on 330 K

More Related