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

2. Shading: anomaly from DJF average
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 :
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
Explain isentropic PV charts
Transition stratosphere troposphere
3D feature intrusion of stratospheric air also called PV streamer
Irreversible deformation of contours formation of a cut-off
Complete seclusion from stratospheric air body
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
For are real case
Typical morphology associated typically with streamers
Subsidence plus dry air from stratosphere within streamer and along western flak
Reduced stability plus upgliding along isentropes => strong convection along eastern flank
Wind field not only at upper-levels but extending down into the lower troposphere if strong anomaly
wind on 850hPa
precipitation

10. Links to Severe Weather
Gondo October 2000
PV-streamer
tropopause
Alps
sea
Investigation of extreme precipitation events over 33 year time period based on the observation based high resolution precip climatology from Frei and Schaer
Working hypothesis from the work of Massacand et al.
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
Link Blocking and streamer can be expected
Use blocking and streamer climatology to investigate that link
Blocking as low pv anomalies
Blocking Climatology TP

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

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
upper-level anticyclone: shifts jet to the north;
local jet intensification
January 16, 1993
Streamfunction Anomaly
POS
NEG
Shading: Daily Mean OLR

16. Shading: instantaneous 250 hPa velocity
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
2 PVU on 310 K
2 PVU on 330 K
2 PVU on 350 K
Shading: instantaneous 250 hPa velocity + - + -
250 hPa Velocity
Anticyclonic WB

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

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

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

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?

25. based on 200 hPa velocity potential
MJO Indices
based on 200 hPa velocity potential

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

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

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

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

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

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