The MJOThe MJO

Not really….it’s Not really….it’s

The Madden Julian The Madden Julian OscillationOscillation

OutlineOutline

What is the MJO?What is the MJO? Where, when, time scale, etc.Where, when, time scale, etc.

The discovery of the MJOThe discovery of the MJO How do we monitor the MJO?How do we monitor the MJO? MJO and ENSOMJO and ENSO Does it influence our weather?Does it influence our weather? ModelingModeling

Weather VariabilityWeather Variability

Interannual Variability – year to year Interannual Variability – year to year variations in weather variations in weather i.e. ENSO, decadal oscillationsi.e. ENSO, decadal oscillations

Intrannual or Subseasonal Intrannual or Subseasonal Variability – variability within the Variability – variability within the same year or season, respectivelysame year or season, respectively i.e. the Madden-Julian oscillation (also i.e. the Madden-Julian oscillation (also

referred to as the 40-50 day oscillation referred to as the 40-50 day oscillation

The MJOThe MJO

Eastward propagation of a coupled Eastward propagation of a coupled area of enhanced and suppressed area of enhanced and suppressed convection (Madden and Julian, convection (Madden and Julian, 1994)1994)

Wave number of 1 (Madden and Wave number of 1 (Madden and Julian, 1994)Julian, 1994)

Madden, R.A and Julian, P.R. 1994

Cellular in NatureCellular in Nature

http://www-das.uwyo.edu/~geerts/cwx/notes/chap12/mjo.html

The MJOThe MJO

30-60 day periodicity30-60 day periodicity Origin in the Indian OceanOrigin in the Indian Ocean Signal becomes ambiguous in Signal becomes ambiguous in

eastern Pacificeastern Pacific 1010oo of equator of equator

http://www.balihilton.com/images/map-world.jpg

More MJO InformationMore MJO Information

Typically strongest from November – Typically strongest from November – March (Madden 1986; Wang and March (Madden 1986; Wang and Rui, 1990)Rui, 1990)

Interannual variation does exist Interannual variation does exist (Gutzler and Madden 1989; Hendon (Gutzler and Madden 1989; Hendon et al. 1999)et al. 1999)

Madden and Julian, 1971

The Discovery of the MJOThe Discovery of the MJO

1971 – Madden and Julian wrote 1971 – Madden and Julian wrote paper entitled ‘Detection of a 40-50 paper entitled ‘Detection of a 40-50 Day Oscillation in the Zonal Wind in Day Oscillation in the Zonal Wind in the Tropical Pacific’the Tropical Pacific’

Examined rawinsonde data at Canton Examined rawinsonde data at Canton Island (3S 172W) Island (3S 172W)

Madden, R.A. and Julian, P.R., 1971

Madden Julian (’71) FiguresMadden Julian (’71) Figures

• Spectral analysis on 8 years of data

• Peaks important here

• Weak easterlies or westerlies (-) at 850mb associated with weak westerlies or easterlies (+) at 150mb and high pressures at the surface (little convection)• All U components of the wind

Phases of MJOPhases of MJO

Hovmoeller Diagram from Sperber 2003

Madden and Julian, 1971

Monitoring the MJOMonitoring the MJO Look between 5Look between 5ooS S

and 5and 5ooNN Use 1971-2000 data Use 1971-2000 data

for meanfor mean

First Way…First Way… Outgoing Outgoing

Longwave Longwave Radiation Radiation AnomaliesAnomalies

Longitude

Time

OLR

More Ways…More Ways…

Velocity Potential Velocity Potential Anomalies Anomalies (divergent (divergent component of the component of the 200mb wind) 200mb wind)

Upper and lower Upper and lower level wind level wind anomaliesanomalies

Does ENSO affect the Does ENSO affect the MJO?MJO?

MJO activity appears to be independent of MJO activity appears to be independent of SST anomalies (i.e. ENSO, etc.) (Slingo et SST anomalies (i.e. ENSO, etc.) (Slingo et al. 1999)al. 1999) Except during the strongest El Nino events Except during the strongest El Nino events

Hendon et al. 1999 showed a slight decrease Hendon et al. 1999 showed a slight decrease in the number of events in the number of events

Slight shift of the MJO to the east Slight shift of the MJO to the east (Hendon et al. 1999)(Hendon et al. 1999)

Does the MJO affect ENSO Does the MJO affect ENSO Initiation?Initiation?

McPhaden, M.J. 1999

Strong pulses in the MJO helped contribute to the spread of the ’97-’98 El Nino

Does the MJO affect the Does the MJO affect the Dissipation of ENSO?Dissipation of ENSO?

Takayabu et al. 1999 showed that the Takayabu et al. 1999 showed that the propagation of the MJO contributed to propagation of the MJO contributed to intensification of the easterly trade winds intensification of the easterly trade winds

Trade winds increased upwelling and led Trade winds increased upwelling and led to an accelerated weakening of the ’97-’98 to an accelerated weakening of the ’97-’98 El Nino EventEl Nino Event

The MJO and Our The MJO and Our WeatherWeather

http://www.cpc.ncep.noaa.gov/products/winter_outlook/pineapple.gif

Jones 2000 showed…Jones 2000 showed…

Extreme precipitation Extreme precipitation events in California are more events in California are more common when tropical common when tropical convection associated with convection associated with the MJO is highthe MJO is high Fewer then when the MJO Fewer then when the MJO is relatively inactiveis relatively inactive Slight preference when Slight preference when convective anomalies over the convective anomalies over the Indian OceanIndian Ocean

Maloney and Hartman, 2000 showed 850mb westerly wind anomalies (cyclonic vorticity) associated with the MJO resulted in double the hurricanes in the east Pacific

Modeling the MJOModeling the MJO

We cannot model the MJO wellWe cannot model the MJO well Models do not resolve convectionModels do not resolve convection Even with convective parameters Even with convective parameters

still difficult to model the tropical still difficult to model the tropical convection associated with the MJO convection associated with the MJO

Potential predictability thought to be Potential predictability thought to be 15-25 days or longer (Waliser et al. 15-25 days or longer (Waliser et al. 2003, Reichler and Roads, 2005)2003, Reichler and Roads, 2005)

SummarySummary

30-60 day oscillation of enhanced and 30-60 day oscillation of enhanced and suppressed convection that’s cellular in naturesuppressed convection that’s cellular in nature

Interannual variations existInterannual variations exist Influences the onset and dissipation of ENSO Influences the onset and dissipation of ENSO Primarily confined to equatorial region, but it Primarily confined to equatorial region, but it

affects weather patterns in the mid latitudes affects weather patterns in the mid latitudes Difficult to model, but potential exists for Difficult to model, but potential exists for

improving forecasts beyond our 10-14 day improving forecasts beyond our 10-14 day limit limit

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