The MJO Not really….it’s The Madden Julian Oscillation

Outline What is the MJO? What is the MJO? Where, when, time scale, etc. Where, when, time scale, etc. The discovery of the MJO The discovery of the MJO How do we monitor the MJO? How do we monitor the MJO? MJO and ENSO MJO and ENSO Does it influence our weather? Does it influence our weather? Modeling Modeling

Weather Variability Interannual Variability – year to year variations in weather Interannual Variability – year to year variations in weather i.e. ENSO, decadal oscillations i.e. ENSO, decadal oscillations Intrannual or Subseasonal Variability – variability within the same year or season, respectively Intrannual or Subseasonal Variability – variability within the same year or season, respectively i.e. the Madden-Julian oscillation (also referred to as the day oscillation i.e. the Madden-Julian oscillation (also referred to as the day oscillation

The MJO Eastward propagation of a coupled area of enhanced and suppressed convection (Madden and Julian, 1994) Eastward propagation of a coupled area of enhanced and suppressed convection (Madden and Julian, 1994) Wave number of 1 (Madden and Julian, 1994) Wave number of 1 (Madden and Julian, 1994) Madden, R.A and Julian, P.R. 1994

Cellular in Nature

The MJO day periodicity day periodicity Origin in the Indian Ocean Origin in the Indian Ocean Signal becomes ambiguous in eastern Pacific Signal becomes ambiguous in eastern Pacific 10 o of equator 10 o of equator

More MJO Information Typically strongest from November – March (Madden 1986; Wang and Rui, 1990) Typically strongest from November – March (Madden 1986; Wang and Rui, 1990) Interannual variation does exist (Gutzler and Madden 1989; Hendon et al. 1999) Interannual variation does exist (Gutzler and Madden 1989; Hendon et al. 1999) Madden and Julian, 1971

The Discovery of the MJO 1971 – Madden and Julian wrote paper entitled ‘Detection of a Day Oscillation in the Zonal Wind in the Tropical Pacific’ 1971 – Madden and Julian wrote paper entitled ‘Detection of a Day Oscillation in the Zonal Wind in the Tropical Pacific’ Examined rawinsonde data at Canton Island (3S 172W) Examined rawinsonde data at Canton Island (3S 172W)

Madden, R.A. and Julian, P.R., 1971 Madden 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 MJO Hovmoeller Diagram from Sperber 2003 Madden and Julian, 1971

Monitoring the MJO Look between 5 o S and 5 o N Look between 5 o S and 5 o N Use data for mean Use data for mean First Way… Outgoing Longwave Radiation Anomalies Outgoing Longwave Radiation Anomalies Longitude TimeTime OLR

More Ways… Velocity Potential Anomalies (divergent component of the 200mb wind) Velocity Potential Anomalies (divergent component of the 200mb wind) Upper and lower level wind anomalies Upper and lower level wind anomalies

Does ENSO affect the MJO? MJO activity appears to be independent of SST anomalies (i.e. ENSO, etc.) (Slingo et al. 1999) MJO activity appears to be independent of SST anomalies (i.e. ENSO, etc.) (Slingo et al. 1999) Except during the strongest El Nino events Hendon et al showed a slight decrease in the number of events Except during the strongest El Nino events Hendon et al showed a slight decrease in the number of events Slight shift of the MJO to the east (Hendon et al. 1999) Slight shift of the MJO to the east (Hendon et al. 1999)

Does the MJO affect ENSO Initiation? McPhaden, M.J  Strong pulses in the MJO helped contribute to the spread of the ’97-’98 El Nino

Does the MJO affect the Dissipation of ENSO? Takayabu et al showed that the propagation of the MJO contributed to intensification of the easterly trade winds Takayabu et al showed that the propagation of the MJO contributed to intensification of the easterly trade winds Trade winds increased upwelling and led to an accelerated weakening of the ’97-’98 El Nino Event Trade winds increased upwelling and led to an accelerated weakening of the ’97-’98 El Nino Event

The MJO and Our Weather Jones 2000 showed…  Extreme precipitation events in California are more common when tropical convection associated with the MJO is high  Fewer then when the MJO is relatively inactive  Slight preference when convective anomalies over the Indian 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 MJO We cannot model the MJO well We cannot model the MJO well Models do not resolve convection Models do not resolve convection Even with convective parameters still difficult to model the tropical convection associated with the MJO Even with convective parameters still difficult to model the tropical convection associated with the MJO Potential predictability thought to be days or longer (Waliser et al. 2003, Reichler and Roads, 2005) Potential predictability thought to be days or longer (Waliser et al. 2003, Reichler and Roads, 2005)

Summary day oscillation of enhanced and suppressed convection that’s cellular in nature day oscillation of enhanced and suppressed convection that’s cellular in nature Interannual variations exist Interannual variations exist Influences the onset and dissipation of ENSO Influences the onset and dissipation of ENSO Primarily confined to equatorial region, but it affects weather patterns in the mid latitudes Primarily confined to equatorial region, but it affects weather patterns in the mid latitudes Difficult to model, but potential exists for improving forecasts beyond our day limit Difficult to model, but potential exists for improving forecasts beyond our day limit

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