Composite Regression Analysis of the 8 Phases of the MJO By: Zachary Handlos

1. Composite Regression Analysis of the 8 Phases of the MJO By: Zachary Handlos

2. Introduction • MJO – What is it? • 8 phases of MJO • Convective phases vs. suppressed phases • MJ 1971 – origins of oscillation • MJ 1994 – Brief History of Research (ie: observational work, Super Clusters, Monsoons, etc...)

3. Wheeler and Hendon (2004) • Performed EOF analysis of combined fields (OLR, zonal wind at 850 hPa and 200 hPa) • Subtracted out as much seasonal, annual variability as possible (ie: ENSO, etc...) • RMM1 and RMM2 = EOF1 and EOF2 • Explain MJO propagation over space • RMM1 – enhanced convection over Maritime Continent • RMM 2 – enhanced convection over the Pacific

4. Goal of This Project: • Understand WH (2004) statistical methods by recreating some of their work • Show the significance of the RMM1 and RMM2 EOF's and their relationship to the MJO, forecasting the MJO • For this presentation, results regarding the composite regression analysis of OLR data considered

5. Composite Regression Analysis • ESRL (NCEP) interpolated OLR data (2.5 deg resolution, daily for May-June) • Subtracted out mean • Regressed OLR onto RMM 1 and RMM2 • Call the regression vectors r1 and r2

6. Composite Regression Analysis • Calculate the value of the OLR regression slope values as a combination of RMM1, RMM2: r = r1-i*r2 OLR = Re{r*exp(i*[(9*π/8)+(j*(π/4))])]} where j = phase (1-8) i = sqrt(-1)

7. Wait Zak...what are you doing here? • Wheeler and Hendon (2004) phase space diagram • Represent MJO phases with combined RMM value • Multiply r by the second term on the RHS of previous equation to composite regression into the 8 phases • Want the real part of equation

13. My Results vs. Wheeler and Hendon (2004) • Used complex, combined RMM regression vector and composite based on earlier algorithm • WH (2004) composite OLR (and wind) anomalies based on results from phase space diagram (Fig. 7 in paper) • Time Frame analyzed: • 1990-2004 (Me) • 1974-2003 (WH 2004)

14. Future Work (Current Research) • Focus: ISCCP cloud regimes (Rossow et al, 2005) • Currently looking at the shape of latent heating profiles, calculating shapes using only precipitation and surface convergence in the ITCZ • Idea: Look at evolution of latent heating profiles, clouds within MJO phases (and SCC's) • Statistical Analysis methods such as composite analysis, EOF analysis, even spectral analysis could be useful

15. References • Madden, R. A. and P. R. Julian, 1971: Detection of a 40-50-day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28:702–708. • Madden, R. A. and P. R. Julian, 1972: Description of global scale circulation cells in the Tropics with a 40-50-day period. J. Atmos. Sci., 29:1109–1123. • Madden, R. A. and P. R. Julian, 1994: Observations of the 40–50-day tropical oscillation—A review. Mon. Wea. Rev., 122:814–837. • Tromeur, E., and W.B. Rossow, 2010: Interaction of tropical deep convection with the large-scale circulation in the MJO. J. Climate, 23, 1837-1853, doi:10.1175/202009JCLI3240.1 • Wheeler, Matthew C., Harry H. Hendon, 2004: An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction. Mon. Wea. Rev., 132, 1917–1932.