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MJO Forecasting Discussion

MJO Forecasting Discussion. Are we happy with the WH04 combined EOF index? other metrics? Comments on the calculation recipe, precip vs OLR Comments on display of phase plot interannual “in” versus “out” for past data and forecasts Require hindcasts and benchmark to evaluate models

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MJO Forecasting Discussion

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  1. MJO Forecasting Discussion • Are we happy with the WH04 combined EOF index? • other metrics? • Comments on the calculation recipe, • precip vs OLR • Comments on display of phase plot • interannual “in” versus “out” for past data and forecasts • Require hindcasts and benchmark to evaluate models • Forecast skill of index (e.g., 0.5 vs 0.75) • Forecast skill as function of MJO phase • simple statistical versus linear inverse model benchmark • case study approach? • Requirements for multi-model ensemble? • data dissemination, hindcasts/reforecasts, CPC visit • How much increased skill should we expect from MJO? • PSD ensemble • experience from global hazards assessment

  2. RMM1 >0 Phase 4-5 Indo; <0 phase 8-1 WH RMM2 >0 Phase 6-7 wPac; <0 phase 2-3 IO Regression RMM1 and 2 at initial time with week 2 verification, forecast or forecast error 1 m/s 3 m/s Week 2 verification Week 2 forecast

  3. MJO’s global teleconnection pattern250 mb , DJF 1979-05, 8 phases, ~27 cases/phase L H L L Western Pacific Ocean 6 2 Indian Ocean H L H L H H H L Rossby wave dispersion “fm trough” Blade et. al., 2007 nonlinear 3 vs. 7 Signals: 0.2-0.4 0.4-0.8 for > 1 index 4-7 days between phases 7 3 L L L H H H L L H L H Matthews and Kiladis, 1999 RWD into east Pac Western Hemisphere Africa 4 8 Maritime Continent Weickmann et. al, 1997 tilts imply sources/sinks 5 1 The global wind oscillation (GWO) is lurking!

  4. Indices used for compositesMJO ->120d rm removed; GWO –> 100d hp filter MJO <– eight phases –> GWO

  5. Proposed recipe(either to be computed by each Centre themselves, or by a single volunteering Centre): a) Use WH04 EOFs (or equivalent precip structures; some Centres may choose to try both) b) WH04 normalization factors for each field (OLR=15.1 Wm-2, u850=1.81 ms-1, u200=4.81 ms-1) c) All use the same climatology computed from NCEP Reanalysis and observed OLR/precip. d) All use the same methodology for removal of ENSO and other low-frequency variability (i.e., the removal of variability linearly related to an ENSO SST index and removal of mean of previous 120 days).

  6. statistical benchmark PSD ensemble

  7. CPC Global Tropics Benefits/Hazards Assessment Description: Week 1-2 outlooks for enhanced/suppressed rainfall and favorable/unfavorable conditions for TC activity Purpose: Provides regional planners with global interests advanced notice on potential hazards/impacts Physical Basis:MJO, GWO, ENSO, other coherent and/or persistent anomalies, interaction with the extratropics Outside Collaboration: ESRL, TPC, NWS WR/CR, and others Tools:Detailed monitoring, ENSO/MJO/GWO composites, MJO objective forecasts (statistical/dynamical), GFS/CFS forecasts Plans: Product more objective in nature, evaluate and apply input associated with subseasonal variability from additional dynamical models, exploit the seasonal cycle more “models don’t predict the MJO very well”

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