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MJO and convectively coupled waves in Navy models

MJO and convectively coupled waves in Navy models. Maria Flatau. Collaborators: Y-J Kim Carolyn Reynolds Justin McLay Piotr Flatau James Ridout. DYNAMO workshop April 13-14, 2009. Operational deterministic forecast RMM index (Wheeler and Hendon 2004).

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MJO and convectively coupled waves in Navy models

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  1. MJO and convectively coupled waves in Navy models Maria Flatau Collaborators: Y-J Kim Carolyn Reynolds Justin McLay Piotr Flatau James Ridout DYNAMO workshop April 13-14, 2009

  2. Operational deterministic forecastRMM index (Wheeler and Hendon 2004) • Good forecasts for MJO initiation in winter • More problems in summer • Propagation over Indian Ocean • Maritime continent barrier • Reduced amplitude over WP • Similar results from ensemble runs (May –Oct 2007 and 2008)

  3. The effect of diurnal SST change? • Average SST change August 1-5 2008 Diurnal warming of “skin SST” as simulated in NOGAPS, using Zeng and Beljaars (2005) scheme

  4. The effect of diurnal SST change on equatorial Kelvin waves Shallow water NSEAMAqua planet NSEAM One long wave Strong peak for one frequency frequency lat lon Broad spectrum wavelength Series of intense short waves frequency lat lon wavelength NSEAM: Navy Spectral Element Atmospheric Model (Giraldo, 2005)

  5. The impact of diurnal SST variations on MJO ensemble forecast (May-June 2007) Diurnal change of skin sst control Stronger signal in the Indian ocean

  6. All forecasts for May-June 2007 control Diurnal change skin sst Stronger MJO in Indian Ocean

  7. The effect on skin skin SST change on Kelvin wave in the ensemble forecast Kelvin wave OLR from NOGAPS analysis filtered for Kelvin waves OLR anomaly from NOAGPS analysis, (shading) and precipitation from TRMM data (white contours) averaged 5S-5N for 2-15May 2007

  8. OLR filtered for Kelvin waves 14 days ensemble mean Skin SST OLR filtered for Kelvin waves 14 days ensemble mean control Skin SST May1-May 15 2007 0N 105E SST increase May5-May7

  9. October 2008 MJO Interaction between the MJO and Rossby wave. Difficult to predict in NOGAPS Associated with large equatorial westerlies (possible influence on termination on IOD episode) Sue Chen will show preliminary COAMPS results

  10. Summary • NOGAPS MJO forecasts have characteristics similar to other models: • relatively good forecast of Indian Ocean • difficulties over Maritime continent • difficulties when strong Rossby wave is present • Including diurnal SST variability causes: • Change of the Kelvin wave spectrum on aqua planet • Increase of MJO strength in NOGAPS • Increase in intensity of Kelvin wave

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