Presentation on theme: "DYNAMO Webinar Series Dynamics of the Madden-Julian Oscillation Field Campaign Climate Variability & Predictability University of Hawaii at Manoa."— Presentation transcript:
DYNAMO Webinar Series Dynamics of the Madden-Julian Oscillation Field Campaign Climate Variability & Predictability University of Hawaii at Manoa
3 THE ULTIMATE GOAL of this project: To improve the prediction skill of Madden-Julian Oscillation (MJO) in the national climate forecast model (NOAA/NCEP CFSv2) ANALYZE the MJOs observed during DYNAMO period REVIEW operational models’ forecasting of the DYNAMO MJOs ASSESS the capability of CFSv2, GFS, and UH models in MJO forecasts QUANTIFY the impacts of air-sea coupling on MJO forecasting Experiment for cumulus parameterizations and SST uncertainty Categorize MJO types: coupled and uncoupled Outline
SST and MJO-filtered OLR Anomalies in DYNAMO Period Oct-MJO Nov-MJO SST (shading); OLR (contours) IOP Five MJO events Thanks-giving TC during Nov. MJO Only two MJO events (Nov. & Mar.) with robust coherent positive SST anomalies leading the convection Air-sea ‘coupling strength’ varies with individual MJO events 4
Prediction of the observed MJO by operational models
Good forecasts of two successive MJO events IC: Oct_17IC: Nov_07 Courtesy of NCEP MJO Discussion Summary led by Jon Gottschalck et al. Bad forecasts of Sep. primary MJO event 5 IC: Sep_20IC: Sep_12
Nov. MJO initiation in CFSv2&UH models IC: Nov_04 6 Both CFSv2 and UH models capture the development of November MJO. Propagation in UH model quite realistic. Propagation in CFSv2 too slow. Shadings: Observation Contours: Forecast Red arrows: Observed minimum values. Green arrows: Forecast minimum values. OLR anomalies
Extended-range forecasts of Nov. MJO initiation 7
Forecasts Initialized on Nov. 18, 2011 OBS CFSv2 UH 13 Propagation in UH model quite realistic. Propagation in CFSv2 too slow. Shadings: Observation Contours: Forecast OLR anomalies
Acknowledgment: Observational surface flux data from Revelle during DYNAMO period are provided by Chris Fairall, Simon de Szoeke, Jim Edson, and Ludovic Bariteau
MJO Skills of GFS, CFSv2, and UH during DYNAMO GFS: 13 days CFSv2&UH: 25/28 days CFSv2&UH MME: 36 days Fu et al. (2013) (Wheeler-Hendon Index, Lin et al. 2008) 14
OLR RMM index Anomaly Correlation (Wang et al. 2014)
Differences in forecast q (RAS – SAS2) with TMI SST from 7 Nov 2011 The lower troposphere above PBL with SAS2 is consistently drier than that with RAS, even before Nov 12 when rainfall rate is small. The drier lower troposphere with SAS2 is related to the larger rainfall rate during the first few days, indicating that the SAS2 convection scheme tend to drive the atmosphere to a drier state to maintain the balance between convection and large-scale dynamics Establishment of such a drier lower troposphere with SAS2 results in a less strong convection response to the underlying SST anomalies. 24 Why does RAS scheme produce better MJO?
CFS Use an alternative convection scheme, e.g., replacing SAS2 with RAS Improve SST accuracy with better intra-seasonal and diurnal variability What can we do to improve MJO prediction in CFS and GFS? 25 GFS Use an alternative convection scheme, e.g., replacing SAS2 with RAS Specify SSTs from another coupled forecast system (e.g., CFS), or couple GFS to a mixed-layer ocean model.
Categorization of MJO types: Coupled and uncoupled
Different Roles of Air-sea Coupling on the Oct. and Nov. MJO Events (UH) Fu et al. (2014) 26
Different Roles of Air-sea Coupling on the Oct. and Nov. MJO Events (GFS) Oct-MJO Nov-MJO Dec-MJO Need Daily SST Forcing 28
29 Summary Only two of five observed MJOs during DYNAMO have robust coherent positive SST anomalies leading MJO convections. The initiation of successive MJO is more predictable than primary MJO. Major MJO forecasting problems include: slow eastward propagation, the Maritime Continent barrier and weak intensity. During DYNAMO period, the MJO forecasting skills for the GFS, CFSv2, and UH models are 13, 25, and 28 days. The equal- weighted MME of the CFSv2 and UH reaches 36 days. Air-sea coupling is important for MJO forecasting and still has plenty rooms to be improved.
31 Summary The interactions between the Nov-MJO and Thanksgiving-TC have been much better represented in the UH and CFSv2 coupled models than that in the atmosphere-only GFS. CFSv2 MJO forecasting may be improved with an alternative cumulus parameterization (e.g., RAS) and more accurate SST prediction. GFS MJO forecasting with an alternative cumulus parameterization (e.g., RAS) and SSTs from CFS, or couple GFS to an mixed-layer ocean model. Two-type MJOs exist: strongly coupled to underlying ocean or largely determined by atmospheric internal dynamics.
31 Publications Fu, X., J.-Y. Lee, P.-C. Hsu, H. Taniguichi, B. Wang, W. Q. Wang, and S. Weaver, 2013: Multi-model MJO forecasting during DYNAMO/CINDY period. Clim. Dyn., 41, 1067-1081. Wang, W. Q., M.-P. Hung, S. Weaver, A. Kumar, and X. Fu, 2013: MJO prediction in the climate forecast system version 2 (CFSv2). Clim. Dyn. Fu, X., W. Q. Wang, J.-Y. Lee and et al.: Distinctive roles of air-sea coupling on different MJO events: A new perspective revealed from the DYNAMO/CINDY field campaign. submitted. Wang, W. Q., A. Kumar, and X. Fu: Dependence of MJO prediction on sea surface temperatures and convection schemes. to be submitted.