1. Signal to Noise Ratios for Global Modes of Subseasonal Atmospheric Variability Edward Berry NOAA/NWS Dodge City, Kansas Klaus Weickmann NOAA/ESRL/PSD Boulder, Colorado Climate Prediction Center November 16, 2007

2. Purpose “Produce signal to noise and risk assessment plots to assist with making probabilistic predictive statements for subseasonal weather events (~weeks 1-4), similar to those done for seasonal time scales. Included are extreme weather events and climate transitions, and their impacts across multiple time scales.”

3.  Case studies from winter/spring 2006-07  Review of the WB(2007) “legacy” GSDM  Introduce the Global Wind Oscillation (GWO)  Present GWO and MJO signal/noise plots  Conclude and future plans Outline

4. USA Cold Regime Stronger coupling to El Nino Weaker coupling to El Nino Strong IO forcing MJO 2 La Nina MJO 2

5. L H L H H L H H L H H H H L H L H L H H H H L H L sink source sink source L H H L H H L H L L H sink H 26 Nov 29 Nov 02 Dec Event that helped “stop El Nino in its tracks” Monitoring the AAM budget flux convergence of AAM ~1 Dec 06 11 Nov 10 Jan 90N 35N Eq 35S 90S Indian Ocean date line Outgoing longwave radiation first in a series of poleward transports across ~30N

6. L H H L L H H L L H H L L H L 1-5 Dec 2006 verification 1-5 Dec 2006 forecast

7. 1. “flip” in transports across 35N (01 Dec 06 ) Start of weak trop/subtrop atmospheric flow 2. major MJO signal 120e (01 Jan 07) Trades blow across El Nino SSTs A 1-2 “climate noise” punch ends 2006-07 El Nino retreat begins

8. Severe cold regime for much of USA 1/30/07 – 2/5/07

9. Legacy GSDM Repeatable evolutionary framework Four stages (e.g., 1=>La Nina; 3=>El Nino) Four time scales including white noise (synoptic details), red noise (teleconnections) and quasi- oscillations (MJO); each undergoes time evolution GSDM is special case where evolution of components is phased to maximize the relative AAM tendency; i.e., linear superposition

10. GLOBAL SYNOPTIC DYNAMIC MODEL (GSDM) Weickmann and Berry (2007): Each stage shows superposition of 3 time scales Wave energy dispersion favors high impact weather across USA Plains Below normal temperatures possible across central and eastern USA High Impact weather event possible along USA west coast Heavy precipitation event possible Southwest USA

11. What is the Global Wind “Oscillation”? Represents portion of GSDM linked with AAM variations due to: – Tropical Convection (implicitly) – Momentum Transports (eddy vs. HC/FC) – Torques (Mountain and friction) Captures broad zonal mean AAM anomalies Provides independent information on the global circulation (a “semi-coherent form of climate noise”) Closely tied to the ENSO cycle GWO Eddy vacillations, mountain torques, etc. AAM Spectrum AAM Tendency Spectrum RMM1 Spectrum MJO MJO, ~30 day 365-day segments; 1968-2006 for AAM and 1979-2006 for MJO

12. 1 2 8 7 6 5 4 3 Analogous to WH2004 MJO phase space plot E W neg tend pos tend max AAM min AAM ….but phase plots rotated and orbits move CW vs CCW

13. MJO GWO Convection Active Indian Ocean Convection active west Pacific Ocean 1-3 major mt. regions adding momentum 1-3 major mt. regions removing momentum Winter 2006-07

14. Stage 1 Stage 2 Stage 3 Stage 4 4/3 5/11 4/9 5/16 5/26 4/16 5/22 “Global Wind Oscillation (GWO)” Define eight stages much like WH(2004) defined eight phases for the MJO Focus on Apr-May-Jun “snr”; week 2 prediction of trough over west USA late May 2007 Angular momentum added to atmosphere Angular momentum removed fm atmosphere #1 #2

15. Poleward propagation of zonal mean zonal wind anomalies produced by momentum transports linked to MJO and GWO 2 4 3 1 2 3 4 1 E E E E E E E E E E W W W W W #1 W #2

16. Statistical Basis for Week-2 Forecast Made 11 May 2007 2 3 45 6 7 81 ~0.3 sigma May 19

17. Now move onto DJF composites MJO: 1979-05 GWO: 1968-05 Daily Signals in 0.258sigma streamfcn: Extratropics: 0.2-0.4  Tropics: 0.4-0.8  for > 1  index

18. Zonal mean characteristics during DJF of GWO (top) and MJO (bot) for relative AAM W E E W E W Broad trop/subtrop signal moderate zonal large global Poleward propagating signal large zonal small global 2 1 3 4 5 6 7 8 1 Stage 05 Stage 15 Stage 25 Stage 35 60N Eq 60S 60N Eq 60S MJO signal “embedded” in GWO

19. Zonal mean GWO signals for DJF ~37 cases AAM tend Calculated AAM tend Mountain torque E E W W W W W W E 5 43 6 2 178 1 Stage 1Stage 2 Stage 3 Stage 4 ~50% mt. component good budget balance

20. Zonal mean MJO signals for DJF ~27 cases AAM tend Calculated AAM tend Mountain torque 5 W W W W W E E 6 7 8 1 1 2 3 4 Stage 1 Stage 2 Stage 3Stage 4 small NH mt. component Poorer budget balance

21. L Indian Ocean Maritime Continent Western Pacific Ocean Western Hemisphere Africa 2 3 4 5 6 7 8 1 L L L L L H H H H H H H H H L L L 4-7 days between phases Matthews and Kiladis, 1999 RWD into east Pac Blade et. al., 2007 nonlinear 3 vs. 7 H The MJO’s global teleconnection pattern 250 mb circulation DJF 79-05, eight phases, ~27 cases/phase Weickmann et. al, 1997 tilts imply sources/sinks The global wind oscillation (GWO) is lurking! L H L L Rossby wave dispersion fm trough

22. How big are MJO signals/impacts during DJF? Signal/Noise for 2 meter air temperature Eight MJO Phases, DJF 1979-2006 Max ~+0.5 sigma => 67% prob > 0 anomaly 2 3 4 5 6 78 1

23. The GWO’s global teleconnection pattern 250 mb psi, DJF 1968-05, 8 phases, 37 cases/phase 2 3 4 5 6 7 8 1 Mountain forcing > 0 adding AAM to mid-lats H H L H H L Mountain forcing < 0 removing AAM fm mid-lats H H L H H L H L L L L 4-8 days between phases eastern hemisphere warm pool active Tropical convection, mountain and “eddy” forcing H H H H H H L L L L L L cyclonic Wave breaking “eddy” forcing > 0 at 20N driving jet south western hemisphere convective regions active “eddy” forcing < 0 at 20N driving jet north anticyclonic Wave breaking L’Heureux & Higgins AO/NAO signal

24. 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” Statement being quantified alternatives being used

25. Summary: Signal to noise ratios presented for MJO and GWO GSDM ~ GWO + MJO Contrasted “sharp” MJO with “fuzzy” GWO Some of what we propose: Global LIM as a predictive tool for the GWO (M. Newman/E. O’lenic) Produce GWO and MJO SNR or risk assessment plots as forecasting aid in all seasons Compare GWO in models with observations; piggyback on MJO model forecast assessment; Apply results to HMT2008 and CPC/GTHA

26. QUESTIONS? Thank you!!!

27. Regime transition ENSO response but IO forcing dominates MJO 2 MJO 3 Westward shift Eastward shift USA Cold Regime

28. 2 3 4 5 6 7 8 1 H H H L L L H H L H L L H H Slow meridional Rossby wave dispersion during transitional phases 1-2/5-6 L H L H H L L H L H L H Indian Ocean Maritime Continent West Pacific Western Hemisphere/ Africa

29. 2 3 4 5 6 7 8 1 L L H H H Fast zonal Rossby wave dispersion during transitional phase 1/5 H L H L L H H L H H L H H L H H MJO?

30. PDF for Apr-May-Jun Stage 2 vs. 4 Western USA 850 Temp Stage 2 Stage 4 ~- 4 ~4 ~-2 ProbabilityProbability Standard Deviation

31. L H L H H L H H L H H H 23 Nov, 250 mb winds Rossby wave dispersion #1 Indian Ocean (IO) source? Convection strong there since 16 Nov. 26 Nov, 250 mb winds Rossby wave dispersion #2 Indian Ocean (IO) source? Durian develops, w. Pacific Ocean 29 Nov, 250 mb winds RWD #2 disperses into Atlantic Large scale circulation anomalies bound Asia, steady response to IO? Durian => Super Typhoon 02 Dec, 250 mb winds Asian jet moves into w. Pacific Tropical source now frm w. Pacific west Pacific wavetrain leads to USA cold wave? L H L H H L H H L H H L H L H L H H H H L H L sink source sink source L H H L H H L H L L H sink H

32. L H L H L HH L H H H H L L L L L L H L H L H H H L L H L L L L H Stage 3 Stage 2 Stage 1 Jan 7, 2007 Jan 9, 2007 L L L Synoptic details of forecast dof #1 H H H H 14 day forecst for Jan 13, 2007 ecmwf ncep cmc psd Forecast based on LIM SV2 + MJO

33. The influence of ENSO, the MJO and the GWO on baroclinic life cycles Life Cycle 1 (LC1) Life Cycle 2 (LC2) northward shifted jet: La Nina; mjo 4 > > > > > > < < < < < < Number of days in the period 16 January - 28 February 1999 1998 LC1 25 2 LC2 2 27 La Nina El Nino Feb. 6 1999 Feb. 5 1998 (Shapiro et al., 2001) statistics pretty good, but strong events anticyclonic break cyclonic break PV - Potential Vorticity High PV Low PV High PV Low PV southward shifted jet: El Nino; mjo 8

34. Relative AAM Frictional torque Mountain torque Lagged regressions on daily unfiltered global AAM tendency Flux convergence of AAM + + -- Global and zonal variations of global synoptic dynamic model (GSDM)

35. 5 H H L L L H H L L L 3 8-16 days away from strong Pacific jet 3-6 days away from weak Pacific jet MJO (top) vs GWO eddy structures L

36. MJO: evolves over 20-80 days ENSO: evolves over 1-2 years Teleconnnection: A connection between climate variations over widely separated parts of the world…..often a consequence of large-scale wave motions, …….(and energy flow) along preferred paths in the atmosphere. global and evolving in time H H L L H MJO: Phase 3 of 8 defined ENSO: Phase “La Nina” of 3 defined 30 events DJF 1979-2005 9 events NDJFM 1948-2000 H H L L L MJO 3 La Nina

37. Staging for 2007-08 Winter The impact of El Nino/La Nina: 1) on seasonal extremes 2) on individual weather systems Ice Storm; 5-10 January 1998 Wolter et al., 1999 Barsugli et al., 1999 high  L H L H L schematic 250 mb winds La Nina phases favored in 2007-08? 40% 30 Climatological risk (20%) Wolter, 2007 - negative MEI tendency cases

38. What is the synoptic evolution? Signal/Noise for ~250 mb streamfunction Four MJO Phases, DJF 1979-2006 Max ~+0.8 sigma => 77% prob > 0 anomaly 2 3 4 5 L H L L H L H L H L H L H H H H H

39. Zonal mean characteristics of GWO (top) and MJO for relative AAM for DJF W E E W E W Broad trop/subtrop signal moderate zonal large global Poleward propagating signal large zonal small global 2 1 3 4 5 6 7 8 1 Stage 05 Stage 15 Stage 25 Stage 35

40. L Indian Ocean Maritime Continent Western Pacific Ocean Western Hemisphere Africa 2 3 4 5 6 7 8 1 L L L L L H H H H H H H H H L L L 4-7 days between phases Signals: 0.2-0.4  0.4-0.8  for > 1  index Matthews and Kiladis, 1999 RWD into east Pac Blade et. al., 2007 nonlinear 3 vs. 7 H The MJO’s global teleconnection pattern 250 mb circulation DJF 79-05, eight phases, ~27 cases/phase Weickmann et. al, 1997 tilts imply sources/sinks The global wind oscillation (GWO) is lurking! L H L L Rossby wave dispersion fm trough

41. E E E W W E E E #4 #3 #2 #1 E E 4 2 3 1 4 4 4 4 4 4 4 2 2 2 2 4 1 2 2 3 4 1 3 2 4 2 1 1 3 1 3 4 4 4 2 4 1 1 3 #5 #6 35 dy 50 dy 80 dy 75 dy 50 dy Atmospheric Angular Momentum IOPs