1 / 41

Signal to Noise Ratios for Global Modes of Subseasonal Atmospheric Variability

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. Purpose.

janetfarr
Download Presentation

Signal to Noise Ratios for Global Modes of Subseasonal Atmospheric Variability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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. Outline • 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

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

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

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

  7. A 1-2 “climate noise” punch ends 2006-07 El Nino 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 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 365-day segments; 1968-2006 for AAM and 1979-2006 for MJO MJO MJO, ~30 day GWO AAM Tendency Spectrum RMM1 Spectrum Eddy vacillations, mountain torques, etc. AAM Spectrum

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

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

  14. 5/11 Stage 2 4/3 5/16 5/26 Stage 1 Stage 3 4/9 4/16 5/22 Stage 4 “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 #1 #2 Angular momentum removed fm atmosphere

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

  16. Statistical Basis for Week-2 Forecast Made 11 May 2007 May 19 ~0.3 sigma 3 4 5 2 6 8 1 7

  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 Stage 05 Stage 25 Stage 15 Stage 35 60N Eq 60S Broad trop/subtrop signal moderate zonal large global W E W E 60N Eq 60S Poleward propagating signal large zonal small global E W 2 4 1 3 5 8 6 1 7 MJO signal “embedded” in GWO

  19. Zonal mean GWO signals for DJF ~37 cases Stage 1 Stage 2 Stage 3 Stage 4 Stage 4 W E W AAM tend good budget balance W E W Calculated AAM tend W E ~50% mt. component W Mountain torque 5 6 2 1 3 4 7 8 1

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

  21. The MJO’s global teleconnection pattern250 mb circulation DJF 79-05, eight 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 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!

  22. 4 5 3 2 1 6 7 8 How big are MJO signals/impactsduring DJF? Signal/Noise for 2 meter air temperature Eight MJO Phases, DJF 1979-2006 Max ~+0.5 sigma => 67% prob > 0 anomaly

  23. The GWO’s global teleconnection pattern250 mb psi, DJF 1968-05, 8 phases, 37 cases/phase Tropical convection, mountain and “eddy” forcing “eddy” forcing < 0 at 20N driving jet north “eddy” forcing > 0 at 20N driving jet south L’Heureux & Higgins AO/NAO signal western hemisphere convective regions active eastern hemisphere warm pool active 2 6 H L L H L H H H H L L L cyclonic Wave breaking anticyclonic Wave breaking 7 3 L H L H H L 4-8 days between phases H 4 8 H L L Mountain forcing < 0 removing AAM fm mid-lats Mountain forcing > 0 adding AAM to mid-lats H L H H L L H 1 5

  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. Thank you!!! QUESTIONS?

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

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

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

  30. PDF for Apr-May-Jun Stage 2 vs. 4 Western USA 850 Temp P r o b a b i l i t y Stage 2 Stage 4 ~-2 ~-4 ~4 Standard Deviation

  31. H H L H L H L 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 L H L H H L H H H sink source H H L source H L L H L H L H H H H sink H L L H H L L L H source H H sink

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

  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 southward shifted jet: El Nino; mjo 8 High PV High PV Low PV Low PV Feb. 6 1999 Feb. 5 1998 anticyclonic break cyclonic break < < < < < < > > > > > > PV - Potential Vorticity Number of days in the period 16 January - 28 February 1999 1998 LC1 25 2 LC2 2 27 La Nina El Nino (Shapiro et al., 2001) statistics pretty good, but strong events

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

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

  36. 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 MJO 3 L MJO: evolves over 20-80 days H H MJO: Phase 3 of 8 defined L L 30 events DJF 1979-2005 La Nina H L H ENSO: evolves over 1-2 years H ENSO: Phase “La Nina” of 3 defined L 9 events NDJFM 1948-2000

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

  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 L H H H L H L H L 2 3 L H H H H L H L 5 4

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

  40. The MJO’s global teleconnection pattern250 mb circulation DJF 79-05, eight 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!

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

More Related