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Coupled Variability in CCSM3

Coupled Variability in CCSM3. Michael Alexander Climate Diagnostics Branch Physical Science Division (PSD) Earth System Research Laboratory (ESRL) Was The Climate Diagnostics Center Christophe Cassou, Clara Deser , Young-Oh Kwon, Adam Phillips. Selective Survey. ENSO

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Coupled Variability in CCSM3

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  1. Coupled Variability in CCSM3 Michael Alexander Climate Diagnostics Branch Physical Science Division (PSD) Earth System Research Laboratory (ESRL) Was The Climate Diagnostics Center Christophe Cassou, Clara Deser, Young-Oh Kwon, Adam Phillips

  2. Selective Survey • ENSO • SST, precipitation • Global Teleconnections • Winter Time Climate/Variability • Patterns: PDO, PNA, NAO/AO, PNA • Extratropical Upper Ocean Processes • Seasonal cycle of Temp, MLD • Winter-to-winter recurrence of SST Anomalies • For more information see: http://www.ccsm.ucar.edu/publications/jclim04/Papers_JCL04.html

  3. Tropical Sea Surface Temperature CSM2 Nino3.4 CSM3 T42 CSM3 T85 OBS

  4. SST Nino3.4 Index:Observed vs. CCSM3 (T42) Observed Model

  5. Power Spectrum of SST Nino3.4 Index T42 CSM3 T42 CSM2 OBS T85 CSM3

  6. ENSO SST Composite Observations CSM3 T85

  7. Warm - Cold ENSO Composites (DJF) SST Precipitation T42 similar 99% sig.

  8. PDO: 1st EOF Of Winter SST Anomalies CCSM3 T42 (Yr : 100 – 999; 26 %) CCSM2 (T42) (Yr : 350 – 999; 20 %) CCSM3 T85 (Yr : 100 – 599; 28 %) Observation (ERSST : 1901 – 2000; 28 %)

  9. Power Spectrum Winter SST Kuroshio Extension Index Observation (ERSST: 1901-2000) ~20 yr CCSM3 T85 (100-599) ~16-20 yr

  10. Regression on SST Kuroshio Extension Index +2ºC per ºC SST KEI +50 W/m2 per ºC SST KEI SST (Winter) Warm SST ~ Heat Flux from Ocean to Atmosphere QNET (Winter) (Contour Interval: 0.2ºC/ºC, 10 W/m2/°C ; Shading: significant at 99 %) • Local QNET responds to the SST anomaly, rather than forcing it.

  11. Lead/-lag correlations in the Kuroshio Extension Region Warmer SST Heat Convergence Heat Convergence Geostrophic Heat Divergence vs. QNET Heat Flux out of Ocean Geostrophic Heat Divergence vs. SST (Low-pass Filter > 10 yr) Ocean heat convergence  +1-2 yr  warmer SST  +1~2 yr  ocean-to-atmosphere QNET

  12. PDO time series and Tair Correlations

  13. NCEP 38.4% Pacific Variability (PNA)EOF 1 500 mb Height (m) DJFM CCSM 40.1%

  14. Pacific Patterns in CCSM3& correlations with Tair Patterns from Cluster analyses Atm Response: El Nino ≠-La Nina e.g. ALE+ most Prevalent in Nina

  15. Leading Patterns SST Variability 20ºS-60ºN CCSM3 (T85)

  16. NCEP CCSM3 49.4% 46.8% North Atlantic Oscillation (NAO) EOF 1 500 mb Height (m) DJFM

  17. NAO+/- & Correlations with Tair in CCSM3 Based on Cluster analyses

  18. March Mixed Layer Depth (m) CCSM3 Levitus

  19. Annual Cycle of Temperature (ºC) & MLDCentral N. Pacific Region: 25ºN-45ºN,165ºE-175ºW CCSM Levitus Reemergence Mechanism

  20. Reemergence in the Central North PacificLead-lag Correlations between the Temp´(month,depth) with Temp´ at the Base Point (Aug-Sep,~50-82m) 0.3 0.6 0.6 Depth (m)

  21. Summary of CCSM3 Variability ENSO • Reasonable timing and amplitude but too biennial compared to nature and too meridionally confined • SLP response over the North Pacific in boreal winter is excellent in T85 version, too weak in T42 version PDO • Leading EOF of CCSM3 winter SST have PDO-like horse-shoe pattern. Amplitude too large in the west • Robust decadal (16-20 yr) SST variability in the Kuroshio Extension. • Local Qnet and QEkman are response to the SST anomaly. Other patterns • NAO/AO, PNA, ALE(WP) Mixed Layer Depth • Seasonal cycle Temp & MLD • Winter MLD slightly too depth in NP and too shallow in N. Atlantic • Reemergence present

  22. Additional ENSO Slides

  23. ENSO Seasonal Cycle Timing of ENSO Events Seasonal Cycle of ENSO Amplitude

  24. Evolution of Observed Composite ENSO

  25. Evolution of Composite ENSO Event (T42 Control)

  26. Precipitation

  27. Warm - Cold ENSO Composite: SLP (DJF) 99% sig.

  28. ENSO in CCSM3 SST and Atmospheric Teleconnections • Compare T42 and T85 versions of CCSM3 (multi-century control integrations) • Compare CCSM3 with CCSM2 (T42 control integrations) • Compare CCSM3 T85 control with CAM3 T85 AMIP integration, 1950-2000

  29. Additional Extratropical Slides

  30. Annual Mean SST (ºC)

  31. Monthly SST Standard Deviation (C) CCSM

  32. Annual Cycle of Monthly Mean & Standard Deviation of SST (°C) along 42ºN CCSM3 NCEP

  33. Seasonal Cycle of Ocean Temp and MLD Pacific: 35N-45N 165E-175W Atlantic: 50N-60N 20W-40W

  34. Mean SLP (mb) DJF

  35. Standard Deviation SLP (mb) DJF

  36. Annual Mean Net Surface Heat Flux (W m-2)

  37. Local Lead-lag Correlations 42º-52ºN between SST and Temp anomalies at the Basepoint SST Lags SST Leads Basepoint: Aug-Sep, 55-85M

  38. Reemergence Indicated by SST correlated with T in summer thermocline

  39. Winter SST Power Spectrum Kuroshio Extension Index Central North Pacific Index ~17 yr

  40. Temperature Variance (°C2) of Annual Means at 200 m CCSM3 White Levitus

  41. Subduction in the Atlantic POP CCSM3 Trajectories based on annual averages on 25.4 surface

  42. Additional PDO Slides

  43. Lateral Ocean Heat Divergence Surface Heat Flux Upper 200 m Heat Budget in the Kuroshio Extension [W/m2]

  44. Winter QEkman Regressed on SST Kuroshio Extension Index SST regression (Contour Interval: 10 W/m2/°C ; Shading: significant at 99 %)

  45. Winter QEkman regressed on SST Kuroshio Extension Index(Low-pass filter > 10 yr) (Contour Interval: 10 W/m2/°C ; Shading: significant at 99 %) • Anomalous QEkman acts as a positive feedback to the SST anomalies.

  46. Pacific Decadal Oscillation1st EOF of Monthly North Pacific SSTA 24.5%

  47. Pacific Decadal Oscillation Index:PC1 of North Pacific SST

  48. Correlation of PDO Index with TS and SLP TS SLP CCSM3 NCEP

  49. Arctic Oscillation: SLP EOF 1 NCEP CCSM3 31.5% 33.7%

  50. NCEP Reanalysis Calendar Year CCSM3 Model Year Arctic Oscillation: PC1 (DJFM)

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