1 / 33

Ensemble Spread and Resolution in Minerva Simulations

Ensemble Spread and Resolution in Minerva Simulations. Ben Cash and Jieshun Zhu Minerva Project Team Minerva Workshop, GMU/ COLA, September 16, 2013. Role of Resolution in Minerva Simulations. Significant Differences in Atmosphere, Ocean Components Multiple atmosphere resolutions

kayo
Télécharger la présentation

Ensemble Spread and Resolution in Minerva Simulations

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. Ensemble Spread and Resolution in Minerva Simulations Ben Cash and Jieshun Zhu Minerva Project Team Minerva Workshop,GMU/COLA, September 16, 2013

  2. Role of Resolution in Minerva Simulations • Significant Differences in Atmosphere, Ocean Components • Multiple atmosphere resolutions • 64, 32, and 16 km • Single ocean resolution • 1 degree, telescoping to 1/3 degree • Lower resolution than ‘low’ resolution atmospheric case in extratropics, comparable near equator • Given difference in scales, how much impact does atmospheric resolution have on ocean? • Ensemble mean SST relatively insensitive to resolution • What about higher order statistics?

  3. Clear difference in ensemble spread between T639 and T319 • Significance? Focus on differences in ratio of ensemble variance • Significance determined by F-test

  4. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 May Values (May Initial Conditions)

  5. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 June Values (May Initial Conditions)

  6. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 July Values (May Initial Conditions)

  7. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 August Values (May Initial Conditions)

  8. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 September Values (May Initial Conditions)

  9. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 October Values (May Initial Conditions)

  10. Ratio of Ensemble Variance: T639 / T319 SST 2000-2011 November Values (May Initial Conditions)

  11. Intra-ensemble variance of SST increases significantly from T319 to T639 • Increase focused primarily in the tropics and subtropics • Result insensitive to choice of 2000-2011 period or 1980-2011 (not shown) • What about T639 to T1279?

  12. Ratio of Ensemble Variance: T1279 / T639 SST 2000-2011 November Values (May Initial Conditions)

  13. No significant change from T639 to T1279 • Consistent with Athena results suggesting many processes captured successfully at T511 • Suggestion of difference in tropical Atlantic, further evidence of tropical origin of difference? • Impact of these differences on overall simulation? • Are differences confined to SST?

  14. Ratio of Ensemble Variance: T639 / T319 Thermocline Depth 2000-2011 May Values (May Initial Conditions)

  15. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 June Values (May Initial Conditions)

  16. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 July Values (May Initial Conditions)

  17. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 August Values (May Initial Conditions)

  18. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 September Values (May Initial Conditions)

  19. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 October Values (May Initial Conditions)

  20. Ratio of Ensemble Variance: T1279 / T639 Thermocline Depth 2000-2011 November Values (May Initial Conditions)

  21. Ratio of Variances: November SST Thermocline pattern much noisier Similar patterns with differences throughout tropics and subtropics Ratio of Variances: November Thermocline

  22. What is driving these differences? • Differences are confined to the tropics and subtropics, little systematic difference in extratropics • True for both May and November starts (not shown) • Not being driven by ‘weather noise’ • Scale dependent noise focused on the tropics • Precipitation?

  23. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 May Values (May Initial Conditions)

  24. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 June Values (May Initial Conditions)

  25. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 July Values (May Initial Conditions)

  26. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 August Values (May Initial Conditions)

  27. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 September Values (May Initial Conditions)

  28. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 October Values (May Initial Conditions)

  29. Ratio of Ensemble Variance: T1279 / T319 Precipitation 2000-2011 November Values (May Initial Conditions)

  30. Summary and Conclusions • Ensemble mean SST bias relatively insensitive to increased resolution • Ensemble variance in tropics and subtropics increases significantly from T319 to T639 • Effect spans multiple ocean levels (SST, Thermocline Depth) • Tropical/Subtropical focus, resolution dependence, suggests role of convection • Pattern of precipitation variance increase consistent with ocean patterns • Ensemble variance does not increase significantly from T639 to T1279 • Consistent with step-change between T159 and T511 in Athena simulations • Critical threshold between T319 and T639?

  31. Meeting Logistics • Dinner! • For those attending dinner, reservation is at 6:30pm. Let me know if you need a ride. • Tomorrow • Breakfast, lunch and break schedule as today • Discussion sessions to cover: • Summary of Day 1 results • Further analysis to be performed • Initial publications and writing responsibilities • Further experiments to be performed

  32. SSTA Spread/RMSE (May ICs 1982-2011) - Leading 7 Months

More Related