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Predicting the Earth System Across Scales: Both Ways

Predicting the Earth System Across Scales: Both Ways. Greg Holland NCAR. Summary: Rationale Approach and Current Focus Improved Simulation of Tropical Modes Requirements for Tropical Cyclone Response to Climate Change. Rationale: Regional Climate. Downscaling Upscaling. 1995.

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Predicting the Earth System Across Scales: Both Ways

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  1. Predicting the Earth System Across Scales: Both Ways Greg Holland NCAR Summary: Rationale Approach and Current Focus Improved Simulation of Tropical Modes Requirements for Tropical Cyclone Response to Climate Change Holland, CCSM Workshop 0606

  2. Rationale: Regional Climate • Downscaling • Upscaling Holland, CCSM Workshop 0606

  3. 1995 Downscaling and Upscaling: Atlantic Tropical Cyclone Trends Satellites Holland, CCSM Workshop 0606

  4. Upscaling: Mean Rainfall Holland, CCSM Workshop 0606

  5. Upscaling and Downscaling: Tropical Modes Observed CCSM (Lin et al 2006) All tropical modes are poorly handled by current climate models. This impacts everything from tropical cyclones to ENSO and interactions with the extratropics. Holland, CCSM Workshop 0606

  6. The Opportunity CCSM/CAM Community Models WRF Community Model Holland, CCSM Workshop 0606

  7. Approach and Current Focus Approach: Nesting the NCAR Weather Research and Forecasting Model into CAM as a 2-way Nested Regional Climate Model (NRCM); • Stage 1: Downscaling over North America (done); • Stage 2: 2-way atmospheric scale interactions in the tropics (current); • Stage 3: NRCM in CAM/CCSM, with coupled ocean model; as a community facility (next). Current Focus: Tropical scale interactions: • Importance of mesoscale organization of convection and its related surface exchanges and radiative influences for forcing tropical modes; • Tropical mode forcing of tropical cyclone development and intensification. Holland, CCSM Workshop 0606

  8. Model Setup Tropical Channel, 36 km, N/S boundaries 1-way nested into NCEP Reanalysis with specified SST, Kain-Fritsch Cu Parameterization, CAM radiation and YSU boundary layer. Precipitable Water (mm) 4 km nested domain inside 12 km and 36 km domains, fully 2-way interactive, Dudia cloud physics, CAM radiation and YSU boundary layer. Wind Speed (m/s) Holland, CCSM Workshop 0606

  9. NRCM Experiments • CAM at T170 Resolution: Jan 1, 1966 to Jan 1 2001 • 36km Channel Model: Jan 1, 1996 to Jan 1, 2001 • 36km Channel + high resolution SST's: Jan 1, 1999 to Jan 1, 2000 • 36km Channel + fluxes: Jan 1, 1996 to Jan 1 1998 • 36km Channel + 12km Maritime domain: Jan 1, 1996 to Feb 12, 1998 • 36km Channel + 12/4km Maritime domains: Jan 1, 1997 to Jul 1, 1997 Holland, CCSM Workshop 0606

  10. Precipitable Water: 1997 Holland, CCSM Workshop 0606

  11. NRCM Simulation Inertia-Gravity Modes present, but too small Improved Rossby Wave, Kelvin and MJO Modes Power Spectra NCEP Analysis Holland, CCSM Workshop 0606

  12. MJO and Easterly Wave Simulation Holland, CCSM Workshop 0606

  13. July 22nd over eastern Indonesia MJO wet phase 28 days August 19th in eastern North Pacific 39 days October 8th westerly wind burst Holland, CCSM Workshop 0606

  14. 0722:00 0701:12 0722:12 0705:12 0711:12 0708:12 0718:12 0715:12 Easterly Wave Interactions with MJO Holland, CCSM Workshop 0606

  15. Simulated Observed NRCM Tropical Cyclone Simulation: Seasonal Distribution 1996-1998 Holland, CCSM Workshop 0606

  16. 1997 1996 1998 Annual Tropical Cyclone Statistics Yellow are Observed; Blue are Simulated. SWIO: Southwest Indian Ocean; WAUS: Western Australia SWP: Southwest Pacific NIO: North Indian Ocean; NWP: Northwest Pacific; ENP: Eastern North Pacific; NAT: North Atlantic. Holland, CCSM Workshop 0606

  17. Tropical Cyclones and Climate Change Holland, CCSM Workshop 0606

  18. AEW Development 9-y Running Mean Holland, CCSM Workshop 0606

  19. Equatorial 90% 92% 81% 55% 36% 42% (Data 1945-2004) Importance of AEW Development >85% of all Major Hurricanes develop from Easterly Waves!!! Holland, CCSM Workshop 0606

  20. East/West Atlantic and Gulf SSTs Holland, CCSM Workshop 0606

  21. The NAO Global Surface Temperature Variability Volcano 1970 Solar Sulfate There is no known natural forcing mechanism that can explain the surface temperature increases since 1960 (Meehl et al 2004, 2006) Notice the warm 1940-50 period in the “natural cycle” Ozone Holland, CCSM Workshop 0606

  22. So what is happening? Compare the record 2005 season with a mean of 1991-1993: • 2005: 27 Storms, 12 hurricanes, 5 cat 4-5; • 1991-1993: 22 storms (total), 12 hurricanes, 2 cat 4-5 • 2995 30% of all AEWs became named storms (normally 10%); • AEWs produced 10 of the 14 hurricanes in 2005, all category 3-5 hurricanes, all tropical cyclones in July and August, and 8 of the 11 tropical cyclones in September and October. Two AEWs also generated two tropical cyclones each, a rare event that last occurred in 1988; • For 1991-1993 only one hurricane developed from AEWs, there were no July storms and only one in October. Holland, CCSM Workshop 0606

  23. 2005 vs 1991-1993 Holland, CCSM Workshop 0606

  24. 7000 km Min OLR S S S 5 4 S 1 5 3 5 4 S S 2 1 S 3 Tropical cyclone formation locations NAT SST-Hurricane Relationships Max SST North Atlantic oceanic and atmospheric response to global warming. Holland, CCSM Workshop 0606

  25. Vorticity Changes; du/dx<0 July 2005 Holland, CCSM Workshop 0606

  26. Assessing Potential Climate Change Impact on Tropical Cyclones: Requirements • Resolve hurricane structure • Simulate tropical atmospheric response to oceanic heat changes • Simulate tropical modes accurately • Simulate feedback between hurricanes and ocean/atmospheric circulations Coupling CCSM/CAM with WRF and a GOM/ROM enables this Holland, CCSM Workshop 0606

  27. Summary • The weather and climate scales are part of a continuum of action across scales; • We have the tools in CAM/CCSM and WRF to open up new frontiers in understanding and predicting these 2-way interactions; • The Petascale Computing Facility provides the capacity; So Lets Do It Thank You Holland, CCSM Workshop 0606

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