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

ESSL Holland, CCSM Workshop 0606 Rationale: Regional Climate Downscaling Upscaling

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

ESSL Holland, CCSM Workshop 0606 Upscaling: Mean Rainfall

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

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

ESSL Holland, CCSM Workshop 0606 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.

ESSL Holland, CCSM Workshop 0606 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. 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) Precipitable Water (mm)

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

ESSL Holland, CCSM Workshop 0606 Precipitable Water: 1997

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

ESSL Holland, CCSM Workshop 0606 MJO and Easterly Wave Simulation

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

ESSL Holland, CCSM Workshop 0606 Easterly Wave Interactions with MJO 0722: : : : : : : :12

ESSL Holland, CCSM Workshop 0606 NRCM Tropical Cyclone Simulation: Seasonal Distribution Observed Simulated

ESSL Holland, CCSM Workshop 0606 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.

ESSL Holland, CCSM Workshop 0606 Tropical Cyclones and Climate Change

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

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

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

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

ESSL Holland, CCSM Workshop 0606 So what is happening? Compare the record 2005 season with a mean of : 2005: 27 Storms, 12 hurricanes, 5 cat 4-5; : 22 storms (total), 12 hurricanes, 2 cat % 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 only one hurricane developed from AEWs, there were no July storms and only one in October.

ESSL Holland, CCSM Workshop vs

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

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

ESSL Holland, CCSM Workshop 0606 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

ESSL Holland, CCSM Workshop 0606 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