1. Bruyere Model Setup RPSEA 0310 Model Set-up and Nesting Approach Cindy Bruyère NCAR Earth System Laboratory National Center for Atmospheric Research NCAR is Sponsored by NSF and this work is partially supported by the Willis Research Network and the Research Program to Secure Energy for America

2. Bruyere Model Setup RPSEA 0310 Two-way nested domain 12 km Over NA Basin 45S - 45N 36 km resolution 51 levels 10 mb TOA 2000 - 2005 NNRP input data Reynolds SST data Periodic EW boundary Phase 1: Tropical Channel

3. Bruyere Model Setup RPSEA 0310 Tropical Channel: Results

4. Bruyere Model Setup RPSEA 0310 WRF 12 km WRF 36 km Image by Steve Dayo @UCAR CCSM ~ 150 km Nested Regional Climate Model Setup

5. Bruyere Model Setup RPSEA 0310 Nested Regional Climate Model Setup CCSM3: –One Current Climate member (1950-1999) –3 ensemble members from 2000-2060 under two A2 and one A1B scenarios (IPCC-AR4) NRCM: –1 ensemble member from 1995-2005, 2020-2030 and 2045-2055 under A2 scenario at 36 km (complete), and 12 km grid spacing (in progress) –No nudging Statistical downscaling of CCSM3 to fill in intermediate periods

6. Bruyere Model Setup RPSEA 0310 Cat 3 Hurricane October 2046 Track density of model tropical and extratropical storms Jan-Dec 1995 Regional Model: Results

7. Bruyere Model Setup RPSEA 0310 Shear in the Model (avg Aug-Oct) Channel NCEP/NCAR Reanalysis NRCM

8. Bruyere Model Setup RPSEA 0310 NCEP/NCAR Reanalysis CCSM Similar Bias in CCSM

9. Bruyere Model Setup RPSEA 0310 Possible Causes of High Shear CCSM exhibits same bias High shear is due to strong Westerly flow at 200mb Entire tropics has warm bias at upper-levels in CCSM, inducing westerly wind anomaly Also an El Niño-like SST anomaly → alters Walker Circulation → contributes to westerly wind anomaly

10. Bruyere Model Setup RPSEA 0310 Sensitivity Studies NCEP/NCAR Reanalysis NRCM + channel configuration NRCM + Reynolds SST NRCM

11. Bruyere Model Setup RPSEA 0310 11 Describe 6-hourly CCSM data for entire simulation (1950-2060) as an average annual cycle plus a perturbation term: CCSM = CCSM + CCSM’ (1) - using a 20-year averaging period (1975-1994), - applied to variables: U,V,Z,T,RH,Surface T and PMSL Do the same for NCEP-NCAR Reanalysis data: NNRP = NNRP + NNRP’ (2) Replace CCSM with NNRP: CCSMc = NNRP + CCSM’ (3) Base climate provided by NCEP-NCAR Reanalysis data and the weather and climate change signal provided by CCSM Bias Correction

12. Bruyere Model Setup RPSEA 0310 Shear after Adjustment NCEP/NCAR Reanalysis Adjusted N. A. Regional Climate NRCM

13. Bruyere Model Setup RPSEA 0310 Regional Model: New Results

14. Bruyere Model Setup RPSEA 0310 Conclusions Tropical Channel runs developed storms in the MDR, although fewer than observed Running NRCM directly forced with CCSM output resulted in no storms in MDR –Strong bias in shear and SST linked with this result Bias corrected CCSM allowed development of storms in MDR Next stage is the completion of the 12km runs