1. On the Multi-Intensity Changes of Hurricane Earl (2010) Daniel Nelson, Jung Hoon Shin, and Da-Lin Zhang Department of Atmospheric and Oceanic Science University of Maryland, College Park

2. Our studies of NASA’s “old” Storms Cecelski, S., and D.-L. Zhang, 2013: Genesis of Hurricane Julia (2010) within an African Easterly wave: Low-level vortices and upper-level warming. J. Atmos. Sci., 70, 3799- 3817. Cecelski, S., D.-L. Zhang, and T. Miyoshi, 2014: Genesis of Hurricane Julia (2010) within an African Easterly wave: Developing and non-developing members from WRF-LETKF ensemble forecasts. J. Atmos. Sci., 71, 2763-2781. Cecelski, S., and D.-L. Zhang, 2014: Genesis of Hurricane Julia (2010) within an African easterly wave: Sensitivity analysis of WRF-LETKF ensemble forecasts. J. Atmos. Sci., 71, 3180-3201. Cecelski, S., and D.-L. Zhang, 2015: Genesis of Hurricane Julia (2010) within an African easterly wave: Sensitivity to ice microphysics. Submitted to J. Appl. Meteor. Climatol. Zhu, L., D.-L. Zhang, S. F. Cecelski, and X. Shen, 2015: Genesis of Tropical Storm Debby (2006) within an African Easterly wave: Roles of the bottom-up and midlevel pouch processes. J. Atmos. Sci., in press. NASA - HS3 Workshop

3. From Cangialosi (2011)

4. NASA - HS3 Workshop From Cangialosi (2011)

5. Previous studies of Hurricane Earl (2010) Rogers et al. (2015) studied multiscale structure and evolution during RI using data from aircraft missions flown into the storm; Chen and Gopalakrishan (2015) modeled the asymmetric RI using the HWRF system with the finest resolution of 3 km; Stevenson et al. (2015) examined the relationship between an inner-core lightning outbreak and the subsequent RI; Shay and Uhlhorn (2015) calculated enthalpy and momentum fluxes in relation to intensity change and underlying upper- ocean thermal structure during Earl’s RI stage. NASA - HS3 Workshop

6. The purposes of this study Examine the multiple intensity and structural changes, including RI and an eyewall replacement cycle; Explore the mechanisms by which SEF occurred and the modeling sensitivity to SEF; and Study the structural changes of upper outflows during RI of Earl and their roles. This work will be conducted using the WRF-ARW with the finest grid size of 1.333 km. NASA - HS3 Workshop

7. Nested-grid domains45/15/5/1.667-km resolutions 45-km domain: 210 x 150 15-km domain: 319 x 319 5-km domain: 301 x 301 1.667-km domain: 271 x 271 Vertical grids50 levels with higher resolution in the lowest 300 hPa and the model top at 30-hPa Planetary Boundary layerThe YSU scheme Cumulus parameterizationThe Betts-Miller scheme for 45/15/5-km domains. No Cumulus scheme for 1.667-km domain. Cloud microphysicsThe Thompson scheme Radiation parameterization: The RRTM longwave scheme, and the Dudhia shortwave scheme Initialization time: 0000 UTC 28 August 2010 with the NCEP re-analysis Model configuration NASA - HS3 Workshop

8. . Model domain configuration and track comparison NASA - HS3 Workshop

9. Time series of the model-simulated (P WRF, V WRF ) and the observed (P OBS, V OBS ) maximum surface wind (m s -1 ) and minimum sea-level pressure (hPa) NASA - HS3 Workshop

10. Time series of the 1000 by 1000 km area-averaged 200-850 hPa vertical wind shear and shear direction. NASA - HS3 Workshop

13. Tangential winds as a function of time and radius (every 5 m s -1 ), superimposed with the radar reflectivity (dBZ), at z = 3 km NASA - HS3 Workshop

16. Z = 14 km NASA - HS3 Workshop

17. Summary and conclusions The WRF-ARW reproduces reasonably well the multiple intensity and structural changes, especially the eyewall replacement cycle, but with a large track error. Results show changes in SSTs, VWS, upper-level flows and environmental moistures during the multiple intensity and structural change period, indicating possible roles of these parameters in affecting the storm intensity and structural changes. NASA - HS3 Workshop