HOT TOWERS AND HURRICANE INTENSIFICATION

1. HOT TOWERS AND HURRICANE INTENSIFICATION Steve Guimond Florida State University

2. Motivation • TC intensification is a complex, non-linearprocess governed by physics on a multitude of scales • Synoptic scale • Vortex scale • Convective scale • Hydrometeor scale • Improving TC intensification (for wide range of applications including energy) hinges on better understanding of inner-core dynamics • In nature, the occurrence of hot towers can often be linked to TC intensification (i.e. Guimond et al. 2009) • But not always!

3. EYE EYE a b c d Motivation • What are hot towers? • How are they distributed?

4. Hurricane Intensification Roadmap Background Vortex Updraft Latent Heat Microphysics Eddy Heat and Momentum Fluxes Asymmetric heating Balanced response Adjustment Nolan and Grasso (2003) Intensity and Structure Change Symmetric heating Balanced response Adjustment Adjustment

5. Hurricane Intensification Roadmap Background Vortex Updraft Collisions & Charging Lightning Latent Heat Microphysics Eddy Heat and Momentum Fluxes Asymmetric heating Balanced response Adjustment Nolan and Grasso (2003) Intensity and Structure Change Symmetric heating Balanced response Adjustment Adjustment

6. My Contribution • Characterizing 4-D latent heating in RI Hurricane • Most estimates of latent heat in TCs are crude • Satellite • Coarse (space/time) • Not enough information (no winds) • Airborne dual-Doppler retrieval • 2 km x 2 km x 1 km x ~30 minutes • Understanding inner-core dynamics that is triggered by hot towers • What spatial/temporal scales of heating does the hurricane “feel” ? • Implications for observing systems  lightning • LANL network ~ 200 m resolution for VHF • Are small scale details of lightning/heating necessary to capture intensification or are bulk quantities sufficient?

7. Latent Heating Retrieval • Based on Roux and Ju (1990) • Solve water budget with Doppler radar • Compute latent heat with vertical velocity & lapse rate • Improvements to algorithm • Examine assumptions (uncover sensitivities) • Reduced uncertainties with ancillary data • Uncertainty estimates on final product

10. Inner-Core Dynamics • Balanced adjustment of hot towers at ~100 m vs. ~2 km and feedbacks onto vortex scale

11. Hurricane Intensification Roadmap Background Vortex Updraft Collisions & Charging Lightning Latent Heat Microphysics Eddy Heat and Momentum Fluxes Asymmetric heating Balanced response Adjustment Nolan and Grasso (2003) Intensity and Structure Change Symmetric heating Balanced response Adjustment Adjustment

12. Inner-Core Dynamics • Balanced adjustment of hot towers at ~100 m vs. ~ 2 km and feedbacks onto vortex scale • Dynamics heavily motivated by observations • Basic-state vortex using Doppler data • Made stable to all wavenumber perturbations • Heating perturbations using EDOP data

13. Peak Updrafts from EDOP Heymsfield et al. 2009

14. Summary and Ongoing Work • Goal: Understand fundamental impacts of hot towers (HTs) on hurricane intensification (Convective and Vortex Scales) • New version of latent heating retrieval • 4-D distribution of heating in RI Hurricane (first time) • Non-linear simulations addressing symmetric and asymmetric dynamics that result from HTs • Balanced adjustment of hot towers at ~100 m vs. ~2 km and feedbacks onto vortex scale • Proxy for lightning = latent heat ? • Help prove the value of lightning data in understanding/predicting dynamics of hurricanes • Physics on fine space/time scales are important • Role of the asymmetric mode

15. Acknowledgments • Gerry Heymsfield (EDOP and dropsonde data) • Paul Reasor and Matt Eastin (Guillermo edits) • Scott Braun (MM5 output) • Robert Black (cloud particle processing) References • Roux and Ju (1990) • Braun et al. (2006), Braun (2006) • Gamache et al. (1993) • Heymsfield et al. (1999) • Reasor et al. (2008) • Black (1990)

16. Idealized Calculation