Electrified Simulations of Hurricane Rita (2005) with Comparisons to LASA Data Steve Guimond 1,2, Jon Reisner 2, Chris Jeffery 2 and Xuan-Min Shao 2 1 Florida State University 2 Los Alamos National Laboratory

Motivation Improve understanding and forecasting of TC intensification

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

Motivation Improve understanding and forecasting of TC intensification –Convective obs hard to come by over ocean Doppler radar coverage very sparse Lightning fills gaps in convective monitoring ?

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

Motivation Improve understanding and forecasting of TC intensification –Convective obs hard to come by over ocean Doppler radar coverage very sparse Lightning fills gaps in convective monitoring ? –Understand relationship between latent heating and lightning –When/where to add energy to system –Differences in where most lightning located (i.e. Molinari et al. 1999; Cecil and Zipser 2002; Squires and Businger 2007) Detection efficiency issue Is eyewall lightning important indicator of structural change ?

New Research Tools –Observational component Los Alamos Sferic Array (LASA; Shao et al. 2000) –Existing VLF array »Records full EMP (allows detection of intracloud and cloud- to-ground strokes) »Lat/Lon, time, height? New Dual VLF-VHF 4-D lightning mapping array –Deployed along banks of Gulf of Mexico –VLF (~2000 km range) –VHF (~500 km range) »Provides precise height retrieval Combine with existing radars –NOAA P-3s, 88Ds, ELDORA?, EDOP?

New Research Tools –Theoretical component Advanced atmospheric model HIGRAD (Reisner et al. 2004) –Compressible Navier-Stokes, non-hydrostatic, explicit convection –Differentiable (smooth) numerics with greatly reduced time errors (option) –Option to use a particle-based (Lagrangian) cloud model which overcomes bin limitations. Coupled to electrification model (Mansell et al. 2005) –Non-inductive charging mechanism using Saunders scheme –Discharge model requires significant tuning »Based on limiters »Tuned to hurricanes based on Fierro et al. (2002)

Do Hot Towers Produce Lightning? Hot Towers or Vortical Hot Towers (i.e. Montgomery et al. 2006) –Deep convection  reach or penetrate trop –Strong, rotating updrafts –Embedded in warm-core cyclone over ocean Effects on microphysics? Next slides… –ER-2 Doppler Radar observations of Hot Towers Linear Depolarization Ratio (LDR) –particle canting angle or asymmetry »horizontal dimension larger than vertical –dielectric constant (i.e. wet or dry) Retrieved vertical velocities (nadir beam) –Lightning Instrument Package (LIP) Aircraft (20 km) electric field mills (x,y,z components) ~1 s sampling, ~200 m horizontal resolution

Hot Tower #1: CAT 2 Dennis (2005) -8 to -15 dB  large, wet, asymmetric ice to large, wet snow aggregates -13 to -17 dB  medium, wet graupel or small hail -18 to -26 dB  small, dry ice particles to dry, low density snow

Hot Tower #2: CAT 4 Emily (2005) -8 to -15 dB  large, wet, asymmetric ice to large, wet snow aggregates -13 to -17 dB  medium, wet graupel or small hail -18 to -26 dB  small, dry ice particles to dry, low density snow

Hurricane Rita Simulations Current configuration –Grid 1,980 km on a side; 4 km inner mesh, stretch to 20 km 35 m stretching to 15 km –Relaxation boundary conditions –Weak, top gravity wave absorber Initialization –Barotropic vortex, max wind of 40 m/s –Initial forcing from Key West 88D reflectivity Storm-centered, gridded, native 1 km –ECMWF operational analyses for large scale –Satellite SSTs, High-res topography

Structure of Latent Heat

HIGRAD vs. LASA Model Observations

Combining Structure and Magnitude

Testing algorithm in model

P-3 Doppler Radar Results

Rita WSR-88D Animation

LASA observations of Rita

P-3 Doppler Radar LH in Guillermo(1997)

P-3 Radar LH: Thermodynamic Sensitivity

New method for LH retrievals –Ability to accept some errors in water budget –Local tendency, radar-derived parameters –LH magnitude relatively insensitive to thermo –Sensitive to vertical velocity (most important) Test mass continuity vertical velocity or use EDOP? ~30 minute radar sampling does nothing for water budget Local tendency à order of mag. less than Qnet Incorporate WSR-88Ds for tendency, heating evolution Hybrid method –Doppler radar and dropsonde Conclusions and Future Work

Future Hurricane Rita Simulations Configuration – km inner mesh –Key West 88D derived Symmetric, baroclinic vortex Symmetric latent heat retrieval (Guimond 2008) –Extended Kalman Filtering data assimilation with LASA (with J. Kao)

Acknowledgments LANL Hurricane Lightning Team References Reisner et al. (2005) Mansell et al. (2005) Molinari et al. (XXXX) Cecil et al. (XXXX)