Tong Zhu and Da-Lin Zhang 2006:J. Atmos. Sci.,63,109-126 Numerical Simulation of Hurricane Bonnie (1998). Part Ⅱ:Sensitivity to Varying Cloud Microphysical Process Tong Zhu and Da-Lin Zhang 2006:J. Atmos. Sci.,63,109-126

Purposes To examine the effects of various cloud microphysics processes on the intensity change, precipitation, and inner-core structures of Hurricane Bonnie (1998). To gain insight into the inner core structural changes of hurricane with different intensities as they interact with the same larger-scale sheared environment.

Experimental The initial hurricane vortex data come form Advanced Microwave Sensing Unit-A data with some surface parameters specified form the Third Convection and Moisture Experiment observations. The model initial data are obtained form NCEP (2.5x2.5) The SST is updated daily using the Tropical Rainfall Measuring Mission Microwave Imager Level Ⅰ. Model setting: the grid resolution is 4 km, PBL boundary condition, Tao-Simpson (1993) cloud microphysics scheme, and a radar scheme. The third field campaign in the CAMEX series (CAMEX-3) was based at Patrick Air Force Base , Florida from 6 August - 23 September, 1998. CAMEX-3 successfully studied Hurricanes Bonnie, Danielle, Earl and Georges. CAMEX-3 collected data for research in tropical cyclone development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.

Impact on hurricane intensity The vertical hydrometer structures may provide insight into the mechanisms by which precipitation and certain inner-core flows are generated. (a). Vertical structures of hydrometeor Graupel helps narrow the lateral eyewall dimension due to its rapid fallout, while the latent heat of fusion primary role in CTL run. (b). Hurricane tracks and intensity Removing the cooling phenomenon enhances the intense of hurricane, and the weak hurricane is effected by environment flow. (c). Vertical heating profiles The updraft is mainly reason for increasing heating (condensation heating).

Snow and Cloud ice are concentrated in outflow stratiform region. Graupel is concentrated primary in strong updraft in eyewall. East-west vertical cross sections, through the hurricane center, of the mixing ratios at intervals of 10-4 (kg/kg), of (a) cloud water (solid) and ice (dash), (b) rainwater (soild) and snow (dash), (c) graupel which are taken from 90-h CTL simulation

NEVP, NGP, NICE VS. CTL (snow and rain) NEVP: The RMW shrinks, with more strong updraft in eyewall. NMLT: Graupel could fall to the surface, leading to generation of wide and upright precipitation regions in the eyewall. NGP: The maximum of snow mixing ratio above the melting level near the maximum updraft. NICE: Cloud Water is widespread in the upper troposphere, but less rainwater above the zero isothermal level.

NMLT VS. CTL (Graupel)

NICE VS. CTL (Cloud water and ice)

NEVP: Because of the more rapid fallout after the phase change ice to liquid, the water loading decreases in melting zone. NMLT: The enhance updraft appear to result from a positive feedback between the low-level convergence of relatively and more moist air. NGP: The terminal velocity of snow is more slowly than graupel, and NGP has the maximum water loading above the melting level. NICE: Cloud Water is widespread in the upper troposphere, floating with the mean flow. Melting layer Vertical profiles of the water loading [g(qi+qs+qg+qc+qr)] that are averaged over an area 250 x 250 (km2) at the hurricane’s surface minimum pressure form the five 90-h sensitivity simulations.

Hurricane tracks and intensity 60 12-hourly tracks of Hurricane Bonnine

NEVP, NICE2 and NMLT increase the intensity NGP and NICE decrease the intensity 10 hPa 50 hPa Three-hourly time series of (a) the minimum central pressure ( ) and (b) the maximum surface wind ( ). 20 m/s 12 m/s

Vertical heating profiles NEVP: The evaporative cooling effect is less important than melting cooling effect as more graupel is generated in more intense updrafts for melting. NMLT: Melting in lower troposphere reduces the heating. NGP: The melting layer (4.5-6 km) is less pronounced with CTL run. NICE: The weakest updraft, the less condensation heating. 1.1℃hk-1m-1 The diabatic heating rates at 90 h

Impact on hurricane structures NEVP NMLT NGP NICE Cloud-Free Zone Heavy Rain Zone The time-azimuth cross sections of radar reflectivity along the updraft core at z=5 km form 5 day simulation.

(a) NEVP (b) MLT (d) NICE (c) NGP Flow vectors and radar reflectivity through the eye center form the 48 h simulations.

NEVP NICE NMLT NGP CTL

The 6-hourly time series of the accumulated precipitation that is integrated within a radius of 100km form the eye center.

NGP NEVP Zhu 2004 Time and west-east cross section of horizontal wind speed at intervals of 5 (m/s) at Z=3 km form 60-78 h simulations (b) vertical cross section of the horizontal wind speed at intervals of 5 (m/s) form 69 h. Shadings denote radar reflectivity at 30 and 40dBz

Summary NICE: The character is with widespread cloud water but litter rainwater in the upper troposphere. Most of latent heating and cloud hydrometeors production occur in the lowest 5 km NGP: There are more extensive clouds in the eyewall, and more ice particle above the melting level. The positive feedback is with the rapid fallout of graupel (NGP vs. CTL). NEVP and NMLT: this rapid development appears to result form a positive feedback between lower level convergence. In the eyewall, more graupe is generated and the melting cooling effect is more important than evaporation cooling. The eyewall replacement scenarios often occur in weak-sheared environment, but it can be find in the different phenomenon depending on the intense of Hurricane in the sensitivity simulations.