Inner-core structure of rapidly intensifying tropical cyclones

Principal Investigators:

• Paul D. Reasor (HRD)
• Robert F. Rogers (HRD)

Project Members:

• Hua C. Leighton (HRD/- CIMAS)
• Jason P. Dunion (HRD/- CIMAS)
• Sundararaman G. Gopalakrishnan (HRD)
• Jun A. Zhang (HRD/- CIMAS)

Collaborating Scientists:

S.S. Chen, University of Miami/RSMAS

I.-I. Lin, National Taiwan University

S. Lorsolo, AIR

C.-C. Wu, National Taiwan University

Objectives:

Investigate various aspects of tropical cyclone inner-core structure and its relationship with intensity change, using a combination of case studies and compositing techniques on a variety of observational and modeling datasets. 

Accomplishments:

Active work on this topic:

1. Investigate vortex- and convective-scale structures associated with TC’s that are intensifying and those that remain steady-state using composites of airborne Doppler radar data.  Notable differences were found in the structure of the axisymmetric radial and vertical flow and vorticity, as well as the number and radial location of deep convective cores relative to the radius of maximum winds (see schematic below).  Paper published in MWR in September 2013 (Click on paper title under "Project Links" for abstract).

 

Summary schematic of the key differences in the inner-core structure of (a) IN and (b) SS tropical cyclones. Black dashed line denotes radius of maximum wind, thick red line denotes radial profile of axisymmetric vertical vorticity (×10⁻⁴ s⁻¹) at 2-km altitude, and thick arrows denote axisymmetric radial and vertical wind. Blue dotted line denotes inflow layer defined by axisymmetric radial flow. Gray scalloped area denotes predominant radius of convective bursts. Insets show plan-view depiction of reflectivity at 2-km altitude [shaded, red (green) denotes high (low) reflectivity] and typical location of convective bursts (× marks). Both reflectivity and convective bursts are rotated relative to 850–200-hPa shear vector (black arrow pointing to right in inset).

 

2. Document the inner-core structure of Hurricane Earl (2010) as it underwent rapid intensification while it was sampled by NOAA P-3 and G-IV, NASA DC-8 and Global Hawk, and Air Force C-130 aircraft.  Focus is on the vortex-scale symmetric and asymmetric structure, in particular the vortex tilt, and the convective-scale structure, in particular the number and radial and azimuthal location of convective bursts, and how they relate to the observed intensification.

3. Examine the structure and evolution of the inner core of Hurricane Earl in 3-km HWRFv3.2 simulations.  Comparisons of structure from Earl simulation with observations and composite structures of intensifying TC’s shows several structural similarities between HWRF simulations and observations.  Further analyses are ongoing.

4. Investigate the mass flux evolution during the rapid intensification of a simulated typhoon (Choi-Wan) and how that evolution varies depending on whether the model is coupled or not.  This work is being done in collaboration with Drs. I.-I. Lin, C.-C. Wu and Shuyi Chen, among others.  

Project Links:

• Airborne Doppler Observations of the Inner-Core Structural Differences between Intensifying and Steady-State Tropical Cyclones

References:

Recent publications relevant to this topic:

Rogers, R.F., P. Reasor, and S. Lorsolo, 2013: Airborne Doppler Observations of the Inner-core Structural Differences between Intensifying and Steady-State Tropical Cyclones. Mon. Wea. Rev., 141, 2970-2991.

Yang, C.-Y., I-I Lin, C.-C. Wu, S.S. Chen, R.F. Rogers, and C. Lee, 2013: Rapid intensification of supertyphoons in the western North Pacific. Mon. Wea. Rev., Manuscript in preparation.

Reasor, Paul D., Matthew D. Eastin, 2012: Rapidly Intensifying Hurricane Guillermo (1997). Part II: Resilience in Shear. Mon. Wea. Rev., 140, 425–444.

Rogers, R.F., S. Lorsolo, P. Reasor, J. Gamache, F.D. Marks, Jr., 2012: Multiscale analysis of tropical cyclone kinematic structure from airborne Doppler radar composites.  Monthly Weather Review, 140, 77-99.

Rogers, R.F., 2010:  Convective-scale structure and evolution during a high-resolution simulation of tropical cyclone rapid intensification. Journal of the Atmospheric Sciences, 67, 44–70.

Reasor, Paul D., Matthew D. Eastin, John F. Gamache, 2009: Rapidly Intensifying Hurricane Guillermo (1997). Part I: Low-Wavenumber Structure and Evolution. Mon. Wea. Rev., 137, 603–631.

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