Dynamics and Physics

Dynamics and Physics

Understanding Tropical Cyclone Structure and Intensity

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Who We Are

The destructive potential of a hurricane is governed by its interaction with the environment and physical processes internal to the storm. Researchers at AOML use a variety of tools to better understand how phenomena from the larger environmental scale down to the cloud and turbulent scale interact (multi-scale interactions) to produce such changes.

We also work closely with scientists from other disciplines to improve the tools available and to apply a new understanding in a way that benefits prediction and improves forecasts.

Objective

Our Objective is to improve our understanding of tropical cyclone structure and intensity change through the application of fundamental physical principles.

| Sim Aberson, Ph.D

| Trey Alvey, Ph.D

| Joe Cione, Ph.D

| Jason Dunion, Ph.D

| Mike Fischer, Ph.D

| Frank Marks, Sc.D

| Paul Reasor, Ph.D

| Rob Rogers, Ph.D

| Jun Zhang, Ph.D

Top News

NOAA Measures Hurricane Tammy from Satellites through the Sea

NOAA hurricane researchers successfully deployed a new uncrewed aircraft system (UAS) into Tropical Storm Tammy (2023) near an uncrewed surfance vehicle, saildrone, to measure parts of the storm too dangerous for humans to go. The Altius 600 UAS was launched from the NOAA WP-3D Orion Hurricane Hunter aircraft by scientists from NOAA’s Atlantic Oceanographic and Meteorological Laboratory during missions into the storm in coordination with the saildrone researchers and pilots.

small gray Altius uncrewed aircraft system model in the foreground with the P-3 aircraft in the bsckground

Read More News

12 Days of AOML Research
NOAA Satelite image of hurricanes Franklin and Idalia near the Southeastern United States
small gray Altius uncrewed aircraft system model in the foreground with the P-3 aircraft in the bsckground
NOAA hurricane researchers successfully deployed a new uncrewed aircraft system (UAS) into Tropical Storm Tammy (2023) to measure parts of the storm too dangerous for humans to go. The Black Swift Technologies S0™ UAS was launched from the NOAA WP-3D Orion Hurricane Hunter aircraft by scientists from NOAA’s Atlantic Oceanographic and Meteorological Laboratory during missions into the storm as it strengthened and headed closer to the Leeward Islands of the Caribbean.

Lightning Presentation

Rob Rogers explains how airborne observations can improve intensity forecasts by enhancing our understanding of the storm environment.

Components of the Multi-Scale Interaction

Storm Environment

A hurricane develops within an atmosphere characterized by evolving larger-scale distributions of moisture and wind, and over an ocean with a more slowly-evolving distribution of temperature. The surrounding atmosphere and ocean below a hurricane is called
the storm environment. Because the storm environment interacts with the hurricane, it is important both to characterize and understand it.

Storm-Environment Interactions

The interaction between a tropical cyclone (whether a hurricane, tropical storm, tropical depression, or a pre-depression) and the environment it encounters plays a critical role in determining whether the storm structure and intensity will change.

Internal Storm Processes

These are physical processes that can operate independently of the storm’s environment, or “internally.” Among other impacts, they are often associated with dramatic short-term changes in storm size and intensity, and are responsible for intense localized winds.

Building a Weather-Ready Nation.

Understanding Hurricane Formation.

Read “Precipitation Processes and Vortex Alignment during the Intensification of a Weak Tropical Cyclone in Moderate Vertical Shear.”

Understanding the formation of a hurricane is critical to preparing coastal communities before severe weather threatens our coasts. Our scientists are studying this question by looking at how these weather patterns change and mature in their environment from small to large scales. Read the latest research below.

storm-env

The Storm Environment

Moisture in the Environment

Dry air masses like the Saharan Air Layer can have about 50% less moisture than the typical tropical atmosphere. This extremely dry air can weaken a tropical cyclone or tropical disturbance by promoting downdrafts around the storm. AOML hurricane scientists investigate how dry air affects storm intensity and structure and how vertical wind shear can magnify the negative effects of dry air.

Vertical Wind Shear

Winds blow from different directions at different levels of the atmosphere. This wind shear can vary greatly with height and across large distances. Low wind shear is generally favorable for tropical cyclone intensification. Scientists at AOML develop methods to measure wind shear around developing tropical cyclones.

Upper Ocean Interaction

Upper ocean properties such as sea surface temperature can affect storm intensity. AOML hurricane scientists investigate how the ocean structure changes before, during and after storm passage and its relationship to intensity change.

storm-env-interactions

Storm-Environment Interactions

Vortex Alignment

Storms struggle to intensify when their circulations are not aligned between the lower and upper levels of the atmosphere, which often happens when they encounter vertical wind shear. AOML hurricane scientists investigate how these storms can become aligned and intensify, even in the presence of this hostile wind environment.

Precipitation Processes

The structure of precipitation (rainfall) and how it’s distributed around the storm can play an important role in determining whether or not the storm will intensify.  Scientists at AOML investigate how the structure and distribution of precipitation changes in relation to the storm environment to allow for intensification.

Planetary Boundary Layer Recovery

Precipitation can bring cool, dry air to the boundary layer, effectively limiting the development of strong thunderstorms in the storm circulation.  Scientists at AOML study how the boundary layer can recover in the presence of vertical wind shear to allow for new development of thunderstorms and storm intensification.

Slide to look at aligned v. unaligned vortex

internal-storm

Internal Storm Processes

Secondary Eyewall Formation

Intense hurricanes often develop so-called secondary eyewalls outside of the initial primary eyewall. AOML hurricane scientists investigate how these secondary eyewalls form and their impact on hurricane intensity.

See Animation

Image of Eyewall Mixing. Credit: ESA/A.Gerst, CC BY-SA 3.0 IGO

Eyewall Mixing

An otherwise circular eyewall can transition into a dynamic mixture of spiral bands and intense localized swirls. Hurricane scientists at AOML investigate how these smaller-scale structures impact hurricane intensification.

Planetary Boundary Layer Dynamics

The layer of the hurricane flow closest to the ocean surface is characterized by turbulent motion. AOML scientists study how the effects of turbulence can be represented in models that are unable to simulate the turbulent motions. They also study how the turbulence contributes to hurricane intensification.

Hurricane Field Program

We Drive Innovative Science.

Experimental Design and the Hurricane Field Program.

Addressing research questions about the dynamics and physics of tropical cyclones is a major factor in how in-flight observations are taken. Because we have a direct line to observations from the Hurricane Field Program, we can capitalize on using these data for cutting-edge hurricane genesis and intensification research.

Read the experimental design plans for the Hurricane Field Program to learn more.

Scientists Rob Rogers and Paul Reasor prepare for hurricane flight into Barry. Photo Credit, NOAA AOML.
Scientists Rob Rogers and Paul Reasor prepare for hurricane flight into Barry. Photo Credit, NOAA AOML.

precip-paper

Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Image of the scientific paper

DesRosiers, A. J., Bell, M. M., Klotzbach, P. J., Fischer, M. S., & Reasor, P. D. (2023). Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Geophysical Research Letters, 50(8), e2022GL101877.

Abstract: As a tropical cyclone (TC) intensifies, the tangential wind field expands vertically and increases in magnitude. Observations and modeling support vortex height as an important TC structural characteristic. The Tropical Cyclone Radar Archive of Doppler Analyses with Recentering data set provides kinematic analyses for calculation of the height of the vortex (HOV) in observed storms. Analyses are azimuthally-averaged with tangential wind values taken along the radius of maximum winds. A threshold-based technique is used to determine the HOV. A fixed threshold HOV strongly correlates with current intensity. A dynamic HOV metric quantifies vertical decay of tangential wind with reduced dependency on intensity. Statistically significant differences are present between dynamic HOV values in groups of steady-state, intensifying, and rapidly-intensifying cases categorized by subsequent changes in pressure.

Download Full Paper

Observed Relationships Between Tropical Cyclone Vortex Height, Intensity, and Intensification Rate

DesRosiers, A. J., Bell, M. M., Klotzbach, P. J., Fischer, M. S., & Reasor, P. D. (2023). Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Geophysical Research Letters, 50(8), e2022GL101877.

Abstract: As a tropical cyclone (TC) intensifies, the tangential wind field expands vertically and increases in magnitude. Observations and modeling support vortex height as an important TC structural characteristic. The Tropical Cyclone Radar Archive of Doppler Analyses with Recentering data set provides kinematic analyses for calculation of the height of the vortex (HOV) in observed storms. Analyses are azimuthally-averaged with tangential wind values taken along the radius of maximum winds. A threshold-based technique is used to determine the HOV. A fixed threshold HOV strongly correlates with current intensity. A dynamic HOV metric quantifies vertical decay of tangential wind with reduced dependency on intensity. Statistically significant differences are present between dynamic HOV values in groups of steady-state, intensifying, and rapidly-intensifying cases categorized by subsequent changes in pressure.

Download Full Paper

Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Image of the scientific paper

Publications & References

  • 2020

    Cione, J.J., G. Bryan, R. Dobosy, J. Zhang, G. de Boer, A.Aksoy, J. Wadler, E.Kalina, B. Dahl, K. Ryan, J. Neuhaus, E. Dumas, F. Marks, A. Farber, T. Hock and X. Chen 2020:  Eye of the Storm: Observing Hurricanes with a Small Unmanned Aircraft System. Bull. Amer. Meteor. Soc. https://doi.org/10.1175/BAMS-D-19-0169.1

    Fischer, M. S., R. F. Rogers, and P. D. Reasor, 2020: The Rapid Intensification and Eyewall Replacement Cycles of Hurricane Irma (2017). Mon. Wea. Rev., 148, 981–1004, https://doi.org/10.1175/MWR-D-19-0185.1.

    Rogers, R. F., P. D. Reasor, J. A. Zawislak, and L. T. Nguyen, 2020: Precipitation Processes and Vortex Alignment during the Intensification of a Weak Tropical Cyclone in Moderate Vertical Shear. Mon. Wea. Rev., 148, 1899–1929, https://doi.org/10.1175/MWR-D-19-0315.1.

  • 2019

    Ahern, K., M.A. Bourassa, R.E. Hart, J.A. Zhang, and R.F. Rogers, 2019: Observed Kinematic and Thermodynamic Structure in the Hurricane Boundary Layer during Intensity Change. Mon. Wea. Rev., 147, 2765–2785, https://doi.org/10.1175/MWR-D-18-0380.1.

    Alvey III, G. R., E. Zipser, J. Zawislak, 2019: How does Hurricane Edouard (2014) evolve toward symmetry before intensification? A high-resolution ensemble study. J. Atmos. Sci., in press.

    Chen, X., J. A. Zhang, and F. D. Marks, 2019: A thermodynamic pathway leading to rapid intensification of tropical cyclones in shear. Geophys. Res. Lett., 46, 9241-9251, https://doi.org/10.1029/2019GL083667

    Chen X., J. A. Zhang, F. D. Marks, R. F. Rogers, and J. J. Cione, 2019: Precipitation Symmetrization and Rapid Intensification of Tropical Cyclones under Shear: J. Atmos. Sci., in review.

    Dunion, J.P., C.D. Thorncroft, and D.S. Nolan. 2019: Tropical cyclone diurnal cycle signals in a hurricane nature run. Mon. Wea. Rev., 147, 363-388, https://doi.org/10.1175/MWR-D-18-0130.1.

    Guimond, S.R., P.D. Reasor, G.M. Heymsfield, and M. McLinden, 2019: The Dynamics of Vortex Rossby Waves and Secondary Eyewall Development in Hurricane Matthew (2016): New Insights from Radar Measurements. J. Atmos. Sci., in review.

    Martinez, J., M.M. Bell, R.F. Rogers, and J.D. Doyle, 2019: Axisymmetric potential vorticity evolution of Hurricane Patricia (2015), J. Atmos. Sci., 76, 2043–2063, https://doi.org/10.1175/JAS-D-18-0373.1.

    Molinari, J., J.A. Zhang, R.F. Rogers, and D. Vollaro, 2019: Repeated Eyewall Replacement Cycles in Hurricane Frances (2004).  Mon. Wea. Rev., 0, https://doi.org/10.1175/MWR-D-18-0345.1.

    Nguyen, L.T., R.F. Rogers, J. Zawislak, and J.A. Zhang, 2019: Assessing the Influence of Convective Downdrafts and Surface Enthalpy Fluxes on Tropical Cyclone Intensity Change in Moderate Vertical Wind Shear. Mon. Wea. Rev., 0, https://doi.org/10.1175/MWR-D-18-0461.1.

    Wadler, J., R.F. Rogers, and P.D. Reasor, 2018a: The relationship between spatial variations in the structure of convective bursts and tropical cyclone intensification as determined by airborne Doppler radar.  Mon. Wea. Rev., 146, 761–780. https://doi.org/10.1175/MWR-D-17-0213.1.

    Zhang, J.A. and R.F. Rogers, 2019: Effects of parameterized boundary layer structure on hurricane rapid intensification in shear. Mon. Wea. Rev., 147, 853-871, https://doi.org/10.1175/MWR-D-18-0010.1.

  • 2018

    Bowers, G. S., Smith, D. M., Kelley, N. A., Martinez‐McKinney, G. F., Cummer, S. A., Dwyer, J. R., et al. ( 2018). A terrestrial gamma‐ray flash inside the eyewall of Hurricane Patricia. Journal of Geophysical Research: Atmospheres, 123, 4977– 4987. https://doi.org/10.1029/2017JD027771

    Didlake, A.C., Paul D. Reasor, and R.F. Rogers, W.-C. Lee, 2018: Dynamics of the transition from spiral rainbands to a secondary eyewall in Hurricane Earl (2010).  J. Atmos. Sci., 75, 2909–2929, https://doi.org/10.1175/JAS-D-17-0348.1.

    Dougherty, E.M., J. Molinari, R.F. Rogers, J.A. Zhang, and J.P. Kossin, 2018: Hurricane Bonnie (1998): Maintaining Intensity during High Vertical Wind Shear and an Eyewall Replacement Cycle. Mon. Wea. Rev., 146, 3383–3399, https://doi.org/10.1175/MWR-D-18-0030.1

    Guimond, S. R. J. A. Zhang, J. Sapp, and S. J. Frasier, 2018: Coherent turbulence in the boundary layer of Hurricane Rita (2005) during an eyewall replacement cycle. J. Atmos. Sci., 75, 3071–3093.

    Leighton, H., S. Gopalakrishnan, J.A. Zhang, R.F. Rogers, Z. Zhang, and V. Tallapragada, 2018: Azimuthal Distribution of Deep Convection, Environmental Factors, and Tropical Cyclone Rapid Intensification: A Perspective from HWRF Ensemble Forecasts of Hurricane Edouard (2014). J. Atmos. Sci., 75, 275–295, https://doi.org/10.1175/JAS-D-17-0171.1

    Wadler, J.B., J.A. Zhang, B. Jaimes, and L.K. Shay, 2018b: Downdrafts and the Evolution of Boundary Layer Thermodynamics in Hurricane Earl (2010) before and during Rapid Intensification. Mon. Wea. Rev., 146, 3545–3565.

  • 2017

    Didlake, A.C., G.M. Heymsfield, P.D. Reasor, and S.R. Guimond, 2017: Concentric Eyewall Asymmetries in Hurricane Gonzalo (2014) Observed by Airborne Radar. Mon. Wea. Rev., 145, 729–749, https://doi.org/10.1175/MWR-D-16-0175.1

    Hazelton, A.T., R.F. Rogers, and R.E. Hart, 2017: Analyzing simulated convective bursts in two Atlantic hurricanes. Part I: Convective burst formation and development.  Mon. Wea. Rev., 145(8), 3073-3094, doi: 10.1175/MWR-D-16-0267.1.

    Hazelton, A.T., R.E. Hart, and R.F. Rogers, 2017: Analyzing simulated convective bursts in two Atlantic hurricanes. Part II: Intensity change due to convective bursts.  Mon. Wea. Rev., 145(8), 3095-3117, doi: 10.1175/MWR-D-16-0268.1.

    Kalina, E.A., S. Matrosov, J. Cione, F. Marks, J. Vivekanandan, R. Black, J. Hubbert, M. Bell, D.  Kingsmill, and A. White 2017: The Ice Water Paths of Small and Large Ice Species in Hurricanes Arthur (2014) and Irene (2011). J. Appl. Meteorol. DOI: http://dx.doi.org/10.1175/JAMC-D-16-0300.1

    Martinez, J., M.M. Bell, J.L. Vigh, and R.F. Rogers, 2017: Examining Tropical Cyclone Structure and Intensification with the FLIGHT+ Dataset from 1999 to 2012. Mon. Wea. Rev., 145, 4401–4421, https://doi.org/10.1175/MWR-D-17-0011.1.

    Nguyen, L.T., R.F. Rogers, and P.D. Reasor, 2017: Thermodynamic and Kinematic Influences on Precipitation Symmetry in Sheared Tropical Cyclones: Bertha and Cristobal (2014). Mon. Wea. Rev., 145, 4423–4446, https://doi.org/10.1175/MWR-D-17-0073.1.

    Smith, R. K., J. A. Zhang and M. T. Montgomery, 2017: The dynamics of intensification in a Hurricane Weather and Research Forecasting  simulation of Hurricane Earl (2010). Q. J. R. Meteorol. Soc., 143, 297-308.

    Zhang, J.A., R.F. Rogers, and V. Tallapragada, 2017: Impact of Parameterized Boundary Layer Structure on Tropical Cyclone Rapid Intensification Forecasts in HWRF. Mon. Wea. Rev., 145, 1413–1426, doi: 10.1175/MWR-D-16-0129.1.

  • 2016

    Abarca, S.F., M.T. Montgomery, S.A. Braun, and J.P. Dunion, 2016: On the secondary eyewall formation of Hurricane Edouard (2016), Mon. Wea. Rev. 144, 3321-3331, https://doi.org/10.1175/MWR-D-15-0421.1.

    Guimond, S.R., G.M. Heymsfield, P.D. Reasor, and A.C. Didlake, 2016: The Rapid Intensification of Hurricane Karl (2010): New Remote Sensing Observations of Convective Bursts from the Global Hawk Platform. J. Atmos. Sci., 73, 3617–3639, https://doi.org/10.1175/JAS-D-16-0026.1

    Rogers, R.F., J.A. Zhang, J. Zawislak, H. Jiang, G.R. Alvey III, E.J. Zipser, and S.N. Stevenson, 2016: Observations of the structure and evolution of Hurricane Edouard (2014) during intensity change.  Part II: Kinematic structure and the distribution of deep convection.  Mon. Wea. Rev., 144, 3355-3376.

    Zawislak, J., H. Jiang, G.R. Alvey III, E.J. Zipser, R.F. Rogers, J.A. Zhang, and S.N. Stevenson, 2016: Observations of the structure and evolution of Hurricane Edouard (2014) during intensity change. Part I: Relationship between the thermodynamic structure and precipitation. Mon. Wea. Rev., 144, 3333-3354.

  • 2015

    Cione, J.J. 2015: The relative roles of the ocean and atmosphere as revealed by buoy air-sea observations in hurricanes. Mon. Wea. Rev. doi: 10.1175/MWR-D-13-00380.1

    Hazelton, A., R.F. Rogers, and R.Hart, 2015: Shear-Relative Asymmetries in Tropical Cyclone Eyewall Slope. Mon. Wea. Rev., 143, 883-903.

    Reasor, P.D. and M.T. Montgomery, 2015: Evaluation of a Heuristic Model for Tropical Cyclone Resilience. J. Atmos. Sci., 72, 1765–1782, https://doi.org/10.1175/JAS-D-14-0318.1

    Rogers, R.F., P.D. Reasor, and J.A. Zhang, 2015: Multiscale structure and evolution of Hurricane Earl (2010) during rapid intensification. Mon. Wea. Rev., 143, 536-562.

    Susca-Lopata, G., J. Zawislak, E.J. Zipser, and R.F. Rogers, 2015: The role of observed environmental conditions and precipitation evolution in the rapid intensification of Hurricane Earl (2010). Mon. Wea. Rev., 143, 2207-2223.

    Zhang, J. A., and F. D. Marks, 2015:  Effects of horizontal diffusion on tropical cyclone intensity change and structure in idealized three-dimensional numerical simulations, Mon. Wea. Rev., 143, 10:  3981-3995.

    Zhang, J. A., D. S. Nolan, R. F. Rogers, and V. Tallapragada, 2015:  Evaluating the impact of improvements in the boundary layer parameterization on hurricane intensity and structure forecasts in HWRF, Mon. Wea. Rev., 143, 3136-3155

  • 2014

    Dunion, J.P., C.D. Thorncroft, and C.S. Velden, 2014: The tropical cyclone diurnal cycle of mature hurricanes. Mon. Wea. Rev., 142, 3900-3919, https://doi.org/10.1175/MWR-D-13-00191.1.

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