scholarly journals Sensitivities of eyewall replacement cycle to model physics, vortex structure, and background winds in numerical simulations of tropical cyclones

2015 ◽  
Vol 120 (2) ◽  
pp. 590-622 ◽  
Author(s):  
Zhenduo Zhu ◽  
Ping Zhu
Keyword(s):  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Vortex Structure ◽  
Eyewall Replacement Cycle ◽  
Replacement Cycle

scholarly journals Comparison of ARCHER MPERC to NHC Analysis

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Lorenzo Pulmano ◽  
Leya Joykutty
Keyword(s):  
Tropical Cyclones ◽  
Passive Microwave ◽  
Central Pacific ◽  
Atlantic Basin ◽  
Wind Speeds ◽  
Eyewall Replacement Cycle ◽  
Eyewall Replacement Cycles ◽  
National Hurricane Center ◽  
Joint Typhoon Warning Center ◽  
Replacement Cycle

Eyewall replacement cycles (ERCs) are events that occur in intense tropical cyclones (TCs) and are difficult to predict.  An ERC event involves a secondary outer eyewall that surrounds the inner eyewall.  The outer eyewall slowly moves towards the eye and weakens the inner eyewall, eventually replacing the inner eyewall.  During this process, wind speeds lower and the structure of a TC becomes disorganized, further weakening the storm.  TCs often restrengthen after an ERC.  Little is known about the process and as such, poses an obstacle to forecasters.  The Automated Rotational Center Hurricane Eye Retrieval (ARCHER) Microwave-based Probability of Eyewall Replacement Cycle (MPERC) is an algorithm that uses 89-95 GHz passive microwave imagery and intensity estimates from the National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), or the Joint Typhoon Warning Center (JTWC) to predict the possibility of an ERC.  The effectiveness and ability of ARCHER MPERC was analyzed and compared to the NHC’s official reports on all Atlantic Basin tropical cyclones from 2017 to 2019.   MPERC ultimately predicted seventeen ERCs in nine tropical cyclones.  Of those, seven were valid ERCs.  The algorithm works well, predicting approximately 41% of the total number of predictions correctly.  However, MPERC did not predict five ERCs that were cited by the NHC.  It was further found that it was true that MPERC produces incorrect results in sheared and dry environments.

scholarly journals Impact of subgrid‐scale processes on eyewall replacement cycle of tropical cyclones in HWRF system

2015 ◽  
Vol 42 (22) ◽  
Author(s):  
Ping Zhu ◽  
Zhenduo Zhu ◽  
Sundararaman Gopalakrishnan ◽  
Robert Black ◽  
Frank D. Marks ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Subgrid Scale ◽  
Eyewall Replacement Cycle ◽  
Replacement Cycle

scholarly journals Accessible Environments for Diurnal-Period Waves in Simulated Tropical Cyclones

2017 ◽  
Vol 74 (8) ◽  
pp. 2489-2502 ◽  
Author(s):  
Morgan E O’Neill ◽  
Diamilet Perez-Betancourt ◽  
Allison A. Wing
Keyword(s):  
Wave Propagation ◽  
Tropical Cyclone ◽  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Diurnal Cycle ◽  
Observational Analysis ◽  
Eyewall Replacement Cycle ◽  
Outflow Region ◽  
Upper Level ◽  
Diurnal Period

Abstract A recent observational analysis has reported significant repeating diurnal signals propagating outward at cloud-top height from tropical cyclone centers. Modeling studies suggest that the visible upper-level impacts reflect a diurnal cycle through the depth of the troposphere. In this study, the possibility of wavelike diurnal responses in tropical cyclones is characterized using 3D cloud-resolving numerical simulations with and without a diurnal cycle. Diurnal waves can only begin to propagate well beyond the storm core, and the outflow region is most receptive to near-core diurnal propagation because of its anticyclonic flow. The tropical cyclone structure appears particularly hostile to diurnal wave propagation during periods when the eyewall experiences a temporary breakdown similar to an eyewall replacement cycle.

scholarly journals The Unconventional Eyewall Replacement Cycle of Hurricane Ophelia (2005)

2021 ◽  
Author(s):  
Muhammad Naufal Razin ◽  
Michael M. Bell
Keyword(s):  
Intensity Change ◽  
Wind Maximum ◽  
Low Level ◽  
Tangential Wind ◽  
Eyewall Replacement Cycle ◽  
Flight Level ◽  
Intensive Observation ◽  
Observation Period ◽  
Replacement Cycle

AbstractHurricane Ophelia (2005) underwent an unconventional eyewall replacement cycle (ERC) as it was a Category 1 storm located over cold sea surface temperatures near 23°C. The ERC was analyzed using airborne radar, flight-level, and dropsonde data collected during the Hurricane Rainband and Intensity Change Experiment (RAINEX) intensive observation period on 11 September 2005. Results showed that the spin-up of the secondary tangential wind maximum during the ERC can be attributed to the efficient convergence of absolute angular momentum by the mid-level inflow of Ophelia’s dominantly stratiform rainbands. This secondary tangential wind maximum strongly contributed to the azimuthal mean tangential wind field, which is conducive for increased low-level supergradient winds and corresponding outflow. The low-level supergradient forcing enhanced convergence to form a secondary eyewall. Ophelia provides a unique example of an ERC occurring in a weaker storm with predominantly stratiform rainbands, suggesting an important role of stratiform precipitation processes in the development of secondary eyewalls.

Doppler Radar Analysis of the Eyewall Replacement Cycle of Hurricane Matthew (2016) in Vertical Wind Shear

2021 ◽  
Author(s):  
Ting-Yu Cha ◽  
Michael M. Bell ◽  
Alexander J. DesRosiers
Keyword(s):  
Wind Shear ◽  
Doppler Radar ◽  
Vertical Wind Shear ◽  
Radar Data ◽  
Secondary Circulation ◽  
Vertical Wind ◽  
High Temporal Resolution ◽  
Radar Observations ◽  
Eyewall Replacement Cycle ◽  
Replacement Cycle

AbstractHurricane Matthew (2016) was observed by ground-based polarimetric radars in Miami (KAMX), Melbourne (KMLB), and Jacksonville (KJAX) and a NOAA P3 airborne tail Doppler radar near the coast of the southeastern United States during an eyewall replacement cycle (ERC). The radar observations indicate that Matthew’s primary eyewall was replaced with a weaker outer eyewall, but unlike a classic ERC, Matthew did not reintensify after the inner eyewall disappeared. Triple Doppler analysis was calculated from the NOAA P3 airborne fore and aft radar scanning combined with the KAMX radar data during the period of secondary eyewall intensification and inner eyewall weakening from 19 UTC 6 October to 00 UTC 7 October. Four flight passes of the P3 aircraft show the evolution of the reflectivity, tangential winds, and secondary circulation as the outer eyewall became well-established. Further evolution of the ERC is analyzed from the ground-based single Doppler radar observations for 35 hours with high temporal resolution at a 5-minute interval from 19 UTC 6 October to 00 UTC 8 October using the Generalized Velocity Track Display (GVTD) technique. The single-Doppler analyses indicate that the inner eyewall decayed a few hours after the P3 flight, while the outer eyewall contracted but did not reintensify and the asymmetries increased episodically. The analysis suggests that the ERC process was influenced by a complex combination of environmental vertical wind shear, an evolving axisymmetric secondary circulation, and an asymmetric vortex Rossby wave damping mechanism that promoted vortex resiliency despite increasing shear.

Are Eyewall Replacement Cycles Governed Largely by Axisymmetric Balance Dynamics?

2015 ◽  
Vol 72 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Sergio F. Abarca ◽  
Michael T. Montgomery
Keyword(s):  
Boundary Layer ◽  
Recent Work ◽  
Balance Model ◽  
Tangential Wind ◽  
Eyewall Replacement Cycle ◽  
Physics Simulation ◽  
Physics Model ◽  
Balance Dynamics ◽  
Eyewall Replacement Cycles ◽  
Replacement Cycle

Abstract The authors question the widely held view that radial contraction of a secondary eyewall during an eyewall replacement cycle is well understood and governed largely by the classical theory of axisymmetric balance dynamics. The investigation is based on a comparison of the secondary circulation and derived tangential wind tendency between a full-physics simulation and the Sawyer–Eliassen balance model. The comparison is made at a time when the full-physics model exhibits radial contraction of the secondary eyewall during a canonical eyewall replacement cycle. It is shown that the Sawyer–Eliassen model is unable to capture the phenomenology of secondary eyewall radial contraction because it predicts a net spindown of the boundary layer tangential winds and does not represent the boundary layer spinup mechanism that has been articulated in recent work.

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