A Lagrangian Trajectory Analysis of Azimuthally Asymmetric Equivalent Potential Temperature in the Outer Core of Sheared Tropical Cyclones

In this study,the characteristics of azimuthally asymmetric equivalent potential temperature(θ_(e))distributions in the outer core of tropical cyclones(TCs)encountering weak and strong vertical wind shear are examined using a Lagrangian trajectory method.Evaporatively forced downdrafts in the outer rainbands can transport low-entropy air downward,resulting in the lowestθ_(e)in the downshear-left boundary layer.Quantitative estimations ofθ_(e)recovery indicate that air parcels,especially those originating from the downshear-left outer core,can gradually revive from a low entropy state through surface enthalpy fluxes as the parcels move cyclonically.As a result,the maximumθ_(e)is observed in the downshear-right quadrant of a highly sheared TC.The trajectory analyses also indicate that parcels that move upward in the outer rainbands and those that travel through the inner core due to shear make a dominant contribution to the midlevel enhancement ofθ_(e)in the downshear-left outer core.In particular,the former plays a leading role in suchθ_(e)enhancements,while the latter plays a secondary role.As a result,moist potential stability occurs in the middle-to-lower troposphere in the downshear-left outer core.

Characteristics of the Outer Rainband Stratiform Sector in Numerically Simulated Tropical Cyclones:Lower-Layer Shear versus Upper-Layer Shear

Idealized numerical simulations are conducted in this study to comparatively investigate the characteristics of the stratiform sector in the outer rainbands of tropical cyclones(TCs)in lower-and upper-layer vertical wind shear(VWS)with moderate magnitude.Consistent with the results in previous studies,the outer rainband stratiform sector of the TCs simulated in both experiments is generally located downshear left.Upper-layer VWS tends to produce stronger asymmetric outflow at upper levels in the downshear-left quadrant than lower-layer shear.This stronger asymmetric outflow transports more water vapor radially outward from the inner core to the outer core at upper levels in the downshear-left quadrant in the upper-layer shear experiment.More depositional growth of both graupel and cloud ice thus occurs downshear left in upper layers in the outer core,yielding more diabatic heating and stronger upward motions,particularly in the stratiformdominated part of the stratiform sector in the upper-layer shear experiment.Resultingly,a better-organized stratiform sector in the outer rainbands is found in the upper-layer VWS experiment than in the lower-layer VWS experiment.The diabatic heating associated with the stratiform sector produces strong midlevel outflow on the radially inward side of,and weak midlevel inflow on the radially outward side of,the heating core,with lower-level inflow beneath the midlevel outflow and upper-level inflow above.The upper-layer VWS tends to produce a deeper asymmetric inflow layer in the outer rainband stratiform sector,with more significant lower-level inflow and tangential jets in the upper-layer VWS experiment.

Examining asymmetric outer-core CAPE in sheared tropical cyclones based on the FNL data set

The asymmetric distribution of convective available potential energy(CAPE)in the outer core of sheared tropical cyclones(TCs)is examined using the National Centers for Environmental Prediction Final operational global analysis data.Larger(smaller)CAPE tends to appear in the downshear(upshear)semicircle.This downshear-upshear contrast in CAPE magnitude becomes much more statistically significant in moderate-to-strong shear.The azimuthally asymmetric CAPE is closely associated with the near-surface equivalent potential temperature(e).Larger surface winds occur in the upshear semicircle in strongly sheared TCs,contributing to larger surface latent heat fluxes in those quadrants.More lowlevel air well fueled by the larger surface latent heat fluxes in the upshear quadrants is cyclonically advected into the downstream quadrants.As a result,larger near-surfacee and CAPE are found in the outer core in the downshear quadrants.

Long-term Outcomes after Second-Generation Cryoballoon Ablation of Atrial Fibrillation and Analysis of Risk Factors Related to Recurrence

Objective:This study is aimed to analyze the long-term safety and effectiveness of second-generation cryoballoon(CB2)ablation in the treatment of atrial fibrillation(AF).Methods:Data from 760 consecutive patients in the Department of Cardiology,General Hospital of Northern Theater Command from August 2016 to December 2018 with drug-refractory symptomatic AF undergoing pulmonary vein isolation(PVI)using CB2 were assessed.Procedure-related safety and freedom from AF and atrial flutter/atria tachycardia through 3 years were determined.The risk factors related to atrial tachyarrhythmia recurrence were analyzed.Results:Acute PVI was achieved in 100%of the 760 patients.Radiofrequency application for additional focal ablation was needed in 11(1.4%)patients and for 14 pulmonary veins(0.5%,14/(760×4))to achieve PVI.A total of 748 patients,including 539 with paroxysmal AF(PAF)and 209 with persistent AF(SAF)completed the follow-up,and only 12(1.6%)patients were lost.The mean follow-up duration was(19±8)months.The rate of major complications was 0.9%,including 0.8%of right phrenic nerve injury,which resolved before discharge.Freedom from all tachyarrhythmias was achieved in 75.0%,69.4%,and 63.2%of patients with PAF,respectively,at 12-,24-,and 36-month follow-up,and in 75.1%,67.4%,and 60.9%for SAF,with no significant differences between the PAF and SAF groups.AF course and the rate of body weight gain were independent risk factors for recurrence at 12 months after ablation(P=0.001 and P=0.009,respectively).Conclusion:PVI using CB2 has a high acute success rate and good safety in the treatment of PAF and SAF.Long course of AF and weight gain after ablation were independent risk factors for recurrence.