Impact of the Low Wavenumber Structure in the Initial Vortex Wind Analyses on the Prediction of the Intensification of Hurricane Patricia (2015)

Abstract

Accurate forecasts of the intensity of tropical cyclones (TCs) are important in both early warning systems and impact assessments because the damage caused by these storms is significantly associated with their intensity. Previous studies have suggested that changes in the intensity of TCs are affected by the dynamic and thermodynamic structures of the inner core, multiscale interactions between the storm and the environmental flow, and the asymmetry of the storm (

The Effect of Initial Vortex Asymmetric Structure on Tropical Cyclone Intensity Change in Response to an Imposed Environmental Vertical Wind Shear

“…We will also demonstrate that the VWS-induced asymmetry could be either enhanced or suppressed by the asymmetric structure in the initial TC vortex depending on the relative phase and strength of the two asymmetric structures. Our finding can help understand why both spinup and spindown members coexist in ensemble forecasts of TC intensity by numerical weather prediction models (e.g., Zhong et al, 2023) and also calls for attention to adequately represent the asymmetric structure of the TC vortex in numerical models.…”

“…Recently, Zhong et al. (2023) found that the spinup and spindown members in ensemble forecasts of TC intensity show oppositely phased distribution in their initial asymmetric wind fields, and they hypothesized that the phased relationships between the direction of VWS and eyewall convection might influence the TC intensity evolution. However, they did not examine the details.…”

“…For example, some dynamical vortex initialization schemes developed so far mainly spin up the axisymmetric vortex, and little attention has been given to the initial asymmetric vortex structure (Cha & Wang, 2013;Liu et al, 2018Liu et al, , 2019. Recently, Zhong et al (2023) found that the spinup and spindown members in ensemble forecasts of TC intensity show oppositely phased distribution in their initial asymmetric wind fields, and they hypothesized that the phased relationships between the direction of VWS and eyewall convection might influence the TC intensity evolution. However, they did not examine the details.…”

Role of the Thermodynamic Structure of the Inner Core in Predicting the Intensification of Hurricane Patricia (2015)

“…It was found that the intensification rates do not have a large spread among the 30 SPU members. Following our previous work (Zhong et al., 2022), we randomly selected 10 of the 30 SPU members to give equal numbers in each group and so create a homogenous sample.…”

“…Our previous study demonstrated that the low wavenumber structure of the initial wind analyses is crucial in the SPU process of Hurricane Patricia, compared with the high wavenumber components (Zhong et al., 2022). However, previous studies have reported that the thermodynamic aspects in terms of the upper‐level warm core and low‐level wet core also play a significant role in determining the changes in intensity of a TC (Emanuel & Zhang, 2017; Stern & Zhang, 2013; Tao & Zhang, 2014, 2019).…”