Large-scale influences on secondary eyewall size


  • Xiaqiong Zhou,

    Corresponding author
    1. IMSG at NCEP, NWS, NOAA, College Park, Maryland, USA
    • Corresponding author: X. Zhou, IMSG at NCEP, NWS, NOAA, 5830 University Research Ct., College Park, MD 20740, USA. (

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  • Bin Wang

    1. International Pacific Research Center and Department of Meteorology, School of Ocean and Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, Hawaii, USA
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[1] Secondary eyewalls are frequently observed in intense tropical cyclones (TCs). The separation distance between the primary eyewall and the secondary eyewall can vary from 10 to more than 100 km. The size of the secondary eyewall is a key factor determining the horizontal scale of the destructive winds and heavy rainfall in these TCs. Previous work suggested that the internal dynamic and thermodynamic structure of the TC affects the radial location of secondary eyewall formation. The potential impact of the large-scale environment is examined by using the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis and best track data sets in this study. It is found that large secondary eyewalls tend to form in weak storms at relatively high latitudes and in environments with high relative humidity, low sea-level pressure, and high low-level vorticity. The performance of a statistical-dynamical model to predict the size of secondary eyewalls is evaluated, and the physical interpretation of the selected predictors is also provided.