Influence of Spatial Heterogeneity in Sea Surface Temperature on Tropical Cyclone Intensity Over the Western North Pacific

This study explores the impact of sea surface temperature (SST) spatial heterogeneity on tropical cyclone (TC) intensity through a combination of observations and simulations, aiming to provide a reference for further improving TC intensity forecasting skills. Two distinct patterns of SST spatial heterogeneity are identified based on a statistical analysis of observational data, when the SST at the TC center is above and below 29.3 degrees C, respectively. One is a warm-core pattern (WCP) with a warm peak SST at the TC center decreasing centrifugally which favors TC development, and the other one is a poleward-decreasing pattern (PDP) with a warm SST at the south decreasing poleward which suppresses TC development. The numerical simulations confirm the opposite influence of the WCP and the PDP on TC intensity. The WCP intensifies TC intensity by strengthening TC secondary circulation, increasing the conversion from ocean heat energy to TC kinetic energy, and compacting TC structure. In contrast, the PDP weakens TC intensity by inducing opposing responses of these processes. The magnitude of TC intensity change caused by SST spatial heterogeneity is comparable to those caused by a 1 degrees C change in SST at the TC center. These findings offer valuable insights into the role of SST spatial heterogeneity in TC development and provide a new perspective to improve TC intensity forecasting by incorporating SST spatial heterogeneity into statistical-dynamic models. Tropical cyclones pose a significant threat to human society, and improving their intensity forecasting is crucial to mitigate their potential damage. However, current forecasting models fail to accurately account for the influence of sea-surface temperature spatial variations on cyclone intensity change. This study identified two types of sea-surface temperature spatial heterogeneity that play opposing roles in tropical cyclone (TC) development: a warm-core pattern positively influences cyclone intensity, while a polar-decreasing pattern negatively affects it. These findings emphasize the critical role of sea-surface temperature spatial heterogeneity in TC intensity and suggest a new perspective for improving intensity forecasting models, which could ultimately help reduce the damage caused by these destructive storms. Two spatial patterns of sea surface temperature (SST) beneath tropical cyclones (TCs) are identified based on SST value at the TC center SST exhibiting a warm-core and poleward-decreasing spatial pattern facilitate and inhibit the development of TC, respectively Spatial heterogeneity in SST modulates the energy conversion from ocean to TC via secondary circulation, leading to changes in TC intensity