AUTHOR=Liu Qingyuan , Song Jinjie , Klotzbach Philip J. 

TITLE=Trends in Western North Pacific Tropical Cyclone Intensity Change Before Landfall

JOURNAL=Frontiers in Earth Science

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.780353

DOI=10.3389/feart.2021.780353

ISSN=2296-6463

ABSTRACT=<p>This study investigates the long-term trend in the average 24-h intensity change (Δ<italic>V</italic><sub>24</sub>) of western North Pacific (WNP) tropical cyclones (TCs) before landfall during June-November for the period from 1970–2019. We find a significant increasing trend in basin-averaged Δ<italic>V</italic><sub>24</sub> during 1970–2019. The increase in Δ<italic>V</italic><sub>24</sub> is significant over the northern South China Sea (17.5°-25°N, 107.5°-120°E) and to the east of the Philippines (7.5°-15°N, 122.5°-132.5°E), implying a slower weakening rate before landfall for the South China Sea and an increased intensification rate before landfall for the region east of the Philippines. We find a significant linkage between changes in Δ<italic>V</italic><sub>24</sub> and several large-scale environmental conditions. The increased Δ<italic>V</italic><sub>24</sub> before landfall in the above two regions is induced by a warmer ocean (e.g., higher sea surface temperatures, maximum potential intensity and TC heat potential) and greater upper-level divergence, with a moister mid-level atmosphere also aiding the Δ<italic>V</italic><sub>24</sub> increase east of the Philippines. Our study highlights an increasing tendency of Δ<italic>V</italic><sub>24</sub> before landfall, consistent with trends in Δ<italic>V</italic><sub>24</sub> over water and over land as found in previous publications.</p>