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An In-Situ Observational Study on the Turbulent Characteristics in the Near-surface Layer during the Landfalling Period of Super Typhoon Maria (2018)
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  • Chen Chen,
  • Jie TANG,
  • Gerard Kilroy,
  • Xiping Zhang,
  • limin Lin,
  • Binke Zhao,
  • Shuai Zhang
Chen Chen
Shanghai Typhoon Institute
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Jie TANG
Shanghai Typhoon Institute

Corresponding Author:[email protected]

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Gerard Kilroy
University of Munich
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Xiping Zhang
Shanghai Typhoon Institute
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limin Lin
Shanghai Typhoon Institute
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Binke Zhao
Shanghai Typhoon Institute
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Shuai Zhang
Shanghai Typhoon Institute
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Abstract

The air-sea exchanges of momentum which are often parameterized by the variation of drag coefficient (CD) and wind speed (un), is largely uncertain at typhoon-force extreme values of un. This paper investigated the relationship between CD and extreme values of un for five different heights using the eddy covariance method from two coastal observation towers during the landfall of Super Typhoon Maria. In particular, our observations include 10-min average un extended to high wind speed of 42.27 m s-1. The relationship between CD and un was parabolic from regression analysis, and the “roll-off” of CD and u* appeared at about 28 m s-1. From the bottom to top heights, the corresponding un of CD extreme were 9.95, 12.72, 22.32, 32.57 and 38.04 m s-1, respectively. The trend of negative tangential turbulent flux with un was found to be the main cause for the CD extreme drifting with heights.