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A new observational evidence of generation and propagation of barotropic Rossby waves induced by tropical instability waves in the Northeastern Pacific
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  • Kang Nyeong Lee,
  • Chanhyung Jeon,
  • Young Ho Seung,
  • Hong-Ryeol Shin,
  • Seung-Kyu Son,
  • Jae-Hun Park
Kang Nyeong Lee
Inha University, Inha University

Corresponding Author:[email protected]

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Chanhyung Jeon
Pusan National University, Pusan National University
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Young Ho Seung
Inha University, Inha University
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Hong-Ryeol Shin
Kongju National University, Kongju National University
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Seung-Kyu Son
Korea Institute of Ocean Science and Technology, Korea Institute of Ocean Science and Technology
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Jae-Hun Park
Inha University, Inha University
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Tropical instability waves (TIWs) in the equatorial eastern Pacific (EEP) exhibit 25–40-day westward-propagating fluctuations with seasonal and inter-annual variations, which are stronger during July–December and La Niña periods. They likely transfer their energy northward by forming barotropic Rossby waves (BTRWs). Long-term near-bottom current measurements at 10.5°N and 131.3°W during 2004–2013 revealed a spectral peak at 25–40 days, where significant coherences were found with satellite-measured sea surface height in a wide region of EEP with maxima approximately 5°N. Simulated deep currents from a data-assimilated ocean model concur with the observed near-bottom currents, and both currents vary seasonally and interannually, consistent with the typical characteristics of TIW. Further analyses using 25–40-day bandpass-filtered barotropic velocity data from the model revealed that they reasonably satisfied the theoretical dispersion relation of TIW-induced BTRW (BTRWTIW). We reconfirmed BTRWTIW propagating northward above 10°N in the northeastern Pacific by in-situ observations.