Remote impacts of low-latitude oceanic climate on coastal upwelling in a marginal sea of the Northwestern Pacific

초록

Upwelling plays an important role in the physical processes and biological variability of coastal regions. Using 40-year-long hydrographic and climate data, the remote impacts of low-latitude oceanic climate on the upwelling along the east coast of Korea were investigated. During El Ni & ntilde;o, the development of anomalously enhanced anti-cyclonic circulation over Northwestern Pacific resulted in relatively strong (similar to 1.1 m s(-1)) southerly winds, compared to La Ni & ntilde;a. During El Ni & ntilde;o, the mean upwelling index was 402 +/- 106 kg m(-1) s(-1), and 10 degrees C isotherm was located at a depth of 32.7 m. During La Ni & ntilde;a, they were 368 +/- 95 kg m(-1) s(-1) and 39.9 m, respectively. During El Ni & ntilde;o, in the approximation, the offshore Ekman transport by wind-induced upwelling and the vertical transport by isotherm were higher than those during La Ni & ntilde;a. This finding can be explained by the increased sea surface height gradient, the subsequent enhanced geostrophic current, the decrease in onshore sea surface temperature, and the increase in chl-a concentration during El Ni & ntilde;o. The intensity of upwelling tended to be stronger (weaker) during periods when El Ni & ntilde;o (La Ni & ntilde;a) and the PDO (Pacific Decadal Oscillation) were in phase than those when they were out of phase. These results suggest that low-latitude climate change could affect the coastal upwelling in the mid-latitude marginal sea through the teleconnection.

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