Seasonal Sea Surface Temperature Asymmetry in the Northwestern Pacific Marginal Seas

Hyeonyeong Kwak,Yang-Ki Cho,Gwang-Ho Seo,Hyo-Seok Park,Yong-Jin Tak,Jang-Won Seo,Sung Hyup You

doi:10.3319/tao.2014.11.21.01(oc)

Abstract

Sea surface temperature (SST) is an important component of climate and weather systems at various time scales. Asymmetric seasonal SST variations in the Northwestern Pacific Marginal Seas (NWPMS) are investigated in this study using observation data and numerical model results. The asymmetry in SST seasonal variation is estimated quantitatively and compared with heat advection and surface net heat flux using SST data and atmospheric variables from the European Centre for Medium-Range Weather Forecast (ECMWF). The SST increases faster than it decreases, whereas air temperature increases slowly. Heat advection and surface heat flux were estimated using numerically modeled SST and ocean currents, which contribute to the asymmetry of seasonal SST variations. Heat advection shows good correlation with the SST seasonal variation asymmetry. Model results without currents along the boundary show more symmetrical SST variations. This suggests that heat advection is a prominent cause of asymmetry in the seasonal variation.

Highlights

Sea surface temperature (SST) plays a key role in changing climate and weather systems at various time scales, via air-sea momentum and heat exchange processes
The seasonal variation in temperature is symmetric if Day Ratio (DR) is 0.5
It is notable that the DR of SST is less than 0.3, and the period of decreasing temperature is more than twice the period of increasing temperature, in the Kuroshio path

Summary

Introduction

Sea surface temperature (SST) plays a key role in changing climate and weather systems at various time scales, via air-sea momentum and heat exchange processes. Research on SST variation is fundamental and crucial for understanding the oceans, atmosphere, fisheries, and ecology. The asymmetric seasonal variation in air temperature, The SST is influenced by air-sea interactions and ocean heat advection from ocean currents. The Kuroshio and Tsushima Currents (KC and TC) are the most important pathways for heat transport, causing SST variations in the Northwestern Pacific Marginal Seas (NWPMS) (Fig. 1). The seasonal variation in SST and its asymmetry might be strongly influenced by air-sea interaction and heat advection in the NWPMS (Kang 1984; Dong et al 2007; Cho et al 2009, 2013; Seo et al 2014)

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Conclusion