Interannual to Interdecadal Variability of the Southern Yellow Sea Cold Water Mass and Establishment of “Forcing Mechanism Bridge”

Yunxia Guo,Dongxue Mo,Yijun Hou

doi:10.3390/jmse9121316

Abstract

The Yellow Sea cold water mass (YSCWM) occupies a wide region below the Yellow Sea (YS) thermocline in summer which is the most conservative water and may contain clearer climate signals than any other water masses in the YS. This study investigated the low-frequency variability of the southern YSCWM (SYSCWM) and established the “forcing mechanism bridge” using correlation analysis and singular value decomposition. On the interannual timescale, the southern oscillation can affect the SYSCWM through both the local winter monsoon (WM) and the sea surface net heat flux. On the decadal timescale, the Pacific decadal oscillation (PDO) can affect the SYSCWM via two “bridges”. First, the PDO affects the SYSCWM intensity by Aleutian low (AL), WM, and surface air temperature (SAT). Second, the PDO affects the SYSCWM by AL, WM, Kuroshio heat transport, and Yellow Sea warm current. The Arctic oscillation (AO) affects the SYSCWM by the Mongolian high, WM, and SAT. Before and after the 1980s, the consistent phase change of the PDO and the AO contributed to the significant decadal variability of the SYSCWM. Finally, one simple formula for predicting the decadal variability of SYSCWM intensity was established using key influencing factors.

Highlights

The Yellow Sea (YS) is a shallow and semienclosed marginal sea of the Pacific Ocean, bordered by the Chinese mainland to the west, the Korean peninsula to the east, and theBohai Bay to the north
It can be seen that the bottom water temperature in the YS warms gradually from winter to spring and that the southern YSCWM (SYSCWM), which disappears in autumn, can be identified clearly in summer
The empirical orthogonal function (EOF) method was used on the interannual components of temperature along section A–B (Figure 1), which spans the whole area of the southern YS, to investigate the interannual spatiotemporal characteristics of the SYSCWM

Summary

Introduction

The Yellow Sea (YS) is a shallow and semienclosed marginal sea of the Pacific Ocean, bordered by the Chinese mainland to the west, the Korean peninsula to the east, and theBohai Bay to the north. The YSCWM occupies almost 30% of the YS area and is present throughout the whole summer every year which becomes one of the most important characteristics of the YS. The YSCWM has a large impact on the hydrographic features and the phytoplankton biomass and production in the YS [2,3,4]. The YSCWM is regarded as a nutrient-rich pool that contributes to the subsurface chlorophyll maximum phenomenon during summer and affects primary production [7,8,9,10,11]. The key species of zooplankton (Calanus sinicus) is favored to survive the hot summer in the YSCWM [12]. The diverse characteristics of the YSCWM have drawn the attention of many international scholars

Objectives

Methods

Results

Discussion

Conclusion