Application of a sea surface temperature front composite algorithm in the Bohai, Yellow, and East China Seas

Abstract

The oceanic front is a narrow zone in which water properties change abruptly within a short distance. The sea surface temperature (SST) front is an important type of oceanic front, which plays a signifi cant role in many fi elds including fi sheries, the military, and industry. Satellite-derived SST images have been used widely for front detection, although these data are susceptible to infl uence by many objective factors such as clouds, which can cause missing data and a reduction in front detection accuracy. However, front detection in a single SST image cannot fully refl ect its temporal variability and therefore, the long-term mean frequency of occurrence of SST fronts and their gradients are often used to analyze the variations of fronts over time. In this paper, an SST front composite algorithm is proposed that exploits the frontal average gradient and frequency more eff ectively. Through experiments based on MODIS Terra and Aqua data, we verifi ed that fronts could be distinguished better by using the proposed algorithm. Additionally through its use, we analyzed the monthly variations of fronts in the Bohai, Yellow, and East China Seas, based on Terra data from 2000 to 2013.

Interannual, Seasonal, and Monthly Variability of Sea Surface Temperature Fronts in Offshore China from 1982–2021

“…The Yellow Sea Ring Front (YSRF), Vietnam Front (VF), and Pacific Ocean east of Taiwan Front (POETF) are named by the authors. The names of these fronts (e.g., Bohai Front (BHF), Seohan Bay Front (SBF), Kyunggi Bay Front (KBF), Jiangsu Front (JSF), Western Chejudo Front (WCF), Eastern Chejudo Front (ECF), Yangtze Bank Ring Front (YBRF), Zhejiang-Fujian Front (ZFF), Kuroshio Front (KF), South China Coastal Front (SCCF), Bakbo Bay Front (BBF)) are based on previous research [10,12,25]. The Liaodong Bay Front (LDBF), Bohai-Laizhou Bay Front (BLBF), Taiwan Strait Front (TWST), and Luzon Front (LF) have had their names changed in reference to previous studies [10,12].…”

“…The fronts also play a key role as principal biogeographical boundaries, and primary and secondary biological productivity is enhanced at fronts, attracting fish, birds, and mammals, including whales [11]. Sea surface temperature (SST) fronts that were traditional and typical oceanic fronts, for example, have received increased attention in terms of predicting fish distribution and ocean hydrodynamics [12]. Therefore, studying and understanding the properties of oceanic fronts is important for studying the processes of ocean ecosystems and ocean hydrodynamics.…”

“…Hickox et al [25] identified ten fronts in the China Sea. Ping et al [12] also discovered a new front in the Bohai Sea, which they named the Liaodong Bay, Bohai Bay, and Laizhou Bay front. In addition, some researchers studied the variety and dynamics of fronts in OC.…”