Exceptionally cold water days in the southern Taiwan Strait: their predictability and relation to La Niña

Abstract

Abstract. The objectives of this study were to assess the predictability of exceptionally cold water in the Taiwan Strait (TS) and to develop a warning system on the basis of the scientific mechanism, which is a component of the information technology system currently under development in Taiwan to protect aquaculture against extreme hazards. Optimum interpolation sea surface temperature (SST) data were used to find exceptionally cold water days from January 1995 to May 2017. We found that the SST and wind speed over the TS are low and strong in La Niña winters, respectively. According to tests conducted using relative operating characteristic curves, predictions based on the Oceanic Niño Index and integrated wind speed can be employed at lead times of 60-120 and 0-25 days, respectively. This study utilized these two proxies to develop a possible warning mechanism and concluded four colors of warning light: (1) blue, meaning normal (0 % occurrence probability); (2) cyan, meaning warning ( ∼ 50 % occurrence probability); (3) yellow, meaning moderate risk (∼ 60 % occurrence probability); and (4) red, meaning high risk (∼ 75 % occurrence probability). Hindcasting winters over the period 1995-2017 successfully predicted the cold water hazards in the winters of 2000, 2008, and 2011 prior to the coldest day by ∼ 20 days.

Marine cold-spells

“…Thus, an unusual cross-strait transport of cold waters contributed to the MCS and the ecological impacts reported in the Penghu Archipelago (Shen et al, 2020). Regional relationships between the strengthened winter monsoon and a La Niña phase may offer pathways toward predictability of MCS in the Taiwan Strait and the development of early warning systems at sub-seasonal to seasonal time scales (Cheng and Chang, 2018).…”

Impact of Vessel Transit on Vocalizations of the Taiwanese Humpback Dolphin

“…The study area lies in the Eastern Taiwan Strait, which experiences tropical storms, monsoons in summer and winter, and an average wind speed of 12 m/s [21][22][23]. The ocean floor around the area is characterized by hard sedimentary rock covered with a thin layer of sandy substrate.…”

Southward spreading of the Changjiang Diluted Water in the La Niña spring of 2008

“…Indeed, the La Niña Feb. of 2008 was exceptionally cold when tons of fish were killed by the cold water around Penghu Is. [43][44][45] . Cross-strait front and eastward flow of the cold CDW in winter/spring are known to occur 20,46,47 but it was rare that the cold water reached Penghu Is.…”