| dc.description.abstract | Marine Heatwaves (MHW) are phenomena characterized by a sudden and significant increase in sea surface temperature, while Marine Cold-Spells (MCS) involve a sudden and significant decrease in sea surface temperature. In recent years, the analysis methods and related issues of MHW and MCS have begun to receive attention. In this study, an MHW event is defined when the sea surface temperature (SST) at a specific location exceeds the 90th percentile of the daily SST for the same location during the 30-year climate base period from 1985 to 2014 and persists for five days or more. The definition of MCS uses the 10th percentile of the same climate base period′s SST as the threshold, and it also requires persistence below this threshold for five days or more. This research utilizes daily SST data from 1985 to 2022, spanning 38 years, to calculate the frequency, duration, warming rate, cooling rate, maximum intensity, cumulative intensity, average intensity, and other indicators as reference values for event characteristics classification. The study analyzes the spatial distribution of different event classifications in the seas surrounding Taiwan and the spatial distribution of various indicators under different climatic conditions. This helps understand the impact of different physical conditions in the seas around Taiwan on MHW and MCS events. Between 1985 and 2022, the average annual duration of events indicates that MHW (50.5 days) is higher than MCS (31.2 days). However, in terms of trends, both maximum intensity and annual duration show that MHW (0.015 ℃, 2.4 days/year) is greater than MCS (0.0036 ℃, -0.96 days/year). Influenced by global warming, the rising global sea temperatures lead to continuous increases in MHW average intensity (0.002 ℃/year), frequency (0.118 times/year), and duration (0.24 days/year). In contrast, MCS shows a slight increase only in average intensity (-0.004 ℃/year), while frequency (-0.10 times/year) and duration (-0.003 days/year) exhibit decreasing trends in these three indicators. Furthermore, we analyzed the differences in various indicators between MHW and MCS in shallow water areas and deep water areas and found that except for the average number of days and duration per month, other indicators were higher in shallow water areas than in deep water areas. Therefore, it is speculated that MHW and MCS events will be affected by the Effect of seawater depth. | en_US |