| 摘要: | 海洋熱浪(Marine heatwave, MHW)是一種海水溫度突然顯著增溫的現象，而海洋寒潮(Marine cold-spells, MCS)則是一種海水溫度突然顯著降溫的現象，近幾年MHW和MCS的分析方法和相關延伸議題開始受到關注。在本研究中MHW事件以該海域位置在該日的海溫超過以1985-2014共30年為氣候基期的第90百分位值海溫數值且持續五天以上時稱之；MCS的定義則是使用相同氣候基期的第10百分位海溫數值做為閾值，並同樣需要低於該閾值持續五天以上。聖嬰現象及太平洋十年震盪(PDO)是在分析MHW和MCS時考量的重要氣候條件，PDO在正相位的時候，東太平洋偏暖而西太平洋偏冷，而負相位則反之，而在聖嬰現象時，也會讓西太平洋偏冷，反聖嬰現象則反之。本研究使用1985-2022間共38年的每日海水表面溫度資料並計算MHW和MCS的頻率、持續時間、升溫率、降溫率以及最大強度、累積強度、平均強度等指標作為事件特性分類的參考值，並分析不同分類的事件在臺灣附近海域的百分比空間分布，以及各指標在不同氣候條件下所呈現的空間分布，能夠了解在台灣周遭海域的不同海洋動力條件下對MHW和MCS事件的影響。1985年到2022年間，在事件的年度天數則是MHW(50.5 days)比MCS(31.2days)要來的高。但從趨勢來說，不管是最大強度還是事件年度天數，都是MHW(0.015 ℃, 2.4 days/year)大於MCS(0.0036 ℃, -0.96 days/year)。受到全球暖化的影響，全球海水溫度上升，造成MHW強度(0.002 ℃/year)、頻率(0.118 times/year)、持續時間(0.24 days/year)不斷上升，而MCS強度(-0.004 ℃/year)、頻率(-0.10 times/year)、持續時間(-0.003 days/year)在這三個指標的趨勢則是下降。並且我們分析海洋熱浪與海洋寒潮在淺水區及深水區各項指標的差異，發現在除了月平均天數及持續天數，其他指標皆是淺水區高於深水區，因此推測海洋熱浪與寒潮事件會受到海水深度的影響。;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. |
