以多組海溫變異推估臺灣梅雨季極端降雨的未來變化

Projections of Extreme Rainfall in Taiwan During the Mei-Yu Season Based on Multiple Sea Surface Temperature Changes

黃柏翰(PO-HAN HUANG) ； 黃婉如(WAN-RU HUANG)

《台灣水利》 67卷1期 (2019/03) Pp. 80-90

摘要

臺灣每年5、6月梅雨季常出現極端降雨事件，其所帶來的災害，常造成當地居民生命與財產上的重大損失。為了瞭解氣候變遷對臺灣梅雨季極端降雨的可能影響，本研究利用高解析度全球模式與動力降度模式模擬結果，檢視現今時期（1980年～2003年）與21世紀末時期（2076年～2099年），臺灣北、中、南及東部地區之梅雨季極端降雨特色變化的區域性差異。在未來變遷的推估方面，本研究採用Mizuta et al.（2014）所提出之4組不同海溫變遷特性當成模式的邊界條件，產生多組未來降雨變化的推估結果，並進行系集分析。系集推估結果顯示，21世紀末臺灣北、中、南部地區之梅雨季極端降雨強度和頻率皆較現今時期增加，而臺灣東部地區的極端降雨強度變化雖不明顯，但是頻率較現今時期增加。4大分區中，以臺灣南部地區為極端降雨變強、變頻繁之最顯著地區。環流場分析結果顯示，21世紀末臺灣附近低層西風增強所帶來的水氣增加、動力輻合增強為造成迎風面（即臺灣南部地區）梅雨季極端降雨變強、變頻繁的可能原因。

關鍵字

梅雨季 ； 極端降雨 ； 模式推估 ； 氣候變遷

並列摘要

In Taiwan, long-term statistical analysis suggests that extreme rainfall occurred in May and June (i.e., the Mei-Yu season) frequently dangers people's lives and causes economic losses. To understand possible impacts of extreme rainfall in Taiwan during the Mei-Yu season under future climate change, this study uses dynamical downscaling simulations driven by a high resolution global model to project the differences of extreme rainfall in Taiwan between two time periods: the end of 21^(st) century (2076~2099; under RCP8.5 scenario) and the present (1980~2003; Historical). The analyses focus on the differences of projected changes in extreme rainfall over four major sub-regions of Taiwan (including northern, central, southern and eastern Taiwan). For the future projection, this study uses four different groups of sea surface temperature changes proposed by Mizuta et al. (2014) as the boundary conditions to drive the models. From the ensemble mean of the multiple future projections, it is noted that extreme rainfall in most sub-regions of Taiwan (including northern, central and southern Taiwan) will become more frequent and more intense by the end of 21^(st) century, as compared to the present. For east Taiwan, the extreme rainfall is projected to be more frequent in the future, but the related change in extreme rainfall intensity is not clear. Among the four sub-regions, southern Taiwan is the region that will have the most significant increase in both intensity and frequency of extreme rainfall in the future as compared to the present. It is suggested that the projected increase in extreme rainfall activities in southern Taiwan is related to the projected increase in large-scale westerly wind, which brings more water vapor and leads to increase in wind convergence over the windward side of Taiwan.

並列關鍵字

Mei-Yu season ； extreme rainfall ； model simulation ； climate change