HR: 1340h
AN: A53B-0875    [Abstracts]
TI: Summer High Temperature Trend in Taiwan
AU: * Liu, C
EM: liucm@ntu.edu.tw
AF: Global Change Research Center, Natioanl Taiwan University, #1, Sec. 4, Roosevelt Rd., Taipei, 106 Taiwan
AU: Lin, S
EM: shlin@gcc.ntu.edu.tw
AF: Global Change Research Center, Natioanl Taiwan University, #1, Sec. 4, Roosevelt Rd., Taipei, 106 Taiwan
AU: Chun, J
EM: ch3@gcc.ntu.edu.tw
AF: Global Change Research Center, Natioanl Taiwan University, #1, Sec. 4, Roosevelt Rd., Taipei, 106 Taiwan
AB: Taiwan was experiencing a rapid warming over the 20$^{th}$ century. In the last century climate record from the Central Weather Bureau, the averaged annual air temperatures have increased about 1.03$^{o}$C~ 1.45$^{o}$C, which is greater than twice of the global increase of 0.6$^{o}$C per century. In this study, the trend of the occurring frequency of summer daily-maximum temperature larger than 35$^{o}$C is analyzed for three different periods: 1900 \sim 1945, 1946\sim 1975 and 1976 \sim 2003. During the first forty\-six years, only six monitoring stations were set up. The highest occurring frequency of 10 days/summer was at Taipei, a basin in northern Taiwan, and the lowest of 0.1 days/summer was at Hengchun, the southern tip of Taiwan. During the second thirty years, a period of global cooling, twenty\-one observations sites were available. Among them, six are mountain stations with rare occurrence of temperature higher than 35$^{o}$C. Taipei had an averaged 16.7 days/summer frequency, which is apparently higher than that in the previous period, while Hengchun was with an averaged 0.2 days/summer. During the latest twenty\-eight years, the period of most significant global warming, the averaged occurring frequency at Taipei has increased to 23.7 days/summer, while Hengchun with 0.4 days/summer. In all, a spatial distribution pattern of high frequency over northern Taiwan then decreasing along western and eastern coasts toward southern region remains the same during all three periods. Since Taipei being the most urbanized and populated city in Taiwan, urbanization is intuitively blamed for resulting a local warming trend higher than the global one. However, through a regression analysis, we note that there exists a decreasing trend over the southwestern corner of Taiwan. For instance, at Kaohsiung, the second largest city with the highest industrial pollution emission, a trend of -1.5 days/decade can be identified during the latest twenty-eight years period, while Taipei with 5.4 days/decade increasing trend. Possibilities of regional cooling caused by aerosol loading and enhanced ventilation caused by summer monsoon are not to be neglected. Furthermore, based on the GCM projected trend provided by IPCC web site, we have estimated that an enlarged increasing trend of the occurring frequency of temperature larger than 35oC in Taiwan. Though uncertainties exist, the results have a significant policy implication.
DE: 3354 Precipitation (1854)
DE: 4215 Climate and interannual variability (3309)
DE: 1803 Anthropogenic effects
DE: 1630 Impact phenomena
DE: 1655 Water cycles (1836)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting