Observed Trends in Extreme Temperature over the Klang Valley, Malaysia

Abstract

This study investigates the recent extreme temperature trends across 19 stations in the Klang Valley, Malaysia, over the period 2006–16. Fourteen extreme index trends were analyzed using the Mann-Kendall non-parametric test, with Sen’s slope as a magnitude estimator. Generally, the annual daily mean temperature, daily mean maximum temperature, and daily mean minimum temperature in the Klang Valley increased significantly, by 0.07°C yr⁻¹, 0.07°C yr⁻¹ and 0.08°C yr⁻¹, respectively. For the warm temperature indices, the results indicated a significant upward trend for the annual maximum of maximum temperature, by 0.09°C yr⁻¹, and the annual maximum of minimum temperature, by 0.11°C yr⁻¹. The results for the total number of warm days and warm nights showed significant increasing trends of 5.02 d yr⁻¹ and 6.92 d yr⁻¹, respectively. For the cold temperature indices, there were upward trends for the annual minimum of maximum temperature, by 0.09°C yr⁻¹, and the annual minimum of minimum temperature, by 0.03°C yr⁻¹, concurrent with the decreases in the total number cold days (TX10P), with −3.80 d yr⁻¹, and cold nights (TN10P), with −4.33 d yr⁻¹. The 34°C and 37°C summer days results showed significant upward trends of 4.10 d yr⁻¹ and 0.25 d yr⁻¹, respectively. Overall, these findings showed upward warming trends in the Klang Valley, with the minimum temperature rate increasing more than that of the maximum temperature, especially in urban areas.

摘 要

本研究利用马来西亚巴生河谷 19 个站的资料, 考察了该区域 2006–2016 年极端温度的变化趋势. 本研究所采用的趋势分析方法为 Mann-Kendall 非参数检验, 用 Sen 斜率估计趋势变化的强度, 以此分析了 14 个极端温度指标的变化趋势. 总体而言, 巴生河谷每年日平均温度、 日平均最高和最低温度都呈显著增加趋势, 增加率分别为 0.07°C yr⁻¹、 0.07°C yr⁻¹ 和 0.08°C yr⁻¹. 就高温指标而言, 每年最高温度和最低温度的最大值均呈上升趋势, 其增加率分别为 0.09°C yr⁻¹ 和 0.11°C yr⁻¹; 每年高温白天和夜晚的总数也呈显著增加趋势, 其增加率分别为 5.02 d yr⁻¹ 和 6.92 d yr⁻¹. 就低温指标而言, 每年最高温度和最低温度的最小值呈现上升趋势, 两者的增加率分别为 0.09°C yr⁻¹ 和 0.03°C yr⁻¹, 与之伴随的是每年低温白天和夜晚总天数的减少 (两者的减少率分别为 −3.88 d yr⁻¹ 和 −4.33 d yr⁻¹). 夏季温度高于 34°C 和 37°C 的天数分别呈 4.10 d yr⁻¹ 和 0.25 d yr⁻¹ 的增加趋势. 整体而言, 本研究结果表明巴生河谷温度增暖的趋势在城区更为显著, 其中最低温度的增加率高于最高温度.