昆明气温1990s中期后年代际增暖特征及其季节性变化

Decadal Warming of Air Temperature of Kunming after Mid-1990s and Its Seasonality Changes

摘要: 云南省昆明市作为中国的春城，气候特征显示出明显的冬暖夏凉的特征。随着近些年来全球变暖，四季如春的昆明也呈现出明显的升温特征。1961~2020年昆明市日平均气温的升温速率约为4℃/100 a，远远高于全球变暖的升温速率。其中，冬季的升温最快，达5.2℃/100 a，其次为春季(4.2℃/100 a)、秋季(3.7℃/100 a)和夏季(3.0℃/100 a)。日最高气温和日最低气温均存在显著的升温特征，但日最低气温的贡献更大，其升温速率远高于日最高气温的升温速率。昆明气温的增暖并不是简单的线性升高，而是在1990s中期出现显著的年代际转型特征，从1993年之前的异常偏冷转变为1994年之后的异常偏暖位相。不同季节的年代际增温幅度不同，日平均气温的年代际平均增温幅度依次从冬(1.9℃)、春(1.5℃)、秋(1.4℃)、夏(1.0℃)递减；日最低气温随季节的年代际增温规律类似，但增温幅度更大，冬、春、秋、夏的年代际增温分别为2.6℃、2.5℃、1.5℃和1.0℃；日最高气温的年代际增温季节变化表现出从春、夏、秋、冬依次增加的特征，但增温幅度最小，分别为0.91℃、1.18℃、1.27℃和1.34℃。气温日较差冬春季大夏秋季小，且在冬春季节年代际减小显著。昆明气温的季节变化呈现出较为“秃顶”的单峰结构，暖季持续时间较长。1990s中期年代际突变之后气温的季节变化都表现出暖季提前、冷季推迟的特征，且日最低气温和日平均气温暖季提前的日数明显多于冷季推迟的日数。昆明气温这种年代际的升温特征与全球变暖下西太平洋副热带高压的西伸北进，以及昆明北部东亚异常暖高压东侧的暖平流输送有关。

Abstract: Kunming, Yunnan Province, as the spring city of China, has an obvious climate characteristic of warm winter and cool summer. With the global warming in recent years, Kunming also presents obvious warming characteristics. During 1961~2020, the daily mean air temperature (DMAT) of Kunming increased at a rate of 4˚C/100 a, which was much higher than that of global warming. Among them, the temperature rise in winter is the fastest, reaching 5.2˚C/100 a, followed by spring (4.2˚C/100 a), autumn (3.7˚C/100 a) and summer (3.0˚C/100 a). Both daily highest air temperature (DHAT) and daily lowest air temperature (DLAT) have significant warming characteristics, but the contribution of DLAT is greater, and its warming rate is much higher than that of DHAT. The warming of temperature in Kunming is not a simple linear increase, but a significant interdecadal shift in the mid-1990s, from an abnormally cold phase before 1993 to an abnormally warm phase after 1994. The amplitudes of decadal warming are not the same in dif-ferent season. The interdecadal warming of DMAT decreased from winter (1.9˚C), spring (1.5˚C), autumn (1.4˚C) and summer (1.0˚C). The interdecadal warming of DLAT with seasons was similar, but the warming amplitude was larger, and the interdecadal warming in winter, spring, autumn and summer were 2.6˚C, 2.5˚C, 1.5˚C and 1.0˚C, respectively. The interdecadal seasonal variation of DHAT showed an increasing trend from spring, summer, autumn and winter, but the warming range was the smallest, which was 0.91˚C, 1.18˚C, 1.27˚C and 1.34˚C, respectively. The diurnal temperature range is larger in winter and spring, smaller in summer and autumn, and decreases significantly in winter and spring after the decadal shift. The seasonal cycle of temperature in Kunming presents a relatively “bald” single-peak structure, and the warm season lasts a long time. After the decadal shift in the mid-1990s, the seasonal temperature changes showed that the warm season was advanced and the cold season was delayed, and the number of days in the warm season was significantly earlier than that in the cold season. The interdecadal warming characteristics of Kunming temperature are related to the westward and northward extension of the Western Pacific subtropical high and the warm advection transport along the east side of the anomalous warm high in the north of Kunming.