【摘要】 依据《气候季节划分》标准，选取我国低纬高原地区2个典型旅游城市——昆明和大理，进行了气候季节平均态，季节开始日期及长度变化，春分、夏至、秋分、冬至节气气温演变分析。（1）昆明、大理是高原“无夏区”，一年仅有春、秋、冬三季，属“春秋型”城市，春、秋季为295 d和290 d，占全年的80.8%和79.5%。（2）随着气候变暖，昆明、大理春、秋、冬三季比例发生了改变，春、秋季增加，冬季缩短，昆明变化幅度强于大理。（3）昆明、大理春季始于2月9日和2月10日，春季长度为117 d和123 d；秋季始于6月7日和6月13日，秋季长度为178 d和167 d；冬季始于12月1日和11月27日，冬季长度为70 d和76 d；昆明、大理“春常在、秋长驻、冬短暂”特征显著。（4）近60年来，昆明、大理春季开始日呈提早趋势，秋季开始日呈稍推迟趋势，冬季开始日呈推迟趋势；昆明、大理春季长度增加；昆明秋季长度略增加，大理秋季长度略减少；昆明、大理冬季长度减少。（5）昆明、大理春分节令日气温阀值为14.8℃和14.2℃，夏至为20.3℃和20.5℃，秋分为17.4℃和17.5℃，冬至均为7.9℃；与我国东部季风区的北京和上海相比，昆明、大理在春分、夏至、秋分、冬至四个节令上具有“春暖、夏凉、秋爽、冬暖”特征；近60年来，四个节令日气温年际变化呈升高趋势，尤以春分、秋分增暖显著。更多还原

【Abstract】 According to the meteorological industry standards of Climatic Seasons Division, Kunming and Dali in Yunnan, two typical tourist cities over a low-latitude plateau in China, were selected to analyze the average state of climatic seasons, the changes of seasonal beginning date and length, and the temperature evolution of spring equinox, summer solstice, autumn equinox and winter solstice. The results are shown as follows.(1) Kunming and Dali lie in a“summer-free region”on the Yunnan-Guizhou plateau. There are only three seasons in a year, namely spring, autumn and winter. They belong to“spring & autumn type”cities. The lengths of spring and autumn seasons are 295 days and 290 days respectively, accounting for80.8% and 79.5% of the whole year.(2) As the climate gets warm, the proportions of the lengths of spring,autumn and winter of Kunming and Dali change. The spring and autumn lengthens while the winter shortens. The changing rate of Kunming is stronger than that of Dali.(3) The spring starts on February 9and February 10 in Kunming and Dali, respectively, and the spring length is 117 days and 123 days,respectively. The autumn starts on June 7 and June 13, and its autumn length is 178 days and 167 days,respectively. The winter starts on December 1 and November 27, and the winter length is 70 days and 76days, respectively. Kunming and Dali are characterized by“stationary spring, long autumn and short winter”.(4) During the recent 60 years, the beginning date of spring in Kunming and Dali shows an advancing trend, the beginning date of autumn takes on a slightly delayed trend, and the beginning date of winter presents a delayed trend. The length of spring increases in Kunming and Dali, the autumn length of Kunming increases slightly while it decreases slightly in Dali, and the winter length of both Kunming and Dali shows a decreasing trend.(5) The temperatures of Kunming and Dali on the spring equinox are14.8 ℃ and 14.2 ℃, 20.3 ℃ and 20.5 ℃ on the summer solstice, 17.4 ℃ and 17.5 ℃ on the autumn equinox, respectively, and 7.9 ℃ on winter solstice for both cities. Compared with Beijing and Shanghai in the monsoon region of eastern China, Kunming and Dali have the characteristics of“warm spring, cool summer, clear autumn and warm winter”in the four solar terms of spring equinox, summer solstice,autumn equinox and winter solstice. In the past 60 years, the interannual variation of temperature on the days of four solar terms has shown an increasing trend, especially for the spring equinox and autumn equinox.更多还原