1981-2015年西藏全区气候季节的变化

Variation of seasons in Tibet Autonomous Region from 1981 to 2015

利用1981-2015年西藏全区39个气象观测站的观测资料,采用修订气候季节划分方法,分析了39站季节起始日与季节长度,代表站的季节极端日期、极端长度、季节早晚、季节长短等级变化趋势及其对农牧业、旅游业的影响。结果表明:西藏近35年来,春、夏、秋、冬季平均起始日分别为2月25日、5月31日、9月15日和11月28日,平均长度分别为99 d、106 d、73 d和87 d,且区域差异比较明显。波密、加查、尼木、狮泉河、申扎站春季的起始日在提前,分别为-5. 8、-1. 2、-3. 3、-2. 5、-2. 3 d·(10a)^(-1);秋冬季的开始日在推迟,分别为1. 4(1. 5)、2. 1(4. 2)、1. 9(4. 4)、1. 0(2. 5)、1. 2(4. 0) d·(10a)^(-1)。春(夏、秋)季持续时间在延长,分别为7. 0(1. 3、0. 1)、0. 04(3. 3、2. 1)、1. 0(4. 6、2. 5)、0. 1(3. 4、1. 6)、1. 7(1. 8、2. 8) d·(10a)^(-1);冬季持续时间在缩短,分别为-8. 5、-5. 4、-7. 8、-5. 1、-6. 2 d·(10a)^(-1)。春季的提前与季节长度的延长,使作物播种期与牧草返青期提早;秋季的推迟与季节长度的缩短使得作物复种机会大;同时对农作物的种植结构、作物品种熟性布局以及旅游业都有一定的影响。

The observations from 39 meteorological observation stations in Tibet Autonomous Region from 1981 through 2015 were analyzed in relation to season changing. The analyses include the initial date and the duration of various seasons, the extreme date and the extreme duration of various seasons, season sooner or later, season getting longer and shorter, including rating of their trends, as well as their change trend and impact on agriculture, animal husbandry and tourism. The results indicate that the 35 a average initial dates of spring, summer, autumn and winter are February 25th, May 31st, September 15th and November 28th, respectively. The 35 a average durations of the four seasons were 99 d, 106 d, 73 d and 87 d, respectively, with an obvious regional difference. The initial date of spring had been -5.8, -1.2, -3.3, 2.5 and 2.3 d·(10a)^-1 sooner in Bomi, Jiacha, Nimu, Shiquanhe and Shenzha, respectively. The initial date of autumn (winter) had been later 1.4 (1.5), 2.1 (4.2), 1.9 (4.4), 1.0 (2.5) and 1.2 (4.0) d·(10a)^-1 in Bomi, Jiacha, Nimu, Shiquanhe and Shenzha, respectively. The duration in spring (summer, autumn) had extended 7.0 (1.3, 0.1), 0.04 (3.3, 2.1), 1.0 (4.6, 2.5), 0.1 (3.4, 1.6) and 1.7 (1.8, 2.8) d·(10a)^-1, respectively, in the five stations. The duration in winter had shortened 8.5, 5.4, 7.8, 5.1 and 6.2 d·(10a)^-1, respectively, in the five stations. The advancing of spring and the extension of spring duration make the planting time and the herbage turning-green early;the postponement of autumn and shortening the autumn duration make the opportunity of replanting crops great;at the same time, it has a certain impact on the planting structure, the mature distribution of crop varieties, as well as on the tourism.