西藏高原地温对气温变化的响应

Response of Soil Temperature to Air Temperature Change in Tibet Plateau

选取1971-2013年西藏西部、中部和东部8个气象站的浅层(5、10、20cm)地温和较深层(40、80cm)地温以及气温逐月的观测资料,采用气候倾向率法、Mann-Kendall(M-K)检验等方法,分析近43a西藏年、季平均气温,年、季平均地温,年平均地气温差的变化趋势以及地温与气温的气候突变关系,并对21世纪地温的变化趋势进行预估。结果表明:(1)各研究站点年平均浅层地温均呈显著上升趋势(P<0.05),其中藏西部和藏中部比藏东部增温显著;各季节几乎地温上升显著,其中冬、春季升幅显著高于夏、秋季。(2)年、季深层地温除昌都无显著变化外,其余站点几乎均呈显著上升趋势(P<0.05),其中狮泉河、日喀则、拉萨各季深层地温升幅显著高于同期浅层地温,而泽当和昌都各季深层地温升幅低于同期浅层地温。(3)研究地温对气温的响应发现,研究期内藏西部的狮泉河浅层年地气温差小于深层,藏中部的日喀则和拉萨浅层年地气温差20世纪90年代前大于深层,90年代后接近或小于深层;藏东部的昌都浅层年地气温差在80年代中期前小于深层,80年代中期后大于深层。各土层年平均地温与年平均气温均呈极显著正相关,不同土层年地温间也呈极显著正相关(P<0.01)。(4)西藏21世纪地温随着气温显著升高,藏西部和藏中部增温幅度整体高于藏东部。年均地温高于气温,且其升温幅度大于气温,气温升高,地温增加,预估至21世纪末,昌都、拉萨、波密地温水平将分别达到偏南的八宿、泽当和察隅现有地温水平,相当于所有站点南移近1个纬度。

Based on the observed data of monthly soil temperature in different depth and air temperature from 8representative meteorological stations in Tibet Plateau from 1971 to 2013,by using the linear trend analysis method and Mann-Kendall method,the changing tendency of annual and seasonal soil temperatures and air temperature,the difference of soil and air temperature(Ts-Ta),and the abrupt change relationship between soil temperatures and air temperature were analyzed,the trend of soil temperatures in the future was predicated.The results showed that annual shallow soil temperature(SST) increased significantly(P < 0.05),in which those in western and central of Tibet Plateau were more significant than that of in eastern,seasonal soil temperature increased significantly,and that in winter and spring were more significant than that of in summer and autumn.Deep soil temperature(DST) increased significantly except for in Qamdo(P < 0.05),even much more than shallow soil temperature in Senggecangbu,Xigaze and Lhasa.The annual difference of SST and air temperature was bigger than DST in Senggecangbu,and similar to that of in Xigaze and Lhasa before 1990 s,but it was equaled to that of DST after 1990 s.The situation in Qamdo was that SST lower than that of DST before 1980 s,and higher than DST after1980 s.There was extremely significant positive correlation between average annual soil temperature in different depth and average annual air temperature,and there was significant positive correlation among soil temperature in different depth(P < 0.01).It was predicted that soil temperatures increased significantly in the future,and increasing range of soil temperature was higher than that of air temperature.It was projected that the soil temperatures in Qamdo,Lhasa and Bome could be approached that of in Baxoi,Tsedang and Zayu by the end of the twenty-first century,respectively,which means all of the sites could be moved one latitude toward south.