近43年西藏高原20cm地温对气温和降水变化的响应

Response of Soil Temperature of 20 cm Depth to Air Temperature and Precipitation in Tibet from 1971 to 2013

为了全面了解西藏高原20 cm耕作层地温受气候变化的影响情况,为西藏生态环境保护及农牧业可持续发展提供科学依据。基于1971—2013年西藏8个气象站的地温、气温和降水资料,分析了地温与气温及降水的变化关系。结果表明:各站年气温和地温均呈显著的增温趋势(P<0.05),冬、春季的气温和地温升温率明显大于夏、秋季;西藏西部和中部各地增温趋势明显大于东部,且大部分站点和时段地温增温率大于气温增温率。年、季气温和地温的年代际变化表现为:20世纪70—80年代偏低,90年代正常,21世纪前10年明显偏高。各站年地温、湿季地温、干季地温与同期气温均呈极显著正相关(P<0.01);湿季西藏中部和东部各站地温与同期降水量呈显著负相关(P<0.05),且不同时段的地温与同期气温及降水的相关程度湿季均大于干季。

The paper aims to fully understand the influence of climate change on soil temperature of 20 cmdepth of the cultivated land in Tibet, and to provide a scientific basis for protecting ecological environment andsustaining the development of farming and animal husbandry. Responses of soil temperature to air temperatureand precipitation were investigated in this paper with the observational data from 8 representativemeteorological stations during the period of 1971-2013. The results showed that the air temperature and thesoil temperature of 20 cm depth increased significantly in western and central Tibet than that in eastern Tibet,presented a significant warming trend, and the rise of the air temperature and the soil temperature in eachseason and of the year also showed the same regional characteristics. The air temperature and the soiltemperature were significantly higher in spring and winter than that in other seasons. It was found that theannual and seasonal air temperature and soil temperature of 20 cm depth were lower than the standard value in1970 s and 1980 s, while normal in 1990 s, and significantly higher than the standard value in the first decade ofthe 21 st century, anomaly of warming in western and central Tibet was bigger than that in eastern Tibet. Thestudy also found that there was an extremely and significantly positive correlation（P〈0.01） between theannual soil temperature, the soil temperature of the rainy season, the soil temperature of the dry season and the air temperature of the same period. It was found that the correlation in the rainy season was greater than that inthe dry season, and there was a significantly negative correlation between soil temperature and precipitation inthe central and eastern Tibet in the rainy season（P〈0.05）, and the correlation between soil temperature andair temperature and precipitation in the rainy season were higher than that in the dry season.