1981-2010年三江平原40～320cm深地温变化特征

Variations of Ground Temperature at the Depths of 40～320 cm in Sanjiang Plain,Northeast China during 1981-2010

利用1981-2010年黑龙江佳木斯气象站40～320cm逐月平均地温观测资料,研究了三江平原地温变化规律、气候突变、异常年份及冻融特征等.结果表明:40～320cm年平均地温呈极显著升温趋势,升幅为0.496～0.574℃.(10a)-1,其中夏季升幅最大;月平均地温呈波形变化,振幅随深度增加而减小;1月随着深度的增加地温逐渐增大,7月地温随深度增加而减小,维持正梯度.除秋季40cm和80cm,冬季320cm平均地温变化相对平稳,未出现地温突变现象,其他各层年、季平均地温均发生了突变;40cm和80cm年平均地温在1981年出现了异常偏冷,320cm年平均地温在20世纪90年代末出现了异常偏冷,40cm和160cm年平均地温在2004年出现了异常偏暖;80cm土壤较40cm冻融时间出现晚,冻结期缩短18d左右,土壤的冻结过程比消融过程要快.

In this paper,the ground temperature change,climate abrupt change,abnormal years and frost characteristics in Sanjiang Plain are studied by using monthly average geothermal observation data at the depths of 40~320 cm from 1981 to 2010.It is found that the yearly average ground temperature at the depths of 40~320 cm in Kiamusze on the Sanjiang Plain is extremely increasing with the rate of 0.496~0.574 ℃·（10a）-1,therein the maximum increase is at the depth of 80 cm and the minimum increase is at the depth of 320 cm.As for the climate trend rates of the seasonal average ground temperature,the increase in summer is the maximum one,while the average ground temperatures at the depths of 40 cm,80 cm and 160 cm are higher than those in autumn and winter.But the average ground temperature at the depth of 320 cm increases obviously in summer.The trend rates of ground temperatures at different depths are a little high,mainly owing to the summer precipitation decreasing.However,the spring and winter precipitation increase results in snow cover deeper,which is favorable to ground temperature saving.The ground temperature changing is fastest at the depth of 40 cm in spring,while that at the depth of 160 cm is slowest.The ground temperature increases fastest in summer at the depths of 80 cm and 160 cm;but in autumn,the temperature increases with depth at the same time,and with a maximum at the 320 cm depth;increasing rate of average ground temperature at the depth of 40 cm is the maximum while that at the 160 cm depth is the minimum.There is a wave fluctuation in the average ground temperature variation at the depth of 40~320 cm.The maximum values at the depths of 40 cm and 80 cm appear in August,while that at the depth of 160 cm depth appears in September and that at the depth of 320 cm appears in October;the minimum value appears in February,but that at the depth of 160 cm appears in March and that at the depth of 320 cm appears in May.The phase of the maximum and minimum of average ground temperature lagged behind with depth.The annual range of average ground temperature in the depth of 40 cm is the largest,and decreases with depth.The annual average ground temperature in Kiamusze increased obviously yearly in the 1980s and the 1990s,but it decreased in the 1980s.The seasonal average ground temperature variation was low in the 1980s,especially in summer.There is obvious vertical variation in the ground temperature profile,with heat flux upwards in January and downwards in July;April and October are ground temperature transition periods.There is not abrupt change in ground temperature at the depth of 40 cm and 80 cm in autumn and at the depth of 320 cm in winter.Abrupt change in ground temperature mainly appeared in the late 1980s and the early 1990s,while there was abrupt change in annual average ground temperature at the depth of 80 cm,and the annual average ground temperature at other depths changed abruptly in the period of 1992-1993.Annual average ground temperatures at the depths of 40 cm and 80 cm were unusual low in 1981 but that at the depths of 320 cm was unusual low in the late 1990s,with an unusual high at the depths of the 40 cm and 160 cm in 2004.Ground at the depth of 40 cm begins to freeze in late November to middle December and begins to thaw in April next year.Ground at the depth of 80 cm begins to freeze in middle December to January next year and begins to thaw in late April to early May.The average frozen period at the depth of 80 cm is 18 d shorter than that at the depth of 40 cm.Ground freezing is much faster than ground thawing.