近35年以来中国西北干旱区对流层顶温度变化特征

Characteristics of the Temporal and Spatial Variations of the Tropopause Temperature in the Arid Region of Northwest China in Recent 35 Years

摘要: 基于1980~2014年NCEP/NCAR的对流层顶温度再分析数据，采用线性趋势法、Mann-Kendall非参数检验法和相关分析法，分析了中国西北干旱区对流层顶温度的时空变化特征，进一步探讨了对流层顶温度年际变化率与地表温度年际变化率、海拔之间的相关性。结果表明：1) 西北干旱区对流层顶温度在近35a呈现下降趋势，全年、夏季、秋季和冬季下降趋势较为显著，而春季下降趋势未通过显著性检验，下降趋势不明显；2) 对流层顶温度年际变化率在全年和四季表现出不同的空间分布，总体上山区下降速率高于其周围盆地的速率。3) 近35a西北干旱区地表温度有明显的上升趋势，其年际变化率与对流层顶温度年际变化率呈显著的负相关；4) 从对流层顶温度的年际变化率与海拔之间关系来看，随着海拔的上升，对流层顶温度的下降速率越快，全年、春季、秋季和冬季的下降速率与海拔相关性显著，而夏季变化率与海拔之间的关系不显著。

Abstract: On the basis of monthly average tropopause temperature data of NCEP/NCAR reanalysis data dur-ing 1980-2014, the spatial and temporal evolution of tropopause temperature over the arid region of Northwest China (ARNC) is studied by linear trend method, Mann-Kendall nonparametric test and correlation analysis. The correlation between the variation of tropopause temperature and surface temperature, and the correlation between the change rate of tropopause temperature and altitude were also investigated. The results are as followed: 1) Tropopause temperature over the ARNC exhibited downward trends in the last 35a. And the annual and seasonal trends decreased significantly expect for the tendency of spring. The change rate of annual, spring, summer, autumn and winter was 0.51˚C/10a, 0.28˚C/10a, 0.88˚C/10a, 0.53˚C/10a, 0.35˚C/10a, respectively. Ob-viously, the rate of summer was the highest. 2) There were abrupt changes in annual and seasonal tropopause temperature variation. To be specific, the abrupt changes of annual and autumn tro-popause temperature occurred around 1992, and the abrupt changes of summer tropopause temperature occurred around 1994. All the three of them declined after abrupt changes. The spring tropopause temperature had three mutation sites, 1983, 1992 and 1994. The tropopause temperature rose after the abrupt change that occurred in 1983, then declined after 1992 and rose again after 1994. But the average temperature after the abrupt change that occurred in 1994 was still lower than the average temperature before 1983. The abrupt changes of winter tipopause temperature occurred around 1986 and 1988. The tropopause temperature rose after 1986, and declined after 1988. And the average temperature after the abrupt changes that occurred 1988 was still lower than the average temperature before the changes that occurred 1986. 3) There were regional differences in the annual variation and seasonal variation of tropopause temperature. Overall, the variation rate of mountains is higher than that of the basins around the mountains. The spatial variation of annual and summer were similar, and had a banding distribution along northeast-southwest direction. The change rate of tropopause temperature was higher in the region between North Slope of Aljin Mountains and the southeast of Tianshan Mountains than that of the area on both sides. The distribution of autumn and winter was more or less alike. Both of them presented high rate in the Tianshan Mountains and the south in its middle part. But there were few differences. The variation rate of Kunlun Mountains was higher than that of Tianshan Mountains in autumn, which were totally in contrast in winter. In spring, variation rate had a different distribution from before. There were a high value area in Kunlun Mountains and a low value area in south slope of Tianshan Mountains. 4) The surface temperature over ARNC presented an obvious upward trend in the period from 1980 to 2014. There was a negative correlation between the rate of the surface temperature trend and the tropopause trend, and the correlation is significant. 5) The variation rate of tropopause temperature increases as the altitude increases. The correlation between variation rate and altitude is significant at annual and seasonal variations except for summer.