采用高山松最大密度重建川西高原近百年夏季气温

川西高原高山松树轮宽度及最大密度分析结果表明,最大密度年表和宽度年表中可提取的气候信息是不同的,在温暖、水分条件适中的地区,采用树木密度指标分析气候要素的变化是有效的途径。树轮宽度主要受5月降水影响,和西南季风活动有关;而最大密度主要指示了夏季(6￣9月)温度。利用转换函数重建了川西高原近百年来夏季(6￣9月)温度,重建序列的方差解释量为51%,(F=52.099,p<0.0001)。重建序列显示川西高原,30年代之前为偏冷期,30年代到60年代为偏暖期,与四川地区近百年的冷暖时期比较一致。与平原地区的成都相比,高原的升温转折点提前3年,表明高原地区对气温变化的响应更为敏感,川西高原地区可能是四川省气候变化的先兆地区。1983年以后川西高原地区夏季温度呈明显的上升趋势,20世纪90年代夏季温度的滑动平均为近百年的最大值,但在90年代初期仍处于均值线以下,表现为凉夏;90年代后半期表现为夏旱。

Reconstruction of Summer Temperature from Maximum Latewood Density of Pinus densata in West Sichuan

Having analyzed the tree ring width and maximum latewood density of Pinus densata from west Sichuan, we obtained the different climate information from tree-ring width and maximum latewood density chronology. The growth of tree ring width was responded principally to the precipitation in May, which might be influenced by the activity of southwest monsoon, whereas the maximum latewood density reflected the summer temperature (June-September). According to the correlation relationship, a transfer function had been used to reconstruct summer temperature for the study area. The explained variance of reconstruction is 51% (F = 52.099, p < 0.0001). In the reconstruction series: before the 1930s, the climate was relatively cold, and relatively warm from 1930 to 1960, and this trend was in accord with the cold-warm period of the last 100 years, west Sichuan. Compared with Chengdu, the warming break point in west Sichuan is 3 years ahead which shows Tibetan Plateau was more sensitive to temperature change. There was an evident summer warming signal after 1983. Although the last-100 running average of summer-temperature in the 1990s was the maximum, the running average of the early 1990s is below the average line and it was cold-summer; summer-drought presented in the late 1990s.