树轮宽度记录的1861年以来松潘地区秋雨指数变化特征及其形成机理

为了分析气候变暖背景下松潘地区秋雨的时空变化特征及其形成机理,利用采自四川省松潘县二道海的冷杉树轮样本建立了树轮宽度标准年表,并重建了松潘地区过去150 a秋雨指数,回归方程的误差缩减值(RE=0.19)、乘积平均数(t=3.46)和F检验值(16.4)都达到了0.01的显著性水平,重建方程稳定可靠。研究结果表明:(1)过去150 a松潘秋雨没有明显的线性变化趋势,但是年代际波动显著,先后出现了3个偏强时段和4个偏弱时段。(2)从秋雨指数突变检验来看,松潘秋雨可以分为3个时期,1861—1910年、1961—2010年为明显波动期,1911—1960年为相对平稳期。(3)不同时期松潘秋雨的形成机理存在显著差异,其中1861—1910年松潘秋雨的强弱主要由北方冷空气的强弱主导,1911—1960年则主要受夏季风系统控制,1961—2010年松潘秋雨受冷暖空气同步异常的影响。总体来说,1861—2010年松潘秋雨主要呈现出年代际波动的变化特征,这种年代际差异主要是由于北方冷空气和夏季风系统对松潘秋雨影响程度的差异造成的。

Characteristics and Formation Mechanism of Autumn Rain Recorded by Tree-Ring Width in Songpan District Since 1861

In order to analyze the temporal and spatial variation characteristics and formation mechanism of autumn rain in Songpan district under the background of climate warming,the standard chronology(STD)was established by using tree-ring samples.On this basis,the autumn rain index in Songpan(ARIS)over the past 150 years was reconstructed using the STD.The error reduction value(RE=0.19),product mean(t=3.46)and F-test value(16.4)of the regression equation reached the significance level of 0.01,indicating that the reconstruction equation is stable and reliable.The reconstruction results show that:(1)there was no evident linear change trend of ARIS in the past 150 years,but the interdecadal fluctuation was significant;there were 3 periods of strong ARIS and 4 weak periods;(2)according to the abrupt change test,ARIS can be divided into three periods:the evident fluctuation characteristics during 1861—1910 and 1961—2010,and the relatively stable change during 1911—1960;(3)the intensity of ARIS was mainly dominated by the strength of cold air in the north during 1861—1910 and by the summer monsoon system during 1911—1960;however,between 1961—2010,it was affected by the synchronous anomaly of both cold and warm air.In general,the autumn rain in Songpan district from 1861 to 2010 mainly showed the characteristics of interdecadal fluctuation.This interdecadal difference was mainly caused by the difference of the influence of the northern cold air and summer monsoon system on the autumn rain in Songpan district.