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通过对甘肃南部腊子口的油松(Pinus tabulaeformis)进行树木年轮分析,首次建立了研究区1824~2011年标准化年表(STD),并与邻近的岷县气象站降水和温度进行相关分析,结果表明,该年表与上一年8月到当年7月的总降水(p8c7)相关性最好,相关系数达到0.644(p<0.01)。据此建立树轮指数与降水量之间的转换方程,该方程解释了实测期41.5%的降水(1952~2008年),并通过一系列稳定性检验,进而重建研究区1824~2011年间188年以来的降水。对重建结果进行11年滑动平均,结果表明,共出现3次极干旱期,分别为1900~1902年,1926~1930年和1997~2000年,尤以1997~2000年最为严重,极干旱期占到重建期的6.38%,而极湿润期只有1937年,仅占0.53%。与邻近区已有的研究对比后发现,1920s~1930s干旱事件在研究区以北区域更为严重。重建结果与赤道东太平洋、中太平洋平均海表温度(SST)呈显著负相关(p<0.1),说明研究区干旱变化与海温存在遥相关关系;多窗谱分析(MTM)结果表明降水存在2~3年和7年周期。ENSO事件时,东亚季风减弱,位于季风边缘区的甘肃南部地区出现干旱化趋势。
Based on the tree-ring analysis of Pinus tabulaeformis in the Lazikou of southern Gansu, the STD of the study area was first established between 1824 and 2011, and was correlated with the precipitation and temperature of the adjacent Minxian weather station The results showed that the correlation between this chronology and the total precipitation (p8c7) from August to July of the previous year was the best, with a correlation coefficient of 0.644 (p <0.01). Based on this, a conversion equation between tree-ring index and precipitation was established, which explained 41.5% of the precipitation during the survey period (from 1952 to 2008) and passed a series of stability tests to reconstruct 188 years from 1824 to 2011 in the study area Since the precipitation. The 11-year moving average of the reconstruction results showed that there were 3 extreme drought periods, which occurred from 1900 to 1902, from 1926 to 1930 and from 1997 to 2000, respectively, especially from 1997 to 2000, with a very dry period To 6.38% of the reconstruction period, while very wetting period was only in 1937, accounting for only 0.53%. Compared with the existing studies in the neighboring areas, it was found that the drought events of 1920s-1930s were more serious in the area north of the study area. There was a significant negative correlation (P <0.1) between the reconstruction results and the equatorial Pacific and Central Pacific Ocean mean sea surface temperature (SST) (p <0.1), indicating a teleconnection relationship between the drought and the SST in the study area. 2 to 3 years and 7 years cycle. In the ENSO event, the monsoon of East Asia weakened and aridification occurred in southern Gansu, which is located in the marginal zone of the monsoon.