本文对定量重建黄土高原降水的传统方法进行了回顾分析,提出了利用新发展的“残差示踪法”定量重建黄土高原古降水变化的两种新方法。一种是利用黄土磁化率和粉尘通量指标的关系进行降水重建的磁化率方法(SUS-approach),另一种是利用黄土~(10)Be浓度与~(10)Be产率和粉尘通量指标的关系进行降水重建的~(10)Be方法(~(10)Be-approach)。上述两种方法定量重建的洛川地区13万年以来降水变化曲线高度一致,但与前人利用现代观测数据建立的气候回归方程等传统方法重建的降水记录具有明显的差异。本文所建立的降水曲线具有明显的细节特征,揭示了粉尘稀释作用对降水指标的影响,显示了该方法的优势。文章同时指出,“残差示踪法”的数学涵义是基于“平均值概念”(MVC),并对此从统计学角度进行了论证。最后,就本文所提出的运用线性回归后的残差进行示踪的新方法与传统的示踪方法之差异作了对比分析。
The Iraditional trace methods for paleoprecipitation reconstruction over Chinese Loess Plateau are first analyzed. Then, two practical applications of the newly developed "Residual Trace Approach" to quantitatively reconstruct the paleoprecipitation over the Chinese Loess Plateau are describecL One is the "SUS-approach" that uses paired measurements of magnetic susceptibility and dust flux in loess-paleosol sediments as proxies, the other is the "^10Be-approach" that uses both atmospheric ^10Be production rate and loess dust flux as proxies. The reconstructed precipitation curves of the past 130 ka over Luochuan loess plateau site by the two approaches are highly correlated. However, they are different to some extent from the other precipitation curves calculated by the individual climofunctions of the previous studies using traditional trace methods, and the detailed variations evident in the new approach offer an advantage over the traditional methods in revealing the dust dilution effect on the reconstructed precipitation. Furthermore, it is pointed out that the mathematical connotation of the "Residual Trace Approach" is equivalent to the "Mean Value Concept (MVC)" which is further explained from a statistical point of view. Finally, the difference of the "Residual Trace Approach" from the traditional trace method is compared.