Decadal Prediction and Stochastic Simulation of Hydroclimate Over Monsoonal Asia

Ghil, Michael¹  Robertson, Andrew W.²  Cook, Edward R.³  D???Arrigo, Rosanne³  Lall, Upmanu⁴  Smyth, Padhraic J.⁵ 

[1] Univ. of California, Los Angeles, CA (United States);IRI (United States);LDEO Tree Ring Lab. (United States);Columbia Water Center (United States);UCI (United States)

关键词: Centennial proxy records;    Data-based closure models;    Empirical model reduction (EMR);    Indus River discharge;    Low-frequency variability (LFV);    Madden-Julian Oscillation (MJO);    Palmer Drought Severity Index (PDSI);    Singular-spectrum analysis (SSA);    Stochastic modeling;    Time series analysis and forecasting;   

DOI  :  10.2172/1168586
RP-ID  :  DOE-UCLA--6694
PID  :  OSTI ID: 1168586

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

We developed further our advanced methods of time series analysis and empirical model reduction (EMR) and applied them to climatic time series relevant to hydroclimate over Monsoonal Asia. The EMR methodology was both generalized further and laid on a rigorous mathematical basis via multilayered stochastic models (MSMs). We identified easily testable conditions that imply the existence of a global random attractor for MSMs and allow for non-polynomial predictors. This existence, in turn, guarantees the numerical stability of the MSMs so obtained. We showed that, in the presence of low-frequency variability (LFV), EMR prediction can be improved further by including information from selected times in the system???s past. This prediction method, dubbed Past-Noise Forecasting (PNF), was successfully applied to the Madden-Julian Oscillation (MJO). Our time series analysis and forecasting methods, based on singular-spectrum analysis (SSA) and its enhancements, were applied to several multi-centennial proxy records provided by the Lamont team. These included the Palmer Drought Severity Index (PDSI) for 1300???2005 from the Monsoonal Asia Drought Atlas (MADA), and a 300-member ensemble of pseudo-reconstructions of Indus River discharge for 1702???2005. The latter was shown to exhibit a robust 27-yr low-frequency mode, which helped multi-decadal retroactive forecasts with no look-ahead over this 300-year interval.