JpGU-AGU Joint Meeting 2020

講演情報

[E] 口頭発表

セッション記号 A (大気水圏科学) » A-CG 大気海洋・環境科学複合領域・一般

[A-CG52] Large Ensemble Modeling Approaches as Tools for Climate and Impacts Research

コンビーナ:Rodgers Keith Bradley(IBS Center for Climate Physics)、見延 庄士郎(北海道大学大学院理学研究院)、塩竈 秀夫(国立環境研究所地球環境研究センター)、水田 亮(気象庁気象研究所)

[ACG52-05] Nonlinear forced change implies nonergodicity and vice-versa: The case of ENSO teleconnections

*Tamas Bodai1,2Axel Timmermann1,2Gabor Drotos3Timea Haszpra4 (1.Pusan National University、2.Center for Climate Physics, Institute for Basic Science, South Korea、3.Instituto de Física Interdisciplinar y Sistemas Complejos, CSIC-UIB, Palma de Mallorca, Spain、4.Institute for Theoretical Physics, Eötvös Loránd University, Budapest, Hungary)

キーワード:ENSO, Indian summer monsoon, teleconnection, global precipitation, ergodicity, Maximum Covariance Analaysis

We study the forced response of the teleconnection between the El Niño–Southern Oscillation (ENSO) and global precipitation in general and the Indian summer monsoon (IM) in particular in the Max Planck Institute Grand Ensemble. The forced response of the teleconnection is defined as the time-dependence of a correlation coefficient evaluated over the ensemble. The ensemble-wise variability is taken either wrt. spatial averages or dominant spatial modes in the sense of Maximal Covariance Analysis or Canonical Correlation Analysis or EOF analysis. We find that the strengthening of the ENSO-IM teleconnection is robustly featured in view of all four teleconnection representations, and both in the historical period and under the RCP8.5 forcing scenario. We also find that this forced change is typically nonlinear by formally rejecting the hypothesis that ergodicity holds, i.e., that expected values of temporal correlation coefficients with respect to the ensemble equal the ensemble-wise correlation coefficient itself. We also provide global maps of the degree of nonlinearity of the forced change of the teleconnection between local precipitation and ENSO.