Climate Change 2021: The Physical Science Basis
Category: UNFCCC
Document Type: Ipcc Report
Role: Annex
Summary of IPCC 2021 Report Annex IV on Global Climate Variability Modes
This document is Annex IV, titled "Modes of Variability," of the Intergovernmental Panel on Climate Change (IPCC) Working Group I (WGI) contribution to the Sixth Assessment Report (AR6), published in 2021. Its primary purpose is to describe the fundamental features of the main modes of large-scale climate variability that were assessed across the chapters of the AR6 WGI Report. The scope covers key modes such as the North Atlantic Oscillation (NAO) and Northern Annular Mode (NAM), Southern Annular Mode (SAM), El Niño–Southern Oscillation (ENSO), Indian Ocean Basin and Dipole Modes, Atlantic Meridional and Zonal Modes, Pacific Decadal Variability (PDV), Atlantic Multi-decadal Variability (AMV), and the Madden–Julian Oscillation (MJO). It explains that these modes are recurrent space-time structures of variability with intrinsic spatial patterns, seasonality, and time scales, often identified using methods like Principal Component Analysis (PCA) or Empirical Orthogonal Functions (EOF). As this is a scientific assessment report annex, it does not contain regulatory obligations, define affected sectors in a regulatory sense, or specify deadlines or compliance dates. The relevant document name is "Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Annex IV: Modes of Variability."
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SAPIMV Annex IV: Modes of Variability Coordinating Lead Authors: Christophe Cassou (France), Annalisa Cherchi (Italy), Yu Kosaka (Japan) Lead Authors: Susanna Corti (Italy), Francois Engelbrecht (South Africa), June-Yi Lee (Republic of Korea), Amanda Maycock (United Kingdom), Shayne McGregor (Australia), Olaf Morgenstern (New Zealand/Germany), Hyacinth C. Nnamchi (Nigeria, Germany/Nigeria), Juan A. Rivera (Argentina), Blair Trewin (Australia) Contributing Author: Adam S. Phillips (United States of America) This annex should be cited as: IPCC, 2021: Annex IV: Modes of Variability [Cassou, C., A. Cherchi, Y. Kosaka (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2153–2192, doi:10.1017/9781009157896.018. 2153 Annex IV Modes of Variability Table of Contents AIV.1 Introduction ������������������������������������������������������������������������������� 2155 AIV.2 The Main Modes of Climate Variability Assessed in AR6 ���������������������������������������������������������������������� 2156 AIV.2.1 North Atlantic Oscillation and Northern Annular Mode ������������������������������������ 2156 AIV.2.2 Southern Annular Mode ���������������������������������������������� 2159 AIV.2.3 El Niño–Southern Oscillation ����������������������������������� 2162 AIV.2.4 Indian Ocean Basin and Dipole Modes ������������� 2164 AIV.2.5 Atlantic Meridional and Zonal Modes ���������������� 2168 AIV.2.6 Pacific Decadal Variability ������������������������������������������ 2171 AIV.2.7 Atlantic Multi-decadal Variability �������������������������� 2174 AIV.2.8 Madden–Julian Oscillation ���������������������������������������� 2177 References ������������������������������������������������������������������������������������������������������� 2180 AIV 2154 Modes of Variability Annex IV AIV.1 Introduction index time series, that is, principal component (PC), describing the temporal evolution tied to the spatial pattern. PCA/EOF is widely This annex describes the fundamental features of the main modes used with gridded datasets and model outputs. Correlation or of large-scale climate variability assessed across chapters in the AR6 regression maps between the climate index time series and other WGI Report. Modes are defined as recurrent space-time structures space-time variables, such as precipitation, temperature or wind, are of variability of the climate system with intrinsic spatial patterns, then calculated to quantify the teleconnection patterns. Altogether, seasonality and time scales. They can arise through the dynamical beyond their physical relevance, modes of climate variability and characteristics of atmospheric circulation, but also through coupling their teleconnection patterns provide a simplified representation between the ocean and the atmosphere, with some interactions with of climate variation affecting weather, from regional (i.e., oceanic land surfaces and sea ice. The variability of the climate system at or continental scale) to worldwide scales (i.e., for some specific ocean- or continental-basin scales, and in particular, on seasonal- phenomena like ENSO), having important impacts on human to-multi-decadal time scales, can be described to a large extent by activities and ecosystems. Modes are often associated with climatic
Tags: Climate Change, Meteorology, Oceans, Report, Research