scholarly journals Common Mechanism for Interannual and Decadal Variability in the East African Long Rains

2020 ◽  
Vol 47 (22) ◽  
Author(s):  
Dean P. Walker ◽  
John H. Marsham ◽  
Cathryn E. Birch ◽  
Adam A. Scaife ◽  
Declan L. Finney
Keyword(s):  
Decadal Variability ◽  
Common Mechanism ◽  
East African ◽  
Interannual And Decadal Variability

scholarly journals Reconciling Theories for Human and Natural Attribution of Recent East Africa Drying

2017 ◽  
Vol 30 (6) ◽  
pp. 1939-1957 ◽  
Author(s):  
Andrew Hoell ◽  
Martin Hoerling ◽  
Jon Eischeid ◽  
Xiao-Wei Quan ◽  
Brant Liebmann
Keyword(s):  
Global Warming ◽  
East Africa ◽  
Decadal Variability ◽  
Coupled Model ◽  
Western Pacific ◽  
East African ◽  
Coupled Models ◽  
Central Pacific ◽  
Model Simulations ◽  
African Rainfall

Abstract Two theories for observed East Africa drying trends during March–May 1979–2013 are reconciled. Both hypothesize that variations in tropical sea surface temperatures (SSTs) caused East Africa drying. The first invokes a mainly human cause resulting from sensitivity to secular warming of Indo–western Pacific SSTs. The second invokes a mainly natural cause resulting from sensitivity to a strong articulation of ENSO-like Pacific decadal variability involving warming of the western Pacific and cooling of the central Pacific. Historical atmospheric model simulations indicate that observed SST variations contributed significantly to the East Africa drying trend during March–May 1979–2013. By contrast, historical coupled model simulations suggest that external radiative forcing alone, including the ocean’s response to that forcing, did not contribute significantly to East Africa drying. Recognizing that the observed SST variations involved a commingling of natural and anthropogenic effects, this study diagnosed how East African rainfall sensitivity was conditionally dependent on the interplay of those factors. East African rainfall trends in historical coupled models were intercompared between two composites of ENSO-like decadal variability, one operating in the early twentieth century before appreciable global warming and the other in the early twenty-first century of strong global warming. The authors find the coaction of global warming with ENSO-like decadal variability can significantly enhance 35-yr East Africa drying trends relative to when the natural mode of ocean variability acts alone. A human-induced change via its interplay with an extreme articulation of natural variability may thus have been key to Africa drying; however, these results are speculative owing to differences among two independent suites of coupled model ensembles.

Interannual and decadal variability in zooplankton communities of the southeast Bering Sea shelf

2002 ◽  
Vol 49 (26) ◽  
pp. 5991-6008 ◽  
Author(s):  
Jeffrey M Napp ◽  
Christine T Baier ◽  
Richard D Brodeur ◽  
Kenneth O Coyle ◽  
Naonobu Shiga ◽  
...  
Keyword(s):  
Bering Sea ◽  
Decadal Variability ◽  
Interannual And Decadal Variability ◽  
Bering Sea Shelf ◽  
Zooplankton Communities

scholarly journals Interannual and decadal variability of Arctic summer sea ice associated with atmospheric teleconnection patterns during 1850-2017

2021 ◽  
pp. 1-89
Author(s):  
Qiongqiong Cai ◽  
Dmitry Beletsky ◽  
Jia Wang ◽  
Ruibo Lei
Keyword(s):  
Sea Ice ◽  
Decadal Variability ◽  
Arctic Sea Ice ◽  
Total Variance ◽  
The Arctic ◽  
Teleconnection Patterns ◽  
Arctic Sea ◽  
Mode 2 ◽  
Interannual And Decadal Variability ◽  
Arctic Summer

AbstractThe interannual and decadal variability of summer Arctic sea ice is analyzed, using the longest reconstruction (1850-2017) of Arctic sea ice extent available, and its relationship with the dominant internal variabilities of the climate system is further investigated quantitatively. The leading empirical orthogonal function (EOF) mode of summer Arctic sea ice variability captures an in-phase fluctuation over the Arctic Basin. The second mode characterizes a sea ice dipolar pattern with out-of-phase variability between the Pacific Arctic and the Atlantic Arctic. Summer sea ice variability is impacted by the major internal climate patterns: the Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO) and Dipole Anomaly (DA), with descending order of importance based on the multiple regression analyses. The internal climate variability of the five teleconnection patterns accounts for up to 46% of the total variance in sea ice mode 1 (thermodynamical effect), and up to 30% of the total variance in mode 2 (dynamical effect). Furthermore, the variability of sea ice mode 1 decreased from 46% during 1953-2017 to 28% during 1979-2017, while the variability of mode 2 increased from 11% during 1953-2017 to 30% during 1979-2017. The increasingly greater reduction of Arctic summer sea ice during the recent four decades was enhanced with the positive ice/ocean albedo feedback loop being accelerated by the Arctic amplification, contributed in part by the atmospheric thermodynamical forcing from -AO, +NAO, +DA, +AMO, and –PDO and by the dynamical transpolar sea ice advection and outflow driven by +DA- and +AMO-derived strong anomalous meridional winds. Further analysis, using multiple large ensembles of climate simulations and single-forcing ensembles, indicates that the mode 1 of summer sea ice, dominated by the multidecadal oscillation, is partially a forced response to anthropogenic warming.

scholarly journals Atmospheric Circulation Regimes in a Nonlinear Quasi-Geostrophic Model

2015 ◽  
Vol 2015 ◽  
pp. 1-19 ◽  
Author(s):  
Henriette Labsch ◽  
Dörthe Handorf ◽  
Klaus Dethloff ◽  
Michael V. Kurgansky
Keyword(s):  
Atmospheric Circulation ◽  
Arctic Oscillation ◽  
Significant Contribution ◽  
Decadal Variability ◽  
Low Frequency ◽  
The Arctic ◽  
Satisfactory Model ◽  
Low Frequency Variability ◽  
Interannual And Decadal Variability ◽  
The Arctic Oscillation

Atmospheric low-frequency variability and circulation regime behavior are investigated in the context of a quasi-geostrophic (QG) three-level T63 model of the wintertime atmospheric circulation over the Northern Hemisphere (NH). The model generates strong interannual and decadal variability, with the domination of the annular mode of variability. It successfully reproduces a satisfactory model climatology and the most important atmospheric circulation regimes. The positive phase of the Arctic Oscillation is a robust feature of the quasi-geostrophic T63 model. The model results based on QG dynamics underlie atmospheric regime behavior in the extratropical NH and suggest that nonlinear internal processes deliver significant contribution to the atmospheric climate variability on interannual and decadal timescales.

The interannual and decadal variability of the sea level in the Japan/East Sea

2009 ◽  
Vol 8 (4) ◽  
pp. 335-342 ◽  
Author(s):  
Tianshun Wang ◽  
Yuguang Liu ◽  
Haibo Zong ◽  
Zengrui Rong
Keyword(s):  
Sea Level ◽  
Decadal Variability ◽  
East Sea ◽  
Interannual And Decadal Variability
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