Intermodel Diversity of Simulated Long-term Changes in the Austral Winter Southern Annular Mode: Role of the Southern Ocean Dipole

2021 ◽  
Author(s):  
Fei Zheng ◽  
Jianping Li ◽  
Shuailei Yao
Keyword(s):  
Southern Ocean ◽  
Southern Annular Mode ◽  
Austral Winter ◽  
Annular Mode ◽  
Long Term Changes

scholarly journals The Role of Eddies in the Southern Ocean Temperature Response to the Southern Annular Mode

2009 ◽  
Vol 22 (3) ◽  
pp. 806-818 ◽  
Author(s):  
James A. Screen ◽  
Nathan P. Gillett ◽  
David P. Stevens ◽  
Gareth J. Marshall ◽  
Howard K. Roscoe
Keyword(s):  
Southern Ocean ◽  
Mesoscale Eddy ◽  
Temperature Response ◽  
Southern Annular Mode ◽  
Polar Front ◽  
Ocean Model ◽  
Positive Anomaly ◽  
Annular Mode ◽  
Coarse Resolution

Abstract The role of eddies in modulating the Southern Ocean response to the southern annular mode (SAM) is examined, using an ocean model run at multiple resolutions from coarse to eddy resolving. The high-resolution versions of the model show an increase in eddy kinetic energy that peaks 2–3 yr after a positive anomaly in the SAM index. Previous work has shown that the instantaneous temperature response to the SAM is characterized by predominant cooling south of 45°S and warming to the north. At all resolutions the model captures this temperature response. This response is also evident in the coarse-resolution implementation of the model with no eddy mixing parameterization, showing that eddies do not play an important role in the instantaneous response. On the longer time scales, an intensification of the mesoscale eddy field occurs, which causes enhanced poleward heat flux and drives warming south of the oceanic Polar Front. This warming is of greater magnitude and occurs for a longer period than the initial cooling response. The results demonstrate that this warming is surface intensified and strongest in the mixed layer. Non-eddy-resolving models are unable to capture the delayed eddy-driven temperature response to the SAM. The authors therefore question the ability of coarse-resolution models, such as those commonly used in climate simulations, to accurately represent the full impacts of the SAM on the Southern Ocean.

scholarly journals Role of the Southern Annular Mode (SAM) in Southern Ocean CO2uptake

2007 ◽  
Vol 21 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
Andrew Lenton ◽  
Richard J. Matear
Keyword(s):  
Southern Ocean ◽  
Southern Annular Mode ◽  
Annular Mode

Long-term changes in microbial water quality indicators in a hydro-power plant reservoir: The role of natural factors and socio-economic changes

AMBIO ◽  
2021 ◽  
Author(s):  
Gunta Spriņġe ◽  
Māris Bērtiņš ◽  
Lesya Gnatyshyna ◽  
Ilga Kokorīte ◽  
Agnese Lasmane ◽  
...  
Keyword(s):  
Water Quality ◽  
Power Plant ◽  
Hydro Power ◽  
Microbial Water Quality ◽  
Economic Changes ◽  
Water Quality Indicators ◽  
Natural Factors ◽  
Long Term Changes

scholarly journals Supplementary material to "The Southern Annular Mode (SAM) influences phytoplankton communities in the seasonal ice zone of the Southern Ocean"

2019 ◽  
Author(s):  
Bruce L. Greaves ◽  
Andrew T. Davidson ◽  
Alexander D. Fraser ◽  
John P. McKinlay ◽  
Andrew Martin ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Southern Annular Mode ◽  
Annular Mode ◽  
Phytoplankton Communities ◽  
Supplementary Material ◽  
Seasonal Ice Zone

TGF-β1-Induced Long-Term Changes in Neuronal Excitability in Aplysia Sensory Neurons Depend on MAPK

2006 ◽  
Vol 95 (5) ◽  
pp. 3286-3290 ◽  
Author(s):  
Jeannie Chin ◽  
Rong-Yu Liu ◽  
Leonard J. Cleary ◽  
Arnold Eskin ◽  
John H. Byrne
Keyword(s):  
Sensory Neuron ◽  
Transforming Growth Factor Beta ◽  
Neuronal Excitability ◽  
Transforming Growth Factor ◽  
Critical Role ◽  
Camp Response Element Binding ◽  
Long Term Changes ◽  
Tgf Β1

Transforming growth factor beta-1 (TGF-β1) plays important roles in the early development of the nervous system and has been implicated in neuronal plasticity in adult organisms. It induces long-term increases in sensory neuron excitability in Aplysia as well as a long-term enhancement of synaptic efficacy at sensorimotor synapses. In addition, TGF-β1 acutely regulates synapsin phosphorylation and reduces synaptic depression induced by low-frequency stimuli. Because of the critical role of MAPK in other forms of long-term plasticity in Aplysia, we examined the role of MAPK in TGF-β1-induced long-term changes in neuronal excitability. Prolonged (6 h) exposure to TGF-β1 induced long-term increases in excitability. We confirmed this finding and now report that exposure to TGF-β1 was sufficient to activate MAPK and increase nuclear levels of active MAPK. Moreover, TGF-β1 enhanced phosphorylation of the Aplysia transcriptional activator cAMP response element binding protein (CREB)1, a homologue to vertebrate CREB. Both the TGF-β1-induced long-term changes in neuronal excitability and the phosphorylation of CREB1 were blocked in the presence of an inhibitor of the MAPK cascade, confirming a role for MAPK in long-term modulation of sensory neuron function.

Response of the Southern Ocean to the Southern Annular Mode: Interannual Variability and Multidecadal Trend

2010 ◽  
Vol 40 (7) ◽  
pp. 1659-1668 ◽  
Author(s):  
A. M. Treguier ◽  
J. Le Sommer ◽  
J. M. Molines ◽  
B. de Cuevas
Keyword(s):  
Kinetic Energy ◽  
Southern Ocean ◽  
Interannual Variability ◽  
Time Scales ◽  
Meridional Circulation ◽  
Southern Annular Mode ◽  
Eddy Kinetic Energy ◽  
Overturning Circulation ◽  
Annular Mode ◽  
Meridional Overturning

Abstract The authors evaluate the response of the Southern Ocean to the variability and multidecadal trend of the southern annular mode (SAM) from 1972 to 2001 in a global eddy-permitting model of the DRAKKAR project. The transport of the Antarctic Circumpolar Current (ACC) is correlated with the SAM at interannual time scales but exhibits a drift because of the thermodynamic adjustment of the model (the ACC transport decreases because of a low renewal rate of dense waters around Antarctica). The interannual variability of the eddy kinetic energy (EKE) and the ACC transport are uncorrelated, but the EKE decreases like the ACC transport over the three decades, even though meridional eddy fluxes of heat and buoyancy remain stable. The contribution of oceanic eddies to meridional transports is an important issue because a growth of the poleward eddy transport could, in theory, oppose the increase of the mean overturning circulation forced by the SAM. In the authors’ model, the total meridional circulation at 50°S is well correlated with the SAM index (and the Ekman transport) at interannual time scales, and both increase over three decades between 1972 and 2001. However, given the long-term drift, no SAM-linked trend in the eddy contribution to the meridional overturning circulation is detectable. The increase of the meridional overturning is due to the time-mean component and is compensated by an increased buoyancy gain at the surface. The authors emphasize that the meridional circulation does not vary in a simple relationship with the zonal circulation. The model solution points out that the zonal circulation and the eddy kinetic energy are governed by different mechanisms according to the time scale considered (interannual or decadal).

scholarly journals Southern Annular Mode Influence on Wintertime Ventilation of the Southern Ocean Detected in Atmospheric O 2 and CO 2 Measurements

2020 ◽  
Vol 47 (4) ◽  
Author(s):  
Cynthia D. Nevison ◽  
David R. Munro ◽  
Nicole S. Lovenduski ◽  
Ralph F. Keeling ◽  
Manfredi Manizza ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Southern Annular Mode ◽  
Annular Mode

Response of the Southern Ocean overturning circulation to extreme Southern Annular Mode conditions

2020 ◽  
Author(s):  
Kial Douglas Stewart ◽  
Andrew McC. Hogg ◽  
Matthew H. England ◽  
Darryn W. Waugh
Keyword(s):  
Southern Ocean ◽  
Southern Annular Mode ◽  
Overturning Circulation ◽  
Annular Mode
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