Sea Surface Temperature Anomalies in the Western Indian Ocean as a Trigger for Atlantic Niño Events

2021 ◽  
Vol 48 (8) ◽  
Author(s):  
Huaxia Liao ◽  
Chunzai Wang
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Western Indian Ocean ◽  
Sea Surface ◽  
Temperature Anomalies ◽  
Sea Surface Temperature Anomalies ◽  
Atlantic Niño

scholarly journals On the Angola Low Interannual Variability and Its Role in Modulating ENSO Effects in Southern Africa

2019 ◽  
Vol 32 (15) ◽  
pp. 4783-4803 ◽  
Author(s):  
Salvatore Pascale ◽  
Benjamin Pohl ◽  
Sarah B. Kapnick ◽  
Honghai Zhang
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Africa ◽  
Southern Oscillation ◽  
Sea Surface ◽  
Atmospheric Variability ◽  
Coupled Modes ◽  
Temperature Anomalies ◽  
Sea Surface Temperature Anomalies

Abstract The Angola low is a summertime low pressure system that affects the convergence of low-level moisture fluxes into southern Africa. Interannual variations of the Angola low reduce the seasonal prediction skills for this region that arise from coupled atmosphere–ocean variability. Despite its importance, the interannual dynamics of the Angola low, and its relationship with El Niño–Southern Oscillation (ENSO) and other coupled modes of variability, are still poorly understood, mostly because of the scarcity of atmospheric data and short-term duration of atmospheric reanalyses in the region. To bypass this issue, we use a long-term (3500 year) run from a 50-km-resolution global coupled model capable of simulating the summertime southern African large-scale circulation and teleconnections. We find that the meridional displacement and strength of the Angola low are moderately modulated by local sea surface temperature anomalies, especially those in proximity of the southeastern African coast, and to a lesser extent by ENSO and the subtropical Indian Ocean dipole. Comparison of the coupled run with a 1000-yr run driven by climatological sea surface temperatures reveals that the interannual excursions of the Angola low are in both cases associated with geopotential height anomalies over the southern Atlantic and Indian Ocean related to extratropical atmospheric variability. Midlatitude atmospheric variability explains almost 60% of the variance of the Angola low variability in the uncoupled run, but only 20% in the coupled run. Therefore, while the Angola low appears to be intrinsically controlled by atmospheric extratropical variability, the interference of the atmospheric response forced by sea surface temperature anomalies weakens this influence.

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