scholarly journals Historical and Projected Changes in the Southern Hemisphere Surface Westerlies

2021 ◽  
Vol 48 (4) ◽  
Author(s):  
Rishav Goyal ◽  
Alex Sen Gupta ◽  
Martin Jucker ◽  
Matthew H. England
2020 ◽  
Author(s):  
Rishav Goyal ◽  
Alexander Sen Gupta ◽  
Martin Jucker ◽  
Matthew H. England

2010 ◽  
Vol 23 (2) ◽  
pp. 440-454 ◽  
Author(s):  
Kevin E. Trenberth ◽  
John T. Fasullo

Abstract The energy budget of the modern-day Southern Hemisphere is poorly simulated in both state-of-the-art reanalyses and coupled global climate models. The ocean-dominated Southern Hemisphere has low surface reflectivity and therefore its albedo is particularly sensitive to cloud cover. In modern-day climates, mainly because of systematic deficiencies in cloud and albedo at mid- and high latitudes, too much solar radiation enters the ocean. Along with too little radiation absorbed at lower latitudes because of clouds that are too bright, unrealistically weak poleward transports of energy by both the ocean and atmosphere are generally simulated in the Southern Hemisphere. This implies too little baroclinic eddy development and deficient activity in storm tracks. However, projections into the future by coupled climate models indicate that the Southern Ocean features a robust and unique increase in albedo, related to clouds, in association with an intensification and poleward shift in storm tracks that is not observed at any other latitude. Such an increase in cloud may be untenable in nature, as it is likely precluded by the present-day ubiquitous cloud cover that models fail to capture. There is also a remarkably strong relationship between the projected changes in clouds and the simulated current-day cloud errors. The model equilibrium climate sensitivity is also significantly negatively correlated with the Southern Hemisphere energy errors, and only the more sensitive models are in the range of observations. As a result, questions loom large about how the Southern Hemisphere will actually change as global warming progresses, and a better simulation of the modern-day climate is an essential first step.


2016 ◽  
Vol 6 (10) ◽  
pp. 917-926 ◽  
Author(s):  
Julie M. Jones ◽  
Sarah T. Gille ◽  
Hugues Goosse ◽  
Nerilie J. Abram ◽  
Pablo O. Canziani ◽  
...  

2021 ◽  
pp. 1-51

Abstract As the leading mode of Pacific variability, the El Niño-Southern Oscillation (ENSO) causes vast and wide-spread climatic impacts, including in the stratosphere. Following discovery of a stratospheric pathway of ENSO to the Northern Hemisphere surface, here we aim to investigate if there is a substantial Southern Hemisphere (SH) stratospheric pathway in relation to austral winter ENSO events. Large stratospheric anomalies connected to ENSO occur on average at high SH latitudes as early as August, peaking at around 10 hPa. An overall colder austral spring Antarctic stratosphere is generally associated with the warm phase of the ENSO cycle, and vice versa. This behavior is robust among reanalysis and six separate model ensembles encompassing two different model frameworks. A stratospheric pathway is identified by separating ENSO events that exhibit a stratospheric anomaly from those that don’t and comparing to stratospheric extremes that occur during neutral-ENSO years. The tropospheric eddy-driven jet response to the stratospheric ENSO pathway is the most robust in the spring following a La Niña, but extends into summer, and is more zonally-symmetric compared to the tropospheric ENSO teleconnection. The magnitude of the stratospheric pathway is weaker compared to the tropospheric pathway and therefore when it is present, has a secondary role. For context, the magnitude is approximately half that of the eddy-driven jet modulation due to austral spring ozone depletion in the model simulations. This work establishes that the stratospheric circulation acts as an intermediary in coupling ENSO variability to variations in the austral spring and summer tropospheric circulation.


2016 ◽  
Vol 48 (1-2) ◽  
pp. 661-681 ◽  
Author(s):  
Sheeba Nettukandy Chenoli ◽  
Muhammad Yunus Ahmad Mazuki ◽  
John Turner ◽  
Azizan Abu Samah

2011 ◽  
Vol 4 (11) ◽  
pp. 741-749 ◽  
Author(s):  
David W. J. Thompson ◽  
Susan Solomon ◽  
Paul J. Kushner ◽  
Matthew H. England ◽  
Kevin M. Grise ◽  
...  

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