The influence of Antarctic topography on jet streams and Rossby waves in the Southern Hemisphere.

2020 ◽  
Author(s):  
Matthew Patterson ◽  
Tim Woollings ◽  
Tom Bracegirdle
Keyword(s):  
Southern Hemisphere ◽  
Rossby Wave ◽  
Rossby Waves ◽  
Wave Structure ◽  
South Pacific ◽  
Substantial Effect ◽  
The South ◽  
Coriolis Parameter ◽  
Antarctic Plateau ◽  
The Antarctic

<p>Eddy-driven jets are sustained through momentum transport by Rossby waves, which propagate along potential vorticity (PV) gradients. In the atmosphere, spatial variations in time-mean PV are mostly dominated by the variation of the Coriolis parameter with latitude. However, at high southern latitudes, a significant perturbation to the distribution and mixing of PV is provided by the Antarctic Plateau, which rises up to 4km above sea level. It is therefore possible that this orography affects Rossby wave propagation and hence affects the circulation in mid-latitudes.</p><p>We show through a set of semi-realistic and idealised experiments, that Antarctic topography plays a fundamental role in shaping the structure of the Southern Hemisphere extratropics. In particular, we perform runs with and without the Antarctic Plateau and demonstrate that the Plateau alters Rossby wave structure and propagation, thereby changing the momentum fluxes. Removal of the Plateau weakens the Indian Ocean jet and has a substantial effect on the flow downstream over the South Pacific. Here, the characteristic split jet pattern is destroyed and the flow at high latitudes stagnates. This also illustrates the prevalence of downstream development in the Southern Hemisphere and the strong connections between the flow over the South Pacific and Indian Oceans.   </p>

Impacts of Detoured Madden-Julian Oscillations on the South Pacific Convergence Zone

2021 ◽  
pp. 1-41
Author(s):  
Lei Zhou ◽  
Ruomei Ruan ◽  
Raghu Murtugudde
Keyword(s):  
Southern Hemisphere ◽  
Rossby Waves ◽  
South Pacific ◽  
South Pacific Convergence Zone ◽  
Boreal Winter ◽  
Convergence Zone ◽  
The South ◽  
Maritime Continent ◽  
Meridional Winds ◽  
Southern Pacific Ocean

AbstractMadden-Julian Oscillations (MJOs) are a major component of tropical intraseasonal variabilities. There are two paths for MJOs across the Maritime Continent; one is a detoured route into the Southern Hemisphere and the other one is around the equator across the Maritime Continent. Here, it is shown that the detoured and non-detoured MJOs have significantly different impacts on the South Pacific convergence zone (SPCZ). The detoured MJOs trigger strong cross-equatorial meridional winds from the Northern Hemisphere into the Southern Hemisphere. The associated meridional moisture and energy transports due to the background states carried by the intraseasonal meridional winds are favorable for reinforcing the SPCZ. In contrast, the influences of non-detoured MJOs on either hemisphere or the meridional transports across the equator are much weaker. The detoured MJOs can extend their impacts to the surrounding regions by shedding Rossby waves. Due to different background vorticity during detoured MJOs in boreal winter, more ray paths of Rossby waves traverse the Maritime Continent connecting the southern Pacific Ocean and the eastern Indian Ocean, but far fewer Rossby wave paths traverse Australia. Further studies on such processes are expected to contribute to a better understanding of extreme climate and natural disasters on the rim of the southern Pacific and Indian Oceans.

The flourishing forests of Antarctica

2007 ◽  
Author(s):  
David Beerling
Keyword(s):  
Sea Level ◽  
The Other ◽  
Cold Weather ◽  
South Pole ◽  
The South ◽  
Altitude Sickness ◽  
Antarctic Plateau ◽  
The Times ◽  
The Antarctic ◽  
As If

By arriving at the South Pole on 14 December 1911, the Norwegian explorer Roald Amundsen (1872–1928) reached his destination over a month ahead of the British effort led by Captain Robert Falcon Scott (1868–1912). As Scott’s party approached the South Pole on 17 January 1912, they were devastated to see from afar the Norwegian’s black flag. On arrival, they discovered the remains of his camp with ski and sledge tracks, and numerous dog footprints. Amundsen, it turned out, had used dogs and diversionary tactics to secure victory while the British team had man-hauled their sledges. These differences were not lost on The Times in London, which marked the achievement with muted praise, declaring it ‘not quite in accordance with the spirit of fair and open competition which hitherto marked Antarctic exploration’. Exhausted, Scott and his men spent time the following day making scientific observations around the Pole, erected ‘our poor slighted Union Jack’, and photographed themselves in front of it (Plate 11). Lieutenant Bowers took the picture by pulling a string to activate the shutter. It is perhaps the most well known, and at the same time the saddest picture, of the entire expedition—a poignant image of the doomed party, all of whom look utterly fed up as if somehow sensing the fate awaiting them. The cold weather, icy wind, and dismal circumstances led Scott to acerbically remark in his diary: ‘Great god! This is an awful place and terrible enough to have laboured to it without the reward of priority.’ By this time, the party had been hauling their sledges for weeks, and all the men were suffering from dehydration, owing to fatigue and altitude sickness from being on the Antarctic plateau that sits nearly 3000m above sea level. Three of them, Captain Oates, Seaman Evans, and Bowers, were badly afflicted with frostbitten noses and cheeks. Ahead lay the return leg, made all the more unbearable by the crippling psychological blow of knowing they had been second to the Pole. After a gruelling 21-day trek in bitterly cold summit winds, the team reached their first cache of food and fuel, covering the distance six days faster than it had taken them to do the leg in the other direction.

scholarly journals Propagation properties of Rossby waves for latitudinal β-plane variations of <I>f</I> and zonal variations of the shallow water speed

2012 ◽  
Vol 30 (5) ◽  
pp. 849-855 ◽  
Author(s):  
C. T. Duba ◽  
J. F. McKenzie
Keyword(s):  
Shallow Water ◽  
Group Velocity ◽  
Rossby Wave ◽  
Rossby Waves ◽  
Low Frequency ◽  
Wave Number ◽  
Coriolis Parameter ◽  
Propagation Properties ◽  
Wave Normal ◽  
Water Speed

Abstract. Using the shallow water equations for a rotating layer of fluid, the wave and dispersion equations for Rossby waves are developed for the cases of both the standard β-plane approximation for the latitudinal variation of the Coriolis parameter f and a zonal variation of the shallow water speed. It is well known that the wave normal diagram for the standard (mid-latitude) Rossby wave on a β-plane is a circle in wave number (ky,kx) space, whose centre is displaced −β/2 ω units along the negative kx axis, and whose radius is less than this displacement, which means that phase propagation is entirely westward. This form of anisotropy (arising from the latitudinal y variation of f), combined with the highly dispersive nature of the wave, gives rise to a group velocity diagram which permits eastward as well as westward propagation. It is shown that the group velocity diagram is an ellipse, whose centre is displaced westward, and whose major and minor axes give the maximum westward, eastward and northward (southward) group speeds as functions of the frequency and a parameter m which measures the ratio of the low frequency-long wavelength Rossby wave speed to the shallow water speed. We believe these properties of group velocity diagram have not been elucidated in this way before. We present a similar derivation of the wave normal diagram and its associated group velocity curve for the case of a zonal (x) variation of the shallow water speed, which may arise when the depth of an ocean varies zonally from a continental shelf.

scholarly journals Comments on “Blocking over the South Pacific and Rossby Wave Propagation”

2000 ◽  
Vol 128 (12) ◽  
pp. 4160-4161 ◽  
Author(s):  
V. Brahmananda Rao ◽  
Sergio H. Franchito ◽  
J. Pablo Reyes Fernandez
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
South Pacific ◽  
The South ◽  
Rossby Wave Propagation

scholarly journals Decadal Variability in the Large-Scale Sea Surface Height Field of the South Pacific Ocean: Observations and Causes

2006 ◽  
Vol 36 (9) ◽  
pp. 1751-1762 ◽  
Author(s):  
Bo Qiu ◽  
Shuiming Chen
Keyword(s):  
Pacific Ocean ◽  
Rossby Wave ◽  
Large Scale ◽  
South Pacific ◽  
Sea Surface Height ◽  
Sea Surface ◽  
South American ◽  
The South ◽  
South Pacific Ocean ◽  
Spatially Varying

Abstract Large-scale sea surface height (SSH) changes in the extraequatorial South Pacific Ocean are investigated using satellite altimetry data of the past 12 yr. The decadal SSH signals in the 1990s were dominated by an increasing trend in the 30°–50°S band and a decreasing trend in the central South Pacific Ocean poleward of 50°S. In recent years since 2002 there has been a reversal in both of these trends. Spatially varying low-frequency SSH signals are also found in the tropical region of 10°–25°S where the decadal SSH trend is negative in the eastern basin, but positive in the western basin. To clarify the causes for these observed spatially varying SSH signals, a 1½-layer reduced-gravity model that includes the wind-driven baroclinic Rossby wave dynamics and the responses forced by SSH changes along the South American coast was adopted. The model hindcasts the spatially varying decadal trends in the midlatitude and the eastern tropical regions well. Accumulation of the wind-forced SSH anomalies along Rossby wave characteristics is found to be important for both previously reported long-term trends and their reversals in recent years. The boundary forcing associated with the time-varying SSH signals along the South American coast is crucial for understanding the observed SSH signals of all time scales in the eastern tropical South Pacific basin, but it has little impact upon the midlatitude interior SSH signals.

The relationship between the Antarctic oscillation and blocking events over the South Pacific and Atlantic Oceans

2013 ◽  
Vol 34 (3) ◽  
pp. 529-544 ◽  
Author(s):  
Monica Cristina Damião Mendes ◽  
Iracema Fonseca Albuquerque Cavalcanti
Keyword(s):  
South Pacific ◽  
Antarctic Oscillation ◽  
The South ◽  
The Antarctic ◽  
The Relationship

An evaluation of the classical and extended Rossby wave theories in explaining spectral estimates of the first few baroclinic modes in the South Pacific Ocean

2007 ◽  
Vol 57 (3) ◽  
pp. 173-187 ◽  
Author(s):  
Angela M. Maharaj ◽  
Paolo Cipollini ◽  
Neil J. Holbrook ◽  
Peter D. Killworth ◽  
Jeffrey R. Blundell
Keyword(s):  
Pacific Ocean ◽  
Rossby Wave ◽  
South Pacific ◽  
The South ◽  
South Pacific Ocean ◽  
Spectral Estimates ◽  
Baroclinic Modes

scholarly journals Submillimeter Site Testing at Dome C, Antarctica

2004 ◽  
Vol 21 (3) ◽  
pp. 256-263 ◽  
Author(s):  
Paolo G. Calisse ◽  
Michael C. B. Ashley ◽  
Michael G. Burton ◽  
Michael A. Phillips ◽  
John W. V. Storey ◽  
...  
Keyword(s):  
South Pole ◽  
Site Testing ◽  
The South ◽  
Atmospheric Opacity ◽  
Antarctic Plateau ◽  
Under Construction ◽  
The Antarctic ◽  
Better Than

AbstractWe have developed a 350 μm radiometer to perform automated site testing in remote regions of Antarctica. In summer 2000–2001 the instrument operated at Concordia, a new station under construction at Dome C on the Antarctic Plateau. We present the results, and compare them with the atmospheric opacity measured at the South Pole in the same five-week period. During these five weeks, observing conditions at Dome C were, on average, substantially better than those at the South Pole.

Ornithology in the Pacific

2000 ◽  
Vol 6 (2) ◽  
pp. 87
Author(s):  
Harry F. Recher
Keyword(s):  
North America ◽  
Southern Hemisphere ◽  
South Pacific ◽  
The South ◽  
The Pacific

The 2nd Southern Hemisphere Ornithological Congress (SHOC II) was held at Griffith University, Brisbane from the 27th of June to the 2nd of July. Ornithological symposia and congresses are frequent events with multiple international and regional meetings held annually in North America and Europe. But for Australasia, and by default the South Pacific, it was a special and long anticipated event.

Sign in / Sign up

Export Citation Format

Share Document