scholarly journals Assessing recent trends in high-latitude Southern Hemisphere surface climate

2016 ◽  
Vol 6 (10) ◽  
pp. 917-926 ◽  
Author(s):  
Julie M. Jones ◽  
Sarah T. Gille ◽  
Hugues Goosse ◽  
Nerilie J. Abram ◽  
Pablo O. Canziani ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
High Latitude ◽  
Surface Climate ◽  
Hemisphere Surface ◽  
Recent Trends

Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change

2011 ◽  
Vol 4 (11) ◽  
pp. 741-749 ◽  
Author(s):  
David W. J. Thompson ◽  
Susan Solomon ◽  
Paul J. Kushner ◽  
Matthew H. England ◽  
Kevin M. Grise ◽  
...  
Keyword(s):  
Climate Change ◽  
Southern Hemisphere ◽  
Ozone Hole ◽  
Surface Climate ◽  
Hemisphere Surface ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Antarctic Ozone Hole

scholarly journals Southern-Hemisphere high-latitude stratospheric warming revisit

2019 ◽  
Vol 54 (3-4) ◽  
pp. 1671-1682
Author(s):  
Yan Xia ◽  
Weixuan Xu ◽  
Yongyun Hu ◽  
Fei Xie
Keyword(s):  
Southern Hemisphere ◽  
High Latitude ◽  
Recent Decade ◽  
Warming Trend ◽  
High Latitudes ◽  
Stratospheric Warming ◽  
Amundsen Sea ◽  
Maximum Warming ◽  
Dipole Pattern ◽  
The Western Pacific

AbstractPrevious studies showed significant stratospheric warming at the Southern-Hemisphere (SH) high latitudes in September and October over 1979–2006. The warming trend center was located over the Southern Ocean poleward of the Western Pacific in September, with a maximum trend of about 2.8 K/decade. The warming trends in October showed a dipole pattern, with the warming center over the Ross and Amundsen Sea, and the maximum warming trend is about 2.6 K/decade. In the present study, we revisit the problem of the SH stratospheric warming in the recent decade. It is found that the SH high-latitude stratosphere continued warming in September and October over 2007–2017, but with very different spatial patterns. Multiple linear regression demonstrates that ozone increases play an important role in the SH high-latitude stratospheric warming in September and November, while the changes in the Brewer-Dobson circulation contributes little to the warming. This is different from the situation over 1979–2006 when the SH high-latitude stratospheric warming was mainly caused by the strengthening of the Brewer-Dobson circulation and the eastward shift of the warming center. Simulations forced with observed ozone changes over 2007–2017 shows warming trends, suggesting that the observed warming trends over 2007–2017 are at least partly due to ozone recovery. The warming trends due to ozone recovery have important implications for stratospheric, tropospheric and surface climates on SH.

Interannual Variability in the Southern Hemisphere Circulation Organized by Stratospheric Final Warming Events

2007 ◽  
Vol 64 (8) ◽  
pp. 2968-2974 ◽  
Author(s):  
Robert X. Black ◽  
Brent A. McDaniel
Keyword(s):  
Southern Hemisphere ◽  
High Latitude ◽  
Large Scale ◽  
Lower Troposphere ◽  
Southern Annular Mode ◽  
Atmospheric Variability ◽  
Middle Latitudes ◽  
Stratospheric Final Warming ◽  
Circulation Change ◽  
Large Scale Atmospheric Circulation

A composite observational analysis is presented demonstrating that austral stratospheric final warming (SFW) events provide a substantial organizing influence upon the large-scale atmospheric circulation in the Southern Hemisphere. In particular, the annual weakening of high-latitude westerlies in the upper troposphere and stratosphere is accelerated during SFW onset. This behavior is associated with a coherent annular circulation change with zonal wind decelerations (accelerations) at high (low) latitudes. The high-latitude stratospheric decelerations are induced by the anomalous wave driving of upward-propagating tropospheric waves. Longitudinally asymmetric circulation changes occur in the lower troposphere during SFW onset with regionally localized height increases (decreases) at subpolar (middle) latitudes. Importantly, the tropospheric and stratospheric circulation change patterns identified here are structurally distinct from the Southern Annular Mode. It is concluded that SFW events are linked to interannual atmospheric variability with potential bearing upon weather and climate prediction.

scholarly journals WAIS Divide ice core suggests sustained changes in the atmospheric formation pathways of sulfate and nitrate since the 19th century in the extratropical Southern Hemisphere

2014 ◽  
Vol 14 (11) ◽  
pp. 5749-5769 ◽  
Author(s):  
E. D. Sofen ◽  
B. Alexander ◽  
E. J. Steig ◽  
M. H. Thiemens ◽  
S. A. Kunasek ◽  
...  
Keyword(s):  
19Th Century ◽  
Southern Hemisphere ◽  
Mole Fraction ◽  
High Latitude ◽  
Marine Boundary Layer ◽  
Ice Core ◽  
Climate Impacts ◽  
Early 19Th Century ◽  
West Antarctic ◽  
Sulfate Formation

Abstract. The 17O excess (Δ17O = δ17O−0.52 × δ18O) of sulfate and nitrate reflects the relative importance of their different production pathways in the atmosphere. A new record of sulfate and nitrate Δ17O spanning the last 2400 years from the West Antarctic Ice Sheet Divide ice core project shows significant changes in both sulfate and nitrate Δ17O in the most recent 200 years, indicating changes in their formation pathways. The sulfate Δ17O record exhibits a 1.1 ‰ increase in the early 19th century from (2.4 ± 0.2) ‰ to (3.5 ± 0.2) ‰, which suggests that an additional 12–18% of sulfate formation occurs via aqueous-phase production by O3, relative to that in the gas phase. Nitrate Δ17O gradually decreases over the whole record, with a more rapid decrease between the mid-19th century and the present day of 5.6 ‰, indicating an increasing importance of RO2 in NOx cycling between the mid-19th century and the present day in the mid- to high-latitude Southern Hemisphere. The former has implications for the climate impacts of sulfate aerosol, while the latter has implications for the tropospheric O3 production rate in remote low-NOx environments. Using other ice core observations, we rule out drivers for these changes other than variability in extratropical oxidant (OH, O3, RO2, H2O2, and reactive halogens) concentrations. However, assuming OH, H2O2, and O3 are the main oxidants contributing to sulfate formation, Monte Carlo box model simulations require a large (≥ 260%) increase in the O3 / OH mole fraction ratio over the Southern Ocean in the early 19th century to match the sulfate Δ17O record. This unlikely scenario points to a~deficiency in our understanding of sulfur chemistry and suggests other oxidants may play an important role in sulfate formation in the mid- to high-latitude marine boundary layer. The observed decrease in nitrate Δ17O since the mid-19th century is most likely due to an increased importance of RO2 over O3 in NOx cycling and can be explained by a 60–90% decrease in the O3 / RO2 mole fraction ratio in the extratropical Southern Hemisphere NOx-source regions.

Cenozoic High Latitude Heterochroneity of Southern Hemisphere Marine Faunas

Science ◽  
1984 ◽  
Vol 224 (4646) ◽  
pp. 281-283 ◽  
Author(s):  
W. J. ZINSMEISTER ◽  
R. M. FELDMANN
Keyword(s):  
Southern Hemisphere ◽  
High Latitude

A Study for IGSO Inclination Angles in the Transmitting Satellite Navigation Constellation

2011 ◽  
Vol 64 (S1) ◽  
pp. S73-S82 ◽  
Author(s):  
Lihua Ma ◽  
Guoxiang Ai ◽  
Haifu Ji
Keyword(s):  
Southern Hemisphere ◽  
High Latitude ◽  
Navigation System ◽  
Satellite Navigation ◽  
Geosynchronous Orbit ◽  
High Quality ◽  
Satellite Navigation System ◽  
Inclination Angles ◽  
Navigation Signals ◽  
China Mainland

Unlike a direct broadcasting satellite navigation system, the transmitting satellite navigation system developed in China uses transponders onboard communication satellites to retransmit navigation signals generated at a ground master station. The transmitting navigation satellite constellation consists of a number of inclined geosynchronous orbit (IGSO) satellites. Considering China's mainland coverage in the northern hemisphere occupies some 62 degrees in longitude, the inclination of the IGSO satellites cannot be too high, or its signals would not be received by the users in the middle and high latitude areas when the IGSO satellite travels over the southern hemisphere. Meanwhile, the latitude of the most southerly station in China mainland that can uplink navigation signals is about 18°N when the IGSO satellite travels to the southern hemisphere. Therefore, there is a need to consider the IGSO inclination to achieve balance between uplinking high-quality navigation signals and covering the high-latitude area. In this work, the navigation performance and availability of the IGSO satellite are examined when navigation signals are uplinked from the stations Lintong and Sanya.

scholarly journals Patterns in Mobility and Modification of Middle- and High-Latitude Southern Hemisphere Dunes on Mars

2018 ◽  
Vol 123 (12) ◽  
pp. 3205-3219 ◽  
Author(s):  
Maria E. Banks ◽  
Lori K. Fenton ◽  
Nathan T. Bridges ◽  
Paul E. Geissler ◽  
Matthew Chojnacki ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
High Latitude

Emergence of Southern Hemisphere circulation changes in response to ozone recovery

2020 ◽  
Author(s):  
Brian Zambri ◽  
Susan Solomon ◽  
David Thompson ◽  
Qiang Fu
Keyword(s):  
Southern Hemisphere ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Montreal Protocol ◽  
Stratospheric Polar Vortex ◽  
Surface Climate ◽  
Antarctic Ozone ◽  
Ozone Depleting Substances ◽  
Circulation Changes

<p>Ozone depletion in the Southern Hemisphere (SH) stratosphere in the late 20<sup>th</sup> century cooled the air there, strengthening the SH stratospheric westerly winds near 60ºS and altering SH surface climate. Since ~1999, trends in Antarctic ozone have begun to recover, exhibiting a flattening followed by a sign reversal in response to decreases in stratospheric chlorine concentration due to the Montreal Protocol, an international treaty banning the production and consumption of ozone-depleting substances. Here we show that the post–1999 increase in ozone has resulted in thermal and circulation changes of opposite sign to those that resulted from stratospheric ozone losses, including a warming of the SH polar lower stratosphere and a weakening of the SH stratospheric polar vortex.  Further, these altered trends extend to the upper troposphere, albeit of smaller magnitudes.  Observed post–1999 trends of temperature and circulation in the stratosphere are about 20–25% the magnitude of those of the ozone depletion era, and are broadly consistent with expectations based on modeled depletion-era trends and variability of both ozone and reactive chlorine, thereby indicating the emergence of healing of dynamical impacts of the Antarctic ozone hole.</p>

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