Article
Meteorology & Atmospheric Sciences
Haoxiang Wang, Jian Rao, Dong Guo, Yixiong Lu, Yimin Liu
Summary: The El Nino-Southern Oscillation (ENSO) and Quasi-Biennial Oscillation (QBO) have individual and combined impacts on the northern winter stratospheric polar vortex. The joint effects of ENSO and QBO result in weakened polar vortex in El Nino-easterly QBO and strengthened polar vortex in La Nina-westerly QBO composites. The observed joint ENSO and QBO signals in the Arctic stratosphere are mostly a linearly superposed combination, and the interference of ENSO and QBO's impacts is also observed in the tropospheric circulation and tropical convections.
Article
Geosciences, Multidisciplinary
Jezabel Curbelo, Gang Chen, Carlos Roberto Mechoso
Summary: This study examines the northern stratosphere in April 2020, where the polar vortex split into two cyclonic vortices during a period with record ozone depletion. The research investigates the dynamical evolution leading to the split, the fate of fluid parcels on the vortex boundary, and the ozone distribution between the vortices resulting from the split. The findings highlight the key role of a flow with a special configuration of barriers to the motion of parcels in causing the split.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
Jiankai Zhang, Chongyang Zhang, Siyi Zhao, Yixi Liu, Shihang Du, Wuke Wang, Jinlong Huang, Mian Xu
Summary: The impacts of changes in the Arctic stratospheric polar vortex (SPV) on frontogenesis in the middle latitudes of the Northern Hemisphere during winter are analyzed. We find that weak SPV years result in stronger and more frequent frontogenesis over West Russia, the Mongolian Plateau, the Mediterranean, and the southern North Atlantic compared to strong SPV years. Conversely, weaker and less frequent frontogenesis occurs over the northern parts of the North Atlantic and North Pacific Oceans during weak SPV years. These changes are attributed to alterations in the tropospheric circulation and temperature gradient associated with SPV changes.
ATMOSPHERIC RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Kamilya Yessimbet, Theodore G. G. Shepherd, Albert C. C. Osso, Andrea K. K. Steiner
Summary: In this study, a causal inference-based framework is applied to investigate and quantify the causal relationships between blocking, upward wave-activity fluxes, and stratospheric polar vortex variability using reanalysis data. The results show that the influence of blocking on the polar vortex is mediated by upward wave-activity fluxes, but the causal pathway is not straightforward. The vortex-strengthening effect of west Pacific blocking on lower stratospheric wave-activity fluxes is only partially mediated by upper tropospheric wave-activity fluxes. Additionally, two-thirds of the effect of upper tropospheric wave-activity fluxes on polar vortex variability is mediated by lower stratospheric wave-activity fluxes. Sudden stratospheric warmings cannot be entirely explained by upward wave-activity fluxes.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Meteorology & Atmospheric Sciences
Zhuoqi Liang, Jian Rao, Dong Guo, Qian Lu, Chunhua Shi
Summary: It is found that changes in the Arctic stratospheric polar vortex have a significant influence on the extratropical troposphere in the mid-to-high latitudes of the Northern Hemisphere. Different states of the polar vortex result in various behaviors of tropospheric circulation and near surface climate, and are also related to different tropospheric teleconnections.
Article
Meteorology & Atmospheric Sciences
Jinlong Huang, Peter Hitchcock
Summary: Using ERA5 reanalysis data, this study identifies seven easily calculable indices of the strength of the Arctic stratospheric vortex and compares their effects on climatological statistics and meteorological properties of strong and weak vortex events. The study also evaluates different definitions of strong vortex events and presents dynamical benchmarks for assessing their representation in climate models. The results highlight the challenges in defining strong vortex events and emphasize the implications of different choices, providing valuable guidance for future studies.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2023)
Article
Meteorology & Atmospheric Sciences
Feiyang Wang, Dan Ye
Summary: This study shows that MJO phase 3 and phase 7 are closely linked to changes in the intensity of the stratospheric polar vortex, acting as precursors to strengthened or weakened vortex events within a 2-week timeframe before onset.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2022)
Article
Environmental Sciences
Dong Guo, Zhuoqi Liang, Qiang Gui, Qian Lu, Qiong Zheng, Shuyang Yu
Summary: This study classifies the Arctic polar vortex into six regimes using the k-mean clustering algorithm and validates the classification with model data. The different regimes have distinct climate patterns and rainfall distributions in the Northern Hemisphere, which also impact the temperatures in mid-latitude regions.
Article
Meteorology & Atmospheric Sciences
Jiankai Zhang, Huayi Zheng, Mian Xu, Qingqing Yin, Siyi Zhao, Wenshou Tian, Zesu Yang
Summary: The impacts of Arctic stratospheric polar vortex (SPV) on wintertime precipitation over the Northern Hemisphere are analyzed based on various datasets. The study finds that weak SPV events lead to increased precipitation over certain regions of the North Pacific Ocean, North Atlantic Ocean, and Southern Europe, while decreasing precipitation over the central North Pacific, northern part of North Atlantic, and Northern Europe. Moreover, the research reveals that the changes in precipitation induced by SPV are stronger over the North Atlantic compared to the North Pacific, and convective precipitation is generally higher during weak SPV events.
Article
Geosciences, Multidisciplinary
Antti Salminen, Timo Asikainen, Kalevi Mursula
Summary: The impact of energetic electron precipitation (EEP) on the polar vortex is modulated by planetary waves, with the strongest strengthening effect observed when planetary wave propagation is enhanced at mid-latitudes and reduced at polar latitudes.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Simon H. Lee, Lorenzo M. Polvani, Bin Guan
Summary: This article investigates the impact of the polar vortex on atmospheric river frequency and other related variables in the Northern Hemisphere winter. The study finds significant differences between strong and weak vortex states, which have important implications for the occurrence of atmospheric rivers and precipitation, particularly in Europe and the Pacific Northwest of North America.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Environmental Sciences
Oscar Dimdore-Miles, Lesley Gray, Scott Osprey, Jon Robson, Rowan Sutton, Bablu Sinha
Summary: Variations in the strength of the Northern Hemisphere winter polar stratospheric vortex can influence surface variability in the Atlantic sector. This study explores the interaction between stratospheric vortex variability and ocean circulation on decadal to multi-decadal timescales. The results show that persistent anomalous vortex behavior leads to oscillatory responses in the Atlantic Meridional Overturning Circulation (AMOC), and AMOC variations on longer timescales can impact the vortex response through the equatorial Pacific and quasi-biennial oscillation. Moreover, the study estimates that around 30% of the recent negative trend in AMOC observations may be attributed to the 8-year SSW hiatus in the 1990s.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Philip Rupp, Jonas Spaeth, Hella Garny, Thomas Birner
Summary: Sudden stratospheric warming (SSW) events provide a forecast opportunity for polar vortex predictions on subseasonal-to-seasonal time scales. Analyzing numerical ensemble simulations, we find that SSWs lead to enhanced predictability due to reduced upward planetary wave fluxes during the radiatively driven recovery phase. This increased predictability is especially noticeable for strong SSWs and occurs even if not all ensemble members predict a major SSW. Additionally, SSWs have a direct impact on the date of the final warming (FW), delaying it due to decreased upward wave fluxes.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
Audrey Lecouffe, Sophie Godin-Beekmann, Andrea Pazmino, Alain Hauchecorne
Summary: This study evaluates the intensity and position of the Southern Hemisphere stratospheric polar vortex edge and analyzes the onset and breakup dates of the polar vortex. The results show that the vortex edge is stronger in late winter and exhibits lower variability in position during this period. There is a long-term increase in intensity and breakup date of the vortex edge, which is linked to the increase in the ozone hole. The solar cycle, QBO, and ENSO modulate the interannual evolution of the vortex edge strength and breakup dates.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Environmental Sciences
Catherine Wespes, Gaetane Ronsmans, Lieven Clarisse, Susan Solomon, Daniel Hurtmans, Cathy Clerbaux, Pierre-Francois Coheur
Summary: In this paper, the authors utilize a 10-year data record from the IASI-A/MetOp infrared sounder to investigate the relationship between temperature decrease and nitric acid (HNO3) loss in the Antarctic stratosphere. They verify the recurrence of specific regimes in the annual cycle of IASI HNO3 and identify the onset of strong HNO3 depletion in the Antarctic winter. The study highlights the capability of the IASI sounder to monitor the evolution of polar stratospheric HNO3.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2022)
Article
Meteorology & Atmospheric Sciences
A. K. Smith, L. A. Holt, R. R. Garcia, J. A. Anstey, F. Serva, N. Butchart, S. Osprey, A. C. Bushell, Y. Kawatani, Y. -H. Kim, F. Lott, P. Braesicke, C. Cagnazzo, C. -C. Chen, H. -Y. Chun, L. Gray, T. Kerzenmacher, H. Naoe, J. Richter, S. Versick, V. Schenzinger, S. Watanabe, K. Yoshida
Summary: The QBOi initiative focuses on comparing simulation of the QBO in current global climate models, with 11 participating models simulating the main variability in zonal winds in the tropical upper stratosphere. While most models simulate the amplitudes and phases of the SAO in zonal wind near the stratopause well, they tend to have more westward time-average zonal winds compared to observations.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2022)
Article
Meteorology & Atmospheric Sciences
Jadwiga H. Richter, Neal Butchart, Yoshio Kawatani, Andrew C. Bushell, Laura Holt, Federico Serva, James Anstey, Isla R. Simpson, Scott Osprey, Kevin Hamilton, Peter Braesicke, Chiara Cagnazzo, Chih-Chieh Chen, Rolando R. Garcia, Lesley J. Gray, Tobias Kerzenmacher, Francois Lott, Charles McLandress, Hiroaki Naoe, John Scinocca, Timothy N. Stockdale, Stefan Versick, Shingo Watanabe, Kohei Yoshida, Seiji Yukimoto
Summary: We compared the response of the Quasi-Biennial Oscillation (QBO) to a warming climate in eleven atmosphere general circulation models and found that there was no consistency in the QBO period response among the models, but there was a consistent decrease in the QBO amplitude. The differences in the QBO period response were strongly related to the changes in gravity wave momentum flux and tropical vertical residual velocity, while the decrease in QBO amplitude was correlated with changes in vertical residual velocity, parameterized gravity wave momentum fluxes, and to some degree the resolved upward wave flux.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2022)
Article
Multidisciplinary Sciences
L. J. Gray, M. J. Brown, J. Knight, M. Andrews, H. Lu, C. O'Reilly, J. Anstey
NATURE COMMUNICATIONS
(2020)
Article
Meteorology & Atmospheric Sciences
John Turner, Hua Lu, John King, Gareth J. Marshall, Tony Phillips, Dan Bannister, Steve Colwell
Summary: This study presents the first Antarctic-wide analysis of extreme near-surface air temperatures, examining temperature distributions, extreme high and low temperatures, variability, and trends at 17 stations. Record high temperatures were mainly influenced by air masses passing over high terrain, while record low temperatures were associated with positive sea ice anomalies over certain seas.
JOURNAL OF CLIMATE
(2021)
Article
Meteorology & Atmospheric Sciences
John C. King, John Turner, Steve Colwell, Hua Lu, Andrew Orr, Tony Phillips, J. Scott Hosking, Gareth J. Marshall
Summary: The observations from Halley Research Station in Antarctica provide a long continuous series of near-surface temperature data, but it is a composite from seven stations on the Brunt Ice Shelf. A sudden cooling associated with the move of stations in 1992 was detected, indicating the need to account for data inhomogeneity in future studies using the Halley record.
JOURNAL OF CLIMATE
(2021)
Article
Environmental Sciences
Stergios Misios, Matthew Kasoar, Elliott Kasoar, Lesley Gray, Joanna Haigh, Stavros Stathopoulos, Konstantinos Kourtidis, Gunnar Myhre, Dirk Olivie, Drew Shindell, Tao Tang
Summary: The study shows that global hydrological sensitivity is higher for solar forcing than greenhouse gas (GHG) forcing, with both types of forcing leading to increased precipitation in the tropical Pacific and warming of the equatorial Pacific. Solar forcing also results in enhanced equatorial precipitation and weakened Walker circulation over the last millennium, suggesting that tropical climate might be more influenced by solar variability than GHG variations.
ENVIRONMENTAL RESEARCH LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
Hua Lu, Lesley J. Gray, Patrick Martineau, John C. King, Thomas J. Bracegirdle
Summary: A new regime index is constructed to capture the seasonal development of the stratospheric polar vortex in the northern winter, based on the standard deviation of Ertel's potential vorticity in the upper stratosphere in November-December. The study found that the narrow-jet flow regime and wide-jet flow regime exhibit significant differences in polar vortex characteristics and lower atmospheric circulation anomalies, potentially improving the accuracy of meteorological forecasts one to two months ahead.
JOURNAL OF CLIMATE
(2021)
Article
Environmental Sciences
Thomas J. Bracegirdle, Hua Lu, Jon Robson
Summary: Climate model biases in the North Atlantic low-level tropospheric westerly jet remain present in CMIP6 models, although reduced compared to CMIP5. The equatorward bias is mainly associated with a weaker-than-observed frequency of poleward excursions of the jet to its northern position. CMIP models with larger equatorward jet biases exhibit weaker correlations between temporal variability in speed of the jet and sea surface conditions over the sub-polar gyre region. The early-winter equatorward bias in jet latitude in CMIP models could partially explain other known biases, such as the weaker-than-observed seasonal-decadal predictability of the NA climate system.
ENVIRONMENTAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
John Turner, Hua Lu, John C. King, Scott Carpentier, Matthew Lazzara, Tony Phillips, Jonathan Wille
Summary: This article investigates a high temperature event in December 1989 in East Antarctica and discusses the factors that led to this event, namely atmospheric rivers and synoptically driven downslope flow. These factors contributed to the further warming of coastal regions, resulting in record-breaking temperatures.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Meteorology & Atmospheric Sciences
Lesley J. Gray, Hua Lu, Matthew J. Brown, Jeff R. Knight, Martin B. Andrews
Summary: This study examines the influence of the Semi-Annual Oscillation (SAO) on major sudden stratospheric warmings (SSWs), using the 2008/2009 SSW as a case-study. The research finds that the westerly-to-easterly phase transition of the SAO in the lower mesosphere is a key factor in determining the timing of SSWs. The study also shows a significant correlation between the timing of SSWs and the equinoctial westerly-to-easterly phase transition in early winter, suggesting that accurate simulation of SAO phase transitions and knowledge of the Quasi-Biennial Oscillation (QBO) phase can improve seasonal forecast skill.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2022)
Article
Meteorology & Atmospheric Sciences
Yuhji Kuroda, Kunihiko Kodera, Kohei Yoshida, Seiji Yukimoto, Lesley Gray
Summary: The influence of the solar cycle on the North Atlantic Oscillation (NAO) can be explained by a top-down mechanism, where the solar signal first appears in the subtropical upper stratosphere and propagates downward to the surface through zonal wind signal. The NAO signal tends to appear in February during years of peak solar activity, and the solar signal is modulated by the appearance of NAO-related sea surface temperature (SST) signal.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2022)
Article
Meteorology & Atmospheric Sciences
Hua Lu, Andrew Orr, John King, Tony Phillips, Ella Gilbert, Steve Colwell, Thomas J. Bracegirdle
Summary: The extreme warm events in the South Orkney Islands are investigated, revealing their characteristics and drivers. The study finds that these events are often influenced by atmospheric rivers and localised fohn warming, and the number of warm events per year has been significantly increasing. This could potentially impact ecosystems by increasing melting of snow and ice.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2023)
Article
Meteorology & Atmospheric Sciences
Hua Lu, Steve Cowell, John King, Andrew Orr, Tony Phillips, Emilia Dobb, Jonathan Xue, Sabina Kucieba, Guy Phillips, Gareth Marshall
Summary: This study compares the near-surface air temperatures at Signy Station with nearby Orcadas station and reanalysis datasets to provide a more comprehensive understanding of weather and climate variability in the South Orkney Islands. The study also examines temperature trends in relation to changes in large-scale circulation and sea surface temperature.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2023)
Article
Environmental Sciences
Andrew Orr, Hua Lu, Patrick Martineau, Edwin P. Gerber, Gareth J. Marshall, Thomas J. Bracegirdle
Summary: This study quantifies differences among four widely used atmospheric reanalysis datasets in their representation of the dynamical changes induced by springtime polar stratospheric ozone depletion in the Southern Hemisphere from 1980 to 2001. The results show a high degree of consistency across the datasets in representing these dynamical changes, but larger differences in terms of wave forcing, residual circulation, and eddy propagation changes, with CFSR exhibiting the most noticeable disparities compared to the other three datasets.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)