Articles | Volume 2, issue 1
https://doi.org/10.5194/wcd-2-111-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-2-111-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
04 Feb 2021
Research article |
| 04 Feb 2021
| 04 Feb 2021
Tropospheric eddy feedback to different stratospheric conditions in idealised baroclinic life cycles
Meteorological Institute Munich, Ludwig Maximilians University, Munich, Germany
Thomas Birner
Meteorological Institute Munich, Ludwig Maximilians University, Munich, Germany
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Felix Jäger, Philip Rupp, and Thomas Birner
Weather Clim. Dynam., 4, 49–60, https://doi.org/10.5194/wcd-4-49-2023, https://doi.org/10.5194/wcd-4-49-2023, 2023
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Mid-latitude weather is dominated by the growth, breaking and decay of baroclinic waves and associated jet shifts. A way to study this process is via idealised life-cycle simulations, which are often classified as LC1 (anticyclonic breaking, poleward shift) or LC2 (cyclonic breaking, equatorward shift), depending on details of the initial state. We show that all systems exhibit predominantly anticyclonic character and poleward net shifts if multiple wave modes are allowed to grow simultaneously.
Philip Rupp and Peter Haynes
Weather Clim. Dynam., 2, 413–431, https://doi.org/10.5194/wcd-2-413-2021, https://doi.org/10.5194/wcd-2-413-2021, 2021
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We study a range of dynamical aspects of the Asian monsoon anticyclone as the response of a simple numerical model to a steady imposed heating distribution with different background flow configurations. Particular focus is given on interactions between the monsoon anticyclone and active mid-latitude dynamics, which we find to have a zonally localising effect on the time-mean circulation and to be able to qualitatively alter the temporal variability of the bulk anticyclone.
Katharina Turhal, Felix Plöger, Jan Clemens, Thomas Birner, Franziska Weyland, Paul Konopka, and Peter Hoor
EGUsphere, https://doi.org/10.5194/egusphere-2024-471, https://doi.org/10.5194/egusphere-2024-471, 2024
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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The tropopause separates the troposphere, the lowest atmospheric layer where weather occurs, from the stratosphere. We computed the PV-gradient (PVG) tropopause, which is based on transport barriers between both layers. In 1980–2017, the PVG tropopause shifted poleward at lower altitudes and equatorward above. These shifts may signify height-dependent changes in atmospheric transport, influencing the distribution of pollutants and, e.g., greenhouse gases responsible for global warming.
Felix Ploeger, Thomas Birner, Edward Charlesworth, Paul Konopka, and Rolf Müller
Atmos. Chem. Phys., 24, 2033–2043, https://doi.org/10.5194/acp-24-2033-2024, https://doi.org/10.5194/acp-24-2033-2024, 2024
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We present a novel mechanism of how regional anomalies in water vapour concentrations in the upper troposphere and lower stratosphere impact regional atmospheric circulation systems. These impacts include a displaced upper-level Asian monsoon circulation and strengthened prevailing westerlies in the Pacific region. Current climate models have biases in simulating these regional water vapour anomalies and circulation impacts, but the biases can be avoided by improving the model transport.
Masatomo Fujiwara, Patrick Martineau, Jonathon S. Wright, Marta Abalos, Petr Šácha, Yoshio Kawatani, Sean M. Davis, Thomas Birner, and Beatriz M. Monge-Sanz
EGUsphere, https://doi.org/10.5194/egusphere-2023-2917, https://doi.org/10.5194/egusphere-2023-2917, 2023
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A climatology of the major variables and terms of the transformed Eulerian-mean (TEM) momentum and thermodynamic equations from four global atmospheric reanalyses is evaluated. The spread among reanalysis TEM momentum balance terms is around 10 % in NH winter and up to 50 % in SH winter. The largest uncertainties in the thermodynamic equation (about 50 %) are found in the vertical advection, which does not show a structure consistent with the differences in heatings.
Frederik Harzer, Hella Garny, Felix Ploeger, Harald Bönisch, Peter Hoor, and Thomas Birner
Atmos. Chem. Phys., 23, 10661–10675, https://doi.org/10.5194/acp-23-10661-2023, https://doi.org/10.5194/acp-23-10661-2023, 2023
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We study the statistical relation between year-by-year fluctuations in winter-mean ozone and the strength of the stratospheric polar vortex. In the latitude–pressure plane, regression analysis shows that anomalously weak polar vortex years are associated with three pronounced local ozone maxima over the polar cap relative to the winter climatology. These response maxima primarily reflect the non-trivial combination of different ozone transport processes with varying relative contributions.
Flossie Brown, Lauren Marshall, Peter H. Haynes, Rolando R. Garcia, Thomas Birner, and Anja Schmidt
Atmos. Chem. Phys., 23, 5335–5353, https://doi.org/10.5194/acp-23-5335-2023, https://doi.org/10.5194/acp-23-5335-2023, 2023
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Large-magnitude volcanic eruptions have the potential to alter large-scale circulation patterns, such as the quasi-biennial oscillation (QBO). The QBO is an oscillation of the tropical stratospheric zonal winds between easterly and westerly directions. Using a climate model, we show that large-magnitude eruptions can delay the progression of the QBO, with a much longer delay when the shear is easterly than when it is westerly. Such delays may affect weather and transport of atmospheric gases.
Felix Jäger, Philip Rupp, and Thomas Birner
Weather Clim. Dynam., 4, 49–60, https://doi.org/10.5194/wcd-4-49-2023, https://doi.org/10.5194/wcd-4-49-2023, 2023
Short summary
Short summary
Mid-latitude weather is dominated by the growth, breaking and decay of baroclinic waves and associated jet shifts. A way to study this process is via idealised life-cycle simulations, which are often classified as LC1 (anticyclonic breaking, poleward shift) or LC2 (cyclonic breaking, equatorward shift), depending on details of the initial state. We show that all systems exhibit predominantly anticyclonic character and poleward net shifts if multiple wave modes are allowed to grow simultaneously.
Jonas Spaeth and Thomas Birner
Weather Clim. Dynam., 3, 883–903, https://doi.org/10.5194/wcd-3-883-2022, https://doi.org/10.5194/wcd-3-883-2022, 2022
Short summary
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Past research has demonstrated robust stratosphere–troposphere dynamical coupling following stratospheric circulation extremes. Here, we use a large set of extended-range ensemble forecasts to robustly quantify the increased risk for tropospheric circulation extremes following stratospheric extreme events. In particular, we provide estimates of the fraction of tropospheric extremes that may be attributable to preceding stratospheric extremes.
Philip Rupp and Peter Haynes
Weather Clim. Dynam., 2, 413–431, https://doi.org/10.5194/wcd-2-413-2021, https://doi.org/10.5194/wcd-2-413-2021, 2021
Short summary
Short summary
We study a range of dynamical aspects of the Asian monsoon anticyclone as the response of a simple numerical model to a steady imposed heating distribution with different background flow configurations. Particular focus is given on interactions between the monsoon anticyclone and active mid-latitude dynamics, which we find to have a zonally localising effect on the time-mean circulation and to be able to qualitatively alter the temporal variability of the bulk anticyclone.
Hella Garny, Roland Walz, Matthias Nützel, and Thomas Birner
Geosci. Model Dev., 13, 5229–5257, https://doi.org/10.5194/gmd-13-5229-2020, https://doi.org/10.5194/gmd-13-5229-2020, 2020
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Numerical models of Earth's climate system have been gaining more and more complexity over the last decades. Therefore, it is important to establish simplified models to improve process understanding. In our study, we present and document the development of a new simplified model setup within the framework of a complex climate model system that uses the same routines to calculate atmospheric dynamics as the complex model but is simplified in the representation of clouds and radiation.
Lina Boljka and Thomas Birner
Weather Clim. Dynam., 1, 555–575, https://doi.org/10.5194/wcd-1-555-2020, https://doi.org/10.5194/wcd-1-555-2020, 2020
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This study addresses the origin and impacts of a source of large-scale atmospheric waves in the lower stratosphere, which have not been examined before. This wave source is caused by interactions of waves of smaller scales. Here we show that as it lies in the lower stratosphere, this wave source can precede extreme events in the stratosphere and that such events can then lead to a response of the tropospheric weather patterns several weeks later (potential for long-term forecasting).
Mohamadou Diallo, Martin Riese, Thomas Birner, Paul Konopka, Rolf Müller, Michaela I. Hegglin, Michelle L. Santee, Mark Baldwin, Bernard Legras, and Felix Ploeger
Atmos. Chem. Phys., 18, 13055–13073, https://doi.org/10.5194/acp-18-13055-2018, https://doi.org/10.5194/acp-18-13055-2018, 2018
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The unprecedented timing of an El Niño event aligned with the disrupted QBO in 2015–2016 caused a perturbation to the stratospheric circulation, affecting trace gases. This paper resolves the puzzling response of the lower stratospheric water vapor by showing that the QBO disruption reversed the lower stratosphere moistening triggered by the alignment of the El Niño event with a westerly QBO in early boreal winter.
Jeremiah P. Sjoberg, Thomas Birner, and Richard H. Johnson
Atmos. Chem. Phys., 17, 8971–8986, https://doi.org/10.5194/acp-17-8971-2017, https://doi.org/10.5194/acp-17-8971-2017, 2017
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Observational estimates of tropical, large-scale fluxes of zonal momentum from troposphere to stratosphere remain challenging. We present an extended technique for estimating the daily amplitudes of these fluxes using data captured from balloon-borne radiosondes. Climatological analysis of our time series matches expectations of annual and interannual variability, indicating reliability in our estimates. Vertical resolution less than 1 km is found to be important for precise estimation.
Anne A. Glanville and Thomas Birner
Atmos. Chem. Phys., 17, 4337–4353, https://doi.org/10.5194/acp-17-4337-2017, https://doi.org/10.5194/acp-17-4337-2017, 2017
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Nearly all air enters the stratosphere through the tropical tropopause, which exerts a control on stratospheric chemistry and climate. By combining satellite observations with a simple 1-D transport model, we study the roles of vertical and horizontal mixing in transport near the tropical tropopause. We find that vertical mixing may play a more significant role than previously assumed, which is potentially as important as slow vertical transport by the residual mass circulation.
Masatomo Fujiwara, Jonathon S. Wright, Gloria L. Manney, Lesley J. Gray, James Anstey, Thomas Birner, Sean Davis, Edwin P. Gerber, V. Lynn Harvey, Michaela I. Hegglin, Cameron R. Homeyer, John A. Knox, Kirstin Krüger, Alyn Lambert, Craig S. Long, Patrick Martineau, Andrea Molod, Beatriz M. Monge-Sanz, Michelle L. Santee, Susann Tegtmeier, Simon Chabrillat, David G. H. Tan, David R. Jackson, Saroja Polavarapu, Gilbert P. Compo, Rossana Dragani, Wesley Ebisuzaki, Yayoi Harada, Chiaki Kobayashi, Will McCarty, Kazutoshi Onogi, Steven Pawson, Adrian Simmons, Krzysztof Wargan, Jeffrey S. Whitaker, and Cheng-Zhi Zou
Atmos. Chem. Phys., 17, 1417–1452, https://doi.org/10.5194/acp-17-1417-2017, https://doi.org/10.5194/acp-17-1417-2017, 2017
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We introduce the SPARC Reanalysis Intercomparison Project (S-RIP), review key concepts and elements of atmospheric reanalysis systems, and summarize the technical details of and differences among 11 of these systems. This work supports scientific studies and intercomparisons of reanalysis products by collecting these background materials and technical details into a single reference. We also address several common misunderstandings and points of confusion regarding reanalyses.
Felix Ploeger and Thomas Birner
Atmos. Chem. Phys., 16, 10195–10213, https://doi.org/10.5194/acp-16-10195-2016, https://doi.org/10.5194/acp-16-10195-2016, 2016
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We investigate the aging of air in the stratosphere caused by transport due to Brewer's circulation, using the Boundary Impulse Evolving Response (BIER) method. The age spectra show multiple peaks caused by the seasonal and inter-annual variations of transport. The modal age is controlled by the residual circulation in the tropics and winter hemisphere extratropics and by mixing in the summer hemisphere. Analysis of the full age spectrum is strongly recommended for model inter-comparisons.
Nicholas A. Davis, Dian J. Seidel, Thomas Birner, Sean M. Davis, and Simone Tilmes
Atmos. Chem. Phys., 16, 10083–10095, https://doi.org/10.5194/acp-16-10083-2016, https://doi.org/10.5194/acp-16-10083-2016, 2016
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In the Hadley cells, air rises at the Equator and sinks over the subtropics, drying the air and creating deserts on land. We investigated simple climate model experiments and found that the Hadley cells expand in response to increasing carbon dioxide. The climate of some models warms more than others, and these models also have greater Hadley cell expansion. This expansion could shift deserts toward more populated areas, with potentially major impacts on water resources and surface climate.
L. C. Paulik and T. Birner
Atmos. Chem. Phys., 12, 12183–12195, https://doi.org/10.5194/acp-12-12183-2012, https://doi.org/10.5194/acp-12-12183-2012, 2012
Related subject area
Atmospheric teleconnections incl. stratosphere–troposphere coupling
Stratospheric influence on the winter North Atlantic storm track in subseasonal reforecasts
How do different pathways connect the stratospheric polar vortex to its tropospheric precursors?
A critical evaluation of decadal solar cycle imprints in the MiKlip historical ensemble simulations
Opposite spectral properties of Rossby waves during weak and strong stratospheric polar vortex events
The teleconnection of extreme El Niño–Southern Oscillation (ENSO) events to the tropical North Atlantic in coupled climate models
Using large ensembles to quantify the impact of sudden stratospheric warmings and their precursors on the North Atlantic Oscillation
The stratosphere: a review of the dynamics and variability
Stratospheric downward wave reflection events modulate North American weather regimes and cold spells
Modulation of the El Niño teleconnection to the North Atlantic by the tropical North Atlantic during boreal spring and summer
Quantifying stratospheric biases and identifying their potential sources in subseasonal forecast systems
Stratospheric modulation of Arctic Oscillation extremes as represented by extended-range ensemble forecasts
The tropical route of quasi-biennial oscillation (QBO) teleconnections in a climate model
Decline in Etesian winds after large volcanic eruptions in the last millennium
Stationary wave biases and their effect on upward troposphere– stratosphere coupling in sub-seasonal prediction models
Stratospheric wave driving events as an alternative to sudden stratospheric warmings
Tropical influence on heat-generating atmospheric circulation over Australia strengthens through spring
Sudden stratospheric warmings during El Niño and La Niña: sensitivity to atmospheric model biases
Minimal impact of model biases on Northern Hemisphere El Niño–Southern Oscillation teleconnections
Resampling of ENSO teleconnections: accounting for cold-season evolution reduces uncertainty in the North Atlantic
The wave geometry of final stratospheric warming events
Origins of multi-decadal variability in sudden stratospheric warmings
Impacts of the North Atlantic Oscillation on winter precipitations and storm track variability in southeast Canada and the northeast United States
The role of Barents–Kara sea ice loss in projected polar vortex changes
Mechanisms and predictability of sudden stratospheric warming in winter 2018
On the intermittency of orographic gravity wave hotspots and its importance for middle atmosphere dynamics
The role of North Atlantic–European weather regimes in the surface impact of sudden stratospheric warming events
Nonlinearity in the tropospheric pathway of ENSO to the North Atlantic
Hilla Afargan-Gerstman, Dominik Büeler, C. Ole Wulff, Michael Sprenger, and Daniela I. V. Domeisen
Weather Clim. Dynam., 5, 231–249, https://doi.org/10.5194/wcd-5-231-2024, https://doi.org/10.5194/wcd-5-231-2024, 2024
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The stratosphere is a layer of Earth's atmosphere found above the weather systems. Changes in the stratosphere can affect the winds and the storm tracks in the North Atlantic region for a relatively long time, lasting for several weeks and even months. We show that the stratosphere can be important for weather forecasts beyond 1 week, but more work is needed to improve the accuracy of these forecasts for 3–4 weeks.
Raphael Harry Köhler, Ralf Jaiser, and Dörthe Handorf
Weather Clim. Dynam., 4, 1071–1086, https://doi.org/10.5194/wcd-4-1071-2023, https://doi.org/10.5194/wcd-4-1071-2023, 2023
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This study explores the local mechanisms of troposphere–stratosphere coupling on seasonal timescales during extended winter in the Northern Hemisphere. The detected tropospheric precursor regions exhibit very distinct mechanisms of coupling to the stratosphere, thus highlighting the importance of the time- and zonally resolved picture. Moreover, this study demonstrates that the ICOsahedral Non-hydrostatic atmosphere model (ICON) can realistically reproduce troposphere–stratosphere coupling.
Tobias C. Spiegl, Ulrike Langematz, Holger Pohlmann, and Jürgen Kröger
Weather Clim. Dynam., 4, 789–807, https://doi.org/10.5194/wcd-4-789-2023, https://doi.org/10.5194/wcd-4-789-2023, 2023
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We investigate the role of the solar cycle in atmospheric domains with the Max Plank Institute Earth System Model in high resolution (MPI-ESM-HR). We focus on the tropical upper stratosphere, Northern Hemisphere (NH) winter dynamics and potential surface imprints. We found robust solar signals at the tropical stratopause and a weak dynamical response in the NH during winter. However, we cannot confirm the importance of the 11-year solar cycle for decadal variability in the troposphere.
Michael K. Schutte, Daniela I. V. Domeisen, and Jacopo Riboldi
EGUsphere, https://doi.org/10.5194/egusphere-2023-1877, https://doi.org/10.5194/egusphere-2023-1877, 2023
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The winter circulation in the stratosphere, a layer of the Earth’s atmosphere between 10 and 50 km height, is tightly linked to the circulation in the lower atmosphere determining our daily weather. This interconnection happens in the form of waves propagating in and between these two layers. Here we use space-time spectral analysis to show that disruptions and enhancements of the stratospheric circulation modify the shape and propagation of waves in both layers.
Jake W. Casselman, Joke F. Lübbecke, Tobias Bayr, Wenjuan Huo, Sebastian Wahl, and Daniela I. V. Domeisen
Weather Clim. Dynam., 4, 471–487, https://doi.org/10.5194/wcd-4-471-2023, https://doi.org/10.5194/wcd-4-471-2023, 2023
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El Niño–Southern Oscillation (ENSO) has remote effects on the tropical North Atlantic (TNA), but the connections' nonlinearity (strength of response to an increasing ENSO signal) is not always well represented in models. Using the Community Earth System Model version 1 – Whole Atmosphere Community Climate Mode (CESM-WACCM) and the Flexible Ocean and Climate Infrastructure version 1, we find that the TNA responds linearly to extreme El Niño but nonlinearly to extreme La Niña for CESM-WACCM.
Philip E. Bett, Adam A. Scaife, Steven C. Hardiman, Hazel E. Thornton, Xiaocen Shen, Lin Wang, and Bo Pang
Weather Clim. Dynam., 4, 213–228, https://doi.org/10.5194/wcd-4-213-2023, https://doi.org/10.5194/wcd-4-213-2023, 2023
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Sudden-stratospheric-warming (SSW) events can severely affect the subsequent weather at the surface. We use a large ensemble of climate model hindcasts to investigate features of the climate that make strong impacts more likely through negative NAO conditions. This allows a more robust assessment than using observations alone. Air pressure over the Arctic prior to an SSW and the zonal-mean zonal wind in the lower stratosphere have the strongest relationship with the subsequent NAO response.
Neal Butchart
Weather Clim. Dynam., 3, 1237–1272, https://doi.org/10.5194/wcd-3-1237-2022, https://doi.org/10.5194/wcd-3-1237-2022, 2022
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In recent years, it has emerged that there is an affinity between stratospheric variability and surface events. Waves from the troposphere interacting with the mean flow drive much of the variability in the polar vortex, sudden stratospheric warmings and tropical quasi-biennial oscillation. Here we review the historical evolution of established knowledge of the stratosphere's global structure and dynamical variability, along with recent advances and theories, and identify outstanding challenges.
Gabriele Messori, Marlene Kretschmer, Simon H. Lee, and Vivien Wendt
Weather Clim. Dynam., 3, 1215–1236, https://doi.org/10.5194/wcd-3-1215-2022, https://doi.org/10.5194/wcd-3-1215-2022, 2022
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Over 10 km above the ground, there is a region of the atmosphere called the stratosphere. While there is very little air in the stratosphere itself, its interactions with the lower parts of the atmosphere – where we live – can affect the weather. Here we study a specific example of such an interaction, whereby processes occurring at the boundary of the stratosphere can lead to a continent-wide drop in temperatures in North America during winter.
Jake W. Casselman, Bernat Jiménez-Esteve, and Daniela I. V. Domeisen
Weather Clim. Dynam., 3, 1077–1096, https://doi.org/10.5194/wcd-3-1077-2022, https://doi.org/10.5194/wcd-3-1077-2022, 2022
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Using an atmospheric general circulation model, we analyze how the tropical North Atlantic influences the El Niño–Southern Oscillation connection towards the North Atlantic European region. We also focus on the lesser-known boreal spring and summer response following an El Niño–Southern Oscillation event. Our results show that altered tropical Atlantic sea surface temperatures may cause different responses over the Caribbean region, consequently influencing the North Atlantic European region.
Zachary D. Lawrence, Marta Abalos, Blanca Ayarzagüena, David Barriopedro, Amy H. Butler, Natalia Calvo, Alvaro de la Cámara, Andrew Charlton-Perez, Daniela I. V. Domeisen, Etienne Dunn-Sigouin, Javier García-Serrano, Chaim I. Garfinkel, Neil P. Hindley, Liwei Jia, Martin Jucker, Alexey Y. Karpechko, Hera Kim, Andrea L. Lang, Simon H. Lee, Pu Lin, Marisol Osman, Froila M. Palmeiro, Judith Perlwitz, Inna Polichtchouk, Jadwiga H. Richter, Chen Schwartz, Seok-Woo Son, Irina Statnaia, Masakazu Taguchi, Nicholas L. Tyrrell, Corwin J. Wright, and Rachel W.-Y. Wu
Weather Clim. Dynam., 3, 977–1001, https://doi.org/10.5194/wcd-3-977-2022, https://doi.org/10.5194/wcd-3-977-2022, 2022
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Forecast models that are used to predict weather often struggle to represent the Earth’s stratosphere. This may impact their ability to predict surface weather weeks in advance, on subseasonal-to-seasonal (S2S) timescales. We use data from many S2S forecast systems to characterize and compare the stratospheric biases present in such forecast models. These models have many similar stratospheric biases, but they tend to be worse in systems with low model tops located within the stratosphere.
Jonas Spaeth and Thomas Birner
Weather Clim. Dynam., 3, 883–903, https://doi.org/10.5194/wcd-3-883-2022, https://doi.org/10.5194/wcd-3-883-2022, 2022
Short summary
Short summary
Past research has demonstrated robust stratosphere–troposphere dynamical coupling following stratospheric circulation extremes. Here, we use a large set of extended-range ensemble forecasts to robustly quantify the increased risk for tropospheric circulation extremes following stratospheric extreme events. In particular, we provide estimates of the fraction of tropospheric extremes that may be attributable to preceding stratospheric extremes.
Jorge L. García-Franco, Lesley J. Gray, Scott Osprey, Robin Chadwick, and Zane Martin
Weather Clim. Dynam., 3, 825–844, https://doi.org/10.5194/wcd-3-825-2022, https://doi.org/10.5194/wcd-3-825-2022, 2022
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This paper establishes robust links between the stratospheric quasi-biennial oscillation (QBO) and several features of tropical climate. Robust precipitation responses, as well as changes to the Walker circulation, were found to be robustly linked to the variability in the lower stratosphere associated with the QBO using a 500-year simulation of a state-of-the-art climate model.
Stergios Misios, Ioannis Logothetis, Mads F. Knudsen, Christoffer Karoff, Vassilis Amiridis, and Kleareti Tourpali
Weather Clim. Dynam., 3, 811–823, https://doi.org/10.5194/wcd-3-811-2022, https://doi.org/10.5194/wcd-3-811-2022, 2022
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We investigate the impact of strong volcanic eruptions on the northerly Etesian winds blowing in the eastern Mediterranean. Μodel simulations of the last millennium demonstrate a robust reduction in the total number of days with Etesian winds in the post-eruption summers. The decline in the Etesian winds is attributed to a weakened Indian summer monsoon in the post-eruption summer. These findings could improve seasonal predictions of the wind circulation in the eastern Mediterranean.
Chen Schwartz, Chaim I. Garfinkel, Priyanka Yadav, Wen Chen, and Daniela I. V. Domeisen
Weather Clim. Dynam., 3, 679–692, https://doi.org/10.5194/wcd-3-679-2022, https://doi.org/10.5194/wcd-3-679-2022, 2022
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Eleven operational forecast models that run on subseasonal timescales (up to 2 months) are examined to assess errors in their simulated large-scale stationary waves in the Northern Hemisphere winter. We found that models with a more finely resolved stratosphere generally do better in simulating the waves in both the stratosphere (10–50 km) and troposphere below. Moreover, a connection exists between errors in simulated time-mean convection in tropical regions and errors in the simulated waves.
Thomas Reichler and Martin Jucker
Weather Clim. Dynam., 3, 659–677, https://doi.org/10.5194/wcd-3-659-2022, https://doi.org/10.5194/wcd-3-659-2022, 2022
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Variations in the stratospheric polar vortex, so-called vortex events, can improve predictions of surface weather and climate. There are various ways to detect such events, and here we use the amount of wave energy that propagates into the stratosphere. The new definition is tested against so-called stratospheric sudden warmings (SSWs). We find that the wave definition has advantages over SSWs, for example in terms of a stronger surface response that follows the events.
Roseanna C. McKay, Julie M. Arblaster, and Pandora Hope
Weather Clim. Dynam., 3, 413–428, https://doi.org/10.5194/wcd-3-413-2022, https://doi.org/10.5194/wcd-3-413-2022, 2022
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Understanding what makes it hot in Australia in spring helps us better prepare for harmful impacts. We look at how the higher latitudes and tropics change the atmospheric circulation from early to late spring and how that changes maximum temperatures in Australia. We find that the relationship between maximum temperatures and the tropics is stronger in late spring than early spring. These findings could help improve forecasts of hot months in Australia in spring.
Nicholas L. Tyrrell, Juho M. Koskentausta, and Alexey Yu. Karpechko
Weather Clim. Dynam., 3, 45–58, https://doi.org/10.5194/wcd-3-45-2022, https://doi.org/10.5194/wcd-3-45-2022, 2022
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El Niño events are known to effect the variability of the wintertime stratospheric polar vortex. The observed relationship differs from what is seen in climate models. Climate models have errors in their average winds and temperature, and in this work we artificially reduce those errors to see how that changes the communication of El Niño events to the polar stratosphere. We find reducing errors improves stratospheric variability, but does not explain the differences with observations.
Nicholas L. Tyrrell and Alexey Yu. Karpechko
Weather Clim. Dynam., 2, 913–925, https://doi.org/10.5194/wcd-2-913-2021, https://doi.org/10.5194/wcd-2-913-2021, 2021
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Tropical Pacific sea surface temperatures (El Niño) affect the global climate. The Pacific-to-Europe connection relies on interactions of large atmospheric waves with winds and surface pressure. We looked at how mean errors in a climate model affect its ability to simulate the Pacific-to-Europe connection. We found that even large errors in the seasonal winds did not affect the response of the model to an El Niño event, which is good news for seasonal forecasts which rely on these connections.
Martin P. King, Camille Li, and Stefan Sobolowski
Weather Clim. Dynam., 2, 759–776, https://doi.org/10.5194/wcd-2-759-2021, https://doi.org/10.5194/wcd-2-759-2021, 2021
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We re-examine the uncertainty of ENSO teleconnection to the North Atlantic by considering the November–December and January–February months in the cold season, in addition to the conventional DJF months. This is motivated by previous studies reporting varying teleconnected atmospheric anomalies and the mechanisms concerned. Our results indicate an improved confidence in the patterns of the teleconnection. The finding may also have implications on research in predictability and climate impact.
Amy H. Butler and Daniela I. V. Domeisen
Weather Clim. Dynam., 2, 453–474, https://doi.org/10.5194/wcd-2-453-2021, https://doi.org/10.5194/wcd-2-453-2021, 2021
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We classify by wave geometry the stratospheric polar vortex during the final warming that occurs every spring in both hemispheres due to a combination of radiative and dynamical processes. We show that the shape of the vortex, as well as the timing of the seasonal transition, is linked to total column ozone prior to and surface weather following the final warming. These results have implications for prediction and our understanding of stratosphere–troposphere coupling processes in springtime.
Oscar Dimdore-Miles, Lesley Gray, and Scott Osprey
Weather Clim. Dynam., 2, 205–231, https://doi.org/10.5194/wcd-2-205-2021, https://doi.org/10.5194/wcd-2-205-2021, 2021
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Observations of the stratosphere span roughly half a century, preventing analysis of multi-decadal variability in circulation using these data. Instead, we rely on long simulations of climate models. Here, we use a model to examine variations in northern polar stratospheric winds and find they vary with a period of around 90 years. We show that this is possibly due to variations in the size of winds over the Equator. This result may improve understanding of Equator–polar stratospheric coupling.
Julien Chartrand and Francesco S. R. Pausata
Weather Clim. Dynam., 1, 731–744, https://doi.org/10.5194/wcd-1-731-2020, https://doi.org/10.5194/wcd-1-731-2020, 2020
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This study explores the relationship between the North Atlantic Oscillation and the winter climate of eastern North America using reanalysis data. Results show that negative phases are linked with an increase in frequency of winter storms developing on the east coast of the United States, resulting in much heavier snowfall over the eastern United States. On the contrary, an increase in cyclone activity over southeastern Canada results in slightly heavier precipitation during positive phases.
Marlene Kretschmer, Giuseppe Zappa, and Theodore G. Shepherd
Weather Clim. Dynam., 1, 715–730, https://doi.org/10.5194/wcd-1-715-2020, https://doi.org/10.5194/wcd-1-715-2020, 2020
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The winds in the polar stratosphere affect the weather in the mid-latitudes, making it important to understand potential changes in response to global warming. However, climate model projections disagree on how this so-called polar vortex will change in the future. Here we show that sea ice loss in the Barents and Kara (BK) seas plays a central role in this. The time when the BK seas become ice-free differs between models, which explains some of the disagreement regarding vortex projections.
Irina A. Statnaia, Alexey Y. Karpechko, and Heikki J. Järvinen
Weather Clim. Dynam., 1, 657–674, https://doi.org/10.5194/wcd-1-657-2020, https://doi.org/10.5194/wcd-1-657-2020, 2020
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In this paper we investigate the role of the tropospheric forcing in the occurrence of the sudden stratospheric warming (SSW) that took place in February 2018, its predictability and teleconnection with the Madden–Julian oscillation (MJO) by analysing the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble forecast. The purpose of the paper is to present the results of the analysis of the atmospheric circulation before and during the SSW and clarify the driving mechanisms.
Ales Kuchar, Petr Sacha, Roland Eichinger, Christoph Jacobi, Petr Pisoft, and Harald E. Rieder
Weather Clim. Dynam., 1, 481–495, https://doi.org/10.5194/wcd-1-481-2020, https://doi.org/10.5194/wcd-1-481-2020, 2020
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Our study focuses on the impact of topographic structures such as the Himalayas and Rocky Mountains, so-called orographic gravity-wave hotspots. These hotspots play an important role in the dynamics of the middle atmosphere, in particular in the lower stratosphere. We study intermittency and zonally asymmetric character of these hotspots and their effects on the upper stratosphere and mesosphere using a new detection method in various modeling and observational datasets.
Daniela I. V. Domeisen, Christian M. Grams, and Lukas Papritz
Weather Clim. Dynam., 1, 373–388, https://doi.org/10.5194/wcd-1-373-2020, https://doi.org/10.5194/wcd-1-373-2020, 2020
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We cannot currently predict the weather over Europe beyond 2 weeks. The stratosphere provides a promising opportunity to go beyond that limit by providing a change in probability of certain weather regimes at the surface. However, not all stratospheric extreme events are followed by the same surface weather evolution. We show that this weather evolution is related to the tropospheric weather regime around the onset of the stratospheric extreme event for many stratospheric events.
Bernat Jiménez-Esteve and Daniela I. V. Domeisen
Weather Clim. Dynam., 1, 225–245, https://doi.org/10.5194/wcd-1-225-2020, https://doi.org/10.5194/wcd-1-225-2020, 2020
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Atmospheric predictability over Europe on subseasonal to seasonal timescales remains limited. However, the remote impact from the El Niño–Southern Oscillation (ENSO) can help to improve predictability. Research has suggested that the ENSO impact in the North Atlantic region is affected by nonlinearities. Here, we isolate the nonlinearities in the tropospheric pathway through the North Pacific, finding that a strong El Niño leads to a stronger and distinct impact compared to a strong La Niña.
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Short summary
We use the simple framework of an idealised baroclinic life cycle to study the tropospheric eddy feedback to different stratospheric conditions and, hence, obtain insights into the fundamental processes of stratosphere–troposphere coupling – in particular, the processes involved in creating the robust equatorward shift in the tropospheric mid-latitude jet that has been observed following sudden stratospheric warming events.
We use the simple framework of an idealised baroclinic life cycle to study the tropospheric eddy...
