Articles | Volume 21, issue 4
https://doi.org/10.5194/acp-21-2781-2021
© 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/acp-21-2781-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
24 Feb 2021
Research article |
| 24 Feb 2021
| 24 Feb 2021
The spring transition of the North Pacific jet and its relation to deep stratosphere-to-troposphere mass transport over western North America
Melissa L. Breeden
CORRESPONDING AUTHOR
NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
Amy H. Butler
NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
John R. Albers
NOAA Physical Sciences Laboratory, Boulder, CO 80305, USA
Cooperative Institute for Research in the Environmental Sciences, University of Colorado Boulder, Boulder, CO 80305, USA
Michael Sprenger
Institute for Atmosphere and Climate Science, ETH Zürich, Zurich, Switzerland
Andrew O'Neil Langford
NOAA Chemical Sciences Laboratory, Boulder, CO 80305, USA
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We explore the predictability of saturation vapor pressure deficit (VPD), a key indicator of wildfire danger, one to 18 months in advance. Seasonal VPD forecasts are generated using a statistical dynamical model that produces high VPD skill related to a long-term warming trend and sea surface temperatures. Understanding where forecast skill comes from is important to for improving forecast models, and this study shows the role of multiple unique processes in contributing to VPD forecasts.
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We compare the month-to-month evolution of daily precipitation over central southwest Asia (CSWA), a data-sparse, food-insecure area prone to drought and flooding. The seasonality of CSWA precipitation aligns with the seasonality of warm conveyor belts (WCBs), the warm, rapidly ascending airstreams associated with extratropical storms, most common from February–April. El Niño conditions are related to more WCBs and precipitation and La Niña conditions the opposite, except in January.
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One of the global hotspots where stratosphere-to-troposphere transport (STT) of ozone takes place is over Pacific North America (PNA). However, we do not know how or if STT over PNA will change in response to climate change. Using climate model experiments forced with
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We use a statistical dynamical model to generate precipitation forecasts for lead times of 2–6 weeks over southwest Asia, which are needed to support humanitarian food distribution. The model signal-to-noise ratio is used to identify a smaller subset of forecasts with particularly high skill, so-called subseasonal forecasts of opportunity (SFOs). Precipitation SFOs are often related to slowly evolving tropical phenomena, namely the El Niño–Southern Oscillation and Madden–Julian Oscillation.
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Atmos. Chem. Phys., 22, 13035–13048, https://doi.org/10.5194/acp-22-13035-2022, https://doi.org/10.5194/acp-22-13035-2022, 2022
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We explore the predictability of saturation vapor pressure deficit (VPD), a key indicator of wildfire danger, one to 18 months in advance. Seasonal VPD forecasts are generated using a statistical dynamical model that produces high VPD skill related to a long-term warming trend and sea surface temperatures. Understanding where forecast skill comes from is important to for improving forecast models, and this study shows the role of multiple unique processes in contributing to VPD forecasts.
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Matthew S. Johnson, Alexei Rozanov, Mark Weber, Nora Mettig, John Sullivan, Michael J. Newchurch, Shi Kuang, Thierry Leblanc, Fernando Chouza, Timothy A. Berkoff, Guillaume Gronoff, Kevin B. Strawbridge, Raul J. Alvarez, Andrew O. Langford, Christoph J. Senff, Guillaume Kirgis, Brandi McCarty, and Larry Twigg
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Katharina Heitmann, Michael Sprenger, Hanin Binder, Heini Wernli, and Hanna Joos
Weather Clim. Dynam., 5, 537–557, https://doi.org/10.5194/wcd-5-537-2024, https://doi.org/10.5194/wcd-5-537-2024, 2024
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Warm conveyor belts (WCBs) are coherently ascending air streams that occur in extratropical cyclones where they form precipitation and often affect the large-scale flow. We quantified the key characteristics and impacts of WCBs and linked them to different phases in the cyclone life cycle and to different WCB branches. A climatology of these metrics revealed that WCBs are most intense during cyclone intensification and that the cyclonic and anticyclonic WCB branches show distinct differences.
Lukas Jansing, Lukas Papritz, and Michael Sprenger
Weather Clim. Dynam., 5, 463–489, https://doi.org/10.5194/wcd-5-463-2024, https://doi.org/10.5194/wcd-5-463-2024, 2024
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Using an innovative approach, the descent of foehn is diagnosed from a Lagrangian perspective based on 15 kilometer-scale simulations combined with online trajectories. The descent is confined to distinct hotspots in the immediate lee of local mountain peaks and chains. Two detailed case studies reveal a varying wave regime to be associated with the descent. Furthermore, additional controlling factors, such as the diurnal cycle, likewise influence the descent activity.
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.
Yonatan Givon, Or Hess, Emmanouil Flaounas, Jennifer Louise Catto, Michael Sprenger, and Shira Raveh-Rubin
Weather Clim. Dynam., 5, 133–162, https://doi.org/10.5194/wcd-5-133-2024, https://doi.org/10.5194/wcd-5-133-2024, 2024
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A novel classification of Mediterranean cyclones is presented, enabling a separation between storms driven by different atmospheric processes. The surface impact of each cyclone class differs greatly by precipitation, winds, and temperatures, providing an invaluable tool to study the climatology of different types of Mediterranean storms and enhancing the understanding of their predictability, on both weather and climate scales.
Stefania Gilardoni, Dominic Heslin-Rees, Mauro Mazzola, Vito Vitale, Michael Sprenger, and Radovan Krejci
Atmos. Chem. Phys., 23, 15589–15607, https://doi.org/10.5194/acp-23-15589-2023, https://doi.org/10.5194/acp-23-15589-2023, 2023
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Models still fail in reproducing black carbon (BC) temporal variability in the Arctic. Analysis of equivalent BC concentrations in the European Arctic shows that BC seasonal variability is modulated by the efficiency of removal by precipitation during transport towards high latitudes. Short-term variability is controlled by synoptic-scale circulation patterns. The advection of warm air from lower latitudes is an effective pollution transport pathway during summer.
Melissa Leah Breeden, Andrew Hoell, John Robert Albers, and Kimberly Slinski
Weather Clim. Dynam., 4, 963–980, https://doi.org/10.5194/wcd-4-963-2023, https://doi.org/10.5194/wcd-4-963-2023, 2023
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We compare the month-to-month evolution of daily precipitation over central southwest Asia (CSWA), a data-sparse, food-insecure area prone to drought and flooding. The seasonality of CSWA precipitation aligns with the seasonality of warm conveyor belts (WCBs), the warm, rapidly ascending airstreams associated with extratropical storms, most common from February–April. El Niño conditions are related to more WCBs and precipitation and La Niña conditions the opposite, except in January.
Thomas Trickl, Martin Adelwart, Dina Khordakova, Ludwig Ries, Christian Rolf, Michael Sprenger, Wolfgang Steinbrecht, and Hannes Vogelmann
Atmos. Meas. Tech., 16, 5145–5165, https://doi.org/10.5194/amt-16-5145-2023, https://doi.org/10.5194/amt-16-5145-2023, 2023
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Tropospheric ozone have been measured for more than a century. Highly quantitative ozone measurements have been made at monitoring stations. However, deficits have been reported for vertical sounding systems. Here, we report a thorough intercomparison effort between a differential-absorption lidar system and two types of balloon-borne ozone sondes, also using ozone sensors at nearby mountain sites as references. The sondes agree very well with the lidar after offset corrections.
Melanie Lauer, Annette Rinke, Irina Gorodetskaya, Michael Sprenger, Mario Mech, and Susanne Crewell
Atmos. Chem. Phys., 23, 8705–8726, https://doi.org/10.5194/acp-23-8705-2023, https://doi.org/10.5194/acp-23-8705-2023, 2023
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We present a new method to analyse the influence of atmospheric rivers (ARs), cyclones, and fronts on the precipitation in the Arctic, based on two campaigns: ACLOUD (early summer 2017) and AFLUX (early spring 2019). There are differences between both campaign periods: in early summer, the precipitation is mostly related to ARs and fronts, especially when they are co-located, while in early spring, cyclones isolated from ARs and fronts contributed most to the precipitation.
Emmanouil Flaounas, Leonardo Aragão, Lisa Bernini, Stavros Dafis, Benjamin Doiteau, Helena Flocas, Suzanne L. Gray, Alexia Karwat, John Kouroutzoglou, Piero Lionello, Mario Marcello Miglietta, Florian Pantillon, Claudia Pasquero, Platon Patlakas, María Ángeles Picornell, Federico Porcù, Matthew D. K. Priestley, Marco Reale, Malcolm J. Roberts, Hadas Saaroni, Dor Sandler, Enrico Scoccimarro, Michael Sprenger, and Baruch Ziv
Weather Clim. Dynam., 4, 639–661, https://doi.org/10.5194/wcd-4-639-2023, https://doi.org/10.5194/wcd-4-639-2023, 2023
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Cyclone detection and tracking methods (CDTMs) have different approaches in defining and tracking cyclone centers. This leads to disagreements on extratropical cyclone climatologies. We present a new approach that combines tracks from individual CDTMs to produce new composite tracks. These new tracks are shown to correspond to physically meaningful systems with distinctive life stages.
Dillon Elsbury, Amy H. Butler, John R. Albers, Melissa L. Breeden, and Andrew O'Neil Langford
Atmos. Chem. Phys., 23, 5101–5117, https://doi.org/10.5194/acp-23-5101-2023, https://doi.org/10.5194/acp-23-5101-2023, 2023
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One of the global hotspots where stratosphere-to-troposphere transport (STT) of ozone takes place is over Pacific North America (PNA). However, we do not know how or if STT over PNA will change in response to climate change. Using climate model experiments forced with
worst-casescenario Representative Concentration Pathway 8.5 climate change, we find that changes in net chemical production and transport of ozone in the lower stratosphere increase STT of ozone over PNA in the future.
Hanna Joos, Michael Sprenger, Hanin Binder, Urs Beyerle, and Heini Wernli
Weather Clim. Dynam., 4, 133–155, https://doi.org/10.5194/wcd-4-133-2023, https://doi.org/10.5194/wcd-4-133-2023, 2023
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Warm conveyor belts (WCBs) are strongly ascending, cloud- and precipitation-forming airstreams in extratropical cyclones. In this study we assess their representation in a climate simulation and their changes under global warming. They become moister, become more intense, and reach higher altitudes in a future climate, implying that they potentially have an increased impact on the mid-latitude flow.
Andreas Schäfler, Michael Sprenger, Heini Wernli, Andreas Fix, and Martin Wirth
Atmos. Chem. Phys., 23, 999–1018, https://doi.org/10.5194/acp-23-999-2023, https://doi.org/10.5194/acp-23-999-2023, 2023
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In this study, airborne lidar profile measurements of H2O and O3 across a midlatitude jet stream are combined with analyses in tracer–trace space and backward trajectories. We highlight that transport and mixing processes in the history of the observed air masses are governed by interacting tropospheric weather systems on synoptic timescales. We show that these weather systems play a key role in the high variability of the paired H2O and O3 distributions near the tropopause.
Hanin Binder, Hanna Joos, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 4, 19–37, https://doi.org/10.5194/wcd-4-19-2023, https://doi.org/10.5194/wcd-4-19-2023, 2023
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Warm conveyor belts (WCBs) are the main cloud- and precipitation-producing airstreams in extratropical cyclones. The latent heat release that occurs during cloud formation often contributes to the intensification of the associated cyclone. Based on the Community Earth System Model Large Ensemble coupled climate simulations, we show that WCBs and associated latent heating will become stronger in a future climate and be even more important for explosive cyclone intensification than in the present.
Michael A. Barnes, Thando Ndarana, Michael Sprenger, and Willem A. Landman
Weather Clim. Dynam., 3, 1291–1309, https://doi.org/10.5194/wcd-3-1291-2022, https://doi.org/10.5194/wcd-3-1291-2022, 2022
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Stratospheric air can intrude into the troposphere and is associated with cyclonic development throughout the atmosphere. Through a highly idealized systematic approach, the effect that different intrusion characteristics have on surface cyclogenetic forcing is investigated. The proximity of stratospheric intrusions to the surface is shown to be the main factor in surface cyclogenetic forcing, whilst its width is an additional contributing factor.
Melissa L. Breeden, John R. Albers, and Andrew Hoell
Weather Clim. Dynam., 3, 1183–1197, https://doi.org/10.5194/wcd-3-1183-2022, https://doi.org/10.5194/wcd-3-1183-2022, 2022
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We use a statistical dynamical model to generate precipitation forecasts for lead times of 2–6 weeks over southwest Asia, which are needed to support humanitarian food distribution. The model signal-to-noise ratio is used to identify a smaller subset of forecasts with particularly high skill, so-called subseasonal forecasts of opportunity (SFOs). Precipitation SFOs are often related to slowly evolving tropical phenomena, namely the El Niño–Southern Oscillation and Madden–Julian Oscillation.
John R. Albers, Amy H. Butler, Andrew O. Langford, Dillon Elsbury, and Melissa L. Breeden
Atmos. Chem. Phys., 22, 13035–13048, https://doi.org/10.5194/acp-22-13035-2022, https://doi.org/10.5194/acp-22-13035-2022, 2022
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Ozone transported from the stratosphere contributes to background ozone concentrations in the free troposphere and to surface ozone exceedance events that affect human health. The physical processes whereby the El Niño–Southern Oscillation (ENSO) modulates North American stratosphere-to-troposphere ozone transport during spring are documented, and the usefulness of ENSO for predicting ozone events that may cause exceedances in surface air quality standards are assessed.
Lukas Jansing, Lukas Papritz, Bruno Dürr, Daniel Gerstgrasser, and Michael Sprenger
Weather Clim. Dynam., 3, 1113–1138, https://doi.org/10.5194/wcd-3-1113-2022, https://doi.org/10.5194/wcd-3-1113-2022, 2022
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This study presents a 5-year climatology of three main foehn types and three deep-foehn subtypes. The main types differ in their large-scale and Alpine-scale weather conditions and the subtypes in terms of the amount and extent of precipitation on the Alpine south side. The different types of foehn are found to strongly affect the local meteorological conditions at Altdorf. The study concludes by setting the new classification into a historic context.
Jan Clemens, Felix Ploeger, Paul Konopka, Raphael Portmann, Michael Sprenger, and Heini Wernli
Atmos. Chem. Phys., 22, 3841–3860, https://doi.org/10.5194/acp-22-3841-2022, https://doi.org/10.5194/acp-22-3841-2022, 2022
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Highly polluted air flows from the surface to higher levels of the atmosphere during the Asian summer monsoon. At high levels, the air is trapped within eddies. Here, we study how air masses can leave the eddy within its cutoff, how they distribute, and how their chemical composition changes. We found evidence for transport from the eddy to higher latitudes over the North Pacific and even Alaska. During transport, trace gas concentrations within cutoffs changed gradually, showing steady mixing.
Jörg Wieder, Claudia Mignani, Mario Schär, Lucie Roth, Michael Sprenger, Jan Henneberger, Ulrike Lohmann, Cyril Brunner, and Zamin A. Kanji
Atmos. Chem. Phys., 22, 3111–3130, https://doi.org/10.5194/acp-22-3111-2022, https://doi.org/10.5194/acp-22-3111-2022, 2022
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We investigate the variation in ice-nucleating particles (INPs) relevant for primary ice formation in mixed-phased clouds over the Alps based on simultaneous in situ observations at a mountaintop and a nearby high valley (1060 m height difference). In most cases, advection from the surrounding lower regions was responsible for changes in INP concentration, causing a diurnal cycle at the mountaintop. Our study underlines the importance of the planetary boundary layer as an INP reserve.
Lukas Bösiger, Michael Sprenger, Maxi Boettcher, Hanna Joos, and Tobias Günther
Geosci. Model Dev., 15, 1079–1096, https://doi.org/10.5194/gmd-15-1079-2022, https://doi.org/10.5194/gmd-15-1079-2022, 2022
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Jet streams are coherent air flows that interact with atmospheric structures such as warm conveyor belts (WCBs) and the tropopause. Individually, these structures have a significant impact on the weather evolution. A first step towards a deeper understanding of the meteorological processes is to extract jet stream core lines, for which we develop a novel feature extraction algorithm. Based on the line geometry, we automatically detect and visualize potential interactions between WCBs and jets.
Andrew O. Langford, Christoph J. Senff, Raul J. Alvarez II, Ken C. Aikin, Sunil Baidar, Timothy A. Bonin, W. Alan Brewer, Jerome Brioude, Steven S. Brown, Joel D. Burley, Dani J. Caputi, Stephen A. Conley, Patrick D. Cullis, Zachary C. J. Decker, Stéphanie Evan, Guillaume Kirgis, Meiyun Lin, Mariusz Pagowski, Jeff Peischl, Irina Petropavlovskikh, R. Bradley Pierce, Thomas B. Ryerson, Scott P. Sandberg, Chance W. Sterling, Ann M. Weickmann, and Li Zhang
Atmos. Chem. Phys., 22, 1707–1737, https://doi.org/10.5194/acp-22-1707-2022, https://doi.org/10.5194/acp-22-1707-2022, 2022
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The Fires, Asian, and Stratospheric Transport–Las Vegas Ozone Study (FAST-LVOS) combined lidar, aircraft, and in situ measurements with global models to investigate the contributions of stratospheric intrusions, regional and Asian pollution, and wildfires to background ozone in the southwestern US during May and June 2017 and demonstrated that these processes contributed to background ozone levels that exceeded 70 % of the US National Ambient Air Quality Standard during the 6-week campaign.
Philippe Besson, Luise J. Fischer, Sebastian Schemm, and Michael Sprenger
Weather Clim. Dynam., 2, 991–1009, https://doi.org/10.5194/wcd-2-991-2021, https://doi.org/10.5194/wcd-2-991-2021, 2021
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The strongest cyclone intensification is associated with a strong dry-dynamical forcing. Moreover, strong forcing and strong intensification correspond to a tendency for poleward cyclone propagation, which occurs in distinct regions in the Northern Hemisphere. There is a clear spatial pattern in the occurrence of certain forcing combinations. This implies a fundamental relationship between dry-dynamical processes and the intensification as well as the propagation of extratropical cyclones.
Raphael Portmann, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 2, 507–534, https://doi.org/10.5194/wcd-2-507-2021, https://doi.org/10.5194/wcd-2-507-2021, 2021
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We explore the three-dimensional life cycle of cyclonic structures
(so-called PV cutoffs) near the tropopause. PV cutoffs are frequent weather systems in the extratropics that lead to high-impact weather. However, many unknowns exist regarding their evolution. We present a new method to track PV cutoffs as 3D objects in reanalysis data by following air parcels along the flow. We study the climatological life cycles of PV cutoffs in detail and propose a classification into three types.
John R. Albers, Amy H. Butler, Melissa L. Breeden, Andrew O. Langford, and George N. Kiladis
Weather Clim. Dynam., 2, 433–452, https://doi.org/10.5194/wcd-2-433-2021, https://doi.org/10.5194/wcd-2-433-2021, 2021
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Weather variability controls the transport of ozone from the stratosphere to the Earth’s surface and water vapor from oceanic source regions to continental land masses. Forecasting these types of transport has high societal value because of the negative impacts of ozone on human health and the role of water vapor in governing precipitation variability. We use upper-level wind forecasts to assess the potential for predicting ozone and water vapor transport 3–6 weeks ahead of time.
Maxi Boettcher, Andreas Schäfler, Michael Sprenger, Harald Sodemann, Stefan Kaufmann, Christiane Voigt, Hans Schlager, Donato Summa, Paolo Di Girolamo, Daniele Nerini, Urs Germann, and Heini Wernli
Atmos. Chem. Phys., 21, 5477–5498, https://doi.org/10.5194/acp-21-5477-2021, https://doi.org/10.5194/acp-21-5477-2021, 2021
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Warm conveyor belts (WCBs) are important airstreams in extratropical cyclones, often leading to the formation of intense precipitation. We present a case study that involves aircraft, lidar and radar observations of water and clouds in a WCB ascending from western Europe across the Alps towards the Baltic Sea during the field campaigns HyMeX and T-NAWDEX-Falcon in October 2012. A probabilistic trajectory measure and an airborne tracer experiment were used to confirm the long pathway of the WCB.
Annika Oertel, Michael Sprenger, Hanna Joos, Maxi Boettcher, Heike Konow, Martin Hagen, and Heini Wernli
Weather Clim. Dynam., 2, 89–110, https://doi.org/10.5194/wcd-2-89-2021, https://doi.org/10.5194/wcd-2-89-2021, 2021
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Convection embedded in the stratiform cloud band of strongly ascending airstreams in extratropical cyclones (so-called warm conveyor belts) can influence not only surface precipitation but also the
upper-tropospheric potential vorticity (PV) and waveguide. The comparison of intense vs. moderate embedded convection shows that its strength alone is not a reliable measure for upper-tropospheric PV modification. Instead, characteristics of the ambient flow co-determine its dynamical significance.
Emmanouil Flaounas, Matthias Röthlisberger, Maxi Boettcher, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 2, 71–88, https://doi.org/10.5194/wcd-2-71-2021, https://doi.org/10.5194/wcd-2-71-2021, 2021
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In this study we identify the wettest seasons globally and address their meteorological characteristics. We show that in different regions the wettest seasons occur in different times of the year and result from either unusually high frequencies of wet days and/or daily extremes. These high frequencies can be largely attributed to four specific weather systems, especially cyclones. Our analysis uses a thoroughly explained, novel methodology that could also be applied to climate models.
Claudia Mignani, Jörg Wieder, Michael A. Sprenger, Zamin A. Kanji, Jan Henneberger, Christine Alewell, and Franz Conen
Atmos. Chem. Phys., 21, 657–664, https://doi.org/10.5194/acp-21-657-2021, https://doi.org/10.5194/acp-21-657-2021, 2021
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Most precipitation above land starts with ice in clouds. It is promoted by extremely rare particles. Some ice-nucleating particles (INPs) cause cloud droplets to already freeze above −15°C, a temperature at which many clouds begin to snow. We found that the abundance of such INPs among other particles of similar size is highest in precipitating air masses and lowest when air carries desert dust. This brings us closer to understanding the interactions between land, clouds, and precipitation.
Stefan Rüdisühli, Michael Sprenger, David Leutwyler, Christoph Schär, and Heini Wernli
Weather Clim. Dynam., 1, 675–699, https://doi.org/10.5194/wcd-1-675-2020, https://doi.org/10.5194/wcd-1-675-2020, 2020
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Most precipitation over Europe is linked to low-pressure systems, cold fronts, warm fronts, or high-pressure systems. Based on a massive computer simulation able to resolve thunderstorms, we quantify in detail how much precipitation these weather systems produced during 2000–2008. We find distinct seasonal and regional differences, such as fronts precipitating a lot in fall and winter over the North Atlantic but high-pressure systems mostly in summer over the continent by way of thunderstorms.
Raphael Portmann, Juan Jesús González-Alemán, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 1, 597–615, https://doi.org/10.5194/wcd-1-597-2020, https://doi.org/10.5194/wcd-1-597-2020, 2020
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In September 2018 an intense Mediterranean cyclone with structural similarities to a hurricane, a so-called medicane, caused severe damage in Greece. Its development was uncertain, even just a few days in advance. The reason for this was uncertainties in the jet stream over the North Atlantic 3 d prior to cyclogenesis that propagated into the Mediterranean. They led to an uncertain position of the upper-level disturbance and, as a result, of the position and thermal structure of the cyclone.
Hanin Binder, Maxi Boettcher, Hanna Joos, Michael Sprenger, and Heini Wernli
Weather Clim. Dynam., 1, 577–595, https://doi.org/10.5194/wcd-1-577-2020, https://doi.org/10.5194/wcd-1-577-2020, 2020
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Warm conveyor belts (WCBs) are important cloud- and
precipitation-producing airstreams in extratropical cyclones. By combining satellite observations with model data from a new reanalysis dataset, this study provides detailed observational insight into the vertical cloud structure of WCBs. We find that the reanalyses essentially capture the observed cloud pattern, but the observations reveal mesoscale structures not resolved by the temporally and spatially much coarser-resolution model data.
Shi Kuang, Bo Wang, Michael J. Newchurch, Kevin Knupp, Paula Tucker, Edwin W. Eloranta, Joseph P. Garcia, Ilya Razenkov, John T. Sullivan, Timothy A. Berkoff, Guillaume Gronoff, Liqiao Lei, Christoph J. Senff, Andrew O. Langford, Thierry Leblanc, and Vijay Natraj
Atmos. Meas. Tech., 13, 5277–5292, https://doi.org/10.5194/amt-13-5277-2020, https://doi.org/10.5194/amt-13-5277-2020, 2020
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Ozone lidar is a state-of-the-art remote-sensing instrument to measure atmospheric ozone concentrations with high spatiotemporal resolution. In this study, we show that an ozone lidar can also provide reliable aerosol measurements through intercomparison with colocated aerosol lidar observations.
Sebastian Schemm, Stefan Rüdisühli, and Michael Sprenger
Weather Clim. Dynam., 1, 459–479, https://doi.org/10.5194/wcd-1-459-2020, https://doi.org/10.5194/wcd-1-459-2020, 2020
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Troughs and ridges are ubiquitous flow features in the upper troposphere and are centerpiece elements of weather and climate research. A novel method is introduced to identify and track the life cycle of troughs and ridges and their orientation. The aim is to close the existing gap between methods that detect the initiation phase and methods that detect the decaying phase of Rossby wave development. Global climatologies, the influence of ENSO and Lagrangian characteristics are discussed.
Li Zhang, Meiyun Lin, Andrew O. Langford, Larry W. Horowitz, Christoph J. Senff, Elizabeth Klovenski, Yuxuan Wang, Raul J. Alvarez II, Irina Petropavlovskikh, Patrick Cullis, Chance W. Sterling, Jeff Peischl, Thomas B. Ryerson, Steven S. Brown, Zachary C. J. Decker, Guillaume Kirgis, and Stephen Conley
Atmos. Chem. Phys., 20, 10379–10400, https://doi.org/10.5194/acp-20-10379-2020, https://doi.org/10.5194/acp-20-10379-2020, 2020
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Measuring and quantifying the sources of elevated springtime ozone in the southwestern US is challenging but relevant to the implications for control policy. Here we use intensive field measurements and two global models to study ozone sources in the region. We find that ozone from the stratosphere, wildfires, and Asia is an important source of high-ozone events in the region. Our analysis also helps understand the uncertainties in ozone simulations with individual models.
Cited articles
Albers, J. R., Perlwitz, J., Butler, A. H., Birner, T., Kiladis, G. N.,
Lawrence, Z. D., and Dias, J.: Mechanisms governing interannual variability
of stratosphere-to-troposphere ozone transport, J. Geophys.
Res.-Atmos., 123, 234–260, https://doi.org/10.1002/2017JD026890,
2018.
Athanasiadis, P. J., Wallace, J. M., and Wettstein, J. J.: Patterns of winter- time jet stream variability and their relation to the storm tracks, J. Atmos. Sci., 67, 1361–1381, https://doi.org/10.1175/2009JAS3270.1, 2010.
Breeden, M. L., Hoover, B. T., Newman, M., and Vimont D. J.: Optimal North
Pacific Blocking Precursors and their Deterministic Subseasonal Evolution
during Boreal Winter, Mon. Weather Rev., 148, 739–761, https://doi.org/10.1175/MWR-D-19-0273.1, 2020.
Breeden, M. L. and Martin J. E.: Analyzing the onset of an extreme North
Pacific Jet Retraction using Piecewise Tendency Diagnosis, Q. J. R.
Meteor. Soc., 144, 1895–1913, https://doi.org/10.1002/qj.3388, 2018.
Christenson, C. E., Martin, J. E., and Handlos Z. J.: A synoptic-climatology
of Northern Hemisphere, cold season polar and subtropical jet superposition
events, J. Climate, 30, 7231–7246, 2017.
Danielsen, E. F.: Project Springfield Report, Tech. Rep. 1517, 110 pp.,
Defense At. Supp. Agency, Washington, D. C., 1964.
Danielsen, E. F.: Stratospheric-tropospheric exchange based on
radioactivity, ozone and potential vorticity, J. Atmos. Sci., 25, 502–518,
1968.
Dee, D. P., Uppala, S. M., Simmons, A. J., et al.: The ERA-Interim reanalysis: Configuration and
performance of the data assimilation system, Q. J. R.
Meteorol. Soc., 137, 553–597, https://doi.org/10.1002/qj.828, 2011.
Eichelberger, S. J. and Hartmann, D. L.: Zonal jet structure and the leading
mode of variability, J. Clim., 20, 5149–5163, 2007.
ETH Zürich:
Feature-based ERA-Interim Climatologies: available at: http://eraiclim.ethz.ch/, last access: 10 January 2019.
Fleming, E. L., Lim, G.-H., and Wallace, J. M.: Differences between the
spring and autumn circulation of the Northern Hemisphere, J. Atmos. Sci.,
44, 1266–1286, 1987.
García-Herrera, R., Calvo, N., Garcia, R., and Giorgetta, M.: Propagation
of ENSO temperature signals into the middle atmosphere: A comparison of two
general circulation models and ERA-40 reanalysis data, J.
Geophys. Res., 111, D06101, https://doi.org/10.1029/2005JD006061,
2006.
Gettelman, A., Hoor, P., Pan, L., Randel, W., Hegglin, M., and Birner, T.:
The extratropical upper troposphere and lower stratosphere, Rev.
Geophys., 49, RG3003, https://doi.org/10.1029/2011RG000355, 2011.
Homeyer, C. R. and Bowman, K. P.: Rossby wave breaking and transport between
the tropics and extratropics above the subtropical jet, J.
Atmos. Sci., 70, 607–626, 2013.
Hoskins, B. J., James, I. N., and White G. H.: The Shape, Propagation and
Mean-Flow Interaction of Large-Scale Weather Systems, J. Atmos. Sci., 40,
1595–1612, https://doi.org/10.1175/1520-0469(1983)040<
1595:TSPAMF>2.0.CO;2, 1983.
Hoskins, B. J., McIntyre, M. E., and Robertson, A. W.: On the use and
significance of isentropic potential vorticity maps, Q. J. R. Meteorol.
Soc., 111, 877–946, https://doi.org/10.1002/qj.49711147002, 1985.
Hoskins, B. J. and Ambrizzi T.: Rossby wave propagation on a realistic
longitudinally varying flow, J. Atmos. Sci., 50, 1661–1671,
https://doi.org/10.1175/1520-0469(1993)050,1661:RWPOAR.2.0.CO;2, 1993.
Hoskins, B. J. and Hodges, K. I.: The Annual Cycle of Northern Hemisphere
Storm Tracks. Part II: Regional Detail, J. Climate, 32, 1761–1775, 2019.
Jaffe, S.C., Martin, J.E., Vimont, D.J., and Lorenz, D.J.: A
synoptic-climatology of episodic, sub-seasonal retractions of the Pacific
jet, Journal of Climate, 24, 2846–2860, 2011.
Keyser, D. and Shapiro, M. A.: A review of the structure and dynamics of
upper-level frontal zones, Mon. Weather Rev., 114, 452–499,
https://doi.org/10.1175/1520- 0493(1986)114<0452:AROTSA>2.0.CO;2, 1986.
Knowland, K. E., Ott, L. E., Duncan, B. N., and Wargan, K.: Stratospheric
intrusion-influenced ozone air quality exceedances investigated in the NASA
MERRA-2 reanalysis, Geophys. Res. Lett., 44, 10691–10701,
https://doi.org/10.1002/2017GL074532, 2017.
Kobayashi, S., Ota, Y., Harada, Y., Ebita, A., Moriya, M., Onoda, H., et
al.: The JRA-55 reanalysis: General specifications and basic
characteristics. Journal of the Meteorological Society of Japan. Ser. II,
93, 5–48. https://doi.org/10.2151/jmsj.2015-001, 2015.
Langford, A., O'Leary, T., Masters, C., Aikin, K., and Proffitt, M.:
Modulation of middle and upper tropospheric ozone at northern midlatitudes
by the El Niño/Southern Oscillation, Geophys. Res. Lett., 25,
2667–2670, 1998.
Langford, A., Aikin, K., Eubank, C., and Williams, E.: Stratospheric
contribution to high surface ozone in Colorado during springtime,
Geophys. Res. Lett., 36, L12801,
https://doi.org/10.1029/2009GL038367, 2009.
Langford, A., Brioude, J., Cooper, O., Senff, C., Alvarez, R., Hardesty, R.,
and Oltmans, S.: Stratospheric influence on surface ozone in the Los Angeles area during late spring and early summer of 2010, J. Geophys.
Res., 117, D00V06, https://doi.org/10.1029/2011JD016766, 2012.
Langford, A. O., Alvarez II, R. J., Brioude, J., et al.: Entrainment of stratospheric air and Asian
pollution by the convective boundary layer in the southwestern U.S., J.
Geophys. Res.-Atmos., 122, 1312–1337, https://doi.org/10.1002/2016JD025987, 2017.
Lareau, N. P. and Horel, J. D.: The Climatology of Synoptic-Scale Ascent over
Western North America: A Perspective on Storm Tracks. Mon. Weather
Rev., 140, 1761–1778, https://doi.org/10.1175/MWR-D-11-00203.1, 2012.
Lefohn, A. S., Wernli, H., Shadwick, D., Oltmans, S. J., and Shapiro, M.:
Quantifying the importance of stratospheric–tropospheric transport on
surface ozone concentrations at high- and low-elevation monitoring sites in
the United States, Atmos. Environ., 62, 646–656,
https://doi.org/10.1016/j.atmosenv.2012.09.004, 2012.
Li, C. and Wettstein, J. J.: Thermally Driven and Eddy-Driven Jet
Variability in Reanalysis, J. Climate, 25, 1587–1596, https://doi.org/10.1175/JCLI-D-11-00145.1, 2012.
Lin, M. Y., Fiore, A. M., Cooper, O. R., Horowitz, L. W., Langford, A. O.,
Levy, H., Johnson, B. J., Naik, V., Oltmans, S. J., and Senff C. J.:
Springtime high surface ozone events over the western United States:
Quantifying the role of stratospheric intrusions, J. Geophys. Res., 117,
D00v22, https://doi.org/10.1029/2012jd018151, 2012.
Lin, M., Horowitz, L. W., Oltmans, S. J., Fiore, A. M., and Fan S.:
Tropospheric ozone trends at Mauna Loa Observatory tied to decadal climate
variability, Nat. Geosci., 7, 136–143, https://doi.org/10.1038/ngeo2066, 2014.
Lin, M., Fiore, A. M., Horowitz, L. W., Langford, A. O., Oltmans, S. J.,
Tarasick, D., and Rieder, H. E.: Climate variability modulates western US
ozone air quality in spring via deep stratospheric intrusions, Nat.
Commun., 12, 7105, https://doi.org/10.1038/ncomms8105, 2015.
Martius, O., Schwierz, C., and Davies, H. C.: Breaking waves at the tropopause in the wintertime Northern Hemisphere: climatological analyses of the orientation and the theoretical LC1/2 classification, J.
Atmos. Sci., 64, 2576–2592, 2007.
Nakamura, H.: Midwinter suppression of baroclinic wave activity in the
Pacific, J. Atmos. Sci., 49, 1629–1642, 1992.
Neu, J. L., Flury, T., Manney, G. L., Santee, M. L., Livesey, N. J., and
Worden, J.: Tropospheric ozone variations governed by changes in
stratospheric circulation, Nat. Geosci., 7, 340–344, 2014.
Newman, M., and Sardeshmukh, P. D.: The impact of the annual cycle on the
North Pacific/North American response to remote low-frequency forcing,
J. Atmos. Sci., 55, 1336–1353, 1998.
NOAA Center for Weather and Climate Prediction, NOAA Oceanic Niño Index:
Cold & Warm Episodes by Season, available at: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php, last access: 8 June 2020.
Pan, L. L., Randel, W. J., Gille, J. C., Hall, W. D., Nardi, B., Massie, S., Yudin, V., Khosravi, R., Konopka, P., and Tarasick, D.: Tropospheric intrusions associated with the secondary tropopause, J. Geophys. Res., 114, D10302, https://doi.org/10.1029/2008JD011374, 2009.
Peters, D. and Waugh, D. W.: Rossby wave breaking in the Southern
Hemisphere wintertime upper troposphere, Mon. Weather Rev., 131, 2623–2634,
2003.
Reed, R. J. and Danielsen E. F.: Fronts in the vicinity of the tropopause,
Arch. Meteor. Geophy. A, 11, 1–17, 1959.
Renwick, J. A. and Wallace, J. M.: Relationships between North Pacific
wintertime blocking, El NinÞo, and the PNA pattern. Mon. Weather Rev., 124,
2017–2076, https://doi.org/10.1175/1520-0493(1996)124,2071:RBNPWB.2.0.co;2, 1996.
Research Data Archive at the National Center for Atmospheric Research: Computational and Information Systems Laboratory, available at: https://rda.ucar.edu/, last access: 11 January 2019.
Rivière, G. and Joly A.: Role of the Low-Frequency Deformation Field on
the Explosive Growth of Extratropical Cyclones at the Jet Exit. Part II:
Baroclinic Critical Region, J. Atmos. Sci., 63, 1982–1995, https://doi.org/10.1175/JAS3729.1, 2006.
Schemm, S. and Sprenger, M.: The Life Cycle of Upper-Level Troughs and Ridges: A Novel Detection Method, Climatologies and Lagrangian Characteristics, Weather Clim. Dynam., 1, 459–479, https://doi.org/10.5194/wcd-1-459-2020, 2020.
Seidel, D. J., Zhang, Y., Beljaars, A., Golaz, J.-C., Jacobson, A. R., and
Medeiros, B.: Climatology of the planetary boundary layer over the
continental United States and Europe, J. Geophys. Res., 117, D17106,
https://doi.org/10.1029/2012JD018143, 2012.
Shapiro, M.: Turbulent mixing within tropopause folds as a mechanism for the
exchange of chemical constituents between the stratosphere and troposphere,
J. Atmos. Sci., 37, 994–1004, 1980.
Shapiro, M., Wernli, H., Bond, N., and Langland, R.: The influence of the
1997–99 El Niño Southern Oscillation on extratropical baroclinic life
cycles over the eastern North Pacific, Q. J. R.
Meteorol. Soc., 127., 331–342, 2001.
Škerlak, B., Sprenger, M., and Wernli, H.: A global climatology of stratosphere–troposphere exchange using the ERA-Interim data set from 1979 to 2011, Atmos. Chem. Phys., 14, 913–937, https://doi.org/10.5194/acp-14-913-2014, 2014.
Škerlak, B., Sprenger, M., Pfahl, S., Tyrlis, E., and Wernli H.: Tropopause
folds in ERA-Interim: Global climatology and relation to extreme weather
events, J. Geophys. Res.-Atmos., 120, 4860–4877, https://doi.org/10.1002/2014JD022787,
2015.
Škerlak, B., Pfahl, S., Sprenger, M., and Wernli, H.: A numerical process study on the rapid transport of stratospheric air down to the surface over western North America and the Tibetan Plateau, Atmos. Chem. Phys., 19, 6535–6549, https://doi.org/10.5194/acp-19-6535-2019, 2019.
Sprenger, M. and Wernli, H.: A northern hemispheric climatology of
cross-tropopause exchange for the ERA15 time period (1979–1993), J.
Geophys. Res., 108, 8521, https://doi.org/10.1029/2002JD002636, 2003.
Sprenger, M., Wernli, H., and Bourqui, M.: Stratosphere–Troposphere
Exchange and Its Relation to Potential Vorticity Streamers and Cutoffs near
the Extratropical Tropopause, J. Atmos. Sci., 64, 1587–1602, https://doi.org/10.1175/JAS3911.1, 2007.
Sprenger, M., Fragkoulidis, G., Binder, H., Croci-Maspoli, M., Graf, P.,
Grams, C. M., Knippertz, P., Madonna, E., Schemm, S., Škerlak, B., and
Wernli H.: Global climatologies of Eulerian and Lagrangian flow features
based on ERA-Interim reanalyses, B. Am. Meteorol. Soc., 98, 1739–1748
https://doi.org/10.1175/BAMS-D-15-00299.1, 2017.
Staley, D. O.: On the mechanism of mass and radioactivity transport from
stratosphere to troposphere, J. Atmos. Sci., 19, 450–467, 1962.
Voulgarakis, A., Hadjinicolaou, P., and Pyle, J.: Increases in global
tropospheric ozone following an El Nino event: Examining stratospheric ozone
variability as a potential driver, Atmos. Sci. Lett., 12,
228–232, 2011.
Wernli, H. and Davies, H. C.: A Lagrangian-based analysis of ex- tratropical
cyclones. I: The method and some applications, Q. J. R.. Meteor. Soc., 123,
467–489, 1997.
Zeng, G. and Pyle, J. A.: Influence of El Niño Southern Oscillation on
stratosphere/troposphere exchange and the global tropospheric ozone budget.
Geophys. Res. Lett., 32, L01814,
https://doi.org/10.1029/2004GL021353, 2005.
Short summary
Prior research has found a maximum in deep stratosphere-to-troposphere mass/ozone transport over the western United States in boreal spring, which can enhance surface ozone concentrations, reducing air quality. We find that the winter-to-summer evolution of the north Pacific jet increases the frequency of stratospheric intrusions that drive transport, helping explain the observed maximum. The El Niño–Southern Oscillation affects the timing of the spring jet transition and therefore transport.
Prior research has found a maximum in deep stratosphere-to-troposphere mass/ozone transport over...
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