Articles | Volume 20, issue 14
Research article 20 Jul 2020
Research article | 20 Jul 2020
Adding value to extended-range forecasts in northern Europe by statistical post-processing using stratospheric observations
Natalia Korhonen et al.
Otto Hyvärinen, Terhi K. Laurila, Olle Räty, Natalia Korhonen, Andrea Vajda, and Hilppa Gregow
Adv. Sci. Res., 18, 127–134,Short summary
Wind speed forecasts have many potential users that could benefit from skilful forecasts. We validated weekly mean speed forecasts for Finland using forecasts from the ECMWF (European Centre for Medium-Range Weather Forecasts). We concentrate on winter (November, December and January) forecasts. The forecasts proved to be skilful until the third week, but the longest skilful lead time depends on how the skill is calculated and what is used as the reference.
Angel Navarro Trastoy, Sebastian Strasser, Lauri Tuppi, Maksym Vasiuta, Markku Poutanen, Torsten Mayer-Gürr, and Heikki Järvinen
Geosci. Model Dev. Discuss.,
Preprint under review for GMDShort summary
Production of satellite products rely on information from different centers. By coupling a weather model and an orbit determination solver we eliminate the dependence on one of the centers. The coupling has proven to be possible in the first stage, where no formatting has been applied to any of the models involved. This opens a window for further development and improvement to a coupling that has proven to be as good as the predecessor model.
Otto Hyvärinen, Terhi K. Laurila, Olle Räty, Natalia Korhonen, Andrea Vajda, and Hilppa Gregow
Adv. Sci. Res., 18, 127–134,Short summary
Wind speed forecasts have many potential users that could benefit from skilful forecasts. We validated weekly mean speed forecasts for Finland using forecasts from the ECMWF (European Centre for Medium-Range Weather Forecasts). We concentrate on winter (November, December and January) forecasts. The forecasts proved to be skilful until the third week, but the longest skilful lead time depends on how the skill is calculated and what is used as the reference.
Terhi K. Laurila, Hilppa Gregow, Joona Cornér, and Victoria A. Sinclair
Weather Clim. Dynam. Discuss.,
Revised manuscript under review for WCDShort summary
We create a climatology of mid-latitude cyclones and windstorms in Northern Europe and investigate how sensitive the minimum pressure and maximum gust of windstorms are to four precursors. Windstorms are more common in the cold season than the warm season whereas the number of mid-latitude cyclones has no annual cycle. The low-level temperature gradient has the strongest impact of all considered precursors on the intensity of windstorms in terms of both the minimum pressure and maximum gust.
Pirkka Ollinaho, Glenn D. Carver, Simon T. K. Lang, Lauri Tuppi, Madeleine Ekblom, and Heikki Järvinen
Geosci. Model Dev., 14, 2143–2160,Short summary
OpenEnsemble 1.0 is a novel dataset that aims to open ensemble or probabilistic weather forecasting research up to the academic community. The dataset contains atmospheric states that are required for running model forecasts of atmospheric evolution. Our capacity to observe the atmosphere is limited; thus, a single reconstruction of the atmospheric state contains some errors. Our dataset provides sets of 50 slightly different atmospheric states so that these errors can be taken into account.
Lauri Tuppi, Pirkka Ollinaho, Madeleine Ekblom, Vladimir Shemyakin, and Heikki Järvinen
Geosci. Model Dev., 13, 5799–5812,Short summary
This paper presents general guidelines on how to utilise computer algorithms efficiently in order to tune weather models so that they would produce better forecasts. The main conclusions are that the computer algorithms work most efficiently with a suitable cost function, certain forecast length and ensemble size. We expect that our results will facilitate the use of algorithmic methods in the tuning of weather models.
Andrea Vajda and Otto Hyvärinen
Adv. Sci. Res., 17, 269–277,Short summary
We studied the applicability of seasonal forecast outputs in agriculture in Finland. The quality of seasonal forecasts output was assessed, and six tailored seasonal forecast indices were co-designed, developed in close collaboration with the Central Union of Agricultural Producers and Forest Owners and piloted with over 200 farmers. Although the tested seasonal forecast indices had a limited skill and need further improvements, the farmers found the climate outlooks useful.
Irina A. Statnaia, Alexey Y. Karpechko, and Heikki J. Järvinen
Weather Clim. Dynam., 1, 657–674,Short summary
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.
Janne Lampilahti, Hanna Elina Manninen, Katri Leino, Riikka Väänänen, Antti Manninen, Stephany Buenrostro Mazon, Tuomo Nieminen, Matti Leskinen, Joonas Enroth, Marja Bister, Sergej Zilitinkevich, Juha Kangasluoma, Heikki Järvinen, Veli-Matti Kerminen, Tuukka Petäjä, and Markku Kulmala
Atmos. Chem. Phys., 20, 11841–11854,Short summary
In this work, by using co-located airborne and ground-based measurements, we show that counter-rotating horizontal circulations in the planetary boundary layer (roll vortices) frequently enhance regional new particle formation or induce localized bursts of new particle formation. These observations can be explained by the ability of the rolls to efficiently lift low-volatile vapors emitted from the surface to the top of the boundary layer where new particle formation is more favorable.
Otto Hyvärinen, Ari Venäläinen, and Andrea Vajda
Adv. Sci. Res., 17, 23–27,Short summary
The monthly mean soil moisture forecasts for forestry are been developed in the Finnish Meteorological Institute in cooperation with Finnish end-users. Such forecasts help in timber harvesting planning, and forecasts could large economic value. Therefore the skillfulness of forecasts was measured. Throughout the year the first month was skillful, and after that it can be hard to say if the forecasts are better than the normal conditions. Winter forecasts are a bit better than summer forecasts.
Victoria A. Sinclair, Mika Rantanen, Päivi Haapanala, Jouni Räisänen, and Heikki Järvinen
Weather Clim. Dynam., 1, 1–25,Short summary
We studied how mid-latitude cyclones are likely to change in the future. We used a state-of-the-art numerical model and performed a control and a
warmexperiment. The total number of cyclones did not change with warming and neither did the average strength, but there were more stronger and more weaker storms in the warm experiment. Precipitation associated with the most extreme mid-latitude cyclones increased by up to 50 % and occurred in a more poleward location in the warmer experiment.
Hannu Valta, Ilari Lehtonen, Terhi K. Laurila, Ari Venäläinen, Mikko Laapas, and Hilppa Gregow
Adv. Sci. Res., 16, 31–37,Short summary
A comparison of forest damage with windstorm intensity in Finland suggests that the volume of forest damage follows approximately a power relation as a function of wind gust speed with a power of ~10. This tentative estimate holds for typical windstorms having mainly westerly winds and affecting large areas in southern and central parts of Finland. The estimate can be utilized when preparing impact-based predictions of windstorms.
Ilari Lehtonen, Ari Venäläinen, Matti Kämäräinen, Antti Asikainen, Juha Laitila, Perttu Anttila, and Heli Peltola
Hydrol. Earth Syst. Sci., 23, 1611–1631,Short summary
Wintertime bearing capacity on different forest soils with respect to timber harvesting in the projected future climate of Finland was estimated by using a soil temperature model and a wide set of downscaled climate model simulations. The results indicate that, particularly, drained peatlands may virtually lack soil frost over large areas in most of winters during the late 21st century. There is thus a clear need to develop new sustainable and efficient logging practices for peatland forests.
Winfried Hoke, Tina Swierczynski, Peter Braesicke, Karin Lochte, Len Shaffrey, Martin Drews, Hilppa Gregow, Ralf Ludwig, Jan Even Øie Nilsen, Elisa Palazzi, Gianmaria Sannino, Lars Henrik Smedsrud, and ECRA network
Adv. Geosci., 46, 1–10,Short summary
The European Climate Research Alliance is a bottom-up association of European research institutions helping to facilitate the development of climate change research, combining the capacities of national research institutions and inducing closer ties between existing national research initiatives, projects and infrastructures. This article briefly introduces the network's structure and organisation, as well as project management issues and prospects.
Tiina Ervasti, Hilppa Gregow, Andrea Vajda, Terhi K. Laurila, and Antti Mäkelä
Adv. Sci. Res., 15, 99–106,Short summary
An online survey was used to map the needs and preferences of the Finnish general public about extended-range forecasts and their presentation. Survey results guided the co-design process of novel extended-range forecasts in the project. The respondents considered that the tailored extended-range forecasts would be beneficial in planning activities, preparing for weather risks and scheduling everyday life. They also valued impact information higher than advice on how to prepare for the impacts.
Atte Harjanne, Riina Haavisto, Heikki Tuomenvirta, and Hilppa Gregow
Adv. Sci. Res., 14, 293–304,Short summary
Weather, climate and climate change can cause significant risks to businesses and public administration. By asking Finnish organizations about their weather and climate risk perceptions and management, this study aims to improve ways climate services can support in adapting to current and future climate. The results indicate that climate risk management is often de-centralized and relies on expert networks but that practices differ between actors.
Otto Hyvärinen, Antti Mäkelä, Matti Kämäräinen, and Hilppa Gregow
Adv. Sci. Res., 14, 89–93,Short summary
Finnish Meteorological Institute and Helen Ltd examined the feasibility of long-range forecasts (longer than two weeks) of temperature for needs of the energy sector in Helsinki, Finland. In this study, we examined the quality of Heating degree day (HDD) forecasts. As the forecasts we used UK Met Office seasonal forecasts. The long-range forecasts of monthly HDD showed some skill in Helsinki in winter 2015–2016, up to two months, especially if the very cold January is excluded.
Matti Kämäräinen, Otto Hyvärinen, Kirsti Jylhä, Andrea Vajda, Simo Neiglick, Jaakko Nuottokari, and Hilppa Gregow
Nat. Hazards Earth Syst. Sci., 17, 243–259,Short summary
Freezing rain is a high-impact wintertime weather phenomenon. The direct damage it causes to critical infrastructure (transportation, communication and energy) and forestry can be substantial. In this work a method for estimating the occurrence of freezing rain was evaluated and used to derive the climatology. The method was able to accurately reproduce the observed, spatially aggregated annual variability. The highest frequencies of freezing rain were found in eastern and central Europe.
Mika Rantanen, Jouni Räisänen, Juha Lento, Oleg Stepanyuk, Olle Räty, Victoria A. Sinclair, and Heikki Järvinen
Geosci. Model Dev., 10, 827–841,Short summary
This paper describes new software OZO, which is a meteorological tool for both studying and research purposes. OZO can be used for investigating physical mechanisms affecting the development of extratropical cyclones. The software is an open-source tool and the distribution is supported by the authors. OZO will be used as a part of the author's PhD, in which the changes in cyclone dynamics due to warmer climate are studied.
Jarmo Mäkelä, Jouni Susiluoto, Tiina Markkanen, Mika Aurela, Heikki Järvinen, Ivan Mammarella, Stefan Hagemann, and Tuula Aalto
Nonlin. Processes Geophys., 23, 447–465,Short summary
The land-based hydrological cycle is one of the key processes controlling the growth and wilting of plants and the amount of carbon vegetation can assimilate. Recent studies have shown that many land surface models have biases in this area. We optimized parameters in one such model (JSBACH) and were able to enhance the model performance in many respects, but the response to drought remained unaffected. Further studies into this aspect should include alternative stomatal conductance formulations.
Hanna K. Lappalainen, Veli-Matti Kerminen, Tuukka Petäjä, Theo Kurten, Aleksander Baklanov, Anatoly Shvidenko, Jaana Bäck, Timo Vihma, Pavel Alekseychik, Meinrat O. Andreae, Stephen R. Arnold, Mikhail Arshinov, Eija Asmi, Boris Belan, Leonid Bobylev, Sergey Chalov, Yafang Cheng, Natalia Chubarova, Gerrit de Leeuw, Aijun Ding, Sergey Dobrolyubov, Sergei Dubtsov, Egor Dyukarev, Nikolai Elansky, Kostas Eleftheriadis, Igor Esau, Nikolay Filatov, Mikhail Flint, Congbin Fu, Olga Glezer, Aleksander Gliko, Martin Heimann, Albert A. M. Holtslag, Urmas Hõrrak, Juha Janhunen, Sirkku Juhola, Leena Järvi, Heikki Järvinen, Anna Kanukhina, Pavel Konstantinov, Vladimir Kotlyakov, Antti-Jussi Kieloaho, Alexander S. Komarov, Joni Kujansuu, Ilmo Kukkonen, Ella-Maria Duplissy, Ari Laaksonen, Tuomas Laurila, Heikki Lihavainen, Alexander Lisitzin, Alexsander Mahura, Alexander Makshtas, Evgeny Mareev, Stephany Mazon, Dmitry Matishov, Vladimir Melnikov, Eugene Mikhailov, Dmitri Moisseev, Robert Nigmatulin, Steffen M. Noe, Anne Ojala, Mari Pihlatie, Olga Popovicheva, Jukka Pumpanen, Tatjana Regerand, Irina Repina, Aleksei Shcherbinin, Vladimir Shevchenko, Mikko Sipilä, Andrey Skorokhod, Dominick V. Spracklen, Hang Su, Dmitry A. Subetto, Junying Sun, Arkady Y. Terzhevik, Yuri Timofeyev, Yuliya Troitskaya, Veli-Pekka Tynkkynen, Viacheslav I. Kharuk, Nina Zaytseva, Jiahua Zhang, Yrjö Viisanen, Timo Vesala, Pertti Hari, Hans Christen Hansson, Gennady G. Matvienko, Nikolai S. Kasimov, Huadong Guo, Valery Bondur, Sergej Zilitinkevich, and Markku Kulmala
Atmos. Chem. Phys., 16, 14421–14461,Short summary
After kick off in 2012, the Pan-Eurasian Experiment (PEEX) program has expanded fast and today the multi-disciplinary research community covers ca. 80 institutes and a network of ca. 500 scientists from Europe, Russia, and China. Here we introduce scientific topics relevant in this context. This is one of the first multi-disciplinary overviews crossing scientific boundaries, from atmospheric sciences to socio-economics and social sciences.
Heikki Järvinen, Teija Seitola, Johan Silén, and Jouni Räisänen
Geosci. Model Dev., 9, 4097–4109,Short summary
This study compares the 20th century multi-annual climate variability modes in reanalysis data sets (ERA-20C and 20CR) and 12 climate model simulations using the randomised multi-channel singular spectrum analysis. The reanalysis data sets are remarkably similar on all timescales, except that the spectral power in ERA-20C is systematically slightly higher than in 20CR. None of the climate models closely reproduce all aspects of the reanalysis spectra, although many aspects are represented well.
Ilari Lehtonen, Matti Kämäräinen, Hilppa Gregow, Ari Venäläinen, and Heli Peltola
Nat. Hazards Earth Syst. Sci., 16, 2259–2271,Short summary
We studied the impact of projected climate change on the risk of snow-induced forest damage in Finland. Although winters are projected to become milder over the whole of Finland, our results suggest than in eastern and northern Finland the risk may increase while in southern and western parts of the country it is projected to decrease. This indicates that there is increasing need to consider the potential of snow damage in forest management in eastern and northern Finland.
I. Lehtonen, A. Venäläinen, M. Kämäräinen, H. Peltola, and H. Gregow
Nat. Hazards Earth Syst. Sci., 16, 239–253,Short summary
The number of large forest fires in Finland will most likely increase during the twenty-first century in response to projected climate change. This would increase the risk that some of the fires could develop into real conflagrations which have become almost extinct in Finland due to effective fire suppression. However, our results show considerable inter-model variability, demonstrating the large uncertainty related to the rate of the projected change in forest-fire danger.
A. K. Kaiser-Weiss, F. Kaspar, V. Heene, M. Borsche, D. G. H. Tan, P. Poli, A. Obregon, and H. Gregow
Adv. Sci. Res., 12, 187–198,Short summary
Wind speed measured at the German stations correlate well with reanalysis fields. Monthly means from two global reanalyses (ERA-20C, ERA-Interim) and one regional reanalysis (COSMO-REA6) were analysed and correlate well for the majority of the German stations. Thus we conclude that the monthly and seasonal anomalies recorded at these stations can be understood as representative for a spatial area comparable to the resolution of the reanalyses, at least for the recent years.
P. Jokinen, A. Vajda, and H. Gregow
Adv. Sci. Res., 12, 97–101,Short summary
Emergency rescue data and weather reanalysis data were combined to study the spatial and decadal characteristics of potential forest damage days in Finland due to windstorms. The most prone area for damage days was the south-western part of Finland. Results also indicated a lull period during the 1990s compared to the 1980s and 2000s, albeit no trend was evident. The study highlighted the importance of not only focusing on wind speeds, but also soil conditions.
J. Tonttila, E. J. O'Connor, A. Hellsten, A. Hirsikko, C. O'Dowd, H. Järvinen, and P. Räisänen
Atmos. Chem. Phys., 15, 5873–5885,
H. Gregow, P. Poli, H. M. Mäkelä, K. Jylhä, A. K. Kaiser-Weiss, A. Obregon, D. G. H. Tan, S. Kekki, and F. Kaspar
Adv. Sci. Res., 12, 63–67,Short summary
Many users of climate information are unaware of the availability of reanalysis feedback data and input observations, and uptake of feedback data is rather low. The most important factors limiting the use of this data is that the users feel that there is no easy interface to get the data or they do not find it at all. The relevant communities should invest resources to develop tools and provide training to bridge the gap between current capabilities and comprehensive exploitation of the data.
O. Hyvärinen, L. Mtilatila, K. Pilli-Sihvola, A. Venäläinen, and H. Gregow
Adv. Sci. Res., 12, 31–36,Short summary
We assessed the quality of the seasonal precipitation forecasts issued by Regional Climate Outlook Forum for Malawi and Zambia. The forecasts, issued in August, are of rainy season rainfall accumulations for early and late season. The forecasts are rather well-calibrated, but cannot discriminate between different events. But these results can be too pessimistic, because forecasts have gone through much development lately, and forecasts using current methodology might have performed better.
H. Vuollekoski, M. Vogt, V. A. Sinclair, J. Duplissy, H. Järvinen, E.-M. Kyrö, R. Makkonen, T. Petäjä, N. L. Prisle, P. Räisänen, M. Sipilä, J. Ylhäisi, and M. Kulmala
Hydrol. Earth Syst. Sci., 19, 601–613,Short summary
The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilising 34 years of meteorological reanalysis data as input to a dew formation model. Continental dew formation was found to be frequent and common, but daily yields were mostly below 0.1mm.
J. Tonttila, H. Järvinen, and P. Räisänen
Atmos. Chem. Phys., 15, 703–714,
P. Räisänen, A. Luomaranta, H. Järvinen, M. Takala, K. Jylhä, O. N. Bulygina, K. Luojus, A. Riihelä, A. Laaksonen, J. Koskinen, and J. Pulliainen
Geosci. Model Dev., 7, 3037–3057,Short summary
Snowmelt influences greatly the climatic conditions in spring. This study evaluates the timing of springtime end of snowmelt in the ECHAM5 model. A key finding is that, in much of northern Eurasia, snow disappears too early in ECHAM5, in spite of a slight cold bias in spring. This points to the need for a more comprehensive treatment of the surface energy budget. In particular, the surface temperature for the snow-covered and snow-free parts of a climate model grid cell should be separated.
P. Ollinaho, H. Järvinen, P. Bauer, M. Laine, P. Bechtold, J. Susiluoto, and H. Haario
Geosci. Model Dev., 7, 1889–1900,
N. Korhonen, A. Venäläinen, H. Seppä, and H. Järvinen
Clim. Past, 10, 1489–1500,
M. Abbas, A. Ilin, A. Solonen, J. Hakkarainen, E. Oja, and H. Järvinen
Nonlin. Processes Geophys. Discuss.,
Revised manuscript not accepted
A. Venäläinen, N. Korhonen, O. Hyvärinen, N. Koutsias, F. Xystrakis, I. R. Urbieta, and J. M. Moreno
Nat. Hazards Earth Syst. Sci., 14, 1477–1490,
P. Ollinaho, P. Bechtold, M. Leutbecher, M. Laine, A. Solonen, H. Haario, and H. Järvinen
Nonlin. Processes Geophys., 20, 1001–1010,
J. Tonttila, P. Räisänen, and H. Järvinen
Atmos. Chem. Phys., 13, 7551–7565,
T. Viskari, E. Asmi, P. Kolmonen, H. Vuollekoski, T. Petäjä, and H. Järvinen
Atmos. Chem. Phys., 12, 11767–11779,
T. Viskari, E. Asmi, A. Virkkula, P. Kolmonen, T. Petäjä, and H. Järvinen
Atmos. Chem. Phys., 12, 11781–11793,
Related subject area
Subject: Dynamics | Research Activity: Atmospheric Modelling | Altitude Range: Stratosphere | Science Focus: Physics (physical properties and processes)The Brewer–Dobson circulation in CMIP6Climate impact of volcanic eruptions: the sensitivity to eruption season and latitude in MPI-ESM ensemble experimentsContributions of equatorial waves and small-scale convective gravity waves to the 2019/20 quasi-biennial oscillation (QBO) disruptionDifferences in the quasi-biennial oscillation response to stratospheric aerosol modification depending on injection strategy and speciesThe advective Brewer–Dobson circulation in the ERA5 reanalysis: climatology, variability, and trendsIs our dynamical understanding of the circulation changes associated with the Antarctic ozone hole sensitive to the choice of reanalysis dataset?The impact of increasing stratospheric radiative damping on the quasi-biennial oscillation periodAnalysis of recent lower-stratospheric ozone trends in chemistry climate modelsAsymmetry and pathways of inter-hemispheric transport in the upper troposphere and lower stratosphereEffects of prescribed CMIP6 ozone on simulating the Southern Hemisphere atmospheric circulation response to ozone depletionReanalysis intercomparison of potential vorticity and potential-vorticity-based diagnosticsSpecified dynamics scheme impacts on wave-mean ﬂow dynamics, convection, and tracer transport in CESM2 (WACCM6)Influence of the El Niño–Southern Oscillation on entry stratospheric water vapor in coupled chemistry–ocean CCMI and CMIP6 modelsReappraising the appropriate calculation of a common meteorological quantity: potential temperatureImpact of Lagrangian transport on lower-stratospheric transport timescales in a climate modelRole of equatorial waves and convective gravity waves in the 2015/16 quasi-biennial oscillation disruptionSensitivity of the Southern Hemisphere circumpolar jet response to Antarctic ozone depletion: prescribed versus interactive chemistryCharacterizing quasi-biweekly variability of the Asian monsoon anticyclone using potential vorticity and large-scale geopotential height fieldClimatological impact of the Brewer–Dobson circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalysesPolar stratospheric clouds initiated by mountain waves in a global chemistry–climate model: a missing piece in fully modelling polar stratospheric ozone depletionUsing the climate feedback response analysis method to quantify climate feedbacks in the middle atmosphereDeep-convective influence on the upper troposphere–lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign resultsThe effect of interactive ozone chemistry on weak and strong stratospheric polar vortex eventsLagrangian gravity wave spectra in the lower stratosphere of current (re)analysesRepresentation of the equatorial stratopause semiannual oscillation in global atmospheric reanalysesA convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphereSensitivity of age of air trends to the derivation method for non-linear increasing inert SF6Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming eventFuture trends in stratosphere-to-troposphere transport in CCMI modelsSimulating age of air and the distribution of SF6 in the stratosphere with the SILAM modelA tropospheric pathway of the stratospheric quasi-biennial oscillation (QBO) impact on the boreal winter polar vortexTemperature and tropopause characteristics from reanalyses data in the tropical tropopause layerThe efficiency of transport into the stratosphere via the Asian and North American summer monsoon circulationsEvidence of small-scale quasi-isentropic mixing in ridges of extratropical baroclinic wavesThe effect of atmospheric nudging on the stratospheric residual circulation in chemistry–climate modelsOn the representation of major stratospheric warmings in reanalysesInfluence of Arctic stratospheric ozone on surface climate in CCMI modelsQuantification of water vapour transport from the Asian monsoon to the stratosphereExtratropical age of air trends and causative factors in climate projection simulationsComposite analysis of the tropopause inversion layer in extratropical baroclinic wavesLagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipeDeriving stratospheric age of air spectra using an idealized set of chemically active trace gasesThe global diabatic circulation of the stratosphere as a metric for the Brewer–Dobson circulationThe importance of interactive chemistry for stratosphere–troposphere couplingFrom ERA-Interim to ERA5: the considerable impact of ECMWF's next-generation reanalysis on Lagrangian transport simulationsOn the value of reanalyses prior to 1979 for dynamical studies of stratosphere–troposphere couplingThe influence of mixing on the stratospheric age of air changes in the 21st centuryStructural changes in the shallow and transition branch of the Brewer–Dobson circulation induced by El NiñoQuantifying the variability of the annular modes: reanalysis uncertainty vs. sampling uncertaintyResponse of Arctic ozone to sudden stratospheric warmings
Marta Abalos, Natalia Calvo, Samuel Benito-Barca, Hella Garny, Steven C. Hardiman, Pu Lin, Martin B. Andrews, Neal Butchart, Rolando Garcia, Clara Orbe, David Saint-Martin, Shingo Watanabe, and Kohei Yoshida
Atmos. Chem. Phys., 21, 13571–13591,Short summary
The stratospheric Brewer–Dobson circulation (BDC), responsible for transporting mass, tracers and heat globally in the stratosphere, is evaluated in a set of state-of-the-art climate models. The acceleration of the BDC in response to increasing greenhouse gases is most robust in the lower stratosphere. At higher levels, the well-known inconsistency between model and observational BDC trends can be partly reconciled by accounting for limited sampling and large uncertainties in the observations.
Zhihong Zhuo, Ingo Kirchner, Stephan Pfahl, and Ulrich Cubasch
Atmos. Chem. Phys., 21, 13425–13442,Short summary
The impact of volcanic eruptions varies with eruption season and latitude. This study simulated eruptions at different latitudes and in different seasons with a fully coupled climate model. The climate impacts of northern and southern hemispheric eruptions are reversed but are insensitive to eruption season. Results suggest that the regional climate impacts are due to the dynamical response of the climate system to radiative effects of volcanic aerosols and the subsequent regional feedbacks.
Min-Jee Kang and Hye-Yeong Chun
Atmos. Chem. Phys., 21, 9839–9857,Short summary
In winter 2019/20, the westerly quasi-biennial oscillation (QBO) phase was disrupted again by easterly winds. It is found that strong Rossby waves from the Southern Hemisphere weaken the jet core in early stages, and strong mixed Rossby–gravity waves reverse the wind in later stages. Inertia–gravity waves and small-scale convective gravity waves also provide negative forcing. These strong waves are attributed to an anomalous wind profile, barotropic instability, and slightly strong convection.
Henning Franke, Ulrike Niemeier, and Daniele Visioni
Atmos. Chem. Phys., 21, 8615–8635,Short summary
Stratospheric aerosol modification (SAM) can alter the quasi-biennial oscillation (QBO). Our simulations with two different models show that the characteristics of the QBO response are primarily determined by the meridional structure of the aerosol-induced heating. Therefore, the QBO response to SAM depends primarily on the location of injection, while injection type and rate act to scale the specific response. Our results have important implications for evaluating adverse side effects of SAM.
Mohamadou Diallo, Manfred Ern, and Felix Ploeger
Atmos. Chem. Phys., 21, 7515–7544,Short summary
Despite good agreement in the spatial structure, there are substantial differences in the strength of the Brewer–Dobson circulation (BDC) and its modulations in the UTLS and upper stratosphere. The tropical upwelling is generally weaker in ERA5 than in ERAI due to weaker planetary and gravity wave breaking in the UTLS. Analysis of the BDC trend shows an acceleration of the BDC of about 1.5 % decade-1 due to the long-term intensification in wave breaking, consistent with climate predictions.
Andrew Orr, Hua Lu, Patrick Martineau, Edwin P. Gerber, Gareth J. Marshall, and Thomas J. Bracegirdle
Atmos. Chem. Phys., 21, 7451–7472,Short summary
Reanalysis datasets combine observations and weather forecast simulations to create our best estimate of the state of the atmosphere and are important for climate monitoring. Differences in the technical details of these products mean that they may give different results. This study therefore examined how changes associated with the so-called Antarctic ozone hole are represented, which is one of the most important climate changes in recent decades, and showed that they were broadly consistent.
Tiehan Zhou, Kevin DallaSanta, Larissa Nazarenko, Gavin A. Schmidt, and Zhonghai Jin
Atmos. Chem. Phys., 21, 7395–7407,Short summary
Stratospheric radiative damping increases with rising CO2. Sensitivity experiments using the one-dimensional mechanistic models of the quasi-biennial oscillation (QBO) indicate a shortening of the simulated QBO period due to the enhancing of the radiative damping. This result suggests that increasing radiative damping may play a role in determining the QBO period in a warming climate along with wave momentum flux entering the stratosphere and tropical vertical residual velocity.
Simone Dietmüller, Hella Garny, Roland Eichinger, and William T. Ball
Atmos. Chem. Phys., 21, 6811–6837,
Xiaolu Yan, Paul Konopka, Marius Hauck, Aurélien Podglajen, and Felix Ploeger
Atmos. Chem. Phys., 21, 6627–6645,Short summary
Inter-hemispheric transport is important for understanding atmospheric tracers because of the asymmetry in emissions between the Southern Hemisphere (SH) and Northern Hemisphere (NH). This study finds that the air masses from the NH extratropics to the atmosphere are about 5 times larger than those from the SH extratropics. The interplay between the Asian summer monsoon and westerly ducts triggers the cross-Equator transport from the NH to the SH in boreal summer and fall.
Ioana Ivanciu, Katja Matthes, Sebastian Wahl, Jan Harlaß, and Arne Biastoch
Atmos. Chem. Phys., 21, 5777–5806,Short summary
The Antarctic ozone hole has driven substantial dynamical changes in the Southern Hemisphere atmosphere over the past decades. This study separates the historical impacts of ozone depletion from those of rising levels of greenhouse gases and investigates how these impacts are captured in two types of climate models: one using interactive atmospheric chemistry and one prescribing the CMIP6 ozone field. The effects of ozone depletion are more pronounced in the model with interactive chemistry.
Luis F. Millán, Gloria L. Manney, and Zachary D. Lawrence
Atmos. Chem. Phys., 21, 5355–5376,Short summary
We assess how consistently reanalyses represent potential vorticity (PV) among each other. PV helps describe dynamical processes in the stratosphere because it acts approximately as a tracer of the movement of air parcels; it is extensively used to identify the location of the tropopause and to identify and characterize the stratospheric polar vortex. Overall, PV from all reanalyses agrees well with the reanalysis ensemble mean.
Nicholas A. Davis, Patrick Callaghan, Isla R. Simpson, and Simone Tilmes
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
Specified dynamics schemes attempt to constrain the atmospheric circulation in a climate model to isolate the role of transport in chemical variability, evaluate model physics, and interpret field campaign observations. We show that the specified dynamics scheme in CESM2 erroneously suppresses convection and induces circulation errors that project onto errors in tracers, even using the most optimal settings. Development of a more sophisticated scheme is necessary for future progress.
Chaim I. Garfinkel, Ohad Harari, Shlomi Ziskin Ziv, Jian Rao, Olaf Morgenstern, Guang Zeng, Simone Tilmes, Douglas Kinnison, Fiona M. O'Connor, Neal Butchart, Makoto Deushi, Patrick Jöckel, Andrea Pozzer, and Sean Davis
Atmos. Chem. Phys., 21, 3725–3740,Short summary
Water vapor is the dominant greenhouse gas in the atmosphere, and El Niño is the dominant mode of variability in the ocean–atmosphere system. The connection between El Niño and water vapor above ~ 17 km is unclear, with single-model studies reaching a range of conclusions. This study examines this connection in 12 different models. While there are substantial differences among the models, all models appear to capture the fundamental physical processes correctly.
Manuel Baumgartner, Ralf Weigel, Allan H. Harvey, Felix Plöger, Ulrich Achatz, and Peter Spichtinger
Atmos. Chem. Phys., 20, 15585–15616,Short summary
The potential temperature is routinely used in atmospheric science. We review its derivation and suggest a new potential temperature, based on a temperature-dependent parameterization of the dry air's specific heat capacity. Moreover, we compare the new potential temperature to the common one and discuss the differences which become more important at higher altitudes. Finally, we indicate some consequences of using the new potential temperature in typical applications.
Edward J. Charlesworth, Ann-Kristin Dugstad, Frauke Fritsch, Patrick Jöckel, and Felix Plöger
Atmos. Chem. Phys., 20, 15227–15245,Short summary
Modeling the stratosphere requires models with good representations of chemical transport. To do this, nearly all models divide the atmosphere into boxes. This creates some unwanted problems. However, the only other option is to divide the atmosphere into balloons, and this method is very complicated. Here, we use a model which uses this balloon-like method to estimate the impacts of this method on chemical transport. We find significant differences in sensitive regions of the stratosphere.
Min-Jee Kang, Hye-Yeong Chun, and Rolando R. Garcia
Atmos. Chem. Phys., 20, 14669–14693,Short summary
In winter 2015/16, the descent of the westerly quasi-biennial oscillation (QBO) jet was interrupted by easterly winds. We find that Rossby–gravity and inertia–gravity waves weaken the jet core in early stages, and small-scale convective gravity waves, as well as horizontal and vertical components of Rossby waves, reverse the wind sign in later stages. The strong negative wave forcing in the tropics results from the enhanced convection, an anomalous wind profile, and barotropic instability.
Sabine Haase, Jaika Fricke, Tim Kruschke, Sebastian Wahl, and Katja Matthes
Atmos. Chem. Phys., 20, 14043–14061,Short summary
Ozone depletion over Antarctica was shown to influence the tropospheric jet in the Southern Hemisphere. We investigate the atmospheric response to ozone depletion comparing climate model ensembles with interactive and prescribed ozone fields. We show that allowing feedbacks between ozone chemistry and model physics as well as including asymmetries in ozone leads to a strengthened ozone depletion signature in the stratosphere but does not significantly affect the tropospheric jet position.
Arata Amemiya and Kaoru Sato
Atmos. Chem. Phys., 20, 13857–13876,Short summary
The spatial pattern of subseasonal variability of the Asian monsoon anticyclone (AMA) is analyzed using long-term reanalysis data, integrating two different views using potential vorticity and the geopotential height anomaly. This study provides a link between two existing description of the Asian monsoon anticyclone, which is important for the understanding of the whole life cycle of its characteristic subseasonal variability pattern.
Daniele Minganti, Simon Chabrillat, Yves Christophe, Quentin Errera, Marta Abalos, Maxime Prignon, Douglas E. Kinnison, and Emmanuel Mahieu
Atmos. Chem. Phys., 20, 12609–12631,Short summary
The climatology of the N2O transport budget in the stratosphere is studied in the transformed Eulerian mean framework across a variety of datasets: a chemistry climate model, a chemistry transport model driven by four reanalyses and a chemical reanalysis. The impact of vertical advection on N2O agrees well in the datasets, but horizontal mixing presents large differences above the Antarctic and in the whole Northern Hemisphere.
Andrew Orr, J. Scott Hosking, Aymeric Delon, Lars Hoffmann, Reinhold Spang, Tracy Moffat-Griffin, James Keeble, Nathan Luke Abraham, and Peter Braesicke
Atmos. Chem. Phys., 20, 12483–12497,Short summary
Polar stratospheric clouds (PSCs) are clouds found in the Antarctic winter stratosphere and are implicated in the formation of the ozone hole. These clouds can sometimes be formed or enhanced by mountain waves, formed as air passes over hills or mountains. However, this important mechanism is missing in coarse-resolution climate models, limiting our ability to simulate ozone. This study examines an attempt to include the effects of mountain waves and their impact on PSCs and ozone.
Maartje Sanne Kuilman, Qiong Zhang, Ming Cai, and Qin Wen
Atmos. Chem. Phys., 20, 12409–12430,Short summary
In this study, we quantify the temperature changes in the middle atmosphere due to different feedback processes using the climate feedback response analysis method. We have found that the change due to the increase in CO2 alone cools the middle atmosphere. The combined effect of the different feedbacks causes the atmosphere to cool less. The ozone feedback is the most important feedback process, while the cloud, water vapour and albedo feedback play only a minor role.
Silvia Bucci, Bernard Legras, Pasquale Sellitto, Francesco D'Amato, Silvia Viciani, Alessio Montori, Antonio Chiarugi, Fabrizio Ravegnani, Alexey Ulanovsky, Francesco Cairo, and Fred Stroh
Atmos. Chem. Phys., 20, 12193–12210,Short summary
The paper presents and evaluates a transport analysis method to study the convective injection of air in the upper troposphere–lower stratosphere of the Asian monsoon anticyclone region. The approach is thereby used to analyse the trace gas data collected during the StratoClim aircraft campaign. The results showed that fresh convective air can be injected fast at a high level of the atmosphere (above 17 km), with potential impacts on the stratospheric chemistry of the Northern Hemisphere.
Jessica Oehrlein, Gabriel Chiodo, and Lorenzo M. Polvani
Atmos. Chem. Phys., 20, 10531–10544,Short summary
Winter winds in the stratosphere 10–50 km above the surface impact climate at the surface. Prior studies suggest that this interaction between the stratosphere and the surface is affected by ozone. We compare two ways of including ozone in computer simulations of climate. One method is more realistic but more expensive. We find that the method of including ozone in simulations affects the surface climate when the stratospheric winds are unusually weak but not when they are unusually strong.
Aurélien Podglajen, Albert Hertzog, Riwal Plougonven, and Bernard Legras
Atmos. Chem. Phys., 20, 9331–9350,Short summary
Thanks to the increase in resolution, numerical weather prediction models resolve a growing fraction of the gravity wave (GW) spectrum. Here, we assess the representation of Lagrangian GW fluctuations by comparing trajectories in the models to long-duration balloon observations. Most characteristics of the observed GW spectrum, such as near-inertial oscillations, are qualitatively present. However, the variability remains underestimated, emphasizing the continuous need for GW parameterizations.
Yoshio Kawatani, Toshihiko Hirooka, Kevin Hamilton, Anne K. Smith, and Masatomo Fujiwara
Atmos. Chem. Phys., 20, 9115–9133,Short summary
This paper reports on a project to compare the representation of the semiannual oscillation (SAO) among six major global atmospheric reanalyses and with recent satellite observations. The differences among the zonal mean zonal wind as represented by the various reanalyses display a prominent equatorial maximum that increases with height. It is shown that assimilation of satellite temperature measurements is crucial for the realistic representation of the tropical upper stratospheric circulation.
Marius Hauck, Harald Bönisch, Peter Hoor, Timo Keber, Felix Ploeger, Tanja J. Schuck, and Andreas Engel
Atmos. Chem. Phys., 20, 8763–8785,Short summary
This study features an extended inversion method that includes transport across the extratropical tropopause to derive age spectra in the lowermost stratosphere from in situ trace gas measurements. The refined method is validated in a model setup and applied to data gained with the HALO research aircraft. Results are congruent with the findings of previous studies so that the method provides a promising toolset for the analysis of stratospheric dynamics based on observations in the future.
Frauke Fritsch, Hella Garny, Andreas Engel, Harald Bönisch, and Roland Eichinger
Atmos. Chem. Phys., 20, 8709–8725,Short summary
We test two methods to derive age of air as a diagnostic of the Brewer–Dobson circulation from non-linear increasing trace gases such as SF6 using a chemistry-climate model and observations. Both the model and the observations show systematic variation of the age of air trend dependent on the chosen assumptions that are required when deriving age of air from measurements. This provides insight into the differences in age of air trends of observations and models.
In-Sun Song, Changsup Lee, Hye-Yeong Chun, Jeong-Han Kim, Geonhwa Jee, Byeong-Gwon Song, and Julio T. Bacmeister
Atmos. Chem. Phys., 20, 7617–7644,Short summary
A modeling study on the effects of propagation of atmospheric gravity waves is carried out for the 2009 sudden stratospheric warming (SSW) event. It is found that gravity-wave-induced momentum fluxes are significantly affected by horizontal refraction and the Earth's curvature effects. Gravity wave convergence and effects of ray geometry also have some impact. In the evolution of the SSW, significantly enhanced momentum fluxes are likely to change nonlocally nearby large-scale vortex structures.
Marta Abalos, Clara Orbe, Douglas E. Kinnison, David Plummer, Luke D. Oman, Patrick Jöckel, Olaf Morgenstern, Rolando R. Garcia, Guang Zeng, Kane A. Stone, and Martin Dameris
Atmos. Chem. Phys., 20, 6883–6901,Short summary
A set of state-of-the art chemistry–climate models is used to examine future changes in downward transport from the stratosphere, a key contributor to tropospheric ozone. The acceleration of the stratospheric circulation results in increased stratosphere-to-troposphere transport. In the subtropics, downward advection into the troposphere is enhanced due to climate change. At higher latitudes, the ozone reservoir above the tropopause is enlarged due to the stronger circulation and ozone recovery.
Rostislav Kouznetsov, Mikhail Sofiev, Julius Vira, and Gabriele Stiller
Atmos. Chem. Phys., 20, 5837–5859,Short summary
Estimates of the age of stratospheric air (AoA), its distribution, and trends, obtained by different experimental methods, differ among each other. AoA derived form MIPAS satellite observations, the richest observational dataset on sulfur hexafluoride (SF6) in the stratosphere, are a clear outlier. With multi-decade simulations of AoA and SF6 in the stratosphere, we show that the origin of the discrepancy is in a methodology of deriving AoA from observations rather than in observational data.
Koji Yamazaki, Tetsu Nakamura, Jinro Ukita, and Kazuhira Hoshi
Atmos. Chem. Phys., 20, 5111–5127,Short summary
It has been well known that the stratospheric quasi-biennial oscillation (QBO) affects the winter Arctic polar vortex. This relation has been explained through stratospheric processes. We show that a tropospheric process also plays a role, especially in early winter, based on data analysis and numerical simulations. The QBO modifies tropical convection, which affects planetary waves in the midlatitude troposphere, then modulating vertical propagation and the polar vortex.
Susann Tegtmeier, James Anstey, Sean Davis, Rossana Dragani, Yayoi Harada, Ioana Ivanciu, Robin Pilch Kedzierski, Kirstin Krüger, Bernard Legras, Craig Long, James S. Wang, Krzysztof Wargan, and Jonathon S. Wright
Atmos. Chem. Phys., 20, 753–770,Short summary
The tropical tropopause layer is an important atmospheric region right in between the troposphere and the stratosphere. We evaluate the representation of this layer in reanalyses data sets, which create a complete picture of the state of Earth's atmosphere using atmospheric modeling and available observations. The recent reanalyses show realistic temperatures in the tropical tropopause layer. However, where the temperature is lowest, the so-called cold point, the reanalyses are too cold.
Xiaolu Yan, Paul Konopka, Felix Ploeger, Aurélien Podglajen, Jonathon S. Wright, Rolf Müller, and Martin Riese
Atmos. Chem. Phys., 19, 15629–15649,Short summary
The Asian and North American summer monsoons (ASM and NASM) have considerable influence on stratospheric chemistry and physics. More air mass is transported from the monsoon regions to the tropical stratosphere when the tracers are released clearly below the tropopause than when they are released close to the tropopause. Results for different altitudes of air origin reveal two transport pathways (monsoon and tropical) from the upper troposphere over the monsoon regions to the tropical pipe.
Daniel Kunkel, Peter Hoor, Thorsten Kaluza, Jörn Ungermann, Björn Kluschat, Andreas Giez, Hans-Christoph Lachnitt, Martin Kaufmann, and Martin Riese
Atmos. Chem. Phys., 19, 12607–12630,Short summary
In this study we present a mixing process around the tropopause in extratropical baroclinic waves. We analyze airborne data from a flight during the WISE campaign in autumn 2017 over the North Atlantic. We use idealized experiments to study the mixing process. Although the process occurs on a small geographical scale, it might be of importance due to its relation to a frequent feature of the extratropical UTLS. The process is relevant for STE but is not fully included in climatologies.
Andreas Chrysanthou, Amanda C. Maycock, Martyn P. Chipperfield, Sandip Dhomse, Hella Garny, Douglas Kinnison, Hideharu Akiyoshi, Makoto Deushi, Rolando R. Garcia, Patrick Jöckel, Oliver Kirner, Giovanni Pitari, David A. Plummer, Laura Revell, Eugene Rozanov, Andrea Stenke, Taichu Y. Tanaka, Daniele Visioni, and Yousuke Yamashita
Atmos. Chem. Phys., 19, 11559–11586,Short summary
We perform the first multi-model comparison of the impact of nudged meteorology on the stratospheric residual circulation (RC) in chemistry–climate models. Nudging meteorology does not constrain the mean strength of RC compared to free-running simulations, and despite the lack of agreement in the mean circulation, nudging tightly constrains the inter-annual variability in the tropical upward mass flux in the lower stratosphere. In summary, nudging strongly affects the representation of RC.
Blanca Ayarzagüena, Froila M. Palmeiro, David Barriopedro, Natalia Calvo, Ulrike Langematz, and Kiyotaka Shibata
Atmos. Chem. Phys., 19, 9469–9484,Short summary
Sudden stratospheric warmings (SSWs) are abrupt rises in the wintertime polar stratosphere that also affect the troposphere. Their study is hampered by the limited observations in the stratosphere and mostly relies on reanalyses, i.e., models that include observations. Here we compare the representation of SSWs by the most used reanalyses. SSW results are consistent across reanalyses but some differences are found, in particular before the satellite era.
Ohad Harari, Chaim I. Garfinkel, Shlomi Ziskin Ziv, Olaf Morgenstern, Guang Zeng, Simone Tilmes, Douglas Kinnison, Makoto Deushi, Patrick Jöckel, Andrea Pozzer, Fiona M. O'Connor, and Sean Davis
Atmos. Chem. Phys., 19, 9253–9268,Short summary
Ozone depletion in the Antarctic has been shown to influence surface conditions, but the effects of ozone depletion in the Arctic on surface climate are unclear. We show that Arctic ozone does influence surface climate in both polar regions and tropical regions, though the proximate cause of these surface impacts is not yet clear.
Matthias Nützel, Aurélien Podglajen, Hella Garny, and Felix Ploeger
Atmos. Chem. Phys., 19, 8947–8966,Short summary
We investigate the transport pathways of water vapour from the upper troposphere in the Asian monsoon region to the stratosphere. In the employed chemistry-transport model we use a tagging method, such that the impact of different source regions on the stratospheric water vapour budget can be quantified. A key finding is that the Asian monsoon (compared to other source regions) is very efficient in transporting air masses and water vapour to the tropical and extratropical stratosphere.
Petr Šácha, Roland Eichinger, Hella Garny, Petr Pišoft, Simone Dietmüller, Laura de la Torre, David A. Plummer, Patrick Jöckel, Olaf Morgenstern, Guang Zeng, Neal Butchart, and Juan A. Añel
Atmos. Chem. Phys., 19, 7627–7647,Short summary
Climate models robustly project a Brewer–Dobson circulation (BDC) acceleration in the course of climate change. Analyzing mean age of stratospheric air (AoA) from a subset of climate projection simulations, we find a remarkable agreement in simulating the largest AoA trends in the extratropical stratosphere. This is shown to be related with the upward shift of the circulation, resulting in a so-called stratospheric shrinkage, which could be one of the so-far-omitted BDC acceleration drivers.
Thorsten Kaluza, Daniel Kunkel, and Peter Hoor
Atmos. Chem. Phys., 19, 6621–6636,Short summary
We present a comprehensive mean evolution of the tropopause inversion layer in mid-latitudes, an atmospheric feature that is located in the region that separates the well-mixed troposphere and the stably stratified stratosphere. We counter-intuitively find this region, which is expected to stabilise atmospheric flow, to exhibit favourable conditions for turbulent exchange between troposphere and stratosphere. This is an important result concerning the overall assessment of exchange processes.
Bärbel Vogel, Rolf Müller, Gebhard Günther, Reinhold Spang, Sreeharsha Hanumanthu, Dan Li, Martin Riese, and Gabriele P. Stiller
Atmos. Chem. Phys., 19, 6007–6034,Short summary
We identified the transport pathways of air masses from the region of the Asian monsoon (e.g. pollution and greenhouse gases caused by increasing population and growing industries in Asia) into the lower stratosphere. Even small changes of the chemical composition of the lower stratosphere have an impact on surface climate (e.g. surface temperatures). Therefore, it is important to identify transport pathways to the stratosphere to allow potential environmental risks to be assessed.
Marius Hauck, Frauke Fritsch, Hella Garny, and Andreas Engel
Atmos. Chem. Phys., 19, 5269–5291,Short summary
The paper presents a modified method to invert mixing ratios of chemically active tracers into stratospheric age spectra. It features an imposed seasonal cycle to include transport seasonality into the spectra. An idealized set of tracers from a model is used as proof of concept and results are in good agreement with the model reference, except for the lowermost stratosphere. Applicability is studied with focus on number of tracers and error tolerance, providing a starting point for future work.
Marianna Linz, Marta Abalos, Anne Sasha Glanville, Douglas E. Kinnison, Alison Ming, and Jessica L. Neu
Atmos. Chem. Phys., 19, 5069–5090,Short summary
The stratospheric circulation is important for transporting ozone and water vapor, and models of the stratosphere differ. The metrics used to compare models are inconsistent between studies and cannot be calculated from observational data. In this paper, we explore a metric for the circulation that can be calculated from observations and examine how it relates to the more commonly used metrics. We find substantial differences in the upper and lower stratosphere depending on the choice of metric.
Sabine Haase and Katja Matthes
Atmos. Chem. Phys., 19, 3417–3432,Short summary
The Antarctic ozone hole influences surface climate in the Southern Hemisphere. Recent studies have shown that stratospheric ozone depletion in the Arctic can also affect the surface. We evaluate the importance of the direct and indirect representation of ozone variability in a climate model for this surface response. We show that allowing feedbacks between ozone chemistry, radiation, and dynamics enhances and prolongs the surface response to Northern Hemisphere spring ozone depletion.
Lars Hoffmann, Gebhard Günther, Dan Li, Olaf Stein, Xue Wu, Sabine Griessbach, Yi Heng, Paul Konopka, Rolf Müller, Bärbel Vogel, and Jonathon S. Wright
Atmos. Chem. Phys., 19, 3097–3124,Short summary
ECMWF's new ERA5 reanalysis provides higher spatiotemporal resolution, yielding an improved representation of meso- and synoptic-scale features of the atmosphere. We assessed the impact of this challenging new data set on Lagrangian trajectory calculations for the free troposphere and stratosphere. Key findings are considerable transport deviations between the ERA5 and ERA-Interim simulations as well as significantly improved conservation of potential temperature in the stratosphere for ERA5.
Atmos. Chem. Phys., 19, 2749–2764,Short summary
Studies of the dynamics of stratosphere–troposphere coupling benefit from long observational records in order to distinguish common dynamical features from unrelated atmospheric variability. On the basis of a comparison between a range of reanalysis products, this study argues that the period from 1958 to 1979 is of significant value in the Northern Hemisphere for this purpose, despite the lack of global satellite records.
Roland Eichinger, Simone Dietmüller, Hella Garny, Petr Šácha, Thomas Birner, Harald Bönisch, Giovanni Pitari, Daniele Visioni, Andrea Stenke, Eugene Rozanov, Laura Revell, David A. Plummer, Patrick Jöckel, Luke Oman, Makoto Deushi, Douglas E. Kinnison, Rolando Garcia, Olaf Morgenstern, Guang Zeng, Kane Adam Stone, and Robyn Schofield
Atmos. Chem. Phys., 19, 921–940,Short summary
To shed more light upon the changes in stratospheric circulation in the 21st century, climate projection simulations of 10 state-of-the-art global climate models, spanning from 1960 to 2100, are analyzed. The study shows that in addition to changes in transport, mixing also plays an important role in stratospheric circulation and that the properties of mixing vary over time. Furthermore, the influence of mixing is quantified and a dynamical framework is provided to understand the changes.
Mohamadou Diallo, Paul Konopka, Michelle L. Santee, Rolf Müller, Mengchu Tao, Kaley A. Walker, Bernard Legras, Martin Riese, Manfred Ern, and Felix Ploeger
Atmos. Chem. Phys., 19, 425–446,Short summary
This paper assesses the structural changes in the shallow and transition branches of the BDC induced by El Nino using the Lagrangian model simulations driven by ERAi and JRA-55 combined with MLS observations. We found a clear evidence of a weakening of the transition branch due to an upward shift in the dissipation height of the planetary and gravity waves and a strengthening of the shallow branch due to enhanced GW breaking in the tropics–subtropics and PW breaking at high latitudes.
Edwin P. Gerber and Patrick Martineau
Atmos. Chem. Phys., 18, 17099–17117,Short summary
The annular modes characterize the variability of the extratropical circulation. We show that they are extremely consistent across all reanalyses during the satellite era (1979 onward). Consequently, uncertainty in the annual cycle of variability of the tropospheric jet streams and their coupling with the stratospheric polar vortices is dominated by sampling uncertainty. Pre-satellite reanalysis of the Northern Hemisphere appears to be of high quality and can help reduce this uncertainty.
Alvaro de la Cámara, Marta Abalos, Peter Hitchcock, Natalia Calvo, and Rolando R. Garcia
Atmos. Chem. Phys., 18, 16499–16513,Short summary
Long chemistry–climate runs are used to investigate the changes that sudden stratospheric warmings (extreme and fast disruptions of the wintertime stratospheric polar vortex) induce on Arctic ozone. Ozone increases rapidly during the onset of the events, driven by deep changes in the stratospheric transport circulation. These anomalies decay slowly, particularly in the lower stratosphere where they can last up to 2 months. Irreversible mixing makes an important contribution to this behavior.
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Reanalysis data of the strength of the polar vortex is applied in the post-processing of the European Centre for Medium-Range Weather Forecasts (ECMWF) winter surface temperature forecasts for weeks 3–4 and 5–6 over northern Europe. In this way, the skill scores of these forecasts are slightly improved. It is also found that, in cases where the polar vortex was weak at the start of the forecast, the mean skill scores of these forecasts were higher than average.
Reanalysis data of the strength of the polar vortex is applied in the post-processing of the...