Academic literature on the topic 'Atmospheric circulation Southern Hemisphere Mathematical models'
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Journal articles on the topic "Atmospheric circulation Southern Hemisphere Mathematical models"
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Braesicke, P., J. Keeble, X. Yang, G. Stiller, S. Kellmann, N. L. Abraham, A. Archibald, P. Telford, and J. A. Pyle. "Circulation anomalies in the Southern Hemisphere and ozone changes." Atmospheric Chemistry and Physics 13, no. 21 (November 4, 2013): 10677–88. http://dx.doi.org/10.5194/acp-13-10677-2013.
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Abstract. We report results from two pairs of chemistry-climate model simulations using the same climate model but different chemical perturbations. In each pair of experiments an ozone change was triggered by a simple change in the chemistry. One pair of model experiments looked at the impact of polar stratospheric clouds (PSCs) and the other pair at the impact of short-lived halogenated species on composition and circulation. The model response is complex with both positive and negative changes in ozone concentration, depending on location. These changes result from coupling between composition, temperature and circulation. Even though the causes of the modelled ozone changes are different, the high latitude Southern Hemisphere response in the lower stratosphere is similar. In both pairs of experiments the high-latitude circulation changes, as evidenced by N2O differences, are suggesting a slightly longer-lasting/stronger stratospheric descent in runs with higher ozone destruction (a manifestation of a seasonal shift in the circulation). We contrast the idealised model behaviour with interannual variability in ozone and N2O as observed by the MIPAS instrument on ENVISAT, highlighting similarities of the modelled climate equilibrium changes to the year 2006–2007 in observations. We conclude that the climate system can respond quite sensitively in its seasonal evolution to small chemical perturbations, that circulation adjustments seen in the model can occur in reality, and that coupled chemistry-climate models allow a better assessment of future ozone and climate change than recent CMIP-type models with prescribed ozone fields.
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Grainger, S., C. S. Frederiksen, and X. Zheng. "Interannual modes of variability of Southern Hemisphere atmospheric circulation in CMIP3 models." IOP Conference Series: Earth and Environmental Science 11 (August 1, 2010): 012027. http://dx.doi.org/10.1088/1755-1315/11/1/012027.
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Barnes, Elizabeth A., Susan Solomon, and Lorenzo M. Polvani. "Robust Wind and Precipitation Responses to the Mount Pinatubo Eruption, as Simulated in the CMIP5 Models." Journal of Climate 29, no. 13 (June 14, 2016): 4763–78. http://dx.doi.org/10.1175/jcli-d-15-0658.1.
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Abstract The volcanic eruption of Mount Pinatubo in June 1991 is the largest terrestrial eruption since the beginning of the satellite era. Here, the monthly evolution of atmospheric temperature, zonal winds, and precipitation following the eruption in 14 CMIP5 models is analyzed and strong and robust stratospheric and tropospheric circulation responses are demonstrated in both hemispheres, with tropospheric anomalies maximizing in November 1991. The simulated Southern Hemisphere circulation response projects strongly onto the positive phase of the southern annular mode (SAM), while the Northern Hemisphere exhibits robust North Atlantic and North Pacific responses that differ significantly from that of the typical northern annular mode (NAM) pattern. In contrast, observations show a negative SAM following the eruption, and internal variability must be considered along with forced responses. Indeed, evidence is presented that the observed El Niño climate state during and after this eruption may oppose the eruption-forced positive SAM response, based on the El Niño–Southern Oscillation (ENSO) state and SAM response across the models. The results demonstrate that Pinatubo-like eruptions should be expected to force circulation anomalies across the globe and highlight that great care must be taken in diagnosing the forced response as it may not fall into typical seasonal averages or be guaranteed to project onto typical climate modes.
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Grainger, Simon, Carsten S. Frederiksen, and Xiaogu Zheng. "Assessment of Modes of Interannual Variability of Southern Hemisphere Atmospheric Circulation in CMIP5 Models." Journal of Climate 27, no. 21 (October 24, 2014): 8107–25. http://dx.doi.org/10.1175/jcli-d-14-00251.1.
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Abstract An assessment is made of the modes of interannual variability in the seasonal mean summer and winter Southern Hemisphere (SH) 500-hPa geopotential height in the twentieth century in models from the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) dataset. Modes of variability of both the slow (signal) and intraseasonal (noise) components in the CMIP5 models are evaluated against those estimated from reanalysis data. There is general improvement in the leading modes of the slow (signal) component in CMIP5 models compared with the CMIP phase 3 (CMIP3) dataset. The largest improvement is in the spatial structures of the modes related to El Niño–Southern Oscillation variability in SH summer. An overall score metric is significantly higher for CMIP5 over CMIP3 in both seasons. The leading modes in the intraseasonal noise component are generally well reproduced in CMIP5 models, and there are few differences from CMIP3. A new total overall score metric is used to rank the CMIP5 models over both seasons. Weighting the seasons by the relative spread of overall scores is shown to be suitable for generating multimodel ensembles for further analysis of interannual variability. In multimodel ensembles, it is found that an ensemble of size 5 or 6 is sufficient in SH summer to reproduce well the dominant modes. In contrast, about 13 models are typically are required in SH winter. It is shown that it is necessary that the selected models individually reproduce well the leading modes of the slow component.
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Totz, Sonja, Alexey V. Eliseev, Stefan Petri, Michael Flechsig, Levke Caesar, Vladimir Petoukhov, and Dim Coumou. "The dynamical core of the Aeolus 1.0 statistical–dynamical atmosphere model: validation and parameter optimization." Geoscientific Model Development 11, no. 2 (February 22, 2018): 665–79. http://dx.doi.org/10.5194/gmd-11-665-2018.
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Abstract. We present and validate a set of equations for representing the atmosphere's large-scale general circulation in an Earth system model of intermediate complexity (EMIC). These dynamical equations have been implemented in Aeolus 1.0, which is a statistical–dynamical atmosphere model (SDAM) and includes radiative transfer and cloud modules (Coumou et al., 2011; Eliseev et al., 2013). The statistical dynamical approach is computationally efficient and thus enables us to perform climate simulations at multimillennia timescales, which is a prime aim of our model development. Further, this computational efficiency enables us to scan large and high-dimensional parameter space to tune the model parameters, e.g., for sensitivity studies. Here, we present novel equations for the large-scale zonal-mean wind as well as those for planetary waves. Together with synoptic parameterization (as presented by Coumou et al., 2011), these form the mathematical description of the dynamical core of Aeolus 1.0. We optimize the dynamical core parameter values by tuning all relevant dynamical fields to ERA-Interim reanalysis data (1983–2009) forcing the dynamical core with prescribed surface temperature, surface humidity and cumulus cloud fraction. We test the model's performance in reproducing the seasonal cycle and the influence of the El Niño–Southern Oscillation (ENSO). We use a simulated annealing optimization algorithm, which approximates the global minimum of a high-dimensional function. With non-tuned parameter values, the model performs reasonably in terms of its representation of zonal-mean circulation, planetary waves and storm tracks. The simulated annealing optimization improves in particular the model's representation of the Northern Hemisphere jet stream and storm tracks as well as the Hadley circulation. The regions of high azonal wind velocities (planetary waves) are accurately captured for all validation experiments. The zonal-mean zonal wind and the integrated lower troposphere mass flux show good results in particular in the Northern Hemisphere. In the Southern Hemisphere, the model tends to produce too-weak zonal-mean zonal winds and a too-narrow Hadley circulation. We discuss possible reasons for these model biases as well as planned future model improvements and applications.
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Lin, Pu, Qiang Fu, and Dennis L. Hartmann. "Impact of Tropical SST on Stratospheric Planetary Waves in the Southern Hemisphere." Journal of Climate 25, no. 14 (July 15, 2012): 5030–46. http://dx.doi.org/10.1175/jcli-d-11-00378.1.
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Abstract The impact of tropical sea surface temperature (SST) on stratospheric planetary waves in the Southern Hemisphere (SH) is investigated in austral spring using observed SST and reanalysis data for the past three decades. Maximum covariance analysis indicates that the tropical SST and the SH stratospheric planetary wave activity are primarily coupled through two modes. The leading two modes show the La Niña–like and the central-Pacific El Niño–like SST anomalies in their positive polarities, respectively, which each are related to enhanced stratospheric planetary wave activity. These two modes also introduce phase shifts to the stratospheric stationary planetary waves: a westward shift is seen for La Niña and an eastward shift for warm SST anomalies is seen in the central Pacific. The Eliassen–Palm fluxes associated with the two modes indicate that the anomalous stratospheric wave activity originates in the troposphere and propagates upward over the mid–high latitudes, so that the linkages between tropical SST and extratropical tropospheric circulation appear to play a key role. Furthermore, the observed circulation anomaly patterns for the two modes change rapidly from spring to summer, consistent with a sharp seasonal transition in the SH basic state. Similar SST and circulation anomaly patterns associated with the two modes are simulated in chemistry–climate models.
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Ivanciu, Ioana, Katja Matthes, Sebastian Wahl, Jan Harlaß, and Arne Biastoch. "Effects of prescribed CMIP6 ozone on simulating the Southern Hemisphere atmospheric circulation response to ozone depletion." Atmospheric Chemistry and Physics 21, no. 8 (April 19, 2021): 5777–806. http://dx.doi.org/10.5194/acp-21-5777-2021.
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Abstract. The Antarctic ozone hole has led to substantial changes in the Southern Hemisphere atmospheric circulation, such as the strengthening and poleward shift of the midlatitude westerly jet. Ozone recovery during the twenty-first century is expected to continue to affect the jet's strength and position, leading to changes in the opposite direction compared to the twentieth century and competing with the effect of increasing greenhouse gases. Simulations of the Earth's past and future climate, such as those performed for the Coupled Model Intercomparison Project Phase 6 (CMIP6), require an accurate representation of these ozone effects. Climate models that use prescribed ozone fields lack the important feedbacks between ozone chemistry, radiative heating, dynamics, and transport. In addition, when the prescribed ozone field was not generated by the same model to which it is prescribed, the imposed ozone hole is inconsistent with the simulated dynamics. These limitations ultimately affect the climate response to ozone depletion. This study investigates the impact of prescribing the ozone field recommended for CMIP6 on the simulated effects of ozone depletion in the Southern Hemisphere. We employ a new state-of-the-art coupled climate model, Flexible Ocean Climate Infrastructure (FOCI), to compare simulations in which the CMIP6 ozone is prescribed with simulations in which the ozone chemistry is calculated interactively. At the same time, we compare the roles played by ozone depletion and by increasing concentrations of greenhouse gases in driving changes in the Southern Hemisphere atmospheric circulation using a series of historical sensitivity simulations. FOCI captures the known effects of ozone depletion, simulating an austral spring and summer intensification of the midlatitude westerly winds and of the Brewer–Dobson circulation in the Southern Hemisphere. Ozone depletion is the primary driver of these historical circulation changes in FOCI. The austral spring cooling of the polar cap in the lower stratosphere in response to ozone depletion is weaker in the simulations that prescribe the CMIP6 ozone field. We attribute this weaker response to a prescribed ozone hole that is different to the model dynamics and is not collocated with the simulated polar vortex, altering the strength and position of the planetary wavenumber one. As a result, the dynamical contribution to the ozone-induced austral spring lower-stratospheric cooling is suppressed, leading to a weaker cooling trend. Consequently, the intensification of the polar night jet is also weaker in the simulations with prescribed CMIP6 ozone. In contrast, the differences in the tropospheric westerly jet response to ozone depletion fall within the internal variability present in the model. The persistence of the Southern Annular Mode is shorter in the prescribed ozone chemistry simulations. The results obtained with the FOCI model suggest that climate models that prescribe the CMIP6 ozone field still simulate a weaker Southern Hemisphere stratospheric response to ozone depletion compared to models that calculate the ozone chemistry interactively.
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Kurzke, H., M. V. Kurgansky, K. Dethloff, D. Handorf, S. Erxleben, D. Olbers, C. Eden, and M. Sempf. "Simulating Southern Hemisphere extra-tropical climate variability with an idealised coupled atmosphere-ocean model." Geoscientific Model Development 5, no. 5 (September 19, 2012): 1161–75. http://dx.doi.org/10.5194/gmd-5-1161-2012.
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Abstract. A quasi-geostrophic model of Southern Hemisphere's wintertime atmospheric circulation with horizontal resolution T21 has been coupled to a global ocean circulation model with a resolution of 2° × 2° and simplified physics. This simplified coupled model reproduces qualitatively some features of the first and the second EOF of atmospheric 833 hPa geopotential height in accordance with NCEP data. The variability patterns of the simplified coupled model have been compared with variability patterns simulated by four complex state-of-the-art coupled CMIP5 models. The first EOF of the simplified model is too zonal and does not reproduce the right position of the centre of action over the Pacific Ocean and its extension to the tropics. The agreement in the second EOF between the simplified and the CMIP5 models is better. The total variance of the simplified model is weaker than the observational variance and those of the CMIP5 models. The transport properties of the Southern Ocean circulation are in qualitative accord with observations. The simplified model exhibits skill in reproducing essential features of decadal and multi-decadal climate variability in the extratropical Southern Hemisphere. Notably, 800 yr long coupled model simulations reveal sea surface temperature fluctuations on the timescale of several decades in the Antarctic Circumpolar Current region.
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Cai, Wenju, and Tim Cowan. "Trends in Southern Hemisphere Circulation in IPCC AR4 Models over 1950–99: Ozone Depletion versus Greenhouse Forcing." Journal of Climate 20, no. 4 (February 15, 2007): 681–93. http://dx.doi.org/10.1175/jcli4028.1.
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Abstract Simulations by the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) models on the Southern Hemisphere (SH) circulation are assessed over the period 1950–99, focusing on the seasonality of the trend and the level of its congruency with the southern annular mode (SAM) in terms of surface zonal wind stress. It is found that, as a group, the models realistically produce the seasonality of the trend, which is strongest in the SH summer season, December–February (DJF). The modeled DJF trend is principally congruent with the modeled SAM trend, as in observations. The majority of models produce a statistically significant positive trend, with decreasing westerlies in the midlatitudes and increasing westerlies in the high latitudes. The trend pattern from an all-experiment mean achieves highest correlation with that from the National Centers for Environmental Prediction (NCEP) data. A total of 48 out of the 71 experiments were run with ozone-depletion forcing, which offers an opportunity to assess the importance of ozone depletion in driving the late-twentieth-century trends. The AR4 model ensemble that contains an ozone-depletion forcing produces an averaged trend that is comparable to the trend from the NCEP outputs corrected by station-based observations. The trend is largely generated after the mid-1970s. Without ozone depletion the trend is less than half of that in the corrected NCEP, although the errors in the observed trend are large. The impact on oceanic circulation is inferred from wind stress curl in the group with ozone-depletion forcing. The result shows an intensification of the southern midlatitude supergyre circulation, including a strengthening East Australian Current flowing through the Tasman Sea. Thus, ozone depletion also plays an important role in the subtropical gyre circulation change over the past decades.
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Sen Gupta, Alexander, Agus Santoso, Andréa S. Taschetto, Caroline C. Ummenhofer, Jessica Trevena, and Matthew H. England. "Projected Changes to the Southern Hemisphere Ocean and Sea Ice in the IPCC AR4 Climate Models." Journal of Climate 22, no. 11 (June 1, 2009): 3047–78. http://dx.doi.org/10.1175/2008jcli2827.1.
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Abstract Fidelity and projected changes in the climate models, used for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), are assessed with regard to the Southern Hemisphere extratropical ocean and sea ice systems. While individual models span different physical parameterizations and resolutions, a major component of intermodel variability results from surface wind differences. Projected changes to the surface wind field are also central in modifying future extratropical circulation and internal properties. A robust southward shift of the circumpolar current and subtropical gyres is projected, with a strong spinup of the Atlantic gyre. An associated increase in the core strength of the circumpolar circulation is evident; however, this does not translate into robust increases in Drake Passage transport. While an overarching oceanic warming is projected, the circulation-driven poleward shift of the temperature field explains much of the midlatitude warming pattern. The effect of this shift is less clear for salinity, where, instead, surface freshwater forcing dominates. Surface warming and high-latitude freshwater increases drive intensified stratification, and a shoaling and southward shift of the deep mixed layers. Despite large intermodel differences, there is also a robust weakening in bottom water formation and its northward outflow. At the same time the wind intensification invigorates the upwelling of deep water, transporting warm, salty water southward and upward, with major implications for sequestration and outgassing of CO2. A robust decrease is projected for both the sea ice concentration and the seasonal cycling of ice volume, potentially altering the salt and heat budget at high latitudes.
Dissertations / Theses on the topic "Atmospheric circulation Southern Hemisphere Mathematical models"
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Mazloff, Matthew R. "Production and analysis of a Southern Ocean state estimate." Thesis, Online version, 2006. http://hdl.handle.net/1912/1282.
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Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2006."September 2006." Bibliography: p. 97-106.
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Hsu, Wei-Ching. "The variability and seasonal cycle of the Southern Ocean carbon flux." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49079.
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Both physical circulation and biogeochemical characteristics are unique in the Southern Ocean (SO) region, and are fundamentally different from those of the northern hemisphere. Moreover, according to previous research, the oceanic response to the trend of the Southern Annual Mode (SAM) has profound impacts on the future oceanic uptake of carbon dioxide in the SO. In other words, the climate and circulation of the SO are strongly coupled to the overlying atmospheric variability. However, while we have understanding on the SO physical circulation and have the ability to predict the future changes of the SO climate and physical processes, the link between the SO physical processes, the air-sea carbon flux, and correlated climate variability remains unknown. Even though scientists have been studying the spatial and temporal variability of the SO carbon flux and the associated biogeochemical processes, the spatial patterns and the magnitudes of the air-sea carbon flux do not agree between models and observations. Therefore, in this study, we utilized a modified version of a general circulation model (GCM) to performed realistic simulations of the SO carbon on seasonal to interannual timescales, and focused on the crucial physical and biogeochemical processes that control the carbon flux. The spatial pattern and the seasonal cycle of the air-sea carbon dioxide flux is calculated, and is broadly consistent with the climatological observations. The variability of air-sea carbon flux is mainly controlled by the gas exchange rate and the partial pressure of carbon dioxide, which is in turn controlled by the compensating changes in temperature and dissolved inorganic carbon. We investigated the seasonal variability of dissolved inorganic carbon based on different regional processes. Furthermore, we also investigated the dynamical adjustment of the surface carbon flux in response to the different gas exchange parameterizations, and conclude that parameterization has little impact on spatially integrated carbon flux. Our simulation well captured the SO carbon cycle variability on seasonal to interannual timescales, and we will improve our model by employ a better scheme of nutrient cycle, and consider more nutrients as well as ecological processes in our future study.
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Verdy, Ariane. "Variability of zooplankton and sea surface temperature in the Southern Ocean." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39197.
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Thesis (S.M.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006.Includes bibliographical references (p. 69-74).
Interactions between physical and biological processes in the Southern Ocean have significant impacts on local ecosystems as well as on global climate. In this thesis, I present evidence that the Southern Ocean circulation affects the variability of zooplankton and sea surface temperature, both of which are involved in air-sea exchanges of carbon dioxide. First, I examine the formation of spatial patterns in the distribution of Antarctic krill (Euphausia superba) resulting from social behavior. Turbulence of the flow is found to provide favorable conditions for the evolution social behavior in an idealized biological-physical model. Second, I analyze observations of sea surface temperature variability in the region of the Antarctic circumpolar current. Results suggest that propagating anomalies can be explained as a linear response to local atmospheric forcing by the Southern Annular Mode and remote forcing by El-Nifio southern oscillation, in the presence of advection by a mean flow.
by Ariane Verdy.
S.M.
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Joubert, Alec Michael. "General circulation model simulations of Southern African regional climate." Thesis, 1994. https://hdl.handle.net/10539/25869.
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Dissertation submitted to the Faculty of Science,
University of the Witwatersraild, Johannesburg
for the Degree of Master of Science.Six general circulation model simulations of present-day southern African climate are assessed, Each of these models are early-generation equilibrium climate models linked to simple mixed-slab oceans. Simulations of surface air temperature over the subcontinent are sensitive to the grid-scale parameterisation of convection in summer. At high latitudes, large simulation errors are caused by errors in the specification of sea-ice albedo feedbacks. Increased spatial resolution and the inclusion of a gravity wave drag term in the momentum equations results in a markedly-improved simulated mean sea level pressure distribution. Tho models successfully simulate the pattern of rainfall seasonality over the Subcontinent, although grid-point simulation of precipitation is unreliable. Treatment of convection, cloud radiative feedbacks and the oceans by this generation of models is simplistic, and consequently there is a large degree of uncertainty associated with predictions of future climate under doubled-carbon dioxide conditions. For this reason, more reliable estimates of future conditions will be achieved using only those models which reproduce present climate most accurately. Early-generation general circulation models suggest a warming of 4°C to 5°C for the southern African region as a whole throughout the year. Over the subcontinent, warming is expected to be least in the tropics, and greatest in the dry subtropical regions in winter. Estimated changes in mean sea level pressure indicate a southward shlft of all pressure systems, with a weakening of the subtropical high pressure belt and mid-latitude westerlies. Little agreement exists between the models concerning predictions of regional precipitation change. However, broad scale changes in precipitation patterns are in accordance with predicted circulation changes over the subcontinent. Generally wetter conditions may be expected in the tropics throughout the year and over the summer rainfall region during summer. Decreased winter rainfall may be expected over the winter rainfall region of the south-western Cape. However, estimated precipitation changes are grid-point specific and therefore must riot be over-interpreted. The present climate validation has resulted in more reliable estimates of future conditions for the southern African region. This approach should be extended to recent slrnulations which include more comprehensive treatment of important physical processes.
Andrew Chakane 2018
Books on the topic "Atmospheric circulation Southern Hemisphere Mathematical models"
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Klimaticheskie posledstvii͡a︡ i͡a︡dernoĭ voĭny: Vybrosy i rasprostranenie opticheski aktivnykh primeseĭ v atmosfere. Moskva: Vychislitelʹnyĭ t͡s︡entr AN SSSR, 1985.
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General circulation model output for forest climate change research and applications. Asheville, N.C. (P.O. Box 2680, Asheville 28802): U.S. Dept. of Agriculture, Forest Service, Southeastern Forest Experiment Station, 1993.
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General circulation model output for forest climate change research and applications. Asheville, N.C: U.S. Dept. of Agriculture, Forest Service, Southeastern Forest Experiment Station, 1993.
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Tibaldi, Stefano, and Franco Molteni. Atmospheric Blocking in Observation and Models. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.611.
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The atmospheric circulation in the mid-latitudes of both hemispheres is usually dominated by westerly winds and by planetary-scale and shorter-scale synoptic waves, moving mostly from west to east. A remarkable and frequent exception to this “usual” behavior is atmospheric blocking. Blocking occurs when the usual zonal flow is hindered by the establishment of a large-amplitude, quasi-stationary, high-pressure meridional circulation structure which “blocks” the flow of the westerlies and the progression of the atmospheric waves and disturbances embedded in them. Such blocking structures can have lifetimes varying from a few days to several weeks in the most extreme cases. Their presence can strongly affect the weather of large portions of the mid-latitudes, leading to the establishment of anomalous meteorological conditions. These can take the form of strong precipitation episodes or persistent anticyclonic regimes, leading in turn to floods, extreme cold spells, heat waves, or short-lived droughts. Even air quality can be strongly influenced by the establishment of atmospheric blocking, with episodes of high concentrations of low-level ozone in summer and of particulate matter and other air pollutants in winter, particularly in highly populated urban areas.Atmospheric blocking has the tendency to occur more often in winter and in certain longitudinal quadrants, notably the Euro-Atlantic and the Pacific sectors of the Northern Hemisphere. In the Southern Hemisphere, blocking episodes are generally less frequent, and the longitudinal localization is less pronounced than in the Northern Hemisphere.Blocking has aroused the interest of atmospheric scientists since the middle of the last century, with the pioneering observational works of Berggren, Bolin, Rossby, and Rex, and has become the subject of innumerable observational and theoretical studies. The purpose of such studies was originally to find a commonly accepted structural and phenomenological definition of atmospheric blocking. The investigations went on to study blocking climatology in terms of the geographical distribution of its frequency of occurrence and the associated seasonal and inter-annual variability. Well into the second half of the 20th century, a large number of theoretical dynamic works on blocking formation and maintenance started appearing in the literature. Such theoretical studies explored a wide range of possible dynamic mechanisms, including large-amplitude planetary-scale wave dynamics, including Rossby wave breaking, multiple equilibria circulation regimes, large-scale forcing of anticyclones by synoptic-scale eddies, finite-amplitude non-linear instability theory, and influence of sea surface temperature anomalies, to name but a few. However, to date no unique theoretical model of atmospheric blocking has been formulated that can account for all of its observational characteristics.When numerical, global short- and medium-range weather predictions started being produced operationally, and with the establishment, in the late 1970s and early 1980s, of the European Centre for Medium-Range Weather Forecasts, it quickly became of relevance to assess the capability of numerical models to predict blocking with the correct space-time characteristics (e.g., location, time of onset, life span, and decay). Early studies showed that models had difficulties in correctly representing blocking as well as in connection with their large systematic (mean) errors.Despite enormous improvements in the ability of numerical models to represent atmospheric dynamics, blocking remains a challenge for global weather prediction and climate simulation models. Such modeling deficiencies have negative consequences not only for our ability to represent the observed climate but also for the possibility of producing high-quality seasonal-to-decadal predictions. For such predictions, representing the correct space-time statistics of blocking occurrence is, especially for certain geographical areas, extremely important.