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In this study we provide a systematic characterization of Rossby wave activity during the 25 sudden stratospheric warming (SSW) and 31 strong polar vortex (SPV) events that occurred in the period 1979–2021, identifying the specific tropospheric and stratospheric waves displaying anomalous behaviour during such events. Space–time spectral analysis is applied to ERA5 data for this purpose, so that both the wavenumber and the zonal phase speed of the waves can be assessed. We find that SSW events are associated with a reduction in the phase speed of Rossby waves, first in the stratosphere and then in the troposphere; SPV events are tied to a simultaneous increase of phase speed across vertical levels. Phase speed anomalies become significant around the event and persist for 2–3 weeks afterwards. Changes of Rossby wave properties in the stratosphere during SSW and SPV events are dominated by changes in the background flow, with a systematic reduction or increase, respectively, in eastward propagation of the waves across most wavenumbers. In the troposphere, on the other hand, the effect of the background flow is also complemented by changes in wave properties, with a shift towards higher wavenumbers during SSW events and towards lower wavenumbers for SPV events. The opposite response between SSW and SPV events is also visible in the meridional heat and momentum flux co-spectra, which highlight from a novel perspective the connection between stratospheric Rossby waves and upward propagation of waves.

In December 2020, the Western North Pacific was active with extratropical low-pressure weather events. During the final week of 2020, there was a record-breaking 1092 millibar high-pressure system over Mongolia, and 24 hours later, a 921 millibar extratropical low-pressure system over Western Alaska. These two extremes were associated with pressure anomalies for the basin and a jet superposition of the polar and subtropical jet streams. Superposition events are rare but occur in this region during winter. The Climate Forecast System Reanalysis (CFSR) data was used to examine jet superposition using 200 and 300 millibar winds and potential vorticity channels or waveguides in relation to the development of extratropical cyclones. Results indicated that PV channeling from Siberia in a northern airstream combined with jet superposition between the subtropical and polar jets resulted in rapid intensification. Using PV channels and their merging as an indicator could be a valuable forecast tool for extratropical cyclone intensification. Analyzing events such as these will allow forecasters to better prepare Naval assets in the Western Pacific for extreme events., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Unusual, persistent configurations of the North Atlantic jet stream affect the weather and climate over Europe. We focus on winter and on intraseasonal and seasonal time scales, and study persistent jet anomalies through the lens of large deviation theory using Coupled Model Intercomparison Project (CMIP6) simulations of the MPI-ESM-LR model and ERA5 reanalysis data. The configurations of interest are defined as long-lasting anomalies of a few months in jet latitude, speed or zonality. Our results show that persistent temperature and precipitation extremes over large European regions are anomalously frequent during the unusual, persistent jet configurations we identify. Furthermore, the relative increase in frequency of surface extremes is larger for more intense surface extremes and/or more extreme jet anomalies. This is relevant in the context of the predictability of these extremes. The highest extreme event frequencies at the surface are observed in case of precipitation over the Mediterranean and Western Europe during anomalously zonal and/or fast jet events, pointing to these jet anomalies matching rather homogeneous large scale atmospheric configurations with a clear surface footprint. Additionally, our results emphasise the usefulness of large deviation rate functions to estimate the frequency of occurrence of persistent jet anomalies. They therefore provide a tool to statistically describe long-lasting anomalies, much like extreme value theory may be used to investigate shorter-lived extreme events., Correction in: Environmental Research Letters, vol. 18, issue 3, article ID 039602DOI: 10.1088/1748-9326/acbdb3

Dynamic Systems Theory (DST) and spectral analysis are employed to study the tropospheric jet stream and the stratospheric polar vortex. The objective is to investigate the relationship between Rossby wave activity and inverse persistence and dimensionality of geopotential height at 250 hPa and 10 hPa, as these two dynamical indicators are expected to show a characteristic behavior of Rossby wave harmonics. The results show that persistent states exhibit suppressed Rossby wave activity for eastward-propagating Rossby waves, whereas it is increased for the westward counterpart. Positive anomalies of spectral power at positive phase speeds are present for less persistent states. Events with low dimensionality relate to the suppression of most Rossby waves, while an increase in spectral power is present during high dimensional states. The results were more pronounced in the stratosphere compared to the troposphere with different spatial patterns of geopotential height anomalies due to additional factors influencing the location of Rossby waves. Furthermore, Sudden Stratospheric Warmings (SSWs) are connected to a decrease in persistence up to 2 weeks prior, followed by a significant increase in persistence and dimensionality, and reduced integrated spectral power. Strong Polar Vortex events (SPVs) exhibit the opposite behavior with an increase in persistence before and a decrease in persistence and dimensionality, and higher ISP afterward. Additionally, SSWs (SPVs) exhibit a suppression (enhancement) of Rossby wave activity in the stratosphere and to a lesser extent in the troposphere for eastwards traveling waves.

In the work a random forest model has been implemented as an interpretable machine learning tool in the effort to estimate the burned areas caused by fire outbreaks in India, Pakistan, and Myanmar in April and May 2022. The proposed model combines environmental and atmospheric (including upper tropospheric) factors suggested to drive patterns of burned areas, and determines the weight of each factor on the propagation of fires. Results demonstrate that the model mimics the actual burned area by considering a combination of vegetation, atmosphere, and human-related variables and improves accuracy by approximately 7% after adding jet stream features. This approach could lead to implement a semi-operational forecast system that may be tested in multiple demonstration sites., The project that gave rise to these results received the support of a fellowship from the ”la Caixa” Foundation (ID 100010434), with fellowship code LCF/BQ/DI21/11860028. This work was also supported by Project PID2020-114623RB-C32 funded by MCIN/ AEI /10.13039/501100011033. In addition, D. Chaparro has received funding from the XXXIII Ramón Areces Postdoctoral grant., Peer Reviewed, Postprint (author's final draft)

isbn: 1527531154, Pages: 170-199

Jet streams are a key component of the climate system, whose dynamics couple closely to regional climate variability. Yet, the link between jet stream variability and vegetation activity has received little attention. Here, we leverage our understanding of the mid-latitude jet stream dynamics over the Euro-Atlantic sector to probe climate–vegetation interactions across Europe. We link indices related to the meridional location of the jet and the large-scale zonal wind speed with remotely-sensed vegetation greenness anomalies during locally-defined growing seasons. Correlations between greenness anomalies and jet latitude anomalies point to a control of the jet stream's variability on vegetation activity over large parts of Europe. This potential control is mediated by the jet latitude anomalies’ correlations with temperature, soil moisture and downward surface solar radiation. The sign and strength of these correlations depend on location and time of the year. Furthermore, jet stream variability modulates conditions at the onset and end of the growing season. The link between jet latitude anomalies and vegetation greenness is not only specific to the climate zone, but also to the landclass and subperiod within the growing season. It is thus important to use a locally-defined growing season for interpreting the atmospheric controls on regional vegetation phenology. Results consistent with the correlation analysis emerge when focussing on local high or low greenness months only or on zonal wind speed anomalies, confirming the relevance of jet variability for vegetation activity.

In this project warm extreme temperature events in the Arctic region during the spring months March, April and May were identified and analysed. In the analysis daily average NCEP reanalysis data from NOAA/OAR/ESRL PSL format was used. The extreme events were retrieved as the highest positive temperature anomalies from the climatological mean, and the synoptic scale plots for the 50 most extreme events were created to identify what patterns caused the extreme warming over the Polar region. By contouring the areas of statistical significance, the regions with a reoccuring pattern were identified. The results conclude that cyclonic activity over the high Arctic extending down over Greenland and northern Canada combined with anomalously high geopotential height over the north Pacific ocean, over the Arctic, and towards Siberia cause the high temperatures over the pole. A weaker Polar Vortex causes perturbations in the jet stream, ridges in these Rossby waves can act as a pathway for warm and moist air from the oceanic regions which has a warming effect in the Arctic. Further analysis can be done to investigate what teleconnections these spring-time extreme events have on a global scale., Under detta projekt har extremt varma temperaturevent i Arktisområdet under vårmånaderna Mars, April och Maj identifierats samt analyserats, genom att använda daglig medelvärdes NCEP reanalys data från NOAA/OAR/ESRL PSL i NetCDF format. De extrema händelserna identifierades genom att ta de största positiva temperaturavvikelserna från ett klimatologiskt medelvärde, storskaliga avvikelseplottar skapades för de 50 mest extrema händelserna för att kunna identifiera meteorologiska mönster som ovanligt varma Arktisdagar. De områden med mest återkommande mönsterna var statistiskt signifikanta och markerades med svarta konturer. Resultaten visar att lågtrycksaktivitet i Arktis som sträcker sig ner över Grönland samt norra Kanada kombinerat med höga geopotentialhöjdavvikelser över Stilla havet och Sibirien som sträcker sig upp mot Nordpolen orsakar ovanligt höga temperaturer i Arktis. En svag polarvirvel orsakar störningar i jetströmmen, dessa ryggar i jetströmmen kan transportera varm fuktig luft från haven mot polen vilket kan ha en värmande effekt. Vidare forskning kan utföras för att identifiera de exakta kopplingarna och konsekvenserna som dessa varma extrema Arktishändelser har globalt.

[ES] Este vídeo tiene como objetivo explicar los cambios que se están produciendo en el océano Ártico y el impacto que tienen en nuestras vidas. Y es que, las temperaturas en el Ártico están aumentando mucho más rápidamente que en el resto del planeta y esto está acelerando el deshielo. Esto implica, entre otros, que haya más agua dulce en el océano Ártico, lo que puede producir cambios en la circulación oceánica global, que regula el clima de la Tierra…El video acaba haciendo énfasis en que lo que ocurre en el Ártico no se queda en el Ártico, sino que tiene consecuencias globales., [CA] Aquest vídeo té com a objectiu explicar els canvis que s'estan produint a l'oceà Àrtic i l'impacte que tenen a les nostres vides. I és que, les temperatures a l'Àrtic estan augmentant molt més ràpidament que a la resta del planeta i això està accelerant el desglaç. Això implica, entre altres, que hi hagi més aigua dolça a l'oceà Àrtic, cosa que pot produir canvis en la circulació oceànica global, que regula el clima de la Terra. El video acaba fent èmfasis en que el que passa a l'Àrtic no es queda a l'Àrtic, sino que te conseqüències globals.

Atmospheric circulation patterns are the primary mechanism by which energy is distributed in the midlatitudes across terrestrial ecosystems. Plant and animal phenology integrate the influence of seasonal atmospheric circulation patterns on surface weather events. As these drivers of climate variability change, and are projected to change, it is important to quantify the observed response of ecosystem growth and processes to drivers of climate variability across scales. In this dissertation, I merge phenology, climatology, and dendrochronology disciplines, novel data availability, and research computing, to quantify and visualize the influence of jet stream variability on phenology across scales: from the individual species to the hemisphere, and from seasons to centuries. First, I examined the influence of multiple seasonal atmospheric circulation indices on a network of trees growing in semi-arid conditions at high altitudes in the Bighorn Mountains, WY (Hudson et al. 2019, Dendrochronologia; Appendix A). While all 11 sites shared a majority of common variance- suggesting a common climate driver- I found that winter and spring circulation pattern signals in annual rings were possibly modulated by microclimate conditions dictating snowpack and water availability into the growing season. I then expanded from one region to the Northern Hemisphere and contracted to the satellite period to determine for which regional ecosystems the spring and fall Northern Hemisphere Jet stream (NHJ) Indices (Belmecheri et al., 2017 Earth Interactions) influenced the length of the growing season (Hudson et al., in prep; Appendix B). Spring and/or fall NHJ influenced length of season for 30% of our domain, although similar NHJ shifts in the spring and fall resulted in very different LOS response- possibly linked to the seasonal limiting factor of temperature and its modulation on water availability for specific land cover and climate types. The final portion of this dissertation focused

Midlatitude atmospheric circulation is projected to shift poleward, yet the Northern Hemisphere jet shift is absent. Competing thermodynamic responses between tropical and Arctic warming have opposing influences on the jets and increase the uncertainties in future projections. This study shows, however, that sea surface temperature (SST) warming in the midlatitude is a major driver for the future midlatitude jet. Coupled Model Intercomparison Program phase 5 models indicate different SST warming between the midlatitude oceans, which induces a weakening of the North Pacific jet and a poleward shift of the North Atlantic jet. Our atmospheric model experiments enable to quantify the relative roles of Arctic, midlatitude, and tropical warming. The competing effects of midlatitude and tropical warming play a substantial role in the future midlatitude jet, hindering any poleward shift of the North Pacific jet, whereas for the North Atlantic jet, midlatitude SST warming is likely to win the competition. Plain Language Summary Midlatitude weather and climate, including extreme events, are strongly influenced by changes in the jet stream and extratropical cyclones. The future midlatitude circulation in the Northern Hemisphere is considered to depend on the competing effects of tropical and Arctic warming, which have opposing influences on position and intensity of the midlatitude jet and, ultimately, increase the uncertainties in future projections. However, we find that ocean warming in the midlatitudes has a major influence on future midlatitude jet. In the North Pacific, sea surface temperature (SST) warming is the strongest in the north of the strong ocean currents, whereas the North Atlantic SST warming has a peak in the strong ocean currents. This different SST warming leads to the contrasting midlatitude jet responses between the oceans with jet cores. Despite a topic of much debate, the impact of Arctic sea ice loss on the jet is suppressed by midlatitude SST warming

The Sentinel-2 satellites in the Copernicus program provide high resolution multispectral images, which are recorded with temporal offsets up to 2.6 s. Moving aircrafts and ships are therefore observed at different positions due to the multispectral band offsets, from which velocities can be determined. We describe an algorithm for detecting aircrafts and ships, and determining their speed, heading, position, length, etc. Aircraft velocities are also affected by the parallax effect and jet streams, and we show how the altitude and the jet stream speed can be determined from the geometry of the aircraft and/or contrail heading. Ship speeds are more difficult to determine as wakes affect the average ship positions differently in the various multispectral bands, and more advanced corrections methods are shown to improve the velocity determination.

There is intense public interest in whether major Arctic changes can and will impact midlatitude weather such as cold air outbreaks on the central and east side of continents. Although there is progress in linkage research for eastern Asia, a clear gap is conformation for North America. We show two stationary temperature/geopotential height patterns where warmer Arctic temperatures have reinforced existing tropospheric jet stream wave amplitudes over North America: a Greenland/Baffin Block pattern during December 2010 and an Alaska Ridge pattern during December 2017. Even with continuing Arctic warming over the past decade, other recent eastern US winter months were less susceptible for an Arctic linkage: the jet stream was represented by either zonal flow, progressive weather systems, or unfavorable phasing of the long wave pattern. The present analysis lays the scientific controversy over the validity of linkages to the inherent intermittency of jet stream dynamics, which provides only an occasional bridge between Arctic thermodynamic forcing and extended midlatitude weather events.

This study details a dynamic and thermodynamic metric (i.e., Extreme Flood Index [EFI]) designed to diagnose the frequency and intensity of extreme precipitation events associated with stagnant mid-latitude flow patterns (i.e., Rex blocks). As the global climate warms, rapid Arctic warming may be helping to slow the mid-latitude westerly jet stream, resulting in increased mid-latitude flow stagnation. The combination of long-duration ascent associated with easterly winds and warm moist air increases the severity of extreme precipitation events; as such, the EFI is specifically designed to detect this potent combination of ingredients. In 2013, a Rex block stalled a low-pressure system over Alberta which caused the worst Canadian flood disaster ever seen. To that end, the recent billion-dollar flood catastrophe produced by Tropical Cyclone (TC) Harvey was also associated with a Rex Block (dynamics) in the presence of warm, moist air (thermodynamics). Despite dynamic differences between TC-related and mid-latitude floods, the EFI is successfully able to detect both. The dynamics component of the EFI is derived from two atmospheric blocking criteria, used operationally by the European Centre for Medium-Range Weather Forecasts (ECMWF) and National Oceanic and Atmospheric Administration (NOAA), respectively, and adapted here for the shorter duration of extreme precipitation events. The EFI’s thermodynamic component utilizes standardized anomalies of equivalent potential temperature. Finally, the ability of the EFI to diagnose and predict high-impact flood events using reanalysis data and operational numerical weather prediction models is explored.

The impact of the Atlantic multidecadal variability (AMV) on the wintertime atmosphere circulation is investigated using three different configurations of the Community Atmospheric Model version 5 (CAM5). Realistic SST and sea ice anomalies associated with the AMV in observations are prescribed in CAM5 (low-top model) and WACCM5 (high-top model) to assess the dependence of the results on the representation of the stratosphere. In a third experiment, the role of ocean–atmosphere feedback is investigated by coupling CAM5 to a slab-ocean model in which the AMV forcing is prescribed through oceanic heat flux anomalies. The three experiments give consistent results concerning the response of the NAO in winter, with a negative NAO signal in response to a warming of the North Atlantic ocean. This response is found in early winter when the high-top model is used, and in late winter with the low-top model. With the slab-ocean, the negative NAO response is more persistent in winter and shifted eastward over the continent due to the damping of the atmospheric response over the North Atlantic ocean. Additional experiments suggest that both tropical and extratropical SST anomalies are needed to obtain a significant modulation of the NAO, with small influence of sea ice anomalies. Warm tropical SST anomalies induce a northward shift of the ITCZ and a Rossby-wave response that is reinforced in the mid-latitudes by the extratropical SST anomalies through eddy–mean flow interactions. This modeling study supports that the positive phase of the AMV promotes the negative NAO in winter, while illustrating the impacts of the stratosphere and of the ocean–atmosphere feedbacks in the spatial pattern and timing of this response.

Explosive cyclones are intense extra-tropical low pressure systems featuring large deepening rates. In the Euro-Atlantic sector, they are a major source of life-threatening weather impacts due to their associated strong wind gusts, heavy precipitation and storm surges. The wintertime variability of the North Atlantic cyclonic activity is primarily modulated by the North Atlantic Oscillation (NAO). In this study, we investigate the interannual and multi-decadal variability of explosive North Atlantic cyclones using track density data from two reanalysis datasets (NCEP and ERA-40) and a control simulation of an atmosphere/ocean coupled General Circulation Model (GCM—ECHAM5/MPIOM1). The leading interannual and multi-decadal modes of variability of explosive cyclone track density are characterized by a strengthening/weakening pattern between Newfoundland and Iceland, which is mainly modulated by the NAO at both timescales. However, the NAO control of interannual cyclone variability is not stationary in time and abruptly fluctuates during periods of 20–25 years long both in NCEP and ECHAM5/MPIOM1. These transitions are accompanied by structural changes in the leading mode of explosive cyclone variability, and by decreased/enhanced baroclinicity over the sub-polar/sub-tropical North Atlantic. The influence of the ocean is apparently important for both the occurrence and persistence of such anomalous periods. In the GCM, the Atlantic Meridional Overturning Circulation appears to influence the large-scale baroclinicity and explosive cyclone development over the North Atlantic. These results permit a better understanding of explosive cyclogenesis variability at different climatic timescales and might help to improve predictions of these hazardous events.

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 218–227, doi:10.1002/2013JC009393., The temperature in the coastal ocean off the northeastern U.S. during the first half of 2012 was anomalously warm, and this resulted in major impacts on the marine ecosystem and commercial fisheries. Understanding the spatiotemporal characteristics of the warming and its underlying dynamical processes is important for improving ecosystem management. Here, we show that the warming in the first half of 2012 was systematic from the Gulf of Maine to Cape Hatteras. Moreover, the warm anomalies extended through the water column, and the local temperature change of shelf water in the Middle Atlantic Bight was largely balanced by the atmospheric heat flux. The anomalous atmospheric jet stream position induced smaller heat loss from the ocean and caused a much slower cooling rate in late autumn and early winter of 2011–2012. Strong jet stream intraseasonal oscillations in the first half of 2012 systematically increased the warm anomalies over the continental shelf. Despite the importance of advection in prior northeastern U.S. continental shelf interannual temperature anomalies, our analyses show that much of the 2012 warming event was attributed to local warming from the atmosphere., K.C. was supported by the Woods Hole Oceanographic Institution Postdoctoral Scholarship, with funding provided by the Cooperative Institute for North Atlantic Region. G.G.G. was supported by grant N00014-11-1-0160 from the Office of Naval Research. S.J.L. was supported by the National Science Foundation under grant OCE-1154575., 2014-07-13

Intense winter cyclones often lead to hazardous weather over Europe. Previous studies have pointed to a link between the North Atlantic Oscillation (NAO) and strong European windstorms. However, the robustness of this relation for cyclones of varying intensities remains largely unexplored. In this paper, the bi-directional relation between the NAO and cyclones impacting Europe is analyzed for the period 1950-2010 focusing on the sensitivity to storm intensity. Evidence is given that explosive (EC) and non-explosive cyclones (NoEC) predominantly develop under different large-scale circulation conditions over the North Atlantic. Whereas NoEC evolve more frequently under negative and neutral NAO phases, the number of EC is larger under a positive NAO phase, typically characterized by an intensified jet toward Western Europe. Important differences are also found on the dynamics of NAO evolution after peak intensity for both cyclone populations. © 2014. American Geophysical Union. All Rights Reserved.

U okviru disertacije ispituje se zaključak bojnih autora koji su predstavili eksperimente u kojima se beleži slabljenje cirkulacije velikih razmera u integracijama klimatskim regionalnim modelom kada se ne primenjuje spektralno forsiranje velikih razmera (npr. VON STORCH i dr., 2000; BINER i dr., 2000; ROCKEL i dr., 2008; SANCHEZ-GOMEZ i dr., 2008; ALEXANDRU i dr., 2009; između ostalih). Porede se uspesi prognoziranja velikih razmera regionalnim Eta modelom i globalnim ECMWF modelom u slučaju ansambla koji čini 26 32-dnevnih prognoza. Dalje, ispituje se šema za bočne granične uslove. Pitanje na koje se traži odgovor je, da li je uveliko zastupljena, ali računski zahtevnija, relaksaciona šema za bočne granične uslove neophodna za uspešno prognoziranje/simuliranje velikih razmera regionalnim klimatskim modelom. Odgovor će se dobiti poređenjem rezultata dobijenih integracijama Eta modela u dve verzije, koje se razlikuju samo po šemi za bočne granične uslove. Jedna šema je, uveliko zastupljena, relaksaciona šema, a druga je originalna Etina šema kod koje se informacija iz globalnog modela dobija samo u jednom spoljašnjem redu tačaka i na izlaznoj granici se ne definišu sve promenljive. Uspesi ova dva skupa prognoza regionalnog Eta modela se porede kako međusobno, tako i sa uspehom globalnog modela od kojeg se uzimaju granični uslovi. Novina u eksperimentu je metod za verifikaciju. U cilju ocene uspeha prognoziranja velikih razmera, prati se tačnost prognoze položaja najjačih vetrova na nivou mlazne struje, za koji se uzima da odgovara nivou pritiska od 250 hPa. Računaju se dva skora: nepristrasna mera šanse da događaj potpadne pod određenu kategoriju (da brzina vetra na nivou 250 hPa potpada pod kategoriju vetra većeg od 45 m s–1) podešena odnosom čestina prognoziranog i osmotrenog događaja (MESINGER, 2008) i odnos čestina prognoziranog i osmotrenog događaja. Za verifikaciju se koriste ECMWF analize. Takođe se računaju u verifikaciji uobičajeni skorovi – RMS razlike kao, A considerable number of authors presented experiments in which degradation of large scale circulation occurred in regional climate integrations when large-scale nudging was not used (e.g., VON STORCH et al., 2000; BINER et al., 2000; ROCKEL et al., 2008; SANCHEZ-GOMEZ et al., 2008; ALEXANDRU et al., 2009). We here revisit this issue by comparing the large scale skill of the Eta RCM against that of the global ECMWF forecasts used as its driver. Another issue we are looking into is that of the lateral boundary condition (LBC) scheme. Specifically, the question we ask is whether the almost universally used but somewhat costly relaxation scheme is necessary for a desirable RCM performance? We address this by running the Eta model in two versions differing in the lateral boundary scheme used. One of these is the traditional relaxation scheme and the other is the Eta model scheme in which information is used at the outermost boundary only and not all variables are prescribed at the outflow boundary. The skills of these two RCM forecasts are compared against each other and also against that of their driver. Our global data dynamically downscaled to address these issues is an ECMWF 32-day ensemble forecast. A novelty in our experiments is the verification used. In order to test the large scale skill we are looking at the forecast position accuracy of the strongest winds at the jet stream level, which we have taken as 250 hPa. We do this by calculating bias adjusted equitable threat scores (MESINGER, 2008) and frequency bias scores for wind speeds greater than a chosen wind speed threshold, with the ECMWF analyses used as truth. For greater confidence we also calculate a traditional RMS difference between the forecast and analyzed winds at this same level. Our results show the Eta RCM skill in forecasting large scales with no interior nudging to be just about the same as that of the driver model. As to the LBC impact no disadvantage compared to relaxation was seen from usin

Preferred jet stream positions and their link to regional circulation patterns over the winter North Atlantic/European sector are investigated to corroborate findings of multimodal behaviour of the jet positions and to analyse patterns of preferred paths and transition probabilities between jet regimes using ERA-40 data. Besides the multivariate Gaussian mixture model, hierarchical clustering and data image techniques are used for this purpose. The different approaches all yield circulation patterns that correspond to the preferred jet regimes, namely the southern, central and the northern positions associated respectively with the Greenland anticyclone or blocking, and two opposite phases of an East Atlantic-like flow pattern. Growth and decay patterns as well as preferred paths of the system trajectory are studied using the mixture model within the delay space. The analysis shows that the most preferred paths are associated with central to north and north to south jet stream transitions with a typical time-scale of about 5 days, and with life cycles of 12 weeks. The transition paths are found to be consistent with transition probabilities. The analysis also shows that wave breaking seems to be the dominant mechanism behind Greenland blocking., AuthorCount:3

Jetströmmar betyder mycket för meteorologer och fungerar som ett hjälpmedel för prognostisering av lågtryck. Kvadrantmodellen för jetströmsstråk beskriver hur det kan bildas lågtryck och konvergens vid marknivå på olika sidor om jetströmmen. Jetströmmar är också av betydelse för flygtrafiken, eftersom man kan spara tid och bränsle genom att flyga in i – eller genom att inte flyga in i – en jetström. Det är känt att jetströmmar ibland kan ge upphov till klarluftsturbulens (CAT), och studier har visat att turbulensen ofta är associerade med stabilt stratifierade zoner i närheten av jetströmmen. Denna studie börjar med en teoridel där jetströmmars uppkomst och kvadrantmodellen redogörs. Teoridelen fortsätter med en kort beskrivning av hur jetströmmar påverkar flygtrafiken och vad det finns för system som varnar för farliga fenomen som är kopplade till jetströmmarna. Det tas även upp att flygturbulensen som upplevs av flygplan inte nödvändigtvis orsakas av termisk eller mekanisk turbulens, utan även kan orsakas av stående vågor. I arbetets senare del görs en fallstudie på två jetströmmar som gav upphov till kraftig flygturbulens under januari månad 2011. Från sonderingsdata beräknades Scorer-parametern och Richardsons tal för att se om dessa värden kunde relateras till flygturbulensen. Resultatet visade att Richardsons tal aldrig föll under 0.25 och antyder därför att det inte fanns någon fullt utvecklad turbulens. Vågor i luften kan därför vara en förklaring till flygturbulensen. Resultatet visade också att Scorer-parametern antog lokala minima och hade tydligare relation till flygturbulensen än Richardsons tal vad gäller flygturbulensens position i höjdled., Jet streams are useful as a tool for meteorologist to make forecasts of low pressure areas. The four quadrant model describing jet streaks reveals how lows and convergence could form over ground levels on different sides of a jet streak. Jet streams are also of great importance for the aviation industry, as one could save time and fuel by flying into – or by not flying into – a jet stream. It is known that the jet streams sometimes can induce Clear Air Turbulence (CAT), and studies have shown that the turbulence is often associated with stable stratified layers in the vicinity of the jet stream. This study starts with a theory section describing the cause of jet streams and the four quadrant model. The theory section continues with a description of why jet streams could be a hazard for airplanes, and also a description of existing reporting and warning systems that are used to prevent pilots from flying into dangerous phenomena. In this section, it is also emphasized that in-flight turbulence not necessarily is a result of thermal or mechanical turbulence, but could also be induced by standing waves in the atmosphere. The latter part of this report is a case study of two jet streaks that was the cause of severe in-flight turbulence in January 2011. The Scorer parameter and the Richardson number were computed using data from atmospheric soundings. The results show that the Richardson number never fell below 0.25, suggesting that there were no fully-developed turbulence. Waves in the air could therefore be an alternative explanation to the reported in-flight turbulence. The results also show that the Scorer parameter had local minima on the levels where the in-flight turbulence occurred. In contrast to this, the Richardson number had no apparent relation to the position of the reported turbulence.

The geographic and temporal variations in tropospheric and stratospheric ozone columns from individual swath measurements of the Ozone Monitoring Instrument (OMI), on the NASA Aura spacecraft, are reasonably well simulated by the University of California, Irvine (UCI) chemistry transport model (CTM) using 1°×1°×40-layer meteorological fields for the year 2005. From the CTM we find that high-frequency spatial variations in tropospheric column ozone (TCO), including around the jet streams, are not generally correlated with variations in stratospheric ozone column, but instead are collocated with folding events involving stratospheric-origin, high-ozone layers below the tropopause. The CTM fold events are verified in many cases with available ozone sondes. Using the OMI Level 2 profiles, and defining tropopause height from our CTM using the European Centre for Medium-Range Weather Forecasts (ECMWF) fields, we find that most of the variations in TCO near CTM folding events are also not correlated with those in stratospheric ozone column. A large fraction of the OMI TCO variance is accurately simulated by the CTM where the variance is significant, especially along the subtropical jets. The absolute tropospheric columns from OMI and CTM agree swath-by-swath, pixel-by-pixel within ±5 Dobson Units (DU) for most cases. Notable exceptions are in the tropics where neither the high ozone from biomass burning nor the low ozone in the convergence zones over the Pacific is found in the OMI observations, because of OMI's insensitivity to the lower troposphere. Another difference is identified with the OMI profiles near the southern subtropical jet. The CTM has a high bias in stratospheric column outside the tropics, due to problems previously identified with the stratospheric circulation in the 40-layer meteorological fields. Overall, we identify ozone folds with short-lived features in TCO that have scales of a few hundred kilometres as observed by OMI.

I studied the atmospheric jet streams of Jupiter and Saturn through numerical simulations. Jupiter and Saturn have approximately 30 and 15 jet streams, respectively, alternatively blowing eastward and westward at the cloud level. My studies are motivated by recent space probe observations of the giant planets, which are revealing vertical structures and time dependent behaviors of the atmospheric jets. Such new findings are important keys to understanding how the jets are driven and maintained. My first project tested the hypothesis that a large convective storm on Saturn observed in 1990 decelerated the equatorial jet. The equatorial jet's speed is reported to be ∼275 ms⁻¹ today, half of the speed measured by the Voyagers in 1980-81. It has been hypothesized that the large storm is responsible for causing the observed slowdown. Our result shows that the storm's effect is insufficient to cause a slowdown of the observed magnitude. The second project investigated the formation of Jovian jet streams, namely, whether Jupiter-like atmospheric jets emerge from self-organization of small initial vortices. Thunderstorms are observed on Jupiter and have been proposed to be the sources of small-scale vorticity. Our result shows that self-organization of initial small vortices leads to east-west jets under various Jupiter-like conditions. Third, I tested the stability of shallow atmospheric jets under Jovian conditions. Deep atmospheric jets have been shown to be stable on Jupiter; however, the possibility that those jets are shallow, with the point of zero-motion at perhaps ∼100-bar level, is not well explored and deserves a thorough examination.

© 2016, Allerton Press, Inc.We consider the problem of calculating the ideal non-compressible fluid flow around the airfoil with jet blowing through a channel in the presence of a point vortex with a given circulation in the flow. The effect of the vortex coordinates on the aerodynamic characteristics of the airfoil is investigated and the optimal position of the vortex for maximal lift is found.

We suggest a method to solve one of the model problems of aerohydrodynamics, namely, a problem of a flow about a point source, from which a fluid with density and total pressure, different from the corresponding values in the incoming flow enters. The calculations are carried out for various values of the determining parameter; and the data are compared with the known results. We revealed the advantages of the suggested method in comparison with the known ones. © Allerton Press, Inc., 2011.

© 2016, Allerton Press, Inc.We consider the problem of calculating the ideal non-compressible fluid flow around the airfoil with jet blowing through a channel in the presence of a point vortex with a given circulation in the flow. The effect of the vortex coordinates on the aerodynamic characteristics of the airfoil is investigated and the optimal position of the vortex for maximal lift is found.

We suggest a method to solve one of the model problems of aerohydrodynamics, namely, a problem of a flow about a point source, from which a fluid with density and total pressure, different from the corresponding values in the incoming flow enters. The calculations are carried out for various values of the determining parameter; and the data are compared with the known results. We revealed the advantages of the suggested method in comparison with the known ones. © Allerton Press, Inc., 2011.

Bakalářská práce zpracovává problematiku vlivu turbulence na letový provoz. Obsahuje základní informace a poznatky pro piloty motorových i bezmotorových letadel. Zvláštní pozornost je věnována turbulenci v bezoblačném prostoru, tryskovému proudění, turbulenci v úplavu a letecké chemické činnosti. Práce je pojata z meteorologického hlediska, jsou zde zahrnuty obecné informace týkající se doprovodných jevů., Bachelor thesis deals with the influence of turbulence on flight operations. It contains basic information and knowledge for pilots of aircrafts and gliders. Special attention is paid to clear air turbulence, jet stream, wake turbulence and air chemical activity. Bachleor thesis is conceived in meteorogical aspect, it includes general information of accompanying phenomena.

Práce pojednává o střihu větru a jeho vlivu na leteckou dopravu. Ten je rozebrán na teoretické úrovni a uveden do praxe v letecké dopravě. Jsou zde zmíněny metody pozorování, predikce, hlášení střihu větru i doporučené postupy pro piloty, kteří střihem větru prolétají. V práci jsou modely počasí, které doprovázelo historicky významné dopravní nehody, popis sledování střihu větru na světových letištích i na letišti Václava Havla v Praze, Ruzyni. Práce obsahuje i analýzu vybraných aerologických výstupů a jejich vztahu k hlášenému střihu větru. Celá práce má za cíl zejména zvýšení povědomí o střihu větru ve vztahu k letecké dopravě. Tedy z úhlu pohledu pilota i leteckého meteorologa., This thesis is about wind shear and its influence on aviation. There is wide theoretical description of wind shear and it’s implemented into aviation practice. There are also methods of observation, forecasting and reporting, for both pilots and meteorologist described. In this thesis, pilots can find useful recommendations for dealing with wind shear during the flight. Every reader can also read about famous aviation accidents and look at models of weather that caused those accidents. At the end of thesis there are analyses of a rawiosonde measurements related to wind shear reports. This whole thesis is focused on increasing awareness of wind shear in aviation from angle of view of both pilots and aviation meteorologist.

Diplomová práce se zabývá tryskovým prouděním. Její rešeršní část pojednává o podmínkách vzniku tryskového proudění, jeho charakteristikách, rozdělení podle zeměpisné polohy a jevech, které tryskové proudění doprovázejí. Obsahuje také popis způsobů měření tryskového proudění a jeho zobrazení v leteckých meteorologických mapách. Dále rozebírá organizaci letového provozu nad severním Atlantikem v dosahu výskytu tryskového proudění. Praktická část práce obsahuje vlastní autorovo řešení, které se týká posouzení časové a ekonomické výhodnosti transatlantických letů plánovaných podle tryskového proudění. Princip vyhodnocení spočíval v porovnání skutečných letů s lety po nejkratších možných tratích. Bylo prokázáno, že ke zmíněným úsporám dochází pouze v oceánských částech letu., This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.

Bakalářská práce zpracovává problematiku vlivu turbulence na letový provoz. Obsahuje základní informace a poznatky pro piloty motorových i bezmotorových letadel. Zvláštní pozornost je věnována turbulenci v bezoblačném prostoru, tryskovému proudění, turbulenci v úplavu a letecké chemické činnosti. Práce je pojata z meteorologického hlediska, jsou zde zahrnuty obecné informace týkající se doprovodných jevů., Bachelor thesis deals with the influence of turbulence on flight operations. It contains basic information and knowledge for pilots of aircrafts and gliders. Special attention is paid to clear air turbulence, jet stream, wake turbulence and air chemical activity. Bachleor thesis is conceived in meteorogical aspect, it includes general information of accompanying phenomena.

Tato diplomová práce komplexně zpracovává problematiku vulkanického popela a jeho vlivu na letectví včetně samotné vulkanické aktivity (podmínek pro její existenci, pro existenci erupcí a jejich základních produktů). Mimo to se práce věnuje následkům, které má vulkanický popel na letadla a letiště, možnostem jeho detekce či sledování a mechanismu jeho šíření ve vzdušném prostoru. Zvláštní důraz je pak kladen na letecké incidenty s ním související a na ohrožení, které představuje pro vzdušný prostor České republiky., This master's thesis deals with the issue of volcanic ash as a complex and its impact on aviation, including the volcanic activity itself (conditions for its existence, for existence of eruptions and their basic products). In addition, the thesis also deals with effect of volcanic ash on aircraft and airports, possibilities of its detection or monitoring as well as mechanism of its spreading in airspace. The emphasis is laid mainly on air incidents related to volcanic ash and on danger it poses to the airspace of the Czech Republic.

Diplomová práce se zabývá tryskovým prouděním. Její rešeršní část pojednává o podmínkách vzniku tryskového proudění, jeho charakteristikách, rozdělení podle zeměpisné polohy a jevech, které tryskové proudění doprovázejí. Obsahuje také popis způsobů měření tryskového proudění a jeho zobrazení v leteckých meteorologických mapách. Dále rozebírá organizaci letového provozu nad severním Atlantikem v dosahu výskytu tryskového proudění. Praktická část práce obsahuje vlastní autorovo řešení, které se týká posouzení časové a ekonomické výhodnosti transatlantických letů plánovaných podle tryskového proudění. Princip vyhodnocení spočíval v porovnání skutečných letů s lety po nejkratších možných tratích. Bylo prokázáno, že ke zmíněným úsporám dochází pouze v oceánských částech letu., This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.

The short term teleconnections associated with an individual western Pacific tropical cyclone have been investigated using an atmospheric general circulation model. The general strategy was to use the GCM, in combination with several tropical cyclone bogusing procedures, to isolate the effects on the global circulation of the tropical cyclone. The bogusing procedures were used to alter the tropical cyclone in the initial conditions for the model. The primary modeling experiments involved using the tropical cyclone bogusing procedures to include or exclude the tropical cyclone from the initial conditions. The difference between model results that contained the tropical cyclone and those that did not were used to analyze the global response to the tropical cyclone. These results showed a strong and persistent teleconnection response in the extratropical northern hemisphere. This response was mainly evident in slowly propagating Rossby waves in the 200 mb height field. Examinations of the teleconnection mechanisms showed that the east Asian-north Pacific jet played a major role in the development of the teleconnection. In particular: (1) the 200 mb height responses showed a consistent relationship with the jet; (2) the jet acted as a waveguide for the Rossby wave energy; and (3) the regions of potential barotropic instability which flank the jet were often colocated with areas of wave amplification., http://archive.org/details/shorttermtelecon1094539760, Lieutenant, United Stattes Navy, Approved for public release; distribution is unlimited.

Práce pojednává o střihu větru a jeho vlivu na leteckou dopravu. Ten je rozebrán na teoretické úrovni a uveden do praxe v letecké dopravě. Jsou zde zmíněny metody pozorování, predikce, hlášení střihu větru i doporučené postupy pro piloty, kteří střihem větru prolétají. V práci jsou modely počasí, které doprovázelo historicky významné dopravní nehody, popis sledování střihu větru na světových letištích i na letišti Václava Havla v Praze, Ruzyni. Práce obsahuje i analýzu vybraných aerologických výstupů a jejich vztahu k hlášenému střihu větru. Celá práce má za cíl zejména zvýšení povědomí o střihu větru ve vztahu k letecké dopravě. Tedy z úhlu pohledu pilota i leteckého meteorologa., This thesis is about wind shear and its influence on aviation. There is wide theoretical description of wind shear and it’s implemented into aviation practice. There are also methods of observation, forecasting and reporting, for both pilots and meteorologist described. In this thesis, pilots can find useful recommendations for dealing with wind shear during the flight. Every reader can also read about famous aviation accidents and look at models of weather that caused those accidents. At the end of thesis there are analyses of a rawiosonde measurements related to wind shear reports. This whole thesis is focused on increasing awareness of wind shear in aviation from angle of view of both pilots and aviation meteorologist.

Diplomová práce se zabývá tryskovým prouděním. Její rešeršní část pojednává o podmínkách vzniku tryskového proudění, jeho charakteristikách, rozdělení podle zeměpisné polohy a jevech, které tryskové proudění doprovázejí. Obsahuje také popis způsobů měření tryskového proudění a jeho zobrazení v leteckých meteorologických mapách. Dále rozebírá organizaci letového provozu nad severním Atlantikem v dosahu výskytu tryskového proudění. Praktická část práce obsahuje vlastní autorovo řešení, které se týká posouzení časové a ekonomické výhodnosti transatlantických letů plánovaných podle tryskového proudění. Princip vyhodnocení spočíval v porovnání skutečných letů s lety po nejkratších možných tratích. Bylo prokázáno, že ke zmíněným úsporám dochází pouze v oceánských částech letu., This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.

Tato diplomová práce komplexně zpracovává problematiku vulkanického popela a jeho vlivu na letectví včetně samotné vulkanické aktivity (podmínek pro její existenci, pro existenci erupcí a jejich základních produktů). Mimo to se práce věnuje následkům, které má vulkanický popel na letadla a letiště, možnostem jeho detekce či sledování a mechanismu jeho šíření ve vzdušném prostoru. Zvláštní důraz je pak kladen na letecké incidenty s ním související a na ohrožení, které představuje pro vzdušný prostor České republiky., This master's thesis deals with the issue of volcanic ash as a complex and its impact on aviation, including the volcanic activity itself (conditions for its existence, for existence of eruptions and their basic products). In addition, the thesis also deals with effect of volcanic ash on aircraft and airports, possibilities of its detection or monitoring as well as mechanism of its spreading in airspace. The emphasis is laid mainly on air incidents related to volcanic ash and on danger it poses to the airspace of the Czech Republic.

In this lesson from the MAPS GIS program at Lane Community College, and as part of the Introduction to Physical Geography course, the Blown Away module has students explore "Boolean login queries to explore tornado patterns and association to the Jet Streams annual movement. The will look for correlations between intensity of events and impact to human life and property." This lesson was originally adapted from an ARCLESSON by Tom Baker and Drew Keller. A link to the web-based map is available as well as several downloadable files including a student lesson and answer sheet and a teaching guide for the module.

Bakalářská práce zpracovává problematiku vlivu turbulence na letový provoz. Obsahuje základní informace a poznatky pro piloty motorových i bezmotorových letadel. Zvláštní pozornost je věnována turbulenci v bezoblačném prostoru, tryskovému proudění, turbulenci v úplavu a letecké chemické činnosti. Práce je pojata z meteorologického hlediska, jsou zde zahrnuty obecné informace týkající se doprovodných jevů., Bachelor thesis deals with the influence of turbulence on flight operations. It contains basic information and knowledge for pilots of aircrafts and gliders. Special attention is paid to clear air turbulence, jet stream, wake turbulence and air chemical activity. Bachleor thesis is conceived in meteorogical aspect, it includes general information of accompanying phenomena.

Práce pojednává o střihu větru a jeho vlivu na leteckou dopravu. Ten je rozebrán na teoretické úrovni a uveden do praxe v letecké dopravě. Jsou zde zmíněny metody pozorování, predikce, hlášení střihu větru i doporučené postupy pro piloty, kteří střihem větru prolétají. V práci jsou modely počasí, které doprovázelo historicky významné dopravní nehody, popis sledování střihu větru na světových letištích i na letišti Václava Havla v Praze, Ruzyni. Práce obsahuje i analýzu vybraných aerologických výstupů a jejich vztahu k hlášenému střihu větru. Celá práce má za cíl zejména zvýšení povědomí o střihu větru ve vztahu k letecké dopravě. Tedy z úhlu pohledu pilota i leteckého meteorologa., This thesis is about wind shear and its influence on aviation. There is wide theoretical description of wind shear and it’s implemented into aviation practice. There are also methods of observation, forecasting and reporting, for both pilots and meteorologist described. In this thesis, pilots can find useful recommendations for dealing with wind shear during the flight. Every reader can also read about famous aviation accidents and look at models of weather that caused those accidents. At the end of thesis there are analyses of a rawiosonde measurements related to wind shear reports. This whole thesis is focused on increasing awareness of wind shear in aviation from angle of view of both pilots and aviation meteorologist.

Tato diplomová práce komplexně zpracovává problematiku vulkanického popela a jeho vlivu na letectví včetně samotné vulkanické aktivity (podmínek pro její existenci, pro existenci erupcí a jejich základních produktů). Mimo to se práce věnuje následkům, které má vulkanický popel na letadla a letiště, možnostem jeho detekce či sledování a mechanismu jeho šíření ve vzdušném prostoru. Zvláštní důraz je pak kladen na letecké incidenty s ním související a na ohrožení, které představuje pro vzdušný prostor České republiky., This master's thesis deals with the issue of volcanic ash as a complex and its impact on aviation, including the volcanic activity itself (conditions for its existence, for existence of eruptions and their basic products). In addition, the thesis also deals with effect of volcanic ash on aircraft and airports, possibilities of its detection or monitoring as well as mechanism of its spreading in airspace. The emphasis is laid mainly on air incidents related to volcanic ash and on danger it poses to the airspace of the Czech Republic.

Diplomová práce se zabývá tryskovým prouděním. Její rešeršní část pojednává o podmínkách vzniku tryskového proudění, jeho charakteristikách, rozdělení podle zeměpisné polohy a jevech, které tryskové proudění doprovázejí. Obsahuje také popis způsobů měření tryskového proudění a jeho zobrazení v leteckých meteorologických mapách. Dále rozebírá organizaci letového provozu nad severním Atlantikem v dosahu výskytu tryskového proudění. Praktická část práce obsahuje vlastní autorovo řešení, které se týká posouzení časové a ekonomické výhodnosti transatlantických letů plánovaných podle tryskového proudění. Princip vyhodnocení spočíval v porovnání skutečných letů s lety po nejkratších možných tratích. Bylo prokázáno, že ke zmíněným úsporám dochází pouze v oceánských částech letu., This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.

Tato diplomová práce komplexně zpracovává problematiku vulkanického popela a jeho vlivu na letectví včetně samotné vulkanické aktivity (podmínek pro její existenci, pro existenci erupcí a jejich základních produktů). Mimo to se práce věnuje následkům, které má vulkanický popel na letadla a letiště, možnostem jeho detekce či sledování a mechanismu jeho šíření ve vzdušném prostoru. Zvláštní důraz je pak kladen na letecké incidenty s ním související a na ohrožení, které představuje pro vzdušný prostor České republiky., This master's thesis deals with the issue of volcanic ash as a complex and its impact on aviation, including the volcanic activity itself (conditions for its existence, for existence of eruptions and their basic products). In addition, the thesis also deals with effect of volcanic ash on aircraft and airports, possibilities of its detection or monitoring as well as mechanism of its spreading in airspace. The emphasis is laid mainly on air incidents related to volcanic ash and on danger it poses to the airspace of the Czech Republic.

Práce pojednává o střihu větru a jeho vlivu na leteckou dopravu. Ten je rozebrán na teoretické úrovni a uveden do praxe v letecké dopravě. Jsou zde zmíněny metody pozorování, predikce, hlášení střihu větru i doporučené postupy pro piloty, kteří střihem větru prolétají. V práci jsou modely počasí, které doprovázelo historicky významné dopravní nehody, popis sledování střihu větru na světových letištích i na letišti Václava Havla v Praze, Ruzyni. Práce obsahuje i analýzu vybraných aerologických výstupů a jejich vztahu k hlášenému střihu větru. Celá práce má za cíl zejména zvýšení povědomí o střihu větru ve vztahu k letecké dopravě. Tedy z úhlu pohledu pilota i leteckého meteorologa., This thesis is about wind shear and its influence on aviation. There is wide theoretical description of wind shear and it’s implemented into aviation practice. There are also methods of observation, forecasting and reporting, for both pilots and meteorologist described. In this thesis, pilots can find useful recommendations for dealing with wind shear during the flight. Every reader can also read about famous aviation accidents and look at models of weather that caused those accidents. At the end of thesis there are analyses of a rawiosonde measurements related to wind shear reports. This whole thesis is focused on increasing awareness of wind shear in aviation from angle of view of both pilots and aviation meteorologist.

Bakalářská práce zpracovává problematiku vlivu turbulence na letový provoz. Obsahuje základní informace a poznatky pro piloty motorových i bezmotorových letadel. Zvláštní pozornost je věnována turbulenci v bezoblačném prostoru, tryskovému proudění, turbulenci v úplavu a letecké chemické činnosti. Práce je pojata z meteorologického hlediska, jsou zde zahrnuty obecné informace týkající se doprovodných jevů., Bachelor thesis deals with the influence of turbulence on flight operations. It contains basic information and knowledge for pilots of aircrafts and gliders. Special attention is paid to clear air turbulence, jet stream, wake turbulence and air chemical activity. Bachleor thesis is conceived in meteorogical aspect, it includes general information of accompanying phenomena.