Variability of the Polar Stratospheric Vortex and Its Impact on Surface Climate Patterns - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Variability of the Polar Stratospheric Vortex and Its Impact on Surface Climate Patterns write by Aditi Sheshadri. This book was released on 2015. Variability of the Polar Stratospheric Vortex and Its Impact on Surface Climate Patterns available in PDF, EPUB and Kindle. This thesis investigates various aspects of the variability of the stratospheric polar vortex and the effect of this variability on tropospheric weather and climate patterns on various timescales. In the first part of this work, an improved idealized model was developed to study the coupled stratosphere-troposphere system. The model is forced by relaxation to a specified equilibrium temperature profile, which varies seasonally only in the stratosphere. This model setup permits the investigation of stratosphere-troposphere interactions on seasonal timescales, without the complication of an internal tropospheric seasonal cycle. The model is forced with different shapes and amplitudes of simple bottom topography, resulting in a range of stratospheric climates. The effect of these different kinds of topography on the seasonal variability of the strength of the polar vortex, the average timing and variability in timing of the final breakup of the vortex (final warming events), the conditions of occurrence and frequency of midwinter warming events, and the impact of the stratospheric seasonal cycle on the troposphere are explored. The inclusion of wavenumber 1 and wavenumber 2 topographies results in very different stratospheric seasonal variability. Hemispheric differences in stratospheric seasonal variability are recovered in the model with appropriate choices of wave-2 topography. In the model experiment with a realistic Northern Hemisphere-like frequency of midwinter warming events, the distribution of the intervals between these events suggest that the model has no year to year memory. When forced with wave-1 topography, the gross features of seasonal variability are similar to those forced with wave-2 topography, but the dependence on forcing magnitude is weaker. Further, the frequency of major warming events has a non-monotonic dependence on forcing magnitude, and never reaches the frequency observed in the northern hemisphere. In the second part of the thesis, the impact of stratospheric ozone depletion on the Antarctic polar vortex and its subsequent influences on southern hemisphere surface climate patterns is investigated. It is verified that stratospheric final warming events have an impact on tropospheric circulation in a simplified GCM with seasonal variations in the stratosphere only. The model produces qualitatively realistic final warming events whose influence extends down to the surface, much like what has been reported in observational analyses. The hypothesis that recent observed trends in surface westerlies in the Southern Hemisphere are directly consequent on observed trends in the timing of stratospheric final warming events is tested. It is confirmed that there is a statistically significant shift towards later final warming events in the years with large ozone depletion. However it is found that the observed trends in surface westerlies cannot be attributed simply to this shift towards later final warming events. Finally, responses of the idealized AGCM to polar stratospheric cooling that mimics the radiative effects of stratospheric ozone depletion are studied. It is found that there are two factors that play a role in setting the magnitude and persistence of the model's surface response to cooling: the seasonal cycle of tropospheric annular mode timescales, and whether or not the imposed cooling leads to the presence of stratospheric westerlies at a time when easterlies were prevalent in the control run. That is, the surface response is sensitive to the timing of the imposed polar stratospheric cooling.
Middle Atmosphere Dynamics
Middle Atmosphere Dynamics - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Middle Atmosphere Dynamics write by David G. Andrews. This book was released on 2016-07-21. Middle Atmosphere Dynamics available in PDF, EPUB and Kindle. For advanced undergraduate and beginning graduate students in atmospheric, oceanic, and climate science, Atmosphere, Ocean and Climate Dynamics is an introductory textbook on the circulations of the atmosphere and ocean and their interaction, with an emphasis on global scales. It will give students a good grasp of what the atmosphere and oceans look like on the large-scale and why they look that way. The role of the oceans in climate and paleoclimate is also discussed. The combination of observations, theory and accompanying illustrative laboratory experiments sets this text apart by making it accessible to students with no prior training in meteorology or oceanography. * Written at a mathematical level that is appealing for undergraduates and beginning graduate students * Provides a useful educational tool through a combination of observations and laboratory demonstrations which can be viewed over the web * Contains instructions on how to reproduce the simple but informative laboratory experiments * Includes copious problems (with sample answers) to help students learn the material.
Variability of the Polar Stratosphere and Its Influence on Surface Weather and Climate
Variability of the Polar Stratosphere and Its Influence on Surface Weather and Climate - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Variability of the Polar Stratosphere and Its Influence on Surface Weather and Climate write by William J. M. Seviour. This book was released on 2014. Variability of the Polar Stratosphere and Its Influence on Surface Weather and Climate available in PDF, EPUB and Kindle.
Stratospheric Polar Vortex Variability in the Northern Hemisphere
Stratospheric Polar Vortex Variability in the Northern Hemisphere - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Stratospheric Polar Vortex Variability in the Northern Hemisphere write by . This book was released on 2019. Stratospheric Polar Vortex Variability in the Northern Hemisphere available in PDF, EPUB and Kindle. Regions that have experienced recent successive cold winters such as the Northeast of North America and Siberia have endured critical social and economic impacts from anomalous low temperatures in recent years, despite warming global temperatures. It is well known that the Tropospheric Polar Vortex (TPV), or jet stream, is a primary influence on many mid-latitude winter weather patterns. However, the strong circumpolar westerlies that maximize at around 60° latitude just above the tropopause, known as the Stratospheric Polar Vortex (SPV), can affect tropospheric circulation and thus winter weather in the Northern Hemisphere. Strong upward propagating waves can affect the geographic extent and strength of the SPV resulting in a weakened polar vortex state, which can in turn bring persistent weather events to the mid-latitudes. Here, an index of SPV spatiotemporal variability is presented using observation based analysis of zonal wind and geopotential height to show changes in SPV behavior at a seasonal scale from 1950-2018. Utilizing the CMIP5 suite of global climate models, historical and projected simulations of the SPV's climatological extent and strength are analyzed from 1915 to the end of this century, taking into account models with enhanced stratospheric representation. Simulated results are largely consistent with trends in the observational data, which suggest continued increases in average SPV size throughout this century. If future SPV disturbances increase in frequency, there could be negative impacts in ecosystem and agricultural health, infrastructure damage, and to human safety. A more advanced understanding of SPV trends and anomalous events could improve forecasts of cold air outbreaks (CAOs) and severe or persistent winter weather.
Sub-seasonal to Seasonal Prediction
Sub-seasonal to Seasonal Prediction - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Sub-seasonal to Seasonal Prediction write by Andrew Robertson. This book was released on 2018-10-19. Sub-seasonal to Seasonal Prediction available in PDF, EPUB and Kindle. The Gap Between Weather and Climate Forecasting: Sub-seasonal to Seasonal Prediction is an ideal reference for researchers and practitioners across the range of disciplines involved in the science, modeling, forecasting and application of this new frontier in sub-seasonal to seasonal (S2S) prediction. It provides an accessible, yet rigorous, introduction to the scientific principles and sources of predictability through the unique challenges of numerical simulation and forecasting with state-of-science modeling codes and supercomputers. Additional coverage includes the prospects for developing applications to trigger early action decisions to lessen weather catastrophes, minimize costly damage, and optimize operator decisions. The book consists of a set of contributed chapters solicited from experts and leaders in the fields of S2S predictability science, numerical modeling, operational forecasting, and developing application sectors. The introduction and conclusion, written by the co-editors, provides historical perspective, unique synthesis and prospects, and emerging opportunities in this exciting, complex and interdisciplinary field. Contains contributed chapters from leaders and experts in sub-seasonal to seasonal science, forecasting and applications Provides a one-stop shop for graduate students, academic and applied researchers, and practitioners in an emerging and interdisciplinary field Offers a synthesis of the state of S2S science through the use of concrete examples, enabling potential users of S2S forecasts to quickly grasp the potential for application in their own decision-making Includes a broad set of topics, illustrated with graphic examples, that highlight interdisciplinary linkages
