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A Dynamic Analysis of the Role of the Planetary- and Synoptic-Scale in the Summer of 2010 Blocking Episodes over the European Part of Russia  [PDF]
Anthony R. Lupo,Igor I. Mokhov,Merseid G. Akperov,Alexander V. Chernokulsky,H. Athar
Advances in Meteorology , 2012, DOI: 10.1155/2012/584257
Abstract: During the summer of 2010, an unusually persistent blocking episode resulted in anomalously warm dry weather over the European part of Russia. The excessive heat resulted in forest and peat fires, impacted terrestrial ecosystems, greatly increased pollution in urban areas, and increased mortality rates in the region. Using the National Centers for Atmospheric Research (NCAR), National Centers for Environmental Prediction (NCEP) reanalysis datasets, the climatological and dynamic character of blocking events for summer 2010 and a precursor May blocking event were examined. We found that these events were stronger and longer lived than typical warm season events. Using dynamic methods, we demonstrate that the July 2010 event was a synoptic-scale dominant blocking event; unusual in the summer season. An analysis of phase diagrams demonstrated that the planetary-scale did not become stable until almost one week after block onset. For all other blocking events studied here and previously, the planetary-scale became stable around onset. Analysis using area integrated regional enstrophy (IRE) demonstrated that for the July 2010 event, synoptic-scale IRE increased at block onset. This was similar for the May 2010 event, but different from case studies examined previously that demonstrated the planetary-scale IRE was prominent at block onset.
A Dynamic Analysis of the Role of the Planetary- and Synoptic-Scale in the Summer of 2010 Blocking Episodes over the European Part of Russia  [PDF]
Anthony R. Lupo,Igor I. Mokhov,Merseid G. Akperov,Alexander V. Chernokulsky,H. Athar
Advances in Meteorology , 2012, DOI: 10.1155/2012/584257
Abstract: During the summer of 2010, an unusually persistent blocking episode resulted in anomalously warm dry weather over the European part of Russia. The excessive heat resulted in forest and peat fires, impacted terrestrial ecosystems, greatly increased pollution in urban areas, and increased mortality rates in the region. Using the National Centers for Atmospheric Research (NCAR), National Centers for Environmental Prediction (NCEP) reanalysis datasets, the climatological and dynamic character of blocking events for summer 2010 and a precursor May blocking event were examined. We found that these events were stronger and longer lived than typical warm season events. Using dynamic methods, we demonstrate that the July 2010 event was a synoptic-scale dominant blocking event; unusual in the summer season. An analysis of phase diagrams demonstrated that the planetary-scale did not become stable until almost one week after block onset. For all other blocking events studied here and previously, the planetary-scale became stable around onset. Analysis using area integrated regional enstrophy (IRE) demonstrated that for the July 2010 event, synoptic-scale IRE increased at block onset. This was similar for the May 2010 event, but different from case studies examined previously that demonstrated the planetary-scale IRE was prominent at block onset. 1. Introduction Blocking events are generally thought of as quiescent phenomena that bring warmer and drier conditions to the areas that they impact and colder, wetter conditions in the upstream and downstream [1–7]. Their influence on the weather upstream and downstream of the main event, however, is well documented (e.g., [1–7]). They often bring anomalously stable weather conditions (high pressure), and this can result in air pollution events over the regions where they occur (e.g., [8–12]). During the cold season, it is the upstream and downstream regions that are more adversely affected by strong cold waves induced by the blocking event (e.g., [2, 7]). During the warm season, the regions were covered by the block suffer excessive heat (e.g., [11, 12]). The blocking episode that occurred over the European part of Russia during the summer of 2010 was devastating, especially over the western part of the country. It is estimated that more than 50,000 Russian inhabitants perished due to the weather conditions associated with the blocking events (see http://ifaran.ru/science/seminars/Summer2010.html). The mortality rates due to the unprecedented summer heat and air pollution associated with the forest and peat fires were
Revisiting the Climatology of Atmospheric Blocking in the Northern Hemisphere

Ho Nam CHEUNG,ZHOU Wen,Hing Yim MOK,Man Chi WU,Yaping SHAO,

大气科学进展 , 2013,
Abstract: In addition to the occurrence of atmospheric blocking, the climatology of the characteristics of blocking events, including duration, intensity, and extension, in four seasons over the Northern Hemisphere was analyzed for the period 1950–2009. The seasonality and spatial variations of these characteristics were studied according to their longitudinal distributions. In general, there were sharp discrepancies in the blocking characteristics between winter and summer, and these differences were more prominent over the Atlantic and Pacific Oceans. The blocking not only occurred more frequently but also underwent stronger amplification in winter; likewise, the blocking occurred less frequently and underwent weaker amplification in summer. There are very strong interrelationships among different blocking characteristics, suggesting that they are supported by similar physical factors. In addition, the relationship between blocking over different regions and East Asian circulation was examined. Ural-Siberia is a major blocking formation region in all seasons that may exert a downstream impact on East Asia. The impact is generally weak in summer, which is due to its lower intensity and smaller duration. However, the extratropical circulation over East Asia in summer can be disturbed persistently by the frequent occurrence of blocking over the Asian continent or the Western Pacific. In particular, the blocking frequency over the Western Pacific significantly increased during the study period. This climatological information provides a background for studying the impact of blocking on East Asian circulation under both present and future climate conditions.
Dominant Folding Pathways of a WW Domain  [PDF]
S. a Beccara,T. Skrbic,R. Covino,P. Faccioli
Quantitative Biology , 2011,
Abstract: We investigate the folding mechanism of the WW domain Fip35 using a realistic atomistic force field by applying the Dominant Reaction Pathways (DRP) approach. We find evidence for the existence of two folding pathways, which differ by the order of formation of the two hairpins. This result is consistent with the analysis of the experimental data on the folding kinetics of WW domains and with the results obtained from large-scale molecular dynamics (MD) simulations of this system. Free-energy calculations performed in two coarse-grained models support the robustness of our results and suggest that the qualitative structure of the dominant paths are mostly shaped by the native interactions. Computing a folding trajectory in atomistic detail only required about one hour on 48 CPU's. The gain in computational efficiency opens the door to a systematic investigation of the folding pathways of a large number of globular proteins.
Characterization of Protein Folding by Dominant Reaction Pathways  [PDF]
Pietro Faccioli
Quantitative Biology , 2008,
Abstract: We assess the reliability of the recently developed approach denominated Dominant Reaction Pathways (DRP) by studying the folding of a 16-residue beta-hairpin, within a coarse-grained Go-type model. We show that the DRP predictions are in quantitative agreement with the results of Molecular Dynamics simulations, performed in the same model. On the other hand, in the DRP approach, the computational difficulties associated to the decoupling of time scales are rigorously bypassed. The analysis of the important transition pathways supports a picture of the beta-hairpin folding in which the reaction is initiated by the collapse of the hydrophobic cluster.
Dominant Folding Pathways of a Beta-Hairpin  [PDF]
Pietro Faccioli,Alice Lonardi,Henri Orland
Quantitative Biology , 2009,
Abstract: We use the Dominant Reaction Pathway (DRP) approach to study the dynamics of the folding of a beta-hairpin, within a model which accounts for both native and non-native interactions. We compare the most probable folding pathways calculated with the DRP method with those obtained directly from molecular dynamics (MD) simulations. We find that the two approaches give completely consistent results. We investigate the effects of the non-native hydrophobic interactions on the folding dynamics found them to be small.
Delay induced bifurcation of dominant transition pathways  [PDF]
Huijun Jiang,Zhonghuai Hou
Statistics , 2011, DOI: 10.1063/1.4749795
Abstract: We investigate delay effects on dominant transition pathways (DTP) between metastable states of stochastic systems. A modified version of the Maier-Stein model with linear delayed feedback is considered as an example. By a stability analysis of the {"on-axis"} DTP in trajectory space, we find that a bifurcation of DTPs will be induced when time delay $\tau$ is large enough. This finding is soon verified by numerically derived DTPs which are calculated by employing a recently developed minimum action method extended to delayed stochastic systems. Further simulation shows that, the delay-induced bifurcation of DTPs also results in a nontrivial dependence of the transition rate constant on the delay time. Finally, the bifurcation diagram is given on the $\tau-\beta$ plane, where $\beta$ measures the non-conservation of the original Maier-Stein model.
Dominant Reaction Pathways in High Dimensional Systems  [PDF]
E. Autieri,P. Faccioli,M. Sega,F. Pederiva,H. Orland
Physics , 2008, DOI: 10.1063/1.3074271
Abstract: This paper is devoted to the development of a theoretical and computational framework to efficiently sample the statistically significant thermally activated reaction pathways, in multi-dimensional systems obeying Langevin dynamics. We show how to obtain the set of most probable reaction pathways and compute the corrections due to quadratic thermal fluctuations around such trajectories. We discuss how to obtain predictions for the evolution of arbitrary observables and how to generate conformations which are representative of the transition state ensemble. We present an illustrative implementation of our method by studying the diffusion of a point particle in a 2-dimensional funneled external potential.
Revisiting the Carrington Event: Updated modeling of atmospheric effects  [PDF]
Brian C. Thomas,Keith R. Arkenberg,Brock R. Snyder II
Physics , 2011,
Abstract: The terrestrial effects of major solar events such as the Carrington white-light flare and subsequent geomagnetic storm of August-September 1859 are of considerable interest, especially in light of recent predictions that such extreme events will be more likely over the coming decades. Here we present results of modeling the atmospheric effects, especially production of odd nitrogen compounds and subsequent depletion of ozone, by solar protons associated with the Carrington event. This study combines approaches from two previous studies of the atmospheric effect of this event. We investigate changes in NOy compounds as well as depletion of O3 using a two-dimensional atmospheric chemistry and dynamics model. Atmospheric ionization is computed using a range-energy relation with four different proxy proton spectra associated with more recent well-known solar proton events. We find that changes in atmospheric constituents are in reasonable agreement with previous studies, but effects of the four proxy spectra used vary more widely than found by one of those studies. In particular, we find greater impact for harder proton spectra, given a constant total fluence. We report computed nitrate deposition values and compare to measured values in ice cores. Finally, we briefly investigate the impact of the modeled ozone depletion on surface-level solar ultraviolet radiation.
Monopole blocking governed by a modified KdV type equation  [PDF]
X. Y. Tang,J. Zhao,F. Huang,S. Y. Lou
Physics , 2008,
Abstract: A type of coupled variable coefficient modified Korteweg-de Vries system is derived from a two-layered fluid system. It is known that the formation, maintenance, and collapse of an atmospheric blocking are always related with large-scale weather or shorts term climate anomalies. One special analytical solution of the obtained system successfully features the evolution cycle of an atmospheric monopole type blocking event. In particular, our theoretical results captures a real monopole type blocking case happened during 19 Feb 2008 to 26 Feb 2008 can be well described by our analytical solution.
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