Modulation of surface meteorological parameters by extratropical planetary-scale Rossby waves

This study examines the link between upper-tropospheric planetary-scale Rossby waves and surface meteorological parameters based on the observations made in association with the Ganges Valley Aerosol Experiment (GVAX) campaign at an extratropical site at Aryabhatta Research Institute of Observational Sciences, Nainital (29.45° N, 79.5° E) during November–December 2011. The spectral analysis of the tropospheric wind field from radiosonde measurements indicates a predominance power of around 8 days in the upper troposphere during the observational period. An analysis of the 200 hPa meridional wind (v200 hPa) anomalies from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis shows distinct Rossby-wave-like structures over a high-altitude site in the central Himalayan region. Furthermore, the spectral analysis of global v200 hPa anomalies indicates the Rossby waves are characterized by zonal wave number 6. The amplification of the Rossby wave packets over the site leads to persistent subtropical jet stream (STJ) patterns, which further affects the surface weather conditions. The propagating Rossby waves in the upper troposphere along with the undulations in the STJ create convergence and divergence regions in the mid-troposphere. Therefore, the surface meteorological parameters such as the relative humidity, wind speeds, and temperature are synchronized with the phase of the propagating Rossby waves. Moreover, the present study finds important implications for medium-range forecasting through the upper-level Rossby waves over the study region

Elimination of the reaction rate 'scale effect': application of the Lagrangian reactive particle-tracking method to simulate mixing-limited, field-scale biodegradation at the Schoolcraft (MI, USA) site

This is the peer reviewed version of the following article: [Ding, D., Benson, D. A., Fernàndez‐Garcia, D., Henri, C. V., Hyndman, D. W., Phanikumar, M. S., & Bolster, D. (2017). Elimination of the reaction rate “scale effect”: Application of the Lagrangian reactive particle‐tracking method to simulate mixing‐limited, field‐scale biodegradation at the Schoolcraft (MI, USA) site. Water Resources Research, 53, 10,411–10,432. https://doi.org/10.1002/2017WR021103], which has been published in final form at https://doi.org/10.1002/2017WR021103. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Measured (or empirically fitted) reaction rates at groundwater remediation sites are typically much lower than those found in the same material at the batch or laboratory scale. The reduced rates are commonly attributed to poorer mixing at the larger scales. A variety of methods have been proposed to account for this scaling effect in reactive transport. In this study, we use the Lagrangian particle-tracking and reaction (PTR) method to simulate a field bioremediation experiment at the Schoolcraft, MI site. A denitrifying bacterium, Pseudomonas Stutzeri strain KC (KC), was injected to the aquifer, along with sufficient substrate, to degrade the contaminant, carbon tetrachloride (CT), under anaerobic conditions. The PTR method simulates chemical reactions through probabilistic rules of particle collisions, interactions, and transformations to address the scale effect (lower apparent reaction rates for each level of upscaling, from batch to column to field scale). In contrast to a prior Eulerian reaction model, the PTR method is able to match the field-scale experiment using the rate coefficients obtained from batch experiments.Peer ReviewedPostprint (author's final draft

Evaluating the role of sediment‐bacteria interactions on Escherichia coli concentrations at beaches in southern Lake Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102640/1/jgrc20481.pd

Solar flares induced D-region ionospheric and geomagnetic perturbations

The D-region ionospheric perturbations caused by solar flares occurred during January 2010 to February 2011, a low solar activity period of current solar cycle 24, have been examined on NWC transmitter signal (19.8 kHz) recorded at an Indian low latitude station, Allahabad (Geographic lat. 25.75 °N, long. 81.85 °E). A total of 41 solar flares, including 21 C-class, 19 M-class and 01 X-class, occurred during the daylight part of the NWC-Allahabad transmitter receiver great circle path. The local time dependence of solar flare effect on the change in the VLF amplitude (ΔA), time delay (Δt) between VLF peak amplitude and X-ray flux peak have been studied during morning, noon and evening periods of local daytime. Using the Long Wave Propagation Capability code V 2.1 the D-region reference height (H/) and sharpness factor (β) for each class of solar flare (C, M and X), have been estimated. It is found that D-region ionospheric parameters (H/, β) strongly depend on the local time of flares occurrence and their classes. The solar flare time electron density estimated by using H/ and β shows maximum increase in electron density of the order of ~80 as compared with normal day values. Electron density was found to increase exponentially with increase in the solar flux intensity. Solar flare effect on horizontal component (H) of the Earth’s magnetic field over an equatorial station, Tirunelveli (Geographic lat., 8.7°N, long., 77.8°E, dip lat., 0.4 ºN), shows a maximum increase in H of ~ 8.5% for M class solar flares. The increase in H is due to the additional magnetic field produced by the ionospheric electrojet over the equatorial station

Low - mid latitude D region ionospheric perturbations associated with 22 July 2009 total solar eclipse: wave -like signatures inferred from VLF observations

We present first report on the periodic wave-like signatures (WLS) in the D region ionosphere during 22 July 2009 total solar eclipse using JJI, Japan, very low frequency (VLF) navigational transmitter signal (22.2 kHz) observations at stations, Allahabad, Varanasi and Nainital in Indian Sector, Busan in Korea, and Suva in Fiji. The signal amplitude increased on 22 July by about 6 and 7 dB at Allahabad and Varanasi and decreased by about 2.7, 3.5, and 0.5 dB at Nainital, Busan, and Suva, respectively, as compared to 24 July 2009 (normal day). The increase/decrease in the amplitude can be understood in terms of modal interference at the sites of modes converted at the discontinuity created by the eclipse intercepting the different transmitter-receiver great circle paths. The wavelet analysis shows the presence of WLS of period ~16–40 min at stations under total eclipse and of period ~30–80 min at stations under partial eclipse (~85–54% totality) with delay times between ~50 and 100 min at different stations. The intensity of WLS was maximum for paths in the partially eclipsed region and minimum in the fully eclipsed region. The features of WLS on eclipse day seem almost similar to WLS observed in the nighttime of normal days (e.g., 24 July 2009). The WLS could be generated by sudden cutoff of the photo-ionization creating nighttime like conditions in the D region ionosphere and solar eclipse induced gravity waves coming to ionosphere from below and above. The present observations shed additional light on the current understanding of gravity waves induced D region ionospheric perturbations

Advancing Global Tobacco Control: Exploring Worldwide Youth Attitudes and Behaviors toward Tobacco Use and Control

Tobacco use continues to be the leading cause of preventable death in the world. The disproportionate increase in tobacco use in low- and middle-income countries needs immediate attention. Many smokers begin smoking as adolescents and are most likely to become permanent smokers. Moreover, youth are highly targeted by tobacco industry strategies. However, a gap exists in literature to understand worldwide youth tobacco use and control. The purpose of this study is to 1) identify factors that influence never-smoking youths‟ smoking susceptibility, 2) explore characteristics that influence youth exposure to environmental tobacco smoke (ETS) and 3) to delineate key determinants of youth support for smoke-free policies (SFPs). Data related to worldwide youth tobacco use was obtained from the Global Youth Tobacco Survey for the years 1999-2008. Simple and multiple logistic regression analyses were conducted, after the sample was weighted for design effect, nonresponse patterns and poststratification. Unadjusted and adjusted odds ratios along with 95% confidence intervals were reported. Around 14% of never-smoking youth were susceptible to smoking worldwide. Around 40% and 50% youth were exposed to ETS inside and outside the home respectively, and 78% supported SPFs globally. Parental and peer smoking was strongly associated with smoking susceptibility in never-smoking youth [AOR 2.63, 95% CI 2.43 to 2.84], and youth exposure to ETS inside [AOR 5.09, 95% CI 4.84 to 5.35] and outside [AOR 2.51, 95% CI 2.39 to 2.63] the home, while anti-smoking school education was negatively associated. Youth having knowledge about smoking harm [AOR 2.37, 95% CI 2.22 to 2.54] supported SFPs, while youth exposed to tobacco industry promotion [AOR 0.83, 95% CI 0.78 to 0.89] did not support. The study highlighted a number of modifiable factors that can be used for augmenting global tobacco control in youth. Well-executed anti-smoking campaigns, parental and peer education, inclusion of anti-tobacco education in school curricula, comprehensive SFPs, and comprehensive ban on tobacco industry strategies are important approaches to prevent tobacco use and advance global tobacco control in youth

Inhibition of metal dusting of alloy 800H by laser surface melting

Metal dusting is a catastrophic carburisation phenomenon that occurs at temperatures of 450-850°C in atmospheres of high carbon activity. The resistance of alloys to corrosion, including metal dusting, relies on the formation of a dense, adherent oxide layer that separates the alloy from the corrosive environment. For such an oxide layer to be protective, it must achieve full surface coverage, be crack-free and be established before significant material degradation has occurred. Formation of a protective oxide scale can be enhanced by increasing the population of rapid diffusion paths for the protective elements (e.g. Cr and Al) to reach the alloy surface. In this work, laser surface melting has been used to improve the metal dusting resistance of Alloy 800H by creating a rapid solidification microstructure and, thereby, increasing the density of rapid diffusion paths. Oxidation during laser processing has been found to be detrimental to metal dusting resistance. However, it has been demonstrated that the resulting oxide can be removed without compromising metal dusting resistance. Results of exposure to a metal dusting atmosphere (20% H2 80% CO at 650°C) are presented. Samples have been examined in plan and cross-section using optical and scanning electron microscopy. Selected samples were also examined by electron probe microanalysis and X-ray diffraction

Modeling Willingness-to-Pay Values for Rural Bus Attributes Under Different Trip Purposes

Modeling Willingness-to-Pay Values for Rural Bus Attributes Under Different Trip Purpose

Chemical Amelioration of Expansive Soils

Expansive soils swell when they absorb water and shrink when water evaporates from them. Hence, lightly loaded civil engineering structures found in these soils are subjected to severe distress. Therefore, there is a need to ameliorate or improve these swelling soils through some innovative methods. This paper discusses chemical stabilisation of expansive soils, a technique in which chemical reagents such as lime and calcium chloride are added to expansive soils to reduce the volumetric changes occurring in expansive soils and also to improve their engineering behaviour

Intriguing aspects of F-region plasma irregularities revealed by the Gadanki radar observations during the SAFAR campaign

Intriguing new results of F-region irregularities observed using the Gadanki MST radar during the SAFAR campaigns, which were conducted during the equinox and summer of 2008 that corresponds to low solar activity condition, are presented. The summer observations are first of its kind from Gadanki. Observations revealed remarkably different morphology of the F-region irregularities in summer when compared to that in equinox. In summer, the F-region irregularities were observed as horizontally stratified structures, while in equinox they were observed as plume structures. Further, the irregularities in summer commenced during the post-midnight hours in contrast to their commencement in the post-sunset hours and occurrence extending to post-midnight hours in equinox. In addition, an intriguing observation of the summer time irregularities is that they occurred when the background electron density was remarkably low as characterized by the disappearance of the F layer trace in the ionograms. An interesting event of equinox that was observed for 10 h and extended beyond the sunrise time displayed multiple plume structures having periods similar to those of the E-region velocity variations. These observations are discussed with due focus on the genesis of postmidnight F-region irregularities and their possible linkage to the E-region dynamics