Climate Change Detection And Attribution Using GPS Radio Occultation And CMIP5 GCM Data

General circulation models (GCMs) show a distinct anthropogenic fingerprint - the thermal expansion of Hadley Cell. This response to the increase of atmospheric concentration of greenhouse gases (GHG) is evident under a variety of forcing scenarios. However the investigation of the anthropogenic signal in the real climate system is challenging because anthropogenic signal is immersed in the natural variability and it requires highly quality data to separate signal from background variability. GPS Radio Occultation (GPS RO) technique becomes close to meeting all of the quality requirements, enabling it to become the benchmark for the climate data. The analysis was implemented for upper troposphere - lower stratosphere (UTLS) region between 50°N and -50°S latitudes. Vertical profiles of temperature and geopotential heights from 2001-2006 CHAMP and 2006-2011 COSMIC missions and CMIP5 GCM data for the same variables and time period were used in this study. Whether the anthropogenic signal is distinguishable from natural variability of the climate is being investigated using optimal fingerprinting technique. Temperature trend patterns allow the detection of climate change on 90% significance level but not the attribution, while the geoptential height trend patterns show that the detection of anthropogenic climate influence is achieved on more than 99% significance level

Evaluating flood potential with GRACE in the United States

Reager and Famiglietti (2009) proposed an index, Reager's Flood Potential Index (RFPI), for early large-scale flood risk monitoring using the Terrestrial Water Storage Anomaly (TWSA) product derived from the Gravity Recovery and Climate Experiment (GRACE). We evaluated the efficacy of the RFPI for flood risk assessment over the continental USA using multi-year flood observation data from 2003 to 2012 by the US Geological Survey and Dartmouth Flood Observatory. In general, we found a good agreement between the RFPI flood risks and the observed floods on regional and even local scales. RFPI demonstrated skill in predicting the large-area, long-duration floods, especially during the summer season

Internal wave activity in the deep Gulf of Mexico

Internal wave activity in the Gulf of Mexico (GoM) is investigated using a fleet of profiling floats. The floats continuously measured temperature and salinity as they drifted at a parking depth of 1500 dbar, allowing for the reconstruction of 2615 time series of isopycnal displacements. Thanks to the dense sampling of the eastern part of the GoM (east of 90°W), the geographical distribution of the internal waves displacement variance and available potential energy (APE) is revealed. The Loop Current (LC) influence region, between the Yucatan shelf to the west and the southern West Florida shelf to the east exhibits increased displacement variance and APE both in the continuum and near-inertial bands, while the north-eastern and central GoM show reduced internal wave activity. As the LC position fluctuates between a retracted and extended mode, we assessed the impact of the presence or absence of the LC in the increased internal wave activity region. It is shown that in the LC influence region, APE is increased (decreased) when the LC is present (absent), suggesting a strong control of the LC on deep internal waves activity. The 1500 dbar flow velocity, bottom roughness, and float altitude also seem to contribute to increased internal waves APE, but their influence is more subtle. Oppositely, no correlation with wind speed or wind intermittency is found

2D/3D Metallic Nano-objects Self-Organized in an Organic Molecular Thin Film

We present the fabrication and investigation of the properties of nanocomposite structures consisting of two-dimensional (2D) and three-dimensional (3D) metallic nano-objects self-organized on the surface and inside of organic molecular thin-film copper tetrafluorophthalocyanine (CuPcF4). Metallic atoms, deposited under ultrahigh vacuum (UHV) conditions onto the organic ultrathin film, diffuse along the surface and self-assemble into a system of 2D metallic overlayers. At the same time, the majority of the metal atoms diffuse into the organic matrix and self-organize into 3D nanoparticles (NPs) in a well-defined manner. The evolution of the morphology and electronic properties of such structures as a function of nominal metal content is studied under UHV conditions using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and photoelectron spectroscopy (PES) techniques. Using HR-TEM, we have observed the periodicity of atomic planes of individual silver NPs. The steady formation of agglomerates from individual single nanocrystallites with intercrystallite boundaries is observed as well. PES reveals generally weak chemical interactions between silver and the organic matrix and n-doping of CuPcF4 at the initial stages of silver deposition, which is associated with charge transfer from the 2D wetting layer on the basis of core-level spectra shift analysis. Copyright © 2020 American Chemical Society

FROM FRESH- TO SEA-WATER AND FROM SHALLOW TO DEEP - A TURBULENCE PERSPECTIVE

Turbulence is an important process governing the mixing of fluid properties in nature. Nowadays, it remains a complex topic in oceanography, and other fields, due to its inherent stochastic nature. It is important in many areas of research, and there are many unresolved problems regarding the understanding of turbulence and the role it is playing in different processes. In my research, I am trying to address some of those questions. The first problem which I am investigating is related to the study of turbulence within the mesoscale eddy system. For the first time, turbulence was estimated from microstructure velocity and temperature fluctuations measured within an anticyclonic eddy originating from the Loop Current in the Gulf of Mexico. This study aims to provide a unique set of measurements that will allow resolving the dynamics of physical and biogeochemical processes related to eddies and shelf processes. The second problem is devoted to the parameterization and estimation of a gas exchange coefficient in river environments. The gas exchange between water bodies and the air is difficult to measure. Thus the Wanninkhof methodology (Wanninkhof et al., 2014) to approximate air-sea gas exchange solely based on wind speed is widely used. However, this approximation may not work in river environments. In rivers, water currents may play a more important role in governing gas exchange than wind. In this study, I compare different approaches to estimate the gas exchange coefficients using field observations during the summer of 2016 on the Yenisei River

Structure Revision of Asperjinone using Computer-Assisted Structure Elucidation (CASE) Methods

<p>The elucidated structure of asperjinone, a natural product isolated from thermophilic Aspergillus terreus, was revised using the expert system Structure Elucidator. The reliability of the revised structure was confirmed using 180 structures containing the (3,3-dimethyloxiran-2-yl)methyl fragment as a basis for comparison and whose chemical shifts contradict the suggested structure.</p> <p> </p

Computer-assisted methods for molecular structure elucidation: realizing a spectroscopist's dream

Abstract Background This article coincides with the 40 year anniversary of the first published works devoted to the creation of algorithms for computer-aided structure elucidation (CASE). The general principles on which CASE methods are based will be reviewed and the present state of the art in this field will be described using, as an example, the expert system Structure Elucidator. Results The developers of CASE systems have been forced to overcome many obstacles hindering the development of a software application capable of drastically reducing the time and effort required to determine the structures of newly isolated organic compounds. Large complex molecules of up to 100 or more skeletal atoms with topological peculiarity can be quickly identified using the expert system Structure Elucidator based on spectral data. Logical analysis of 2D NMR data frequently allows for the detection of the presence of COSY and HMBC correlations of "nonstandard" length. Fuzzy structure generation provides a possibility to obtain the correct solution even in those cases when an unknown number of nonstandard correlations of unknown length are present in the spectra. The relative stereochemistry of big rigid molecules containing many stereocenters can be determined using the StrucEluc system and NOESY/ROESY 2D NMR data for this purpose. Conclusion The StrucEluc system continues to be developed in order to expand the general applicability, provide improved workflows, usability of the system and increased reliability of the results. It is expected that expert systems similar to that described in this paper will receive increasing acceptance in the next decade and will ultimately be integrated directly to analytical instruments for the purpose of organic analysis. Work in this direction is in progress. In spite of the fact that many difficulties have already been overcome to deliver on the spectroscopist's dream of "fully automated structure elucidation" there is still work to do. Nevertheless, as the efficiency of expert systems is enhanced the solution of increasingly complex structural problems will be achievable.</p

Elucidating "Undecipherable" Chemical Structures Using Computer Assisted Structure Elucidation Approaches

<p>Structure elucidation using 2D NMR data and application of traditional methods of structure elucidation is known to fail for certain problems. In this work it is shown that Computer-Assisted Structure Elucidation (CASE) methods are capable of solving such problems. We conclude that it is now impossible to evaluate the capabilities of novel NMR experimental techniques in isolation from expert systems developed for processing fuzzy, incomplete and contradictory information obtained from 2D NMR spectra.</p

Structure Revision of Asperjinone using Computer-Assisted Structure Elucidation (CASE) Methods

<p>The elucidated structure of asperjinone, a natural product isolated from thermophilic Aspergillus terreus, was revised using the expert system Structure Elucidator. The reliability of the revised structure was confirmed using 180 structures containing the (3,3-dimethyloxiran-2-yl)methyl fragment  as a basis for comparison and whose chemical shifts contradict the suggested structure.</p