Article
Environmental Sciences
Konstantina Nakoudi, Christoph Ritter, Iwona S. Stachlewska
Summary: This study explores the long-term properties of cirrus clouds for the first time over an Arctic site, finding that cirrus clouds are generally associated with colder and calmer wind conditions, but their properties do not strongly depend on temperature and wind speed, with wintertime cirrus appearing thicker and with more spherical ice particles. The majority of cirrus at the Arctic site are associated with westerly flow and tend to be optically thicker and consist of more spherical ice particles compared to lower latitudes.
Article
Geochemistry & Geophysics
T. P. Mangan, J. M. C. Plane, B. J. Murray
Summary: Water ice clouds form in the mesospheres of terrestrial planets in the solar system through vapor deposition at low pressures and temperatures, leading to a variety of crystalline and amorphous phases. Research shows that direct deposition of ice can result in the formation of stable hexagonal ice at lower temperatures compared to warming stacking disordered ice. The three phases of water ice observed here may be possible in the mesospheres of Earth and Mars, while on Venus only amorphous ice is likely to form.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Environmental Sciences
Jing Feng, Yi Huang
Summary: The study found that tropical cyclone events significantly increase the occurrence frequency of TTL clouds, mainly contributed by overshooting deep convection. Using a synergistic method with satellite observations, a vertically oscillating pattern of temperature anomalies above tropical cyclones was discovered.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Environmental Sciences
Julia Schneider, Kristina Hohler, Robert Wagner, Harald Saathoff, Martin Schnaiter, Tobias Schorr, Isabelle Steinke, Stefan Benz, Manuel Baumgartner, Christian Rolf, Martina Kramer, Thomas Leisner, Ottmar Mohler
Summary: Homogeneous freezing of aqueous sulfuric acid aerosol particles was studied through laboratory experiments at the AIDA cloud simulation chamber. The results showed deviations from the water activity criterion-based predictions at lower temperatures, but agreement at higher temperatures. The ice saturation ratios of sulfuric acid aerosol particles increased with decreasing temperatures, impacting model predictions of cirrus cloud occurrence.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Geosciences, Multidisciplinary
Luca Palchetti, Marco Barucci, Claudio Belotti, Giovanni Bianchini, Bertrand Cluzet, Francesco D'Amato, Samuele Del Bianco, Gianluca Di Natale, Marco Gai, Dina Khordakova, Alessio Montori, Hilke Oetjen, Markus Rettinger, Christian Rolf, Dirk Schuettemeyer, Ralf Sussmann, Silvia Viciani, Hannes Vogelmann, Frank Gunther Wienhold
Summary: Measurements of the far-infrared (FIR) emission spectrum in the atmosphere are limited due to detection complexity and air absorption at ground level. This study collected FIR spectral radiance data using the FIRMOS instrument at high altitude, contributing to the preparatory activities of the upcoming ESA FIR mission FORUM.
EARTH SYSTEM SCIENCE DATA
(2021)
Article
Geosciences, Multidisciplinary
M. K. Sporre, J. Friberg, C. Svenhag, O. Sourdeval, T. Storelvmo
Summary: This study investigates the impact of downwelling sulphate aerosol on midlatitude cirrus clouds during springtime using three satellite data sets. The results show that cirrus clouds in the northern hemisphere have lower ice water content, ice crystal number concentrations, and cloud fraction when the aerosol load in the lowermost stratosphere is elevated by volcanism. However, the cirrus clouds in the southern hemisphere show no significant changes with downwelling aerosol levels. The reduction in cirrus ice water content and cloud fraction in the northern hemisphere implies that volcanic aerosol can cool the climate through reduced warming from cirrus clouds.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Environmental Sciences
Yuxin Zhao, Jiming Li, Lijie Zhang, Cong Deng, Yarong Li, Bida Jian, Jianping Huang
Summary: This study investigates the diurnal variations in cloud cover and cloud vertical distribution over the Tibetan Plateau. The results show that total cloud cover peaks in the morning and varies spatially and temporally. The study also reveals the dominant presence of opaque cirrus clouds over the plateau, which exhibit significant diurnal variations.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2023)
Article
Meteorology & Atmospheric Sciences
Diana L. Pereira, Ma Montserrat Silva, Rocio Garcia, Graciela B. Raga, Harry Alvarez-Ospina, Giovanni Carabali, Irma Rosas, Leticia Martinez, Eva Salinas, Sandra Hidalgo-Bonilla, Luis A. Ladino
Summary: This study found differences in ice nucleating abilities between tropical urban areas and rural regions, with the influence of human activities in cities contrasting with the impact of biological materials in rural sites. Bacteria and fungal propagules were consistently present in cloud water and rainwater samples. INPs concentrations in rainwater samples collected in tropical regions were lower compared to other areas, suggesting unique characteristics in tropical latitudes.
ATMOSPHERIC RESEARCH
(2021)
Article
Environmental Sciences
Yi Wang, Ping Yang, Michael D. King, Bryan A. Baum
Summary: An improved remote sensing technique is proposed in this study to infer an optimal model for ice particles in cirrus clouds using multi-angle polarimetric measurements at 865 nm. The hexagonal column aggregate model works well for most pixels in this proof-of-concept study, but the retrieval cost function is high when large zenith angles are included. Further studies are needed to better understand the selected ice particle models at scattering angles smaller than 100 degrees.
Article
Physics, Fluids & Plasmas
Yu. S. Reznichenko, A. Yu. Dubinskii, S. I. Popel
Summary: We propose a theoretical model to explain the formation and evolution of plasma-dust clouds observed in the Martian ionosphere by the Curiosity rover. The model includes the sedimentation of dust particles, growth of dust seeds through carbon dioxide nucleation, charging of dust particles, and changes in electron and ion number densities over time. The model successfully explains the layered structure of the dust cloud and calculates the characteristic size and charge of the dust particles.
PLASMA PHYSICS REPORTS
(2023)
Article
Meteorology & Atmospheric Sciences
Gianluca Di Natale, Marco Barucci, Claudio Belotti, Giovanni Bianchini, Francesco D'Amato, Samuele Del Bianco, Marco Gai, Alessio Montori, Ralf Sussmann, Silvia Viciani, Hannes Vogelmann, Luca Palchetti
Summary: The study conducted long-wave downwelling spectral radiance measurements using the Far-Infrared Radiation Mobile Observation System (FIRMOS) spectrometer at the Zugspitze in Germany, allowing retrieval of optical and microphysical properties of ice and mixed clouds with good agreement with previous works. Comparisons were made between optical depths retrieved from FIRMOS and selected cases calculated from lidar data, with evaluation of power-law relationships between backscattering and extinction for ice and mixed clouds.
ATMOSPHERIC MEASUREMENT TECHNIQUES
(2021)
Article
Meteorology & Atmospheric Sciences
X. I. P. I. N. G. Zeng, Z. B. I. G. N. I. E. W. Ulanowski, Andrew J. Heymsfield, Y. A. N. S. E. N. Wang, X. I. A. O. W. E. N. LI
Summary: The stability of ice crystal orientation was studied by modeling the airflow around ice crystals at moderate Reynolds number. An ice crystal was approximated by a cylinder with three parameters: diameter D, length L, and zenith angle of the axis O. The torque acting on ice crystals was simulated at different O, and a special O with zero horizontal torque, denoted as Oe, was sought as an equilibrium of ice crystal orientation. Multiple equilibriums of ice crystal orientation were found via numerical simulations.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2023)
Article
Multidisciplinary Sciences
Armin Kalita, Maximillian Mrozek-McCourt, Thomas F. Kaldawi, Philip R. Willmott, N. Duane Loh, Sebastian Marte, Raymond G. Sierra, Hartawan Laksmono, Jason E. Koglin, Matt J. Hayes, Robert H. Paul, Serge A. H. Guillet, Andrew L. Aquila, Mengning Liang, Sebastien Boutet, Claudiu A. Stan
Summary: This article studies the freezing process of supercooled water droplets in a vacuum environment, using optical microscopy and X-ray laser diffraction. The research found that long-range crystalline order formed in ice crystals in less than 1 ms after freezing.
Article
Meteorology & Atmospheric Sciences
Christiane Voigt, Jos Lelieveld, Hans Schlager, Johannes Schneider, Joachim Curtius, Ralf Meerkoetter, Daniel Sauer, Luca Bugliaro, Birger Bohn, John N. Crowley, Thilo Erbertseder, Silke Gross, Valerian Hahn, Qiang Li, Mariano Mertens, Mira L. Poehlker, Andrea Pozzer, Ulrich Schumann, Laura Tomsche, Jonathan Williams, Andreas Zahn, Meinrat Andreae, Stephan Borrmann, Tiziana Braeuer, Raphael Doerich, Andreas Doernbrack, Achim Edtbauer, Lisa Ernle, Horst Fischer, Andreas Giez, Manuel Granzin, Volker Grewe, Hartwig Harder, Martin Heinritzi, Bruna A. Holanda, Patrick Joeckel, Katharina Kaiser, Ovid O. Krueger, Johannes Lucke, Andreas Marsing, Anna Martin, Sigrun Matthes, Christopher Poehlker, Ulrich Poeschl, Simon Reifenberg, Akima Ringsdorf, Monika Scheibe, Ivan Tadic, Marcel Zauner-Wieczorek, Rolf Henke, Markus Rapp
Summary: During the spring of 2020, the COVID-19 pandemic led to significant reductions in emissions from industry and transportation, resulting in observable changes in atmospheric composition. These changes included reductions in nitrogen dioxide and carbon monoxide concentrations in urban areas, as well as decreases in total reactive nitrogen, carbon monoxide, and fine mode aerosol concentrations in German cities. The reduction in aerosol mass below 5 km altitude, along with changes in sky color and increased shortwave radiation at the surface, were also observed.
BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY
(2022)
Article
Meteorology & Atmospheric Sciences
Gwenore F. Pokrifka, Alfred M. Moyle, Jerry Y. Harrington
Summary: An electrodynamic levitation thermal-gradient diffusion chamber was used to grow small ice particles in a controlled environment. The growth characteristics of the ice particles were measured at different temperatures and supersaturations. The results showed that the growth of the particles was limited by attachment kinetics at low supersaturation, but enhanced by the development of branches and hollowed facets at high supersaturation. The effects of branching and hollowing were quantified using two different models, and the relative frequencies of the model parameters were used to derive supersaturation-dependent mass-size relationships for cloud modeling applications.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2023)
Editorial Material
Multidisciplinary Sciences
Thomas C. Hansen
Summary: Water ice is found in various environments across the universe, and the construction of the phase diagram for crystalline phases of ice is still ongoing. A recently reported high-pressure phase, ice XIX, has ambiguous structure that requires further study.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Raphael Finger, Nadine Kurtzemann, Thomas C. Hansen, Holger Kohlmann
Summary: A sapphire single-crystal gas-pressure cell has been developed for in situ neutron powder diffraction, allowing unobstructed optical access by neutrons. It successfully tested high-pressure hydrogen (deuterium) gas performance at different temperatures. The cell provides detailed descriptions of all components and offers high time resolution for studying reaction pathways involving hydrogen (deuterium) uptake or release.
JOURNAL OF APPLIED CRYSTALLOGRAPHY
(2021)
Article
Chemistry, Physical
Mikhail A. Kuzovnikov, Vladimir E. Antonov, Thomas Hansen, Alexandre S. Ivanov, Alexander Kolesnikov, Valery Kulakov, Vitaly D. Muzalevsky, Stanislav Savvin, Marek Tkacz
Summary: Three hydrides - PdHx, MoHx, and TiHx - exhibit an inverse isotope effect in superconductivity, where the phase with a heavier hydrogen isotope, deuterium, has a higher critical temperature. The origin of this effect is not yet certain, but the commonly accepted explanation points to the strong anharmonicity of optical hydrogen vibrations.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Crystallography
Raphael Finger, Marc Widenmeyer, Thomas C. Hansen, Dirk Wallacher, Stanislav Savvin, Marko Bertmer, Anke Weidenkaff, Holger Kohlmann
Summary: Temperature-dependent crystal structure alterations in Ba2In2O5, particularly with Cr doping, result in significant disorder and stabilization of the tetragonal polymorph, while high water content leads to a dynamic situation for the protons. These findings provide insight into how to adjust the physical properties of Ba2In2O5 for different applications.
Article
Chemistry, Multidisciplinary
Raphael Finger, Thomas C. Hansen, Holger Kohlmann
Summary: In situ neutron diffraction is an important technique for characterizing functional materials. A new sapphire single-crystal gas-pressure cell has been developed and evaluated, allowing for studying materials under different temperature and hydrogen pressure conditions. The cell has higher maximum temperatures and lower background noise compared to earlier versions.
JOURNAL OF APPLIED CRYSTALLOGRAPHY
(2022)
Article
Chemistry, Physical
Gohil S. Thakur, Thomas C. Hansen, Walter Schnelle, Shuping Guo, Oleg Janson, Jeroen van den Brink, Claudia Felser, Martin Jansen
Summary: The synthesis, crystal structure, and magnetic properties of a new 2:1 ordered triple perovskite Sr3CaOs2O9 were reported. It exhibits a unique buckled honeycomb lattice of osmium, high Neel temperature of approximately 385 K, and electrical insulating behavior.
CHEMISTRY OF MATERIALS
(2022)
Article
Chemistry, Inorganic & Nuclear
Simon R. Larsen, Vitalii Shtender, Daniel Hedlund, Erna K. Delczeg-Czirjak, Premysl Beran, Johan Cedervall, Alena Vishina, Thomas C. Hansen, Heike C. Herper, Peter Svedlindh, Olle Eriksson, Martin Sahlberg
Summary: The atomic and magnetic structures of Mn(Co,Ge)2, which crystallizes in a superstructure of the MgZn2-type structure, have been reported. The system exhibits different magnetic structures at different temperatures.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Rasmus Palm, Kenneth Tuul, Frank Elson, Elisabetta Nocerino, Ola K. Forslund, Thomas C. Hansen, Jaan Aruvali, Martin Mansson
Summary: This study investigates the influence of adding relatively low amounts of mesoporous carbon black on the decomposition and reforming processes of hydrogen storage material NaAlH4 through in situ diffraction. The results show that even with low concentrations, mesoporous carbon black can significantly enhance the reversibility of hydrogen storage in NaAlH4.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Materials Science, Ceramics
Ahmet Bahadir Yildiz, Hu Yixuan, R. Prasath Babu, Thomas C. Hansen, Mirva Eriksson, Kolan Madhav Reddy, Peter Hedstro
Summary: We have designed a novel multi-principal element carbide system (Ti,Zr,Hf,W)C and successfully synthesized a single-phase (Ti,Zr,Hf,W)C. The material exhibits high nanohardness and fracture toughness. Aging studies show the stability of the single-phase carbide solid solution even within the predicted miscibility gap of the system. Electron microscopy characterization reveals phase separation and the formation of lamellar structure and precipitates. The decomposition kinetics is sluggish due to reduced driving force.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2022)
Article
Crystallography
Andre Goetze, Siobhan Christina Stevenson, Thomas Christian Hansen, Holger Kohlmann
Summary: Binary intermetallic compounds, such as FePd3, have attracted attention due to their physical, magnetic, and catalytic properties. In this study, the hydrogenation properties of ordered FePd3 and disordered Fe0.25Pd0.75 were investigated using various in situ methods. The results showed that FePd3 absorbs small amounts of hydrogen at room temperature and follows the Sieverts' law. The [Pd-6] octahedral voids were filled with hydrogen atoms as the hydrogen pressure increased, leading to a decrease in long-range order of Fe and Pd atoms. The magnetic moments of iron atoms in FePd3 exhibited a temperature dependence that was consistent with a 3D Ising or Heisenberg model.
Article
Chemistry, Multidisciplinary
Sandeep K. Gupta, Hannah H. Nielsen, Andreas M. Thiel, Emil A. . Klahn, Erxi Feng, Huibo B. Cao, Thomas C. Hansen, Eddy Lelievre, Arsen Gukasov, Iurii Kibalin, Sebastian Dechert, Serhiy Demeshko, Jacob Overgaard, Franc Meyer, Franc Meyer
Summary: In this study, a highly anisotropic single-ion magnet (SIM) with stability under ambient conditions was synthesized and comprehensively characterized. The influence of the ligand field on the degeneracy and population of d-orbitals in a specific coordination environment was investigated, providing important insights for the rational design and enhancement of magnetic anisotropy in SIMs.
Article
Materials Science, Multidisciplinary
John M. Wilkinson, Stephen J. Blundell, Sebastian Biesenkamp, Markus Braden, Thomas C. Hansen, Kacper Koteras, Wojciech Grochala, Paolo Barone, Jose Lorenzana, Zoran Mazej, Gasper Tavcar
Summary: KAgF3 is a quasi-one-dimensional quantum antiferromagnet with interesting structural and magnetic transitions. At low temperatures, it orders as an A-type antiferromagnet with an ordered moment. Previous magnetometry study provides evidence for an intermediate phase at T-N1 < T < T-N2, but its nature remains unknown.
Article
Chemistry, Multidisciplinary
Daniel Risskov Sorensen, Andreas Ostergaard Drejer, Michael Heere, Anatoliy Senyshyn, Matthias Frontzek, Thomas Hansen, Christophe Didier, Vanessa K. Peterson, Dorthe Bomholdt Ravnsbaek, Mads Ry Vogel Jorgensen
Summary: In operando powder diffraction is a powerful tool for investigating battery electrode materials. While X-ray powder diffraction is routine, neutron powder diffraction is still less established. Researchers have developed a new electrochemical cell for in operando neutron powder diffraction that is easy to use and can cycle electrode materials under electrochemical conditions similar to standard laboratory cells.
Article
Materials Science, Multidisciplinary
N. Qureshi, H. E. Fischer, S. X. M. Riberolles, T. C. Hansen, M. Ciomaga Hatnean, O. A. Petrenko
Summary: In this study, we investigate the short-range magnetic spin correlations in two compounds of rare-earth strontium oxides using total-scattering powder neutron diffraction, reverse Monte Carlo simulations, and magnetic pair-distribution function analysis. The compounds exhibit a distorted honeycomb lattice, leading to significant geometrical frustration due to antiferromagnetic exchange between magnetic ions. The results demonstrate the ordering of the short-range spin correlations above the respective Néel temperatures, indicating the dominance of nearest and next-nearest interactions.
Article
Physics, Multidisciplinary
Qianhui Xu, Yi Liu, Sijie Hao, Jiahui Qian, Cheng Su, Chin-Wei Wang, Thomas Hansen, Zhendong Fu, Yixi Su, Wei Li, Guang-Han Cao, Yinguo Xiao, Wentao Jin
Summary: The ground-state magnetic structures of Eu2+ spins in RbEu(Fe1-xNix)(4)As-4 superconductors have been studied using neutron powder diffraction measurements. It is observed that the magnetic propagation vector of the Eu sublattice diminishes with increasing Ni doping, leading to a reduction in the rotation angle between neighboring Eu layers. The magnetic structure transitions from a helical modulation to a collinear ferromagnetic structure as the superconductivity is suppressed.
PHYSICAL REVIEW RESEARCH
(2022)