Article
Meteorology & Atmospheric Sciences
Qilong Li, Xueling Cheng, Xiaodong Zeng, Guangqing Zhou, Jian Huang, Lin Wu, Qingcun Zeng
Summary: Using observational data from an offshore monitoring platform, we analyzed the variations in mean wind field, turbulence, and turbulent flux of three typhoons. We found that the turbulent fluctuation intensity and friction velocity increase with wind speed before and after landfall, but decrease during landfall due to the transition from land-based turbulence to sea-based turbulence. The relationships between the friction velocity and drag coefficient and wind speed are also influenced by whether the typhoon makes landfall and the relative position of the landfall site.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2022)
Article
Geosciences, Multidisciplinary
Yilan Li, Guitao Shi, Zhenlou Chen, Musheng Lan, Minghu Ding, Zhengjie Li, Meredith G. Hastings
Summary: The latitudinal gradients of atmospheric nitrate (NO3-) sources and production in the marine boundary layer of the Northern Hemisphere were investigated using atmospheric samples collected during the 2017 and 2018 Chinese Arctic Expedition cruises. The concentration and isotopic composition of atmospheric NO3- showed significant variations along different latitudes. The study found that continental sources dominated atmospheric NO3- in both mid- and high-latitudes, while oceanic RONO2 emissions accounted for a substantial portion of the NO3- budget in mid-latitudes. The different isotopic compositions of NO3- in different latitudes suggest distinct main production pathways.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Mechanics
Paolo Blondeaux, Giovanna Vittori
Summary: By investigating the stability of the boundary layer generated by the oscillations of a plate, critical values of Reynolds number for instability can be determined, corresponding to the transition from laminar to disturbed laminar, intermittently turbulent, and fully turbulent regimes in the flow.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Dongik Yoon, Hyun Jin Park, Yuji Tasaka, Yuichi Murai
Summary: This study experimentally investigates bubbles sliding near inclined walls to understand their behavior within turbulent boundary layers. The shape of the bubbles is found to vary with changes in channel inclination. A measurement technique involving optoacoustic and ultrasound pulsed Doppler methods is utilized to determine the sliding motion, diameter, advection velocity, liquid velocity profiles, and maximum distance of the bubbles. The results confirm that buoyancy has an enhanced effect on the slip velocity of the bubble with increased inclination, and drag and buoyancy determine the bubble's shape in inclined conditions. The measured drag coefficient increases with the inclination angle up to 35 degrees, and a modeling equation for the drag coefficient is proposed based on the Weber number, inclination angle, and ellipticity of the bubble. This equation is applicable to bubbles within turbulent boundary layers.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Engineering, Civil
Quentin Bucquet, Isabelle Calmet, Laurent Perret, Magdalena Mache
Summary: This work assesses the performance of the drag-porosity model implemented in ARPS atmospheric Large-Eddy Simulation (LES) solver for simulating the atmospheric boundary layer over the urban canopy. The flow over an idealized urban canopy consisting of cubes with various packing densities is investigated. The model is able to reproduce the key features of the flow over urban terrain, including turbulent coherent structures and their characteristic scales.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2023)
Article
Mechanics
T. Agarwal, B. Cukurel, I Jacobi
Summary: This study investigates the perturbation of the laminar boundary layer by free-stream travelling waves and demonstrates that highly localized skin friction modification can be achieved through steady streaming. The results show that upstream-travelling waves always produce negative streaming, while downstream-travelling waves can produce either positive or negative streaming depending on the forcing strength and streamwise location.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Oceanography
M. Lindhart, S. G. Monismith, A. Khrizman, D. Mucciarone, R. Dunbar
Summary: The study found that the boundary layer of coral reefs exhibits spatial homogeneity to a certain extent, and friction velocities obtained from a single instrument generally represent the entire study site. However, some discrepancies were observed between instruments, especially when measuring localized flow features.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Oceanography
Y. Zu, P. Lu, M. Lepparanta, B. Cheng, Z. Li
Summary: The study investigated the form drag characteristics of the bottom topography of ridged sea ice through experiments and numerical simulations. It found that the local form drag coefficient varies with keel depth and slope angle in turbulent conditions, suggesting significant impact on sea-ice drift and deformation. The average value of the local form drag coefficient was recommended as 0.75 for sea-ice dynamic models.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2021)
Article
Mechanics
Yitong Fan, Marco Atzori, Ricardo Vinuesa, Davide Gatti, Philipp Schlatter, Weipeng Li
Summary: The study on the use of blowing and suction control strategies in wall-bounded turbulence shows that blowing enhances the contribution of large-scale motions and suppresses that of small scales, while suction behaves contrarily. However, the contributions related to cross-scale interactions remain almost unchanged with different control strategies.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Environmental Sciences
Guoyin Wang, Wennan Leng, Shaojing Jiang, Bangjun Cao
Summary: The study indicates that atmospheric diffusion conditions in the Sichuan Basin have improved from 1979 to 2019, primarily characterized by an increase in ventilation coefficient and a decrease in air stagnation frequency, which helps mitigate the effects of air pollutant emissions.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2021)
Article
Mechanics
Dongik Yoon, Hyun Jin Park, Yuji Tasaka, Yuichi Murai
Summary: The motion of bubbles sliding beneath a tilted model ship was experimentally studied to explore the fundamentals of a hydrodynamic force acting on bubbles inside the liquid-phase boundary layer. The contribution of bubble buoyancy to bubble motion in the main direction of flow was obtained when the angle of the ship was changed positively and negatively. The velocity of large bubbles was found to decrease under the negative slope condition and increase under the positive slope condition due to the buoyancy effect. The velocity of small bubbles, however, was mainly affected by liquid flow.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Engineering, Aerospace
Camilo Riano-Rios, Riccardo Bevilacqua, Warren E. Dixon
Summary: This paper introduces a differential atmospheric drag-based control algorithm for rendezvous with a noncooperative target in Low Earth Orbit. The design of an adaptive controller addresses the challenge of using a differential input that requires knowledge of physical parameters. Numerical simulations validate the controller design and evaluate its performance under nonlinearities and input saturation.
Article
Mechanics
Alan H. Duong, Thomas C. Corke, Flint O. Thomas
Summary: Experiments using active flow control successfully reduced the viscous drag in turbulent boundary layers and decreased the wall-normal vorticity component, improving turbulence characteristics.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Environmental Sciences
Anjali S. Nair, Priyanka Singh, Kirti Soni, Kuldeep Meena, Rina Sharma
Summary: Aerosols have a significant impact on the development of the Atmospheric Boundary Layer (ABL), leading to increased air pollution in megacities. The ABL Height (ABLH) and Ventilation coefficient (VC) play a crucial role in determining the vertical dispersion of pollutants. Evaluating the influence of aerosols on ABLH is essential to address the complex problem of air pollution. The study conducted over Delhi from 2019 to 2021 quantitatively evaluates the radiation effect of aerosols on ABL. It qualitatively demonstrates that high aerosol loading reduces ABLH, resulting in increased aerosol and PM2.5 concentrations. The reduction in ABLH subsequently decreases the VC.
Article
Environmental Sciences
Zhen Yuan, Cheng-Lei Pei, Heng-Xiang Li, Lang Lin, Rui Hou, Shan Liu, Kai Zhang, Ming -Gang Cai, Xiang-Rong Xu
Summary: This study conducted field observations at the Canton Tower in Guangzhou, China to investigate the vertical distribution of atmospheric microplastics (AMPs). It found that the distribution of AMPs followed similar layer patterns as other air pollutants, but with different concentrations. The majority of AMPs consisted of polyethylene terephthalate and rayon fibers, and their abundance decreased with increasing altitude due to atmospheric thermodynamics and wind speed. This study provided valuable data for understanding the environmental fate of AMPs.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Meteorology & Atmospheric Sciences
Dieter Scherer, Florian Antretter, Steffen Benders, Joerg Cortekar, Stefan Emeis, Ute Fehrenbach, Guenter Gross, Guido Halbig, Jens Hasse, Bioern Maronga, Siegfried Raasch, Katharina Scherber
METEOROLOGISCHE ZEITSCHRIFT
(2019)
Article
Meteorology & Atmospheric Sciences
Dieter Scherer, Felix Ament, Stefan Emeis, Ute Fehrenbach, Bernd Leitl, Katharina Scherber, Christoph Schneider, Ulrich Vogt
METEOROLOGISCHE ZEITSCHRIFT
(2019)
Article
Energy & Fuels
Beatriz Canadillas, Richard Foreman, Volker Barth, Simon Siedersleben, Astrid Lampert, Andreas Platis, Bughsin Djath, Johannes Schulz-Stellenfleth, Jens Bange, Stefan Emeis, Thomas Neumann
Article
Energy & Fuels
Andreas Platis, Marie Hundhausen, Moritz Mauz, Simon Siedersleben, Astrid Lampert, Konrad Baerfuss, Bughsin Djath, Johannes Schulz-Stellenfleth, Beatriz Canadillas, Thomas Neumann, Stefan Emeis, Jens Bange
Summary: An analysis of the recovery of offshore wind farm wakes in the German Bight was conducted using in situ data collected onboard a research aircraft. The observed recovery rates were compared to a simple analytical wake recovery model, showing that while the data generally matched the model, there were some discrepancies that suggested further optimization is needed for factors like wind park layout and turbulence. Mesoscale modeling also revealed discrepancies in wake recovery rates compared to measurements.
Article
Meteorology & Atmospheric Sciences
Stefan Emeis
Summary: Precipitation data from four weather stations in Bavaria, Germany, show an increase in annual precipitation and precipitation intensity on wet days, as well as a slight increase in dry days. The increase in maximum daily precipitation amounts is less than the increase in the annual precipitation amount. The length of dry spells is also increasing.
METEOROLOGISCHE ZEITSCHRIFT
(2021)
Article
Meteorology & Atmospheric Sciences
Andreas Platis, Marie Hundhausen, Astrid Lampert, Stefan Emeis, Jens Bange
Summary: The study reveals that the dissipation of wake downstream of large offshore wind farms depends on atmospheric stability, with a clear relationship between stability and wind direction. Stability is primarily determined by lapse rate, and stability classification is influenced by the measurement height.
BOUNDARY-LAYER METEOROLOGY
(2022)
Article
Meteorology & Atmospheric Sciences
Stefan Emeis
Summary: Analytical top-down and bottom-up wind-farm models are crucial tools for assessing yields from large wind farms and their wakes, but limitations exist, such as the need for wind turbine hub height to be small compared to atmospheric boundary-layer height, and implications of blockage effects.
BOUNDARY-LAYER METEOROLOGY
(2022)
Article
Geosciences, Multidisciplinary
Matthias Zeeman, Christopher Claus Holst, Meinolf Kossmann, Daniel Leukauf, Christoph Muenkel, Andreas Philipp, Rayk Rinke, Stefan Emeis
Summary: Three-dimensional observations of the ABL in the City Centre of Stuttgart showed the development of distinctive layers with high directional deviation from the flow aloft, recurring as a dominant diurnal pattern on representative days in winter and summer.
FRONTIERS IN EARTH SCIENCE
(2022)
Review
Meteorology & Atmospheric Sciences
Johannes Schulz-Stellenfleth, Stefan Emeis, Martin Doerenkaemper, Jens Bange, Beatriz Canadillas, Thomas Neumann, Joerge Schneemann, Ines Weber, Kjell Zum Berge, Andreas Platis, Bughsin Djath, Julia Gottschall, Lukas Vollmer, Thomas Rausch, Mares Barekzai, J. Hammel, G. Steinfeld, Astrid Lampert
Summary: This paper provides an overview of coastal effects and their potential impact on offshore wind farms, with a focus on the German Bight. It discusses phenomena related to the stability of the boundary layer and analyzes spatial variations of vertical heat fluxes in the coastal zone. The study highlights the need to consider multiple spatial and temporal scales to understand and describe coastal effects.
METEOROLOGISCHE ZEITSCHRIFT
(2022)
Article
Management
Stefan Emeis, Joachim Fallmann
Summary: Making urban areas more sustainable requires the integration of scientific results with the building, shaping, and governance of cities. This conceptual paper explores the interactions between science, local governance, and regulatory processes, and suggests that updating laws, norms, and standards is essential for integrating new scientific findings into procedures for sustainable cities.
Article
Green & Sustainable Science & Technology
Tobias Klaas-Witt, Stefan Emeis
Summary: This study analyzes the factors influencing the errors in lidar wind measurements in complex terrain, and proposes a new approach to understand the impact of reduced half-cone opening angles on the errors. The results show that orographic complexity, roughness and forest characteristics, and atmospheric stability greatly affect lidar error estimation.
WIND ENERGY SCIENCE
(2022)
Review
Construction & Building Technology
Joachim Fallmann, Stefan Emeis
DEVELOPMENTS IN THE BUILT ENVIRONMENT
(2020)
Article
Meteorology & Atmospheric Sciences
Andreas Platis, Jens Bange, Konrad Baerfuss, Beatriz Canadillas, Marie Hundhausen, Bughsin Djath, Astrid Lampert, Johannes Schulz-Stellenfleth, Simon Siedersleben, Thomas Neumann, Stefan Emeis
METEOROLOGISCHE ZEITSCHRIFT
(2020)
Article
Geosciences, Multidisciplinary
Astrid Lampert, Konrad Baerfuss, Andreas Platis, Simon Siedersleben, Bughsin Djath, Beatriz Canadillas, Robert Hunger, Rudolf Hankers, Mark Bitter, Thomas Feuerle, Helmut Schulz, Thomas Rausch, Maik Angermann, Alexander Schwithal, Jens Bange, Johannes Schulz-Stellenfleth, Thomas Neumann, Stefan Emeis
EARTH SYSTEM SCIENCE DATA
(2020)
Article
Geosciences, Multidisciplinary
Simon K. Siedersleben, Andreas Platis, Julie K. Lundquist, Bughsin Djath, Astrid Lampert, Konrad Baerfuss, Beatriz Canadillas, Johannes Schulz-Stellenfleth, Jens Bange, Tom Neumann, Stefan Emeis
GEOSCIENTIFIC MODEL DEVELOPMENT
(2020)