Article
Mechanics
Scott Morgan, Christopher Davies, Christian Thomas
Summary: The study investigates the control of stationary convective instabilities in the rotating disk boundary layer by modulating the disk rotation rate periodically. The addition of a time-periodic modulation stabilizes the flow and raises the critical Reynolds number for the onset of instabilities. Energy analysis shows a reduction in Reynolds stress energy production and an increase in viscous dissipation across the boundary layer with the time-periodic modulation. Comparisons are made with other control techniques such as distributed surface roughness and compliant walls.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Yue Xiao, Bin Zhang, Moli Zhao, Shaowei Wang
Summary: The linear instability of the buoyancy-driven flow adjacent to an inclined heated wall immersed in a thermally stratified medium is studied theoretically and numerically. The results demonstrate the significant influence of the tile angle and Prandtl number on the spatiotemporal properties of the flow.
Article
Geosciences, Multidisciplinary
E. W. Luiz, S. Fiedler
Summary: We provide evidence that convectively generated cold pools can drive low-level jets (LLJ), based on observation. During a three-month campaign in Germany, we found that 6.8% of identified LLJ profiles were connected to cold pools. Most of these cold pool-driven LLJs appeared with the cold pool front and lasted for up to two hours. We also observed a cold pool that favored the formation of a several-hours long LLJ.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Lu Zhang, Hongsheng Zhang, Qianhui Li, Wei Wei, Xuhui Cai, Yu Song, Ali Mamtimin, Minzhong Wang, Fan Yang, Yu Wang, Chenglong Zhou
Summary: The deep convective boundary layer in the Taklimakan Desert plays a vital role in the climate system in East Asia. This study used observation experiments and large-eddy simulation to uncover the turbulent mechanisms behind its formation. It was revealed that the daily maximum depth of the boundary layer was independent of surface heating, and a weak temperature inversion and a near-neutral residual layer existed above the CBL in the late-morning. The distinct boundary-layer process was found to entrain free-tropospheric air and warm the residual layer, which contributed to the growth of the CBL.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Thermodynamics
Marilize Everts, Mostafa Mahdavi, Mohsen Sharifpur, Josua P. Meyer
Summary: The thermal and hydrodynamic features of developing mixed convective laminar flow in a long horizontal tube were investigated numerically and experimentally. It was found that the conventional understanding of the merging boundary layer in internal tube flows needed modification, and methods were proposed to determine the development of the hydrodynamic and thermal boundary layers. The experimental and numerical results showed that the local mixed convective Nusselt numbers decreased near the tube inlet but increased along the tube length as secondary flow increased significantly.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Meteorology & Atmospheric Sciences
Yan Liu, Zhe-Min Tan, Zhaohua Wu
Summary: This study investigates the convective response under multiscale forcing using a month-long cloud-permitting simulation of the Madden-Julian Oscillation (MJO). The results show that the convective response time scale depends on the spatial and temporal scales of the convective systems. The convective response process includes two phases: shallow convection development and shallow-to-deep convection transition, which are controlled by synoptic-scale boundary layer moisture convergence and lower-tropospheric specific humidity.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2022)
Article
Mechanics
Yu K. Rudenko, N. A. Vinnichenko, Yu Yu Plaksina, A. Pushtaev, A. Uvarov
Summary: The development of convective flow from a line heat source located at the liquid surface, when thermocapillary convection is inhibited by a surface film, is studied. Experimental and numerical results show that the vertical stratification of the system is stable and the flow is driven by a horizontal pressure gradient formed by non-uniform heating.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Meteorology & Atmospheric Sciences
Wojciech W. Grabowski
Summary: Water availability at the Earth surface affects the surface heat flux Bowen ratio, which in turn affects the development of convective boundary layer and convection over land during the day.
QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY
(2023)
Article
Physics, Multidisciplinary
Tom Dror, Ilan Koren, Huan Liu, Orit Altaratz
Summary: Shallow cloud fields exhibit different patterns that have significant impacts on their radiative effects and climate change. It has been found that these organized patterns are derived from the steady state of convection cells, and can be better simulated in climate models through parameterization to capture their feedback in a warming climate.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
S. Ahmad, M. Farooq
Summary: This article presents a mathematical analysis of flow using stretching mechanism of a thin needle, discussing the influence of hybrid nanomaterial under thermal slip conditions and how stratified parameters affect heat transfer rates, as well as how mixed convective phenomenon assists flow features.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Environmental Sciences
Yupeng Teng, Tianyan Li, Hongbin Chen, Shuqing Ma
Summary: Previous studies have shown that reflected waves can be observed by weather radar, even on sunny days. Turbulence and biological scatterers can also play a significant role in the scattering process. In this study, a dual-frequency antenna multiplexing radar system was used to observe clear-air Bragg scattering (CABS) not only at the edge of the convective boundary layer (CBL), but also above the CBL. Additionally, the variation in the height of the CABS layers above the CBL was found to be consistent with the negative second derivative of horizontal wind speed measured by a coherent Doppler Lidar.
Article
Thermodynamics
A. Sukhanovskii, A. Vasiliev
Summary: This study conducts numerical simulations of Rayleigh-Benard convection in a cubic cavity to examine the structure of the thermal boundary layer under mixed boundary conditions. The study aims to investigate the physical mechanism that leads to an increase in heat flux with spatial frequency of the conducting-adiabatic pattern. The results show that the temperature boundary layer at the bottom is highly non-uniform due to factors such as the conducting-adiabatic pattern, large-scale circulation, and small-scale motions over the conducting plates. The thickness of the thermal boundary layer strongly depends on the size of the conducting plates and can be significantly smaller than in classical Rayleigh-Benard convection, resulting in an increased heat flux.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Environmental Sciences
R. B. Schulte, M. C. van Zanten, S. Rutledge-Jonker, D. P. J. Swart, R. J. Wichink Kruit, M. C. Krol, W. A. J. van Pul, J. Vila-Guerau de Arellano
Summary: The study investigates diurnal variability of the atmospheric ammonia budget over unfertilized grassland by combining observations with a conceptual atmospheric boundary layer model. It identifies the contribution of four governing processes to the NH3 diurnal cycle and paves the way for future research on the NH3 surface-atmosphere exchange at subdaily scales. The model closely fits the observations with prescribed surface flux, but requires an unrealistic budget representation to achieve this close fit, indicating potential limitations in representing ammonia surface flux.
ATMOSPHERIC ENVIRONMENT
(2021)
Article
Geosciences, Multidisciplinary
Jose Dias Neto, Louise Nuijens, Christine Unal, Steven Knoop
Summary: This paper presents an experimental setup for retrieving high-resolution horizontal wind speed and direction profiles using wind lidar and cloud radar measurements. The CMTRACE campaign conducted in the Netherlands generated seamless wind profiles from the surface to cloud tops. The data processing steps for generating level 1 and level 2 data are described, and statistical analyses show a high correlation and small bias between lidar and radar measurements.
EARTH SYSTEM SCIENCE DATA
(2023)
Article
Meteorology & Atmospheric Sciences
Xiaoyan Zhang, Changjie Cai, Xiao-Ming Hu, Lan Gao, Xiyan Xu, Jun Hu, Haishan Chen
Summary: Aerosols with different vertical distribution and optical properties can affect the development of the convective boundary layer, with absorbing aerosols having the strongest suppression effect on CBL development. The aerosol cooling effect by reducing solar radiation and surface heat flux inhibits CBL development, and specifying background aerosol extinction coefficient in numerical experiments is crucial for accurate assessment of aerosol radiative forcing and CBL-aerosol interactions.
ATMOSPHERIC RESEARCH
(2022)
Article
Biology
Boya Gao, Karl R. Wotton, Will L. S. Hawkes, Myles H. M. Menz, Don R. Reynolds, Bao-Ping Zhai, Gao Hu, Jason W. Chapman
PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
(2020)
Article
Entomology
Yun-Ping Wang, Xiong-Bing Tu, Pei-Jiong Lin, Shuang Li, Chao-Min Xu, Xin-Qiao Wang, Don R. Reynolds, Jason Chapman, Ze-Hua Zhang, Gao Hu
Article
Meteorology & Atmospheric Sciences
Charlotte Wainwright, David Richter
Summary: The study investigates the sensitivity of marine fog formation to cloud-droplet number concentration, turbulent mixing, and air-sea temperature difference using Large-Eddy Simulation (LES). The research finds that the strength of the fog is highly sensitive to all three factors, with even small changes in cloud-droplet concentration potentially halving or doubling the liquid water content of the fog.
BOUNDARY-LAYER METEOROLOGY
(2021)
Article
Meteorology & Atmospheric Sciences
David H. Richter, Theodore MacMillan, Charlotte Wainwright
Summary: The study utilizes a large-eddy simulation model coupled with a Lagrangian cloud model to analyze marine fog, highlighting the bimodal droplet distribution phenomenon caused by high supersaturation levels.
BOUNDARY-LAYER METEOROLOGY
(2021)
Article
Biodiversity Conservation
Birgen Haest, Phillip M. Stepanian, Charlotte E. Wainwright, Felix Liechti, Silke Bauer
Summary: Climate change has drastically altered the timing of biological events globally, impacting the migration patterns of various animal species. While temperature did not seem to affect bat migration, wind conditions played a crucial role in spring migration phenology, and precipitation influenced autumn migration phenology in a study conducted at Bracken Cave, Texas. The findings highlight the importance of weather radar analyses in addressing knowledge gaps on climate impacts on bat migration.
GLOBAL CHANGE BIOLOGY
(2021)
Article
Multidisciplinary Sciences
Gao Hu, Constanti Stefanescu, Tom H. Oliver, David B. Roy, Tom Brereton, Chris Van Swaay, Don R. Reynolds, Jason W. Chapman
Summary: The study identifies the environmental drivers of population dynamics of a migratory butterfly, showing that factors such as vegetation productivity and wind conditions in sub-Saharan Africa play crucial roles in determining the size of immigration to western Europe. These findings suggest that regular mass migrations link populations of the painted lady butterfly on both sides of the Sahara, making it the longest known annual insect migration circuit.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Meteorology & Atmospheric Sciences
Charlotte Wainwright, Rachel Y-W Chang, David Richter
Summary: This study used theoretical methods to estimate the aerosol activation properties and found that the hygroscopicity parameter of particles varied widely in the research area during foggy weather. The effective peak supersaturation values were mainly concentrated between 0.01% and 0.07%, with most values below 0.04%. The minimum 50% dry activation diameter of particles generally ranged between 300 and 400 nm, with little activation of particles with diameters below 300 nm.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2021)
Letter
Multidisciplinary Sciences
Constanti Stefanescu, Gao Hu, Tom H. Oliver, Don R. Reynolds, Jason W. Chapman
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Multidisciplinary Sciences
Myles H. M. Menz, Martina Scacco, Hans-Martin Burki-Spycher, Hannah J. Williams, Don R. Reynolds, Jason W. Chapman, Martin Wikelski
Summary: This article investigates the behavioral strategies of nocturnally migrating death's-head hawkmoths during long-distance flights, revealing that they maintain flight trajectories using an internal compass, allowing them to take full advantage of seasonal resources.
Article
Biodiversity Conservation
Will L. S. Hawkes, Edward Walliker, Boya Gao, Olivia Forster, Katharine Lacey, Toby Doyle, Richard Massy, Nicholas W. Roberts, Don R. Reynolds, Ozge Ozden, Jason W. Chapman, Karl R. Wotton
Summary: Migratory insects are vital components of terrestrial ecosystems, but their full contribution is challenging to understand. This study collected data on migratory insects in the Karpaz peninsula in northeast Cyprus and found that their migration is correlated with temperature and wind direction, with origins from locations including Syria, Iraq, and Saudi Arabia.
Article
Ecology
Charlotte E. Wainwright, Sabrina N. Volponi, Phillip M. Stepanian, Don R. Reynolds, David H. Richter
Summary: This study presents a method using image processing techniques on cloud radar data to examine the fate of migrating insects when they encounter rainfall. It distinguishes flying insects from raindrops by analyzing velocity spectra and compares the relative density of insects before, during, and after rainfall. The method was demonstrated on a case of insect migration in Oklahoma, USA, revealing reconstructed images of migrating insect layers during rainfall.
METHODS IN ECOLOGY AND EVOLUTION
(2023)
Article
Ecology
Jian Zhu, Xiao Chen, Jie Liu, Yuying Jiang, Fajun Chen, Jiahao Lu, Hui Chen, Baoping Zhai, Don R. Reynolds, Jason W. Chapman, Gao Hu
Summary: This study reveals that the autumn migration of insects in East China, particularly for M. separata, is essential for maintaining stable pest populations. The position of cold high-pressure systems in September plays a crucial role in determining the population size in the following year.
Article
Biodiversity Conservation
Hua Lv, Meng-Yuan Zhai, Juan Zeng, Yi-Yang Zhang, Feng Zhu, Hui-Mei Shen, Kun Qiu, Bo-Ya Gao, Don R. Reynolds, Jason W. Chapman, Gao Hu
Summary: In East China, the migration patterns of the brown planthopper, a serious rice pest, have shifted due to climate-induced changes in wind and precipitation. The weakening of southwest winds and increased rainfall in South China have resulted in shorter migratory journeys for the pest, leading to a decline in outbreaks in the rice-growing area of the Lower Yangtze River Valley since 2001. These changes are driven by shifts in the position and intensity of the Western Pacific subtropical high system.
GLOBAL CHANGE BIOLOGY
(2023)
Editorial Material
Multidisciplinary Sciences
T. Lehmann, R. Bamou, J. W. Chapman, D. R. Reynolds, P. A. Armbruster, A. Dao, A. S. Yaro, T. R. Burkot, Y. -m. Linton
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)