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A computational fluid dynamics (CFD) model that solves the steady-state Reynolds-Averaged Navier-Stokes (RANS) equations for buoyant compressible pollution dispersion under different meteorological conditions is developed. A 6.4 km by 6.4…

Fluid Dynamics · Physics 2022-11-15 Zhihao Li , Rebecca Tanzer-Gruener , Albert Presto , Peter Adams , Satbir Singh

The connectivity pattern of networks, which are based on a correlation between ground level temperature time series, shows a dominant dense stripe of links in the southern ocean. We show that statistical categorization of these links yields…

Atmospheric and Oceanic Physics · Physics 2015-06-15 Yang Wang , Avi Gozolchiani , Yosef Ashkenazy , Yehiel Berezin , Oded Guez , Shlomo Havlin

Studying the ambient solar wind, a continuous pressure-driven plasma flow emanating from our Sun, is an important component of space weather research. The ambient solar wind flows in interplanetary space determine how solar storms evolve…

Advanced adaptive optics (AO) instruments on ground-based telescopes require accurate knowledge of the atmospheric turbulence strength as a function of altitude. This information assists point spread function reconstruction, AO temporal…

The site survey for the Advanced Technology Solar Telescope concluded recently after more than two years of data gathering and analysis. Six locations, including lake, island and continental sites, were thoroughly probed for image quality…

The calibration of weather radar for detecting meteorological phenomena has advanced rapidly, aiming to enhance accuracy. Utilizing an unmanned aerial vehicle (UAV) equipped with a suspended metal sphere introduces an efficient calibration…

Signal Processing · Electrical Eng. & Systems 2024-07-09 Jiabiao Zhao , Da Li , Jiayuan Cui , Houjun Sun , Jianjun Ma

Reynolds-Averaged Navier-Stokes(RANS) method will still play a vital role in the following several decade in aerospace engineering. Although RANS models are widely used, empiricism and large discrepancies between models reduce the…

Fluid Dynamics · Physics 2018-07-05 Weiwei Zhang , Linyang Zhu , Yilang Liu , Jiaqing Kou

For high contrast imaging systems, the time delay is one of the major limiting factors for the performance of the extreme adaptive optics (AO) sub-system and, in turn, the final contrast. The time delay is due to the finite time needed to…

Instrumentation and Methods for Astrophysics · Physics 2019-04-08 Maaike van Kooten , Niek Doelman , Matthew Kenworthy

Accurate wind speed forecasting is of great importance for many economic, business and management sectors. This paper introduces a new model based on convolutional neural networks (CNNs) for wind speed prediction tasks. In particular, we…

Machine Learning · Computer Science 2020-07-27 Kevin Trebing , Siamak Mehrkanoon

Numerical simulations of turbulent round jets, using explicit-filtered LES technique, are performed, for three different Reynolds numbers(Re = 3600, 88000, 400000), to understand the Reynolds number effect on subsonic jets with Mach number…

Fluid Dynamics · Physics 2017-11-22 Ramanathan Varadharajan

Atmospheric turbulence is the one of the major limiting factors for ground-based astronomical observations. In this paper, the problem of short-term forecasting seeing is discussed. The real data that were obtained by atmospheric optical…

Instrumentation and Methods for Astrophysics · Physics 2018-06-26 Matwey V. Kornilov

Accurate wind power forecasts depend on reliable wind speed forecasts. Numerical Weather Predictions (NWPs) utilize huge amounts of computing time, but still have rather low spatial and temporal resolution. However, stochastic wind speed…

Applications · Statistics 2015-09-10 Daniel Ambach , Carsten Croonenbroeck

Turbulent signals are known to exhibit burst-like activities, which affect the turbulence statistics at both large and small scales of the flow. In our study, we pursue this problem from the perspective of an event-based framework, where…

Fluid Dynamics · Physics 2023-01-26 Subharthi Chowdhuri , Tirtha Banerjee

Computation of propagation effects in the neutral atmosphere, namely path delay, extinction, and bending angle is a trivial task provided the 4D state of the atmosphere is known. Unfortunately, the mixing ratio of water vapor is highly…

Instrumentation and Methods for Astrophysics · Physics 2015-02-25 Leonid Petrov

The characterization of the wind speed vertical distribution V(h) is fundamental for an astronomical site for many different reasons: (1) the wind speed shear contributes to trigger optical turbulence in the whole troposphere, (2) a few of…

Instrumentation and Methods for Astrophysics · Physics 2010-09-21 S. Hagelin , E. Masciadri , F. Lascaux

This work presents an autoregressive generative diffusion model (DiffObs) to predict the global evolution of daily precipitation, trained on a satellite observational product, and assessed with domain-specific diagnostics. The model is…

Computational Physics · Physics 2024-04-11 Jason Stock , Jaideep Pathak , Yair Cohen , Mike Pritchard , Piyush Garg , Dale Durran , Morteza Mardani , Noah Brenowitz

Nullifying the servo bandwidth errors improves the strehl ratio by a substantial quantity in adaptive optics systems. An effective method for predicting atmospheric turbulence to reduce servo bandwidth errors in real time closed loop…

Instrumentation and Methods for Astrophysics · Physics 2011-09-14 Akondi Vyas , M B Roopashree , B Raghavendra Prasad

A version of model is proposed, which is aimed for getting parameters of the atmospheric layer and upper water layer with account of the wind-wave state. The dynamics of the atmospheric boundary layer is realized in version of papers [1,…

Atmospheric and Oceanic Physics · Physics 2011-08-12 Vladislav Polnikov , Iliya Kabatchenko

Measurements of the optical turbulence profile above Siding Spring Observatory were conducted during 2005 and 2006. This effort was largely motivated by the need to predict the statistical performance of adaptive optics at Siding Spring.…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Michael Goodwin , Charles Jenkins , Andrew Lambert

The propagation speed of a circumstellar pattern revealed in the plane of the sky is often assumed to represent the expansion speed of the wind matter ejected from a post-main-sequence star at the center. We point out that the often-adopted…

Solar and Stellar Astrophysics · Physics 2023-08-31 Hyosun Kim