scholarly journals Concurrent calculation of radiative transfer in the atmospheric simulation in ECHAM-6.3.05p2

2021 ◽  
Vol 14 (12) ◽  
pp. 7439-7457
Author(s):  
Mohammad Reza Heidari ◽  
Zhaoyang Song ◽  
Enrico Degregori ◽  
Jörg Behrens ◽  
Hendryk Bockelmann
Keyword(s):  
Radiative Transfer ◽  
High Performance ◽  
Atmospheric Model ◽  
Southern Annular Mode ◽  
Decomposition Approach ◽  
Atmospheric Teleconnection ◽  
Internal Climate Variability ◽  
Grid Points ◽  
Scientific Results ◽  
Radiation Scheme

Abstract. ​​​​​​​The scalability of the atmospheric model ECHAM6 at low resolution, as used in palaeoclimate simulations, suffers from the limited number of grid points. As a consequence, the potential of current high-performance computing architectures cannot be used at full scale for such experiments, particularly within the available domain decomposition approach. Radiation calculations are a relatively expensive part of the atmospheric simulations, taking up to approximately 50 % or more of the total runtime. This current level of cost is achieved by calculating the radiative transfer only once in every 2 h of simulation. In response, we propose extending the available concurrency within the model further by running the radiation component in parallel with other atmospheric processes to improve scalability and performance. This paper introduces the concurrent radiation scheme in ECHAM6 and presents a thorough analysis of its impact on the performance of the model. It also evaluates the scientific results from such simulations. Our experiments show that ECHAM6 can achieve a speedup of over 1.9× using the concurrent radiation scheme. By performing a suite of stand-alone atmospheric experiments, we evaluate the influence of the concurrent radiation scheme on the scientific results. The simulated mean climate and internal climate variability by the concurrent radiation generally agree well with the classical radiation scheme, with minor improvements in the mean atmospheric circulation in the Southern Hemisphere and the atmospheric teleconnection to the Southern Annular Mode. This empirical study serves as a successful example that can stimulate research on other concurrent components in atmospheric modelling whenever scalability becomes challenging.

scholarly journals Concurrent Calculation of Radiative Transfer in the Atmospheric Simulation in ECHAM-6.3.05p2

2021 ◽  
Author(s):  
Mohammad Reza Heidari ◽  
Zhaoyang Song ◽  
Enrico Degregori ◽  
Jörg Behrens ◽  
Hendryk Bockelmann
Keyword(s):  
Radiative Transfer ◽  
High Performance ◽  
Atmospheric Model ◽  
Decomposition Approach ◽  
Atmospheric Processes ◽  
Grid Points ◽  
Scientific Results ◽  
And Performance ◽  
Performance Computing ◽  
Radiation Scheme

Abstract. The scalability of the atmospheric model ECHAM6 at low resolution, as used in palaeoclimate simulations, suffers from the limited number of grid points. As a consequence, the potential of current high performance computing architectures cannot be used at full scale for such experiments, particularly within the available domain-decomposition approach. Radiation calculations are a relatively expensive part of the atmospheric simulations taking approximately up to over 50 % of the total runtime. This current level of cost is achieved by calculating the radiative transfer only once in every two simulation hours. In response, we propose to extend the available concurrency within the model further by running the radiation component in parallel with other atmospheric processes to improve scalability and performance. This paper introduces the concurrent radiation scheme in ECHAM6 and presents a thorough analysis of its impact on the performance of the model. It also evaluates the scientific results from such simulations. Our experiments show that ECHAM6 can achieve a speedup over 1.9x using the concurrent radiation scheme. This empirical study serves as a successful example that can stimulate research on other concurrent components in atmospheric modeing whenever scalability becomes challenging.

scholarly journals A module to convert spectral to narrowband snow albedo for use in climate models: SNOWBAL v1.0

2018 ◽  
Author(s):  
Christiaan T. van Dalum ◽  
Willem Jan van de Berg ◽  
Quentin Libois ◽  
Ghislain Picard ◽  
Michiel R. van den Broeke
Keyword(s):  
Radiative Transfer ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Greenland Ice Sheet ◽  
Atmospheric Model ◽  
Shortwave Radiation ◽  
Transfer Model ◽  
Snow Albedo ◽  
Radiation Scheme

Abstract. Snow albedo schemes in regional climate models often lack a sophisticated radiation penetration scheme and generally compute only a broadband albedo. Here, we present the Spectral-to-NarrOWBand ALbedo module (SNOWBAL, version 1.0) to couple effectively a spectral albedo model with a narrowband radiation scheme. Specifically, the Two-streAm Radiative TransfEr in Snow model (TARTES) is coupled with the European Center for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System atmospheric radiation scheme based on the rapid radiation transfer model, which is embedded in the regional climate model RACMO2. This coupling allows to explicitly account for the effect of clouds, snow impurities and snow metamorphism on albedo. Firstly, we present a narrowband albedo method to project the spectral albedos of TARTES onto the 14 spectral bands of the ECMWF shortwave radiation scheme using a representative wavelength (RW) for each band. Using TARTES and spectral downwelling surface irradiance derived with the DIScrete Ordinate Radiative Transfer atmospheric model, we show that RWs primarily depend on the solar zenith angle (SZA) and cloud content. Secondly, we compare the TARTES narrowband albedo, using offline RACMO2 results for South Greenland, with the broadband albedo parameterizations of Gardner and Sharp (2010), currently implemented in RACMO2, and the multi-layered parameterization of Kuipers Munneke et al. (2011, PKM). The actual absence of radiation penetration in RACMO2 leads on average to a higher albedo compared with TARTES narrowband albedo. Furthermore, large differences between the TARTES narrowband albedo and PKM and RACMO2 are observed for high SZA and clear-sky conditions, and after melt events when the snowpack is very inhomogeneous. This highlights the importance of accounting for spectral albedo and radiation penetration to simulate the energy budget of the Greenland ice sheet.

scholarly journals High-performance sampling of generic determinantal point processes

2020 ◽  
Vol 378 (2166) ◽  
pp. 20190059 ◽  
Author(s):  
Jack Poulson
Keyword(s):  
Point Process ◽  
Spectral Decomposition ◽  
High Performance ◽  
Point Processes ◽  
Cholesky Factorization ◽  
Determinantal Point Processes ◽  
Determinantal Point Process ◽  
Decomposition Approach ◽  
Map Inference ◽  
Sampling Schemes

Determinantal point processes (DPPs) were introduced by Macchi (Macchi 1975 Adv. Appl. Probab. 7 , 83–122) as a model for repulsive (fermionic) particle distributions. But their recent popularization is largely due to their usefulness for encouraging diversity in the final stage of a recommender system (Kulesza & Taskar 2012 Found. Trends Mach. Learn. 5 , 123–286). The standard sampling scheme for finite DPPs is a spectral decomposition followed by an equivalent of a randomly diagonally pivoted Cholesky factorization of an orthogonal projection, which is only applicable to Hermitian kernels and has an expensive set-up cost. Researchers Launay et al. 2018 ( http://arxiv.org/abs/1802.08429 ); Chen & Zhang 2018 NeurIPS ( https://papers.nips.cc/paper/7805-fast-greedy-map-inference-for-determinantal-point-process-to-improve-recommendation-diversity.pdf ) have begun to connect DPP sampling to LDL H factorizations as a means of avoiding the initial spectral decomposition, but existing approaches have only outperformed the spectral decomposition approach in special circumstances, where the number of kept modes is a small percentage of the ground set size. This article proves that trivial modifications of LU and LDL H factorizations yield efficient direct sampling schemes for non-Hermitian and Hermitian DPP kernels, respectively. Furthermore, it is experimentally shown that even dynamically scheduled, shared-memory parallelizations of high-performance dense and sparse-direct factorizations can be trivially modified to yield DPP sampling schemes with essentially identical performance. The software developed as part of this research, Catamari ( hodgestar.com/catamari ) is released under the Mozilla Public License v.2.0. It contains header-only, C++14 plus OpenMP 4.0 implementations of dense and sparse-direct, Hermitian and non-Hermitian DPP samplers. This article is part of a discussion meeting issue ‘Numerical algorithms for high-performance computational science’.

scholarly journals PROJECT MANAGEMENT AS A TOOL FOR DEVELOPMENT ENGINEERING CENTER, BASED AT THE UNIVERSITY

2016 ◽  
Vol 2 (1) ◽  
pp. 240-244
Author(s):  
Малыхина ◽  
Irina Malykhina ◽  
Брежнев ◽  
Aleksey Brezhnev
Keyword(s):  
Project Management ◽  
High Performance ◽  
Building Materials ◽  
Innovative Development ◽  
Research And Innovation ◽  
Steady Growth ◽  
Scientific Results ◽  
The University ◽  
Development Engineering ◽  
Difficult Times

Today, the domestic economy is going through difficult times associated with the instability of the geopolitical situation in the world, a strengthening of the sanctions policy of Western countries to-wards the Russian Federation, limited access to foreign investment and other factors that directly affect the speed and quality of economic development of the state. However, Russia today is on the path of innovative development, so the generation and usage in industry innovation is a priority. Recognition of necessity of innovative development of Russia determines the importance of improving and obtaining good results in such a relatively young activities for our country as project management and engineering. In this paper, the influence of project management as a form of innovative management in the development of the engineering centre, based at the University. Steady growth in demand for engineering services, which contribute to qualitative and effective implemen-tation of the latest technological solutions in production, largely due to the significant complexity of scientific results in scientific, research and innovation. Therefore, the use of the principles and methods of project management creates the conditions for high performance implementation of innovation projects, which include the creation and development of engineering centers, including in the field of building materials industry.

scholarly journals Service for parallel applications based on JINR cloud and HybriLIT resources

2019 ◽  
Vol 214 ◽  
pp. 07012 ◽  
Author(s):  
Nikita Balashov ◽  
Maxim Bashashin ◽  
Pavel Goncharov ◽  
Ruslan Kuchumov ◽  
Nikolay Kutovskiy ◽  
...  
Keyword(s):  
High Performance ◽  
Cloud Service ◽  
Parallel Applications ◽  
Cloud Infrastructure ◽  
Modular Architecture ◽  
Practical Applications ◽  
Speed Up ◽  
Scientific Results ◽  
Computational Resources ◽  
Performance Computing

Cloud computing has become a routine tool for scientists in many fields. The JINR cloud infrastructure provides JINR users with computational resources to perform various scientific calculations. In order to speed up achievements of scientific results the JINR cloud service for parallel applications has been developed. It consists of several components and implements a flexible and modular architecture which allows to utilize both more applications and various types of resources as computational backends. An example of using the Cloud&HybriLIT resources in scientific computing is the study of superconducting processes in the stacked long Josephson junctions (LJJ). The LJJ systems have undergone intensive research because of the perspective of practical applications in nano-electronics and quantum computing. In this contribution we generalize the experience in application of the Cloud&HybriLIT resources for high performance computing of physical characteristics in the LJJ system.

scholarly journals Exponential Synchronization for Second-Order Nodes in Complex Dynamical Network with Communication Time Delays and Switching Topologies

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Miao Yu ◽  
Weipeng Shang ◽  
Zhigang Chen
Keyword(s):  
High Performance ◽  
Sufficient Conditions ◽  
Second Order ◽  
Exponential Synchronization ◽  
Decomposition Approach ◽  
Dynamical Network ◽  
Synchronization Problem ◽  
Communication Time ◽  
Communication Topology

This paper is devoted to the study of exponential synchronization problem for second-order nodes in dynamical network with time-varying communication delays and switching communication topologies. Firstly, a decomposition approach is employed to incorporate the nodes’ inertial effects into the distributed control design. Secondly, the sufficient conditions are provided to guarantee the exponential synchronization of second-order nodes in the case that the information transmission is delayed and the communication topology is balanced and arbitrarily switched. Finally, to demonstrate the effectiveness of the proposed theoretical results, it is applied to the typical second-order nodes in dynamical network, as a case study. Simulation results indicate that the proposed method has a high performance in synchronization of such network.

Hyperspectral Aquatic Radiative Transfer Modeling Using a High-Performance Cluster Computing-Based Approach

2012 ◽  
Vol 49 (2) ◽  
pp. 275-298 ◽  
Author(s):  
Anthony M. Filippi ◽  
Budhendra L. Bhaduri ◽  
Thomas Naughton ◽  
Amy L. King ◽  
Stephen L. Scott ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
High Performance ◽  
Cluster Computing ◽  
Radiative Transfer Modeling

Massively Parallel Computational Fluid Dynamics With Large Eddy Simulation in Complex Geometries

2011 ◽  
Author(s):  
Andrew Duggleby ◽  
Joshua L. Camp ◽  
Yuval Doron ◽  
Paul F. Fischer
Keyword(s):  
Computer Aided Design ◽  
High Performance ◽  
Complex Geometry ◽  
Spectral Element ◽  
Computational Time ◽  
Model And Simulation ◽  
Large Eddy ◽  
Order Of Magnitude ◽  
Grid Points ◽  
Pipe Geometry

To perform complex geometry large eddy simulations in an industrially relevant timeframe, one must reduce the total time to half a day (overnight simulation). Total time includes the time of developing the mesh from the computer-aided design (CAD) model and simulation time. For reducing CAD-to-mesh time, automatic meshing algorithms can generate valid but often non-efficient meshes with often up to an order of magnitude more grid points than a custom-based mesh. These algorithms are acceptable only if paired with high-performance computing (HPC) platforms comprising thousands to millions of cores to significantly reduce computational time. Efficient use of these tools calls for codes that can scale to high processor counts and that can efficiently transport resolved scales over the long distances and times made feasible by HPC. The rapid convergence of high-order discretizations makes them particularly attractive in this context. In this paper we test the combination of automatic hexahedral meshing with a spectral element code for incompressible and low-Mach-number flows, called Nek5000, that has scaled to P >262,000 cores and sustains >70% parallel efficiency with only ≈7000 points/core. For our tests, a simple pipe geometry is used as a basis for comparing with previous fully resolved direct numerical simulations.

scholarly journals Evaluation of ECMWF Radiation Scheme Using Aircraft Observations of Spectral Irradiance above Clouds

2020 ◽  
Vol 77 (8) ◽  
pp. 2665-2685
Author(s):  
Kevin Wolf ◽  
André Ehrlich ◽  
Mario Mech ◽  
Robin J. Hogan ◽  
Manfred Wendisch
Keyword(s):  
Radiative Transfer ◽  
Radiation Field ◽  
Analysis Data ◽  
Radar Reflectivity ◽  
Spectral Irradiance ◽  
Transfer Model ◽  
Pressure System ◽  
Novel Approach ◽  
Research Aircraft ◽  
Radiation Scheme

Abstract A novel approach to compare airborne observations of solar spectral irradiances measured above clouds with along-track radiative transfer simulations (RTS) is presented. The irradiance measurements were obtained with the Spectral Modular Airborne Radiation Measurement System (SMART) installed on the High Altitude and Long Range Research Aircraft (HALO). The RTS were conducted using the operational ecRad radiation scheme of the Integrated Forecast System (IFS), operated by the European Centre for Medium-Range Weather Forecasts (ECMWF), and a stand-alone radiative transfer solver, the library for Radiative transfer (libRadtran). Profiles of observed and simulated radar reflectivity were provided by the HALO Microwave Package (HAMP) and the Passive and Active Microwave Transfer Model (PAMTRA), respectively. The comparison aims to investigate the capability of the two models to reproduce the observed radiation field. By analyzing spectral irradiances above clouds, different ice cloud optical parameterizations in the models were evaluated. Simulated and observed radar reflectivity fields allowed the vertical representation of the clouds modeled by the IFS to be evaluated, and enabled errors in the IFS analysis data (IFS AD) and the observations to be separated. The investigation of a North Atlantic low pressure system showed that the RTS, in combination with the IFS AD, generally reproduced the observed radiation field. For heterogeneously distributed liquid water clouds, an underestimation of upward irradiance by up to 27% was found. Simulations of ice-topped clouds, using a specific ice optics parameterization, indicated a systematic underestimation of broadband cloud-top albedo, suggesting major deficiencies in the ice optics parameterization between 1242 and 1941 nm wavelength.

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