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The Weather Research and Forecasting (WRF) model is a mesoscale numerical weather prediction system, which is widely used in major high-performance server platforms. This study focuses on the performance evaluation and optimization of WRF on Huawei's self-developed kunpeng 920 processor platform, aiming to improve the operational efficiency of WRF. The results of the study show that the scalability of WRF on kunpeng 920 processor is well performed; the performance of WRF on kunpeng 920 processor is improved by 32.6% after invoking the Fast Math Library and Domain Decomposition Core Tile Division optimization. In terms of IO, the main optimizations are parallel IO and asynchronous IO. Eventually, the single output time of WRF is reduced from 37.28 s in serial IO mode to 0.14 s in asynchronous IO mode, and the overall running time is reduced from 1078.80 s to 807.94 s. [ABSTRACT FROM AUTHOR]

Machine learning and deep learning algorithms in artificial intelligence are able to process intricate data and discern patterns. For instance, in climate change research, artificial intelligence can analyze climate models and observational data to offer more precise predictions and evaluations. The DualET model contained wavelet transform and sequence decomposition blocks for the extraction of information features from image and sequence data, respectively, to improve the correlation of spatial and temporal features. [Extracted from the article]

This paper proposes a series of parallel optimizations on a high-resolution ocean model, the LASG/IAP Climate System Ocean Model (LICOM), which was independently developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences. The version of LICOM that we used was LICOM 2.1. In order to improve the parallel performance of LICOM, a series of parallel optimization methods were applied. We optimized the parallelization scheme to tackle the problem of load imbalance. Some communication optimizations were implemented, including data packing, the application of the least communication algorithm, and the replacement of communications with calculations. Furthermore, for the calculation procedures, we implemented some mature optimizations and expanded functions in a loop. Additionally, a hybrid of MPI and OpenMP, as well as an asynchronous parallel IO, was used. In this work, the optimized version of LICOM 2.1 was able to achieve a speedup of more than two times compared with the original code. The parallelization scheme optimization and the communication optimization produced considerable improvement in performance in the large-scale parallelization. Meanwhile, the newly optimized LICOM could scale up to 245,760 processor cores. However, for the original version, there was no speedup when scaled up to over 10,000 processor cores. Additionally, the problem of jumpy wall time during the time integration process was also tackled with this optimization. Finally, we conducted a practical simulation from 1993 to 2007 by using the optimized version of LICOM 2.1. The results showed that the mesoscale vortex was well simulated by the model. [ABSTRACT FROM AUTHOR]

A high-resolution (1/20∘) global ocean general circulation model with graphics processing unit (GPU) code implementations is developed based on the LASG/IAP Climate System Ocean Model version 3 (LICOM3) under a heterogeneous-compute interface for portability (HIP) framework. The dynamic core and physics package of LICOM3 are both ported to the GPU, and three-dimensional parallelization (also partitioned in the vertical direction) is applied. The HIP version of LICOM3 (LICOM3-HIP) is 42 times faster than the same number of CPU cores when 384 AMD GPUs and CPU cores are used. LICOM3-HIP has excellent scalability; it can still obtain a speedup of more than 4 on 9216 GPUs compared to 384 GPUs. In this phase, we successfully performed a test of 1/20∘ LICOM3-HIP using 6550 nodes and 26 200 GPUs , and on a large scale, the model's speed was increased to approximately 2.72 simulated years per day (SYPD). By putting almost all the computation processes inside GPUs, the time cost of data transfer between CPUs and GPUs was reduced, resulting in high performance. Simultaneously, a 14-year spin-up integration following phase 2 of the Ocean Model Intercomparison Project (OMIP-2) protocol of surface forcing was performed, and preliminary results were evaluated. We found that the model results had little difference from the CPU version. Further comparison with observations and lower-resolution LICOM3 results suggests that the 1/20∘ LICOM3-HIP can reproduce the observations and produce many smaller-scale activities, such as submesoscale eddies and frontal-scale structures. [ABSTRACT FROM AUTHOR]

The second version of Chinese Academy of Sciences Earth System Model (CAS‐ESM 2) is described with emphasis on the development process, strength and weakness, and climate sensitivities in simulations of the Coupled Model Intercomparison Project (CMIP6) DECK experiments. CAS‐ESM 2 was built as a numerical model to simulate both the physical climate system as well as atmospheric chemistry and carbon cycle. It is a newcomer in the international modeling community to provide sufficiently independent solutions of climate simulations from those of other models. Performances of the model in simulating the basic states of the radiation budget of the atmosphere and ocean, precipitation, circulations, variabilities, and the twentieth century warming are presented. Model biases and their possible causes are discussed. Strength includes horizontal heat transport in the atmosphere and oceans, vertical profile of the Atlantic Meridional Overturning Circulation; weakness includes the double intertropical convergence zone (ITCZ) and stronger amplitude of the El Niño–Southern Oscillation (ENSO) that are also common in many other models. The simulated the twentieth century warming shares a similar discrepancy with observations as in several other models—less warming in the 1920s and stronger cooling in the 1960s than in observation—at the time when there was a steep increase of anthropogenic aerosols. As a result, the twentieth century warming is about 60% of the observed warming despite that the model simulated a similar slope of warming trend after 1980 to observation. The model has an equilibrium climate sensitivity of 3.4 K with a positive cloud feedback from the shortwave radiation. Plain Language Summary: This paper describes the second version of Chinese Academy of Sciences Earth System Model (CAS‐ESM 2) along with simulation results from the Coupled Model Intercomparison Project (CMIP6) DECK experiments. Performances of the model in simulating the radiation budget of the atmosphere and ocean, precipitation, circulations, variabilities, and the twentieth century warming are presented. The simulated the twentieth century warming shares a similar discrepancy with observations as in several other models—less warming in the 1920s and stronger cooling in the 1960s than in observation—at the time when there was a steep increase of anthropogenic aerosols. As a result, the twentieth century warming is about 60% of the observed warming despite that the model simulated a similar slope of warming trend after 1980 to observation. Key Points: The second version of Chinese Academy of Sciences Earth System Model (CAS‐ESM 2) is describedStrength and weakness of the model simulations from the CMIP6 DECK experiments are described along possible causesThe model has an equilibrium climate sensitivity of 3.4 K with a positive cloud feedback from the shortwave radiation [ABSTRACT FROM AUTHOR]

Climatic simulations rely heavily on high-performance computing. As one of the atmospheric radiative transfer models, the rapid radiative transfer model for general circulation models (RRTMG) is used to calculate the radiative transfer of electromagnetic radiation through a planetary atmosphere. Radiation physics is one of the most time-consuming physical processes, so the RRTMG presents large-scale and long-term simulation challenges to the development of efficient parallel algorithms that fit well into multicore clusters. This paper presents a method for improving the calculative efficiency of radiation physics, an RRTMG long-wave radiation scheme (RRTMG_LW) that is accelerated on a graphics processing unit (GPU). First, a GPU-based acceleration algorithm with one-dimensional domain decomposition is proposed. Then, a second acceleration algorithm with two-dimensional domain decomposition is presented. After the two algorithms were implemented in Compute Unified Device Architecture (CUDA) Fortran, a GPU version of the RRTMG_LW, namely G-RRTMG_LW, was developed. Results demonstrated that the proposed acceleration algorithms were effective and that the G-RRTMG_LW achieved a significant speedup. In the case without I/O transfer, the 2-D G-RRTMG_LW on one K40 GPU obtained a speed increase of 18.52× over the baseline performance on a single Intel Xeon E5-2680 CPU core. [ABSTRACT FROM AUTHOR]

Load imbalance is a common problem to be tackled urgently in large scale data-driven simulation systems or data intensive computing. According to the coupler, the Chinese Academy of Sciences-Earth System Model (CAS-ESM) implements one-way nesting of the Institute of Atmospheric Physics of Chinese Academy of Sciences Atmospheric General Circulation Model version 4.0 (IAP AGCM4.0) and Weather Research and Forecasting model (WRF). The METGRID (meteorological grid) and REAL program modules in the WRF are used to process meteorological data. In the CAS-ESM, the load of the METGRID module is seriously unbalanced on many CPU cores. The load imbalance has a serious impact on the processing speed of meteorological data, so this study designs an optimization algorithm to solve the problem. Numerical experiments show that compared to before optimization, the optimization algorithm can solve the load imbalance of the METGRID, and the computation speed of the METGRID and REAL modules after optimization on 64 CPU cores is about 7.2 times faster than before. Meanwhile, the whole computation speed of the CAS-ESM can improve by 217.53%. In addition, results indicate that they also can reach to a similar speedup on different numbers of CPU cores. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The earth system model is one of the most complicated computer simulation software in the human development history, which is the basis of understanding and predicting the climate change, and an important tool to support the climate change related decisions. CAS-ESM, Chinese Academy of Science Earth System Model, is developed by the Institute of Atmospheric Physics(IAP) and its cooperators. This system contains the complete components of the climate system and ecological environment system including global atmospheric general circulation model(AGCM), global oceanic general circulation model(OGCM), ice model, land model, atmospheric chemistry model, dynamic global vegetation model(DGVM), ocean biogeochemistry model(OBM) and regional climate model(RCM), etc. Since CAS-ESM is a complex system and is designed as a scalable and pluggable system, a parallel software platform(SC-ESSP) is needed. SC-ESSP will be developed as an open software platform running on Chinese earth system numerical simulation facilities for different developers and users, which requires that the component models need to be standard and unified, and the platform should be pluggable, high performance and easy-to-use. To achieve this goal, based on the platform of Community Earth System Model(CESM), a parallel software application platform named SC-ESAP is designed for CAS-ESM, mainly including compile and run scripts, standard and unified component models, 3-D coupler component, coupler interface creator and some parallel and optimization work. A component framework SC-ESMF will be developed based on the framework SC-Tangram for the more distant future. [ABSTRACT FROM AUTHOR]

In the present study, the LASG/IAP Climate system Ocean Model version 2 (LICOM2) was implemented to replace the original ocean component in the Community Earth System Model version 1.0.4 (CESM1) to form a new coupled model referred to as CESM1+LICOM2. The simulation results from a 300-yr preindustrial experiment by using this model were evaluated against both observations and the Flexible Global Ocean-Atmosphere-Land System Model with grid-atmospheric model version 2 (FGOALS-g2). It was found that CESM1+LICOM2 simulates well the mean features of the ocean, sea ice, and atmosphere, relative to models used in the Coupled Model Intercomparison Experiment (CMIP5), when compared with observations. The spatial distribution of SST bias in CESM1+LICOM2 is similar to that in the Community Climate System Model version 4 (CCSM4). The simulated climate variabilities, such as ENSO and Pacific decadal oscillation, are also reasonably simulated when compared with observations. The successful implementation of LICOM2 in the CESM1 framework greatly enhances the capability of LICOM2 in conducting high-resolution simulations and model tuning. Compared with FGOALS-g2, the simulations of both SST and Atlantic meridional overturning circulation are significantly improved in CESM1+LICOM2. The former can be mainly attributed to the atmospheric model, and the latter to the improvement in the parameterization of diapycnal mixing. The study provides a base to further improve the present version of LICOM and its functionalities in the coupled model FGOALS at both low and high resolutions. [ABSTRACT FROM AUTHOR]

Air pollution forecast is becoming more and more important nowadays. The numerically sticky chemical ordinary differential equations (ODEs) is a critical component of air pollution models. Various solvers have been designed for the chemical ODEs in the past. However, they are either slow or imprecise. In our previous work, we have designed a nonnegativity preserved efficient chemical solver MBE, which is an acronym for Modified-Backward-Euler. In this paper, we review MBE method and prove its convergence and stability mathematically, which guarantee that MBE results converge to the exact solutions as the step-size becomes smaller and MBE results with relatively small step-size can be used as the standard. Then we apply MBE to the Nested Air Quality Prediction Modeling System (NAQPMS). Comparison between MBE and the most popular solver LSODE is also made. Considering the speed and precision, MBE is a better choice for the air pollution forecast. [ABSTRACT FROM AUTHOR]

The construction of configuration-interaction (CI) expansions from a matrix product state (MPS) involves numerous matrix operations and the skillful sampling of important configurations in a large Hilbert space. In this work, we present an efficient procedure for constructing CI expansions from MPS employing the parallel object-oriented Charm++ programming framework, upon which automatic load-balancing and object migrating facilities can be employed. This procedure was employed in the MPS-to-CI utility (Moritz et al., J. Chem. Phys. 2007, 126, 224109), the sampling-reconstructed complete active-space algorithm (SR-CAS, Boguslawski et al., J. Chem. Phys. 2011, 134, 224101), and the entanglement-driven genetic algorithm (EDGA, Luo et al., J. Chem. Theory Comput. 2017, 13, 4699). It enhances productivity and allows the sampling programs to evolve to their population-expansion versions, for example, EDGA with population expansion (PE-EDGA). Further, examples of 1,2-dioxetanone and firefly dioxetanone anion (FDO - ) molecules demonstrated the following: (a) parallel efficiencies can be persistently improved by simply by increasing the proportions of the asynchronous executions and (b) a sampled CAS-type CI wave function of a bi-radical-state FDO - molecule utilizing the full valence (30e,26o) active space can be constructed within a few hours with using thousands of cores., (© 2020 Wiley Periodicals LLC.)