Petaflops Geospace Simulations

近年来，一个共同的努力，以发展全球环流模式的地球？的磁层和它？太阳风和地球的相互作用？地球的高层大气一直是空间科学界的一个主要焦点。 在实现这一目标方面已经取得了很大的进展，但很明显，计算需求非常大。 该项目将开发一个具有petaflop能力的OpenGGCM（开放地球空间大气环流模型）版本，这是一个耦合的地球社区模型。磁层、电离层和热层。OpenGGCM在计算上具有挑战性的部分是MHD磁层核心代码，在目前的代码中，该代码分辨率不足，缺乏一些必要的物理模型来模拟磁层-太阳风相互作用的一些关键方面。petaflop OpenGGCM将通过包含针对新硬件（如IBM Cell Broadband Engine（CBE））的优化代码来克服这些限制。该项目还将开发一个代码库，智能地减少和压缩模拟输出的数据。这种I/O减少对于千万亿次模拟是必要的，因为I/O带宽和容量跟不上CPU性能。压缩技术将使用小波压缩来减少输出数据，然后将其写入存储器。这将有助于从模拟中提取最佳信息量。该项目为下一代地球空间模拟奠定了基础，这有望使空间物理学最基本问题的研究成为可能。这将是第一次真正的多尺度模拟，涵盖了从磁层的全球尺度到流体近似崩溃的最小尺度的所有尺度。模型分辨率的提高将大大减少数值效应，并使研究湍流及其影响等耗散敏感现象成为可能。I/O减少算法的发展引入了一种新的方法来减轻千万亿次系统固有的I/O瓶颈。在此项目期间开发的所有代码将公开提供。具体来说，支持千万亿次的P-OpenGGCM将在社区协调建模中心（CCMC）按需运行，开发用于利用CBE架构和执行I/O压缩的库将公开提供。OpenGGCM不仅是一种研究工具，也是空间天气预测的候选模型，因此具有重大社会影响的潜力。该项目的模型改进将大大提高其在这方面的价值。压缩库将是通用工具，可用于任何千万亿次模拟使用三维直线网格上的时间序列数据。

In recent years a concerted effort to develop General Circulation Models of Earth?s magnetosphere and it?s interaction with the solar wind and Earth?s upper atmosphere has been a major focus of the space sciences community. Much progress has been made toward this goal, but it has become clear that the computational requirements are very large. This project will develop a petaflop-capable version of the OpenGGCM (Open Geospace General Circulation Model), which is a coupled community model of the Earth?s magnetosphere, ionosphere, and thermosphere. The computationally challenging part of the OpenGGCM is the MHD magnetosphere core code which, in the current code, is under-resolved and lacks some of the necessary physics to model some of the key aspects of the magnetosphere - solar wind interaction. The petaflop OpenGGCM will overcome these limitations by including optimized code for new hardware, such as the IBM Cell Broadband Engine (CBE). The project will also develop a code library that intelligently reduces and compresses the data output from the simulation. Such I/O reduction becomes necessary for petascale simulations because I/O bandwidth and capacity does not keep pace with CPU performance. The compression technique will use wavelet compression to reduce output data before they are written to storage. This will facilitate the extraction of the optimal amount of information from the simulation. This project lays the groundwork for the next generation of geospace simulations, which promise to allow the study of the most fundamental problems of space physics. These will be the first true multiscale simulations that encompass all scales from the global scale of the magnetosphere down to the smallest scales at which the fluid approximation breaks down. The increased model resolution will dramatically reduce numerical effects and will make it possible to study dissipation sensitive phenomena such as turbulence and its effects. The development of I/O reduction algorithms introduces a new approach to mitigate the I/O bottlenecks inherent to petascale systems. All code developed during this project will be publicly available. Specifically, the petascale enabled P-OpenGGCM will be made available at the Community Coordinated Modeling Center (CCMC) for runs on demand, and the libraries developed to exploit the CBE architecture and to perform I/O compression will be made publicly available. The OpenGGCM is not just a research tool but also a candidate model for Space Weather prediction, and thus has the potential for a significant societal impact. The model improvements from this project will enhance its value in this capacity significantly. The compression libraries will be generic tools that can be utilized by any petascale simulation using time series data on three-dimensional rectilinear grids.