Numerical weather prediction on the one hand needs a very large number of floating point calculations, but on the other hand is very time-critical. Therefore, the largest computers available, i.e., the "supercomputers", have usually been acquired by the national meteorological services long before they were used in other fields of research or business. Since the available technology limits the speed of any single computer, parallel computations have become necessary to achieve further improvements in the number of results produced per time unit. This book collects the papers presented at two workshops held at ECMWF on the topic of parallel processing in meteorological models. It provides an insight into the state-of-the-art in using parallel processors operationally and allows extrapolation to other time-critical applications. It also shows trends in migrating to massive parallel systems in the near future.

A preliminary exploration is made of the uses of multiprocessing computers for large scale NWP using spectral models. In general if global communication between processors is relatively fast and easy, then implementing spectral models is feasible. The global spectral model is recast in terms of latitude and wavenumber tasks. This approach has a number of advantages: The entire algorithm is macrotasked. Only a handful of crucial pointers need to be locked. The spectral transform calculations are localized so that arithmetic always follows the same ordering and all results are exactly reproducible. The latitude wavenumber tasking scheme is implemented and tested on the Sequent Balance, a shared memory multiple instruction multiple data device. It is argued that this scheme could be easily extended and applied to larger machines of this class and provide a good starting point for distributed memory machines. The potential of single instruction multiple data machines is huge. A proposed algorithm for this class of machine uses a processor for each horizontal grid point. Keywords: Numerical weather prediction; Multiprocessors; Atmosphere models; Weather forecasting. (edc).

The Dawn of Massively Parallel Processing in Meteorology presents collected papers of the third workshop on this topic held at the European Centre of Medium-Range Weather Forecasts (ECMWF). It provides an insight into the state of the art in using parallel processors operationally, and allows extrapolation to other time-critical applications. It also documents the advent of massively parallel systems to cope with these applications.

Supercomputing is an important science and technology that enables the scientist or the engineer to simulate numerically very complex physical phenomena related to large-scale scientific, industrial and military applications. It has made considerable progress since the first NATO Workshop on High-Speed Computation in 1983 (Vol. 7 of the same series). This book is a collection of papers presented at the NATO Advanced Research Workshop held in Trondheim, Norway, in June 1989. It presents key research issues related to: - hardware systems, architecture and performance; - compilers and programming tools; - user environments and visualization; - algorithms and applications. Contributions include critical evaluations of the state-of-the-art and many original research results.

This book constitutes the proceedings of the 26th International Conference on Parallel and Distributed Computing, Euro-Par 2020, held in Warsaw, Poland, in August 2020. The conference was held virtually due to the coronavirus pandemic. The 39 full papers presented in this volume were carefully reviewed and selected from 158 submissions. They deal with parallel and distributed computing in general, focusing on support tools and environments; performance and power modeling, prediction and evaluation; scheduling and load balancing; high performance architectures and compilers; data management, analytics and machine learning; cluster, cloud and edge computing; theory and algorithms for parallel and distributed processing; parallel and distributed programming, interfaces, and languages; multicore and manycore parallelism; parallel numerical methods and applications; and accelerator computing.

Weather forecasting and climatology have traditionally been users of the world's fastest supercomputers. The recent emergence of massively parallel supercomputers as likely successors to current vector supercomputers has created an acute need to convert weather and climate models to suit parallel supercomputers with thousands of processors. Several major efforts are underway worldwide to accomplish this. ECMWF has established itself as the central venue for bringing together operational weather forecasters, climate researchers and parallel computer manufacturers to share their experience on these efforts every second year. The recent dramatic developments in supercomputer manufacturing have made the 1992 ECMWF Workshop timelier than before.