ESMF 8.6.0 released

[Gerhard Theurich - NOAA Affiliate]

Dear all,

The ESMF Core Team is pleased to announce the ESMF 8.6.0 release. It is now available for download at https://github.com/esmf-org/esmf/releases/tag/v8.6.0. Release notes and known issues are also available in the usual format on the ESMF website: https://earthsystemmodeling.org/static/releases.html#8_6_0.

The 8.6.0 release of ESMF introduces two major new features: spherical vector regridding and integrated accelerator device management. Both features are provided at an early stage of the implementation, expected to be fleshed out over the course of the next several releases. In addition to these new developments, the release includes a number of improvements of existing functionality.

Support for spherical vector regridding has been requested by a number of groups over the years, and a basic implementation of the feature is now available in ESMF 8.6.0.  One of the advantages of mapping vectors through 3D Cartesian space, as opposed to regridding the individual components separately, is improved accuracy of the results, especially in the polar regions. The initial implementation of this feature included with 8.6.0 is limited to 2D tangential vectors (expressed in terms of east and north components) on a spherical geometry (e.g. an ESMF_Grid with ESMF_COORDSYS_SPH_DEG) and requires that the vector components are stored in a single ungridded Field dimension of size 2. We expect these and other restrictions to be relaxed in future releases and welcome feedback from the community to help prioritize.

Accelerator device solutions that are capable of managing multi-component applications are likely to become critical as coupled systems are run on hardware that provides most of the compute power in the form of GPUs. ESMF 8.6.0 provides novel development in this area, building on the experience gained from CPU resource management for multi-component ESMF applications based on the petList concept, and its recent extension to ESMF-managed threading. The user has now the option to associate an analogous list for accelerator devices (devList) with each component. ESMF implements the required bookkeeping, providing component context specific device information. Paired with standard accelerator programming paradigms, such as OpenACC or OpenMP, this allows component code to target the desired devices for offloading. The current implementation is considered a proof of concept, and refinements of the feature are expected in future releases.

Among the areas of the framework that received incremental improvements is ESMX, where it is now possible to modify ESMF run-time behavior via ESMF_RUNTIME_* options in the ESMX run-time configuration file for convenience. Small functional improvements also went into the Array and Field Create() methods that now allow creation from the slice of an existing object. Handling this situation on the ESMF level can significantly simplify user code.

Further progress was made for multi-tile I/O support for Fields and Arrays. It is now possible to perform I/O for multi-tile Arrays and Fields with layouts other than 1 DE per PET. Related to I/O, the "normalization" attribute in mapping files written by the ESMF regrid weight generation methods and applications was corrected to set the value “N/A” for anything other than the conservative regridding methods.

Incremental progress, bug fixes, portability and performance improvements were made in several other areas of the framework. This includes full support for the NVHPC compiler suite, tracing support for MPI calls on all platforms, resolving crashes observed with the Darshan and Cray Performance Analysis Tools, and finally addition of a public C API for the ESMF trace feature.

For a full list of release notes and known issues see https://github.com/esmf-org/esmf/releases/tag/v8.6.0 or https://earthsystemmodeling.org/static/releases.html#8_6_0.

As always, please write esmf_s...@ucar.edu with any questions or issues concerning ESMF.

With best regards,

The ESMF Core Team