University of Colorado
The ESMF v6.3.0r release concludes a development cycle that was focused on supporting advanced capabilities for a wide variety of applications in modeling and data services. ESMF can be used in multiple ways: 1) to create high-performance, interoperable component-based modeling systems; 2) as a source of data communication, time management, metadata handling, and other libraries; 3) as a fast, parallel generator of interpolation weights from file for many different grids (see the ESMF_RegridWeightGen application website); and 4) as a Python grid remapping library (see the ESMPy website).
Highlights of v6.3.0r relative to the last public release (ESMF v5.2.0r) include enhanced regridding capabilities, new component-level features such as fault-tolerance, and more complete exchange grid interfaces. This release also includes a reference version of the National Unified Operational Prediction Capability (NUOPC) Layer, a set of conventions and templates that increases the interoperability of ESMF-based modeling systems.
The ESMF regridding functions have been expanded to include a wider range of grids, interpolation methods, and control options. ESMF now supports during-run and offline regridding of unstructured grids composed of polygons with an arbitrary number of sides as well as non-conservative regridding on either cell centers or corners of unstructured grids. The first order conservative interpolation method has been extended to work on 3D grids, and nearest-neighbor interpolation methods were added. There is also a new option to allow the user to select between great circle and Cartesian line paths when calculating interpolation weights on a sphere. Grid files that follow the Climate and Forecast (CF) UGRID convention and the CF GRIDSPEC convention are both supported for various object creation methods and regridding. The ESMF_RegridWeightGen application for calculating interpolation weights from file added the option to calculate the interpolation and conservation error for the generated weights for a quick analysis of their quality.
ESMF components have been extended in a few ways. The component interfaces can support fault-tolerant interactions between components based on a user-controlled "timeout" mechanism, a feature developed in collaboration with the NOAA Global Systems Division. The practical use cases of this feature are large ensemble configurations where individual ensemble members may crash or become unresponsive during the course of a simulation run. Another new component-level feature is the ability to transfer either logically rectangular Grid or unstructured Mesh objects between components that run on different sets of processors. This is useful when implementing coupled systems where a component needs to access fields of another component on that component's native grid.
Another area that has matured is the exchange grid (XGrid), which conserves flux quantities as they pass through the interface between domains. The implementation now allows combinations of logically rectangular Grids and unstructured Meshes to be supplied on either side of the XGrid. Weights generated by regridding through the XGrid can be renormalized by user-supplied source or destination area, and area and centroid information can be retrieved.
There are many other features and options added throughout ESMF, detailed in the release notes. Backward compatibility of the Fortran user interface with the ESMF v5.2.0r release series was preserved for all methods that are labeled backward compatible in the Reference Manual; the majority of methods fall into this category.
(ESMF v6.3.0r release date: January 31, 2014.)
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Public releases have undergone exhaustive testing and are expected to be stable. They are fully supported. Internal releases fix bugs or add capabilities not yet in public releases. They may not be fully tested, and come with no guarantee of support. The last internal release was ESMF v6.2.0, on May 17, 2013.
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