This image illustrates the improvement in predicted sea ice concentrations achieved at the Naval Research Laboratory by taking a standalone sea ice model and coupling it to an ocean model using the Earth System Modeling Framework (ESMF), then comparing the output of the standalone and coupled versions with observations. ESMF, a software package based at NCAR and supported and developed by a multi-agency collaboration, defines standard software interfaces so that models from different research and operational sites can be combined into a variety of integrated systems. The image demonstrates that integrated modeling systems created using ESMF are being used to explore aspects of the Earth system that have far-reaching and profound social consequences.
This diagram shows the structure of the GEOS-5 atmospheric general circulation model running at the NASA Goddard Global Modeling and Assimilation Office. This model was developed from the ground up using ESMF. Each box is an ESMF component, and every component has a standard interface so that it is swappable. This indicates ESMF's value for a broad range of new modeling challenges: models can be configured and adapted to simulate many different physical processes with increasing ease.
Priority 4: Creating an Earth System Knowledge Environment
Earth System Modeling Framework (ESMF) and ESMF-based Initiatives
Background
The Earth System Modeling Framework (ESMF) was motivated by the growing complexity of developing Earth system models. These are constructed of separate software components representing physical domains and processes; for example, atmosphere, ocean, and sea ice. The components, which are often developed at separate sites, are coupled together into integrated systems to create realistic simulations. An additional complication is that the models are computationally intensive and must be designed to run on supercomputers with parallel processors. ESMF defines a set of standard software interfaces and a set of high-performance tools for common functions, such as grid interpolation.
ESMF components are arranged in a hierarchical structure to form applications. The lower figure shows an example: it diagrams the architecture of the GEOS-5 AGCM developed at NASA Goddard. This model was built from the ground up using ESMF. Each box, including the couplers, is an ESMF component with a standard interface. The GEOS modeling system can be systematically extended or reconfigured. Exchanges are facilitated both for large, composite components, such as the atmospheric dynamics package, and at the level of a particular physics parameterization.
The ESMF 3 distribution contains:
- Tools for building components and couplers, and a set of low-level utilities for common modeling functions such as regridding, calendar management, and data redistribution
- Concurrent or sequential execution, single or multiple executable modes
- Support for configuring ensembles
- Fortran interfaces and complete documentation, some C++ interfaces
- Support for Linux, IBM, Cray X1, SGI, Mac, and other platforms
Funding and Timeframe
ESMF has transitioned to multi-agency funding support and is the technical basis for an increasing number of modeling projects and programs. These include the DoD Battlespace Environments Institute, the NASA Modeling Analysis and Prediction Program, the NOPP Community Sediment Transport Model, multiple space weather initiatives, and a host of smaller projects.
ESMF is now in its fourth year and has started its second funding cycle. The project has four more years of funding under NASA and Department of Defense sponsorship. ESMF is also supported through NCAR Core funds, which have no term limit. In the next four years, the ESMF group anticipates two more major releases: ESMF 4, focusing on rework and extensions to the grid representation and regridding software, and ESMF 5, focusing on consistency and standardization of interfaces.
Rationale
ESMF is a full realization of the NCAR strategic goal to create a common modeling infrastructure that serves the climate and weather domain and enables the integration of Earth systems with space weather models, hydrological components, and other related domains. It is a key element of NCAR's strategic priority of "Creating an Earth system knowledge environment" that will integrate the suite of scientific software at NCAR to better support science workflows. Looking beyond NCAR, ESMF is a realization of the goals expressed by the broader community to develop cross-institutional and cross-agency infrastructure that enables them to collectively reuse software and exchange components.
Progress
During FY2006, the ESMF team made significant advances in community adoption, software development, and organizational maturity.
Community adoption: There are now more than three dozen ESMF components available, representing physical domains such as ocean and land, processes such as radiation and chemistry, and computational functions such as data assimilation. The entire Space Weather Modeling Framework also provides ESMF interfaces to enable interoperation of space and Earth components. Numerous applications built using these components have transitioned to routine use, public distribution, and operations. These include the NASA GEOS-5 atmospheric general circulation model, the NCEP Global Forecast System, and the coupled HYCOM ocean and CICE sea ice models.
Software development: The ESMF team completely redesigned its central data structures for additional flexibility in supporting unstructured, curvilinear, and multi-patch grids. This capability was released in the ESMF 3.0.0 beta version in May 2006.
Organizational maturity: It is essential to the ESMF vision that development priorities are set by the community on an ongoing and regular basis. To this end, the ESMF Change Review Board was created and has met quarterly since August 2005. It consists of representatives from the ESMF customer base who are charged with setting priorities and schedules for the project.
Plans and Impact
In FY2007 the ESMF team will continue to work toward the transition of prototype components and applications into working research and operational codes. Software development will focus on optimization for very large processor counts, redesign of the framework grid interfaces and implementation, and increasing consistency of behavior. The ESMF team will be working toward integration into the Earth System Knowledge Environment through collaborations with the Earth System Curator, Earth System Grid, and Community Data Portal projects.
Widespread use of ESMF represents a paradigm shift in the way weather and climate models are constructed. Through the composition of modeling codes using components, and increased code interoperability, community building, and standard tools, ESMF is beginning to make model development easier and to facilitate new, multi-agency science collaborations. The end result is an Earth science community better equipped to explore basic research issues and better equipped to answer questions about the impacts of Earth science on society.
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