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NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Emergence of the Earth System Modeling Framework NCAR/LANL CCSM Climate Data Assimilation Weather GFDL FMS Suite NASA GMAO Analysis NSIPP Seasonal Forecast MITgcm Cecelia De. Luca NCEP Forecast Symposium on the 50 th Anniversary of ONWP www. esmf. ucar. edu

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Motivation In NWP, seasonal prediction and climate research. . . increased emphasis on detailed representation of individual physical processes; requires many teams of specialists to contribute components to an overall modeling system In computing technology. . . increase in hardware and software complexity in high-performance computing, shift toward the use of scalable computing architectures In software … development of frameworks (integrated libraries), such as the GFDL Flexible Modeling System (FMS) and Goddard Earth Modeling System (GEMS) that encourage software reuse and interoperability The ESMF is a community effort to tame the complexity of models and the computing environment. It leverages, unifies and extends existing software frameworks, breaking down institutional barriers www. esmf. ucar. edu and creating new opportunities for scientific contribution and

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH ESMF Project Description GOALS: To increase software reuse, interoperability, ease of use and performance portability in climate, weather, and data assimilation applications PRODUCTS: • Core framework: Software for coupling geophysical components and utilities for building components • Applications: Deployment of the ESMF in 15 of the nation’s leading climate and weather models, assembly of 8 new science-motivated applications Reuse Interoperability Ease of Adoption Performance METRICS: 15 applications use ESMF component coupling services and 3+ utilities 8 new applications comprised of never-before coupled components RESOURCES and TIMELINE: www. esmf. ucar. edu starting February 2002 2 codes adopt ESMF with < 2% lines of code changed, or within 120 FTEhours No more than 10% overhead in time to solution, no degradation in scaling $9. 8 M from NASA ESTO over 3 years,

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH ESMF Architecture 1. ESMF provides an environment for assembling geophysical components into applications, with support for ensembles and hierarchies. 2. ESMF provides a toolkit that components use to i. increase interoperability ii. improve performance portability iii. abstract common services www. esmf. ucar. edu

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Hierarchies and Ensembles ESMF encourages applications to be assembled hierarchically and intuitively Coupling interfaces are standard at each layer Components can be used in different contexts Seasonal Forecast ocean atmland atm coupler physics www. esmf. ucar. edu land dycore Ensemble Forecast assim_atm sea ice assim_atm assim ESMF supports ensembles with multiple instances of components running sequentially (and soon, concurrently)

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH ESMF In More Detail… • Fortran interfaces (mixed-language implementation) • Multi-platform support (SGI, Compaq, IBM, Linux - Intel, PGI, NAG, Absoft) • Clear, simple hierarchy of data objects (arrays, fields, bundles of fields, components) for developing modeling codes • Toolkits for communications (redist, halo, etc. ), time management, error handling and logging, resource files, IO • Regridding library is on-line, parallelized version of SCRIP from LANL • Tools for multithreading, cache blocking, and load balancing integrated into the architecture – development has been highly performance-aware! • Data objects and toolkits have consistent naming and behavior across the framework www. esmf. ucar. edu

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH The Benefits • Standard interfaces to modeling components promote increased interoperability between centers, faster movement of modeling components from research to operations • The ability to construct models hierarchically enables developers to add new modeling components more systematically and easily, facilitates development of complex coupled systems • Multi-use objects mean that the same data structure can carry information about decomposition, communications, IO, coupling – this makes code smaller and simpler, and therefore less bug-prone and easier to maintain • Shared utilities encourage efficient code development, higher quality tools, more robust codes www. esmf. ucar. edu

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Open Development • Open source • Currently ~800 unit tests, ~15 system tests are bundled with the ESMF distribution, can be run in non-exhaustive or exhaustive modes • Results of nightly tests on many platforms are accessible on a Test and Validation webpage • Test coverage, lines of code, requirements status are available on a Metrics webpage • Exhaustive Reference Manual, including design and implementation notes, is available on a Downloads and Documentation webpage • Development is designed to allow users clear visibility into the workings and status of the system, to allow users to perform their own diagnostics, and to encourage community ownership www. esmf. ucar. edu

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH ESMF Key Accomplishments • Public delivery of prototype ESMF v 1. 0 in May 2003 • Monthly ESMF internal releases with steadily increasing functionality • Completion of first 3 coupling demonstrations using ESMF in March 2004 – NCAR CAM with NCEP SSI – NCAR CAM with MITgcm ocean – GFDL B-grid atmosphere with MITgcm ocean – All codes above running as ESMF components and coupled using the framework, codes available from Applications link on website – Other codes running as ESMF components: MOM 4, GEOS-5 – Less than 2% lines of source code change • On track for delivery of ESMF v 2. 0 on 23 June 2004 www. esmf. ucar. edu rd

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Interoperability Experiments Completed 1 GFDL B-grid atmosphere coupled to MITgcm ocean Atmosphere, ocean, and coupler are set up as ESMF components Uses ESMF regridding tools 3 2 Temperature SSI import Temperature SSI export Temperature difference NCAR Community Atmospheric Model (CAM) coupled to NCEP Spectral Statistical Interpolation (SSI) System, both set up as ESMF components www. esmf. ucar. edu Experiment utilizes same observational stream used operationally at NCEP NCAR Community Atmospheric Model (CAM) coupled to MITgcm ocean Atmosphere, ocean, and coupler are set up as ESMF components Uses ESMF regridding tools

NSF NCAR | NASA GSFC | DOE LANL | NOAA NCEP GFDL | MIT | U MICH Next Steps – Integration with data archives and metadata standardization efforts, anticipate collaboration with Earth System Grid (ESG) and European infrastructure project PRISM – Integration with scientific model intercomparison projects (MIPs), anticipate collaboration with the Program for Climate Model Diagnosis and Intercomparison (PCMDI), other community efforts – Integration with visualization and diagnostic tools for end -to-end modeling support, anticipate collaboration with the Earth Science Portal (ESP) – ESMF “vision” for the future articulated in multi-agency white paper on the Publications and Talks webpage www. esmf. ucar. edu