Earth System Modeling Framework

Workshop on “Coupling Technologies for Earth System Modelling : Today and Tomorrow”

CERFACS, Toulouse (France) – Dec 15th to 17th 2010

Ryan O’KuinghttonsRobert OehmkeCecelia DeLuca

Motivation

In climate research and numerical weather prediction.. 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, as we shift toward the use of scalable computing architectures

In software …emergence of frameworks to promote code reuse and interoperability

The ESMF is a focused community effort to tame the complexity of models and the computing environment. It leverages, unifies and extends existing softwareframeworks, creating new opportunities for scientific contribution and collaboration.

Evolution

Phase 1: 2002-2005NASA’s Earth Science Technology Office ran a solicitation to develop an Earth System Modeling Framework (ESMF).A multi-agency collaboration (NASA/NSF/DOE/NOAA) won the award. The core development team was located at NCAR.A prototype ESMF software package (version 2r) demonstrated feasibility.

Phase 2: 2005-2010New sponsors included Department of Defense and NOAA.Many new applications and requirements were brought into the project, motivating a complete redesign of framework data structures (version 3r).

Phase 3: 2010-2015The core development team moved to NOAA/CIRES for closer alignment with federal models.Basic framework development will be complete with version 5r (ports, bugs, feature requests, interoperability templates, user support etc. still require resources).The focus is on increasing adoption and creating a community of interoperable codes.

Components

• ESMF is based on the idea of components – functionally distinct sections of code that are wrapped in standard interfaces

• Components may represent either a physical domain or a function• Components can be arranged hierarchically, helping to organize the

structure of complex models

GEOS-5

surface fvcore gravity_wave_drag

history agcm

dynamics physics

chemistry moist_processes radiation turbulence

infrared solar lake land_ice data_ocean land

vegetation catchment

coupler

coupler coupler

coupler

coupler

coupler

coupler

ESMF components in the GEOS-5 atmospheric GCM

Architecture

Low Level Utilities

Fields and Grids Layer

Model Layer

Components LayerGridded ComponentsCoupler Components

ESMF Infrastructure

User Code

ESMF Superstructure

MPI, NetCDF, …External Libraries

• ESMF provides a superstructure for assembling geophysical components into applications.

• ESMF provides an infrastructure that modelers use to– Generate and apply

interpolation weights– Handle metadata, time

management, data I/O and communications, and other functions

– Access third party libraries

Standard Interfaces

• All ESMF components have the same three standard methods:– Initialize– Run– Finalize

• Each standard method has the same simple interface:

call ESMF_GridCompRun (myComp, importState, exportState, clock, …)

Where:myComp points to the componentimportState is a structure containing input fieldsexportState is a structure containing output fieldsclock contains timestepping information

Steps to adopting ESMF• Divide the application into components

(without ESMF)• Copy or reference component input and

output data into ESMF data structures• Register components with ESMF• Set up ESMF couplers for data exchange

• Interfaces are wrappers and can often be setup in a non-intrusive way

Data Representation Options

1. Representation in index space (Arrays)• One or more tiles

store indices and topology• Sparse matrix multiply for remapping with user supplied interpolation weights• Highly scalable - no global information held

locally, uses distributed directory approach (Devine 2002) for access to randomly distributed objects in an efficient, scalable way

2. Representation in physical space (Fields)• Built on Arrays + some form of Grid• Grids may be logically rectangular, unstructured mesh, or observational data• Remapping using parallel interpolation weight generation - bilinear, higher order, or

first order conservative

Supported Array distributions

Coupling Options• Lots of flexibility in

coupling approaches• Single executable• Multiple executable

– Array send/rcv withInterCommpackage (PVM)

– Web service option– Other options

• Couplingcommunicationscan be called either from within a coupler or directly from a gridded component – useful when it is inconvenient to return from a component in order to perform a coupling operation

• Recursive components for nesting higher resolution regions• Ensemble management with either concurrent or sequential execution of

ensemble members

Comp A Comp B

Comp A Comp B

Contributed by U MarylandCoupler

Array send/recv

Multiple executable options

Metadata Handling and Usage

•Metadata is broken down into name/value pairs by the Attribute class– Can be attached at any level of the ESMF object hierarchy– Document data provenance to encourage self describing models– Automate some aspects of model execution and coupling

- Actively exploring in this direction with workflows and web services

•Standard metadata is organized by Attribute packages – Used to aggregate, store, and output model metadata– Can be nested, distributed, and expanded to suite specific needs

- Designed around accepted metadata standards

•Emerging conventions– Climate and Forecast (CF)– ISO standards– METAFOR Common Information Model (CIM)

Summary of Features

• Fast parallel remapping: unstructured or logically rectangular grids, 2D and 3D, using bilinear, higher order, or conservative methods, integrated (during runtime) or offline (from files)

• Multiple strategies for support of nested grids• Core methods are scalable to tens of thousands of processors• Supports hybrid (threaded/distributed) programming for optimal

performance on many computer architectures• Multiple coupling and execution modes for flexibility• Time management utility with many calendars (Gregorian, 360-day, no-

leap, Julian day, etc.), forward/reverse time operations, alarms, and other features

• Metadata utility supports emerging standards in flexible and useful way• Runs on 25+ platform/compiler combinations, exhaustive test suite and

documentation• Couples between Fortran and/or C-based model components

Class Structure

DELayoutCommunications

StateData imported or exported

FieldBundleCollection of fields

GridCompLand, ocean, atm, … model

F90

Superstructure

Infrastructure

FieldPhysical field, e.g. pressure

Grid, LocStream, Mesh (C++)LogRect, Unstruct, etc.

Data Communications

C++RegridComputes interp weights

CplCompXfers between GridComps

UtilitiesMachine, TimeMgr, LogErr, I/O, Config, Attributes etc.

ArrayHybrid F90/C++ arrays

RouteStores comm paths

DistGridGrid decomposition

XgridExchange grid

Component Overhead

• Representation of the overhead for ESMF wrapped native CCSM4 component

• For this example, ESMF wrapping required NO code changes to scientific modules

• No significant performance overhead

(< 3% is typical)

• Few code changes for codes that are modular

• Platform: IBM Power 575, bluefire, at NCAR• Model: Community Climate System Model (CCSM)• Versions: CCSM_4_0_0_beta42 and

ESMF_5_0_0_beta_snapshot_01 • Resolution: 1.25 degree x 0.9 degree global grid

with 17 vertical levels for both the atmospheric and land model, i.e. 288x192x17 grid. The data resolution for the ocean model is 320x384x60.

Remapping Performance

• ESMF parallel conservative remapping is scalable and accurate

• Bilinear could use additional optimization

• ESMF parallel conservative remapping is scalable and accurate

• Bilinear could use additional optimization

• All ESMF interpolation weights are generated with unstructured mesh

• Increases flexibility with 2D and 3D grids

• Adds overhead to bilinear interpolation

• Greatly improves performance over existing conservative methods

• Platform: Cray XT4, jaguar, at ORNL• Versions: ESMF_5_2_0_beta_snapshot_07 • Resolution: - fv0.47x0.63: CAM Finite Volume grid, 576x384- ne60np4: 0.5 degree cubed sphere grid, 180x180x6

A Common Model Architecture

• The US Earth system modeling community is converging on a common modeling architecture

• Atmosphere, ocean, sea ice, land, wave, and other models are ESMF or ESMF-like components called by a top-level driver or coupler

• Many models are componentizing further

Navy Coupled Ocean Atmosphere Mesoscale Prediction System / Wavewatch III Navy Operational Global Atmospheric Prediction SystemHybrid Coordinate Ocean Model – CICE Sea Ice

NOAA National Environmental Modeling SystemNOAA GFDL MOM4 Ocean

NASA GEOS-5 Atmospheric General Circulation Model

NCAR Community Earth System ModelWeather Research and Forecast Model

HAF Kinematic Solar Wind-GAIM Ionosphere

pWASH123 Watershed-ADCIRC Storm Surge Model

Features and Benefits:

•Interoperability promotes code reuse and cross-agency collaboration•Portable, fast, fully featured toolkits enhance capability•Automatic compliance checking for ease of adoption

ESMF-enabled systems include:

A Common Model ArchitectureA Common Model Architecture

A Common Model Architecture

• Increasingly, models in the U.S. follow a common architecture

• Atmosphere, ocean, sea ice, land, and/or wave models are components called by a top-level driver/coupler

• Components use ESMF or ESMF-like interfaces (see left)

• Many major U.S. weather and climate models either follow this architecture (CCSM/CESM, COAMPS, NEMS), want to follow this architecture for future coupled systems (NOGAPS), or have a different style of driver but could provide components to this architecture (GEOS-5, FMS)

Even non-ESMF codes now look like ESMF …

ESMF:ESMF_GridCompRun(gridcomp, importState,exportState, clock, phase, blockingFlag, rc)

CESM (non-ESMF version):atm_run_mct(clock, gridcomp, importState,exportState)(argument names changed to show equivalence)

WRF

HYCOM

CICE IcePOP Ocean

CCSM4/CESM

NMM-B Atm PhysNMM-B Atm DynamicsNEMS

NMM History

GFS Atm Phys GFS Atm DynamicsGFS

GFS I/O

FV Cub Sph DycoreGEOS-5 GWD GEOS-5 FV Dycore

GEOS-5 Atm Dynamics

GEOS-5

GSI

GEOS-5 Moist Proc

GEOS-5 Turbulence

GEOS-5 LW Rad GEOS-5 Solar Rad

GEOS-5 Radiation

GEOS-5 Aeros Chem

GOCART

Strat ChemParam Chem

GEOS-5 Atm Chem

GEOS-5 Ocean BiogeoGEOS-5 Salt WaterPoseidon GEOS-5 Data Ocean

GEOS-5 OGCM

GEOS-5 Topology

GEOS-5 Land Ice

GEOS-5 Lake GEOS-5 Veg Dyn GEOS-5 Catchment

GEOS-5 Land

GEOS-5 Surface

GEOS-5 Atm PhysicsGEOS-5 Hiistory

ESMF Model Map 2010

NOAADepartment of DefenseUniversityNASADepartment of EnergyNational Science Foundation

ESMF coupling complete

Component (thin lines)Model (thick lines)

LegendOvals show ESMF components and modelsthat are at the working prototype level orbeyond.

Tracer Advection

CLM Land CAM Atm FIM

Land Info System

HAF

GAIM

MOM4

SWAN

ADCIRCpWASH123

COAMPSWWIII

NCOM

NOGAPS

NUOPC Layer: Goals

• National Unified Operational Prediction Capability is a consortium of operation weather prediction centers

• Standardize implementation of ESMF across NASA, NOAA, Navy, and other model applications

• Demonstrate improved level of interoperability– Specific goals described in the NUOPC Common Model

Architecture Committee report

– CMA report - http://www.weather.gov/nuopc/CMA_Final_Report_1%20Oct%2009_baseline.pdf?

– NUOPC website - http://www.weather.gov/nuopc

NUOPC Layer: Products• Software templates to guide development of a common

architecture for components and couplers• A software layer to narrow the scope of ESMF interfaces• NUOPC Compliance Checker software (initial implementation

available with ESMF_5_1_0)• Comprehensive tutorial materials• Websites, repositories, trackers, and other collaborative tools

• NUOPC Layer Guidance Documents (posted on ESMF website)

• ESMF - www.earthsystemmodeling.org

Other ESMF related projects …• Earth System Curator (sponsors NSF/NASA/NOAA)

– Implementation of the METAFOR Common Information Model in the Earth System Grid (ESG) portal for the 5th Coupled Model Intercomparison Project

– Using ESMF Attributes to generate the METAFOR CIM schema directly from models

– Atmosphere/hydrological model coupling using OpenMI and ESMF web services

• Earth Science Gateway on the TeraGrid (sponsor NSF)– End-to-end self-documented workflows from web-based

model configuration to data archival, with Purdue and NCAR

• Global Interoperability Program (sponsor NOAA)– Support for projects involved with interoperability,

infrastructure development, and global modeling education