Overview of ESMF in the Community Climate System Model (CCSM) Erik Kluzek NCAR -- CCSM Software Engineering Group (CSEG) Erik Kluzek NCAR -- CCSM Software Engineering Group (CSEG)

July 21, 2005Erik Kluzek -- NCAR2 Outline eIntroduction to CCSM Projects using ESMF e ESMF Stage-1 Code Development dStage-1 Requirements and Overall Design dSimple pseudo-code examples of Stage-1 design e River Transport Model Project e Data-7 Model Project e ESMF Infrastructure in CCSM eConclusion

July 21, 2005Erik Kluzek -- NCAR3 Introduction to CCSM Projects using ESMF 1. ESMF Stage-1 Code Development -- Implement a sequential driver using ESMF that replaces stand-alone CAM. 2. River Transport Model (RTM) Re-Gridding -- Use ESMF to make the CCSM river-routing model distributed. 3. Data-7 Model Project -- Rewrite of CCSM data-models designed with the ability to use ESMF superstructure from the get-go. 4. ESMF utilities in CCSM -- Plan on using ESMF utilities such as: time-manager, ConfigAtt, LogErr and I/O.

July 21, 2005Erik Kluzek -- NCAR4 ESMF Stage-1 Code Development e Goal: Implement a single-executable sequential version of CCSM that replicates the answers from stand-alone CAM. e Process: Developed and approved evaluation plan, project requirements and design documents. Staged implementation, frequent iterative design/review. e Status: Currently modifying CAM toward desired product with staged commits on development version. e Motivation: Initially work from a simpler non- concurrent version of CCSM, that can show replication of answers on different configurations of tasks/threads using a more widely used model than CCSM.

July 21, 2005Erik Kluzek -- NCAR5 ESMF Stage-1 Overall Design e New SPMD, sequential CCSM: Replace stand-alone CAM with a single-executable fully sequential implementation of CCSM (which we currently do not have). e Reduce code-duplication: Will reduce code duplication between CAM and CCSM. e Plug and Play: Active, data, and dead components can be interchanged in the system. e Easy to make driver concurrent for Stage-2: After Stage-1 a concurrent system will be developed that only involves changing the hub and driver components. The underlying separable model components won’t change.

July 21, 2005Erik Kluzek -- NCAR6 Overview of ESMF Stage-1 Project Requirements eKeep backwards compatibility with both CCSM and all stand-alone CAM configurations. eHub-spoke design of CCSM used with five components: atmosphere, land, ocean, sea-ice, and hub. eList of fields exchanged -- same as CCSM3. eAmount of model code modified should be kept to the minimum. eTop level driver referred to as Sequential CCSM. eCapability to easily swap different types of components in (active, data or dead). eConfine ESMF to a thin wrapper layer. eSequential and concurrent mode should share as much code as possible.

July 21, 2005Erik Kluzek -- NCAR7 Example of ESMF Layer

July 21, 2005Erik Kluzek -- NCAR8 Top Level Sequential CCSM

July 21, 2005Erik Kluzek -- NCAR9 Top level Plug and Play Sequential Driver Do while(.not. ESMF_IsStopTime( sync_clock ) ) call ESMF_CplCompRun( cpl=atm2hub_cpl, import=hub_export, export=atm_import,& clock=sync_clock, phase=1 ) ! Run Atmosphere phase 1 call ESMF_GridCompRun( gc=atm_gc, in=atm_import, out=atm_export, sync_clock, phase=1 ) call ESMF_CplCompRun( cpl=atm2hub_cpl, in=atm_export, out=hub_import, phase=2 & clock=sync_clock ) ! Run hub to prepare land import call ESMF_GridCompRun( gc=hub_gc, in=hub_import, out=hub_export, phase=1, clock=sync_clock ) call ESMF_CplCompRun( cpl=hub2lnd_cpl, in=hub_export out=lnd_import, phase=3,& clock=sync_clock ) ! Run Land call ESMF_GridCompRun( in=lnd_import, out=lnd_export, phase=1, clock=sync_clock ).. Similarly for ice, and ocean and second phase run-methods. End do

July 21, 2005Erik Kluzek -- NCAR10 Plug and Play ESMF Component Module Atm_gridcomp Use cam_comp, only: cam_input_t, cam_output_t, cam_init, cam_run1, cam_run2, cam_final Contains ! Register methods with ESMF Public atm_register ! ! Following are called only through ESMF ! Public :: atm_init, atm_run1, atm_run2, atm_final ! Convert between ESMF import/export states into CAM input/output derived types Private :: convert_import2camin, convert_output2export. End module

July 21, 2005Erik Kluzek -- NCAR11 Model Component non-ESMF Layer Module cam_comp Public data types :: cam_input_t, cam_output_t Contains Subroutine cam_alloc( cam_in, cam_out ) Subroutine cam_init( cam_in, cam_out ) Subroutine cam_run1( cam_in, cam_out ) Subroutine cam_run2( cam_in, cam_out ) Subroutine cam_finalize( cam_in, cam_out ) End module cam_comp

July 21, 2005Erik Kluzek -- NCAR12 River Transport Model Re-gridding ePrototyping the use of ESMF re- gridding infrastructure for the eventual creation of a high- resolution parallel biogeochemical river transport model. eFound and resolved problems in ESMF for conservative re-grid on widely differing grid scales.

July 21, 2005Erik Kluzek -- NCAR13 Data-7 Model Project eTotal re-write of CCSM data-model components. eRequirements for utilization of ESMF superstructure (initial, run, final phases) is being done from the ground up. eWe will prototype the new system with ESMF superstructure and concurrency in the late fall.

July 21, 2005Erik Kluzek -- NCAR14 Use of ESMF Infrastructure in CCSM eCurrently use prototype ESMF time- manager in two CCSM components, we will update to ESMF2 in the fall independent of Stage-1 evaluation plan. eCCSM is also interested in the use of ESMF ConfigAtt and LogErr utilities in CCSM.

July 21, 2005Erik Kluzek -- NCAR15 Conclusions eCCSM has several active projects utilizing ESMF: Stage-1, RTM, Data-7, and Infrastructure. eThe Stage-1 Project is taking considerable time and resources, but will payoff in having a well-designed flexible and extensible system built around ESMF. eThe Data-7 project will be able to evaluate ESMF concurrency. eThe RTM project has helped to find and resolve issues with ESMF re-gridding.