1. Mesoscale & Microscale Meteorological Division / NCAR ESMF and the Weather Research and Forecast Model John Michalakes, Thomas Henderson Mesoscale and Microscale Meteorology Division National Center for Atmospheric Research michalak@ucar.edu Thomas Black Environmental Modeling Center NOAA / National Centers for Environmental Prediction

2. Weather Research and Forecast Model Goals: Develop an advanced mesoscale forecast and assimilation system, and accelerate research advances into operations Large collaborative effort to develop next-generation community model with direct path to operations Advanced Software Architecture –Modular, flexible, extensible –Portable and efficient –Designed for HPC Applications –Atmospheric Research –Numerical Weather Prediction –Coupled modeling systems –Air quality research/prediction –High resolution regional climate –prediction –Air quality research and prediction –Regional climate + DTC

3. Weather Research and Forecast Model Goals: Develop an advanced mesoscale forecast and assimilation system, and accelerate research advances into operations Large collaborative effort to develop next-generation community model with direct path to operations Advanced Software Architecture –Modular, flexible, extensible –Portable and efficient –Designed for HPC Applications –Atmospheric Research –Numerical Weather Prediction –Coupled modeling systems –Air quality research/prediction –High resolution regional climate –prediction –Air quality research and prediction –Regional climate ARW solver Physics Interfaces Plug-compatible physics NMM solver Top-level Control, Memory Management, Nesting, Parallelism, External APIs mediation driver model

4. Mesoscale & Microscale Meteorological Division / NCAR ESMF Support WRFV2.2 fully interoperable as ESMF component –Runs stand-alone without ESMF, or –Fully integrated component in ESMF –Distributed with ESMF unit test coupled “data” ocean Infrastructure: –ESMF Time Manager using reference implementation or shared implementation with CCSM Superstructure: “Wrapperized” –Top level init-run-finalize convention –ESMF conforms to “coupling as I/O” and is integrated with WRF Registry

5. Mesoscale & Microscale Meteorological Division / NCAR WRF Model Coupling Extension of WRF I/O API –MCEL (U. Southern Miss.) –MCT (Argonne NL) –ESMF Projects –WRF/ROMS, WRF/ADCIRC/SWAN/LSOM –Very high resolution urban airflow modeling (Fei Chen, NCAR; CFD Corp.) –Coupled WRF/HYCOM Katrina simulation MCEL MCT ESMF Superstructure ESMF

6. WRF/HYCOM Coupling (ESMF) WRF and HYCOM two-way coupled through ESMF to improve modeling of hurricane intensification Synchronization is through successive calls to components by ESMF top-level driver Status: –WRF an ESMF component (NCAR), Init-run-finalize at top level Import/export through WRF I/O API ESMF Time Manager WRF I/O in ESMF –HYCOM-ESMF (NRL) WRF I/O API WRF component ESMF WRF Component Interface HYCOM component ESMF WRF Component Interface ESMF Superstructure ESMF Infrastructure WRF export state: Surface winds & air temps Precipitation Radiation fluxes WRF import state: SST, Roughness length HYCOM export state: SSTs HYCOM import state: Winds Precipitation Radiation fluxes execution control regridding …

7. Mesoscale & Microscale Meteorological Division / NCAR WRF/LIS Coupling through ESMF LIS = Land Information System –NASA GSFC (lis.gsfc.nasa.gov) –Incorporates CLM, Noah, and VIC land surface models Initial WRF-LIS prototype by Sujay Kumar (GSFC) –Coupled via WRF surface driver using ESMF –All ESMF objects manufactured by LIS Planned –WRF provides ESMF_State objects to LIS –Extend to allow different grids

8. Mesoscale & Microscale Meteorological Division / NCAR Interoperability Supported metadata formats: NetCDF+parallel, HDF+parallel, GRIB[1&2] Participating in continuing refinement of Climate and Forecast metadata convention –Participate in GOESSP meetings to discuss conventions (go-essp.gfdl.noaa.gov) –Provide feedback for Balaji’s “Gridspec” proposal (www.gfdl.noaa.gov/~vb/gridstd/gridstd.html)www.gfdl.noaa.gov/~vb/gridstd/gridstd.html

9. Mesoscale & Microscale Meteorological Division / NCAR Interoperability Share goals with Earth System Curator –Similar approaches may apply to forecast V&V, managing ensembles, etc. Earth System Curator-Numerical Model Metadata (NMM) standard –http://ncas-cms.nerc.ac.uk/NMM/index.phphttp://ncas-cms.nerc.ac.uk/NMM/index.php –Full specification of an “experiment” Automatic testing of component compatibility

10. Mesoscale & Microscale Meteorological Division / NCAR Dynamic Load Balancing Key obstacle for Petascale; opportunity for new approaches, e.g. PGAS languages Instrument WRF using PAPI Generated high-resolution traces over 8 day period in July ’05 Characterize dynamic load from microphysics as functions of –Decomposition –Sizes, trajectories, other characteristics of load features Workload Characterization of Physics-Induced Load Imbalance in WRF (draft NCAR TM, 2007)

11. Mesoscale & Microscale Meteorological Division / NCAR Dynamic Load Balancing Figure 6: Maximum, average, minimum, and standard-deviation of load imbalance over eight-day measurement period as function of subdomain size. Workload Characterization of Physics-Induced Load Imbalance in WRF (draft NCAR TM, 2007) Key obstacle for Petascale; opportunity for new approaches, e.g. PGAS languages Instrument WRF using PAPI Generated high-resolution traces over 8 day period in July ’05 Characterize dynamic load from microphysics as functions of –Decomposition –Sizes, trajectories, other characteristics of load features

12. Mesoscale & Microscale Meteorological Division / NCAR Plans Convergence of ESMF and WRF software –WRF as ESMF component (current) –Support for additional infrastructure elements –Support for ESMF components coupled in WRF call tree –Continue to follow, participate in data- interoperability standardization (C.F., Curator)