A brief introduction to NEMS NMMB Tutorial March 2, 2016 Mark Iredell

What is NEMS? NEMS stands for: NOAA Environmental Modeling System A shared, portable, high performance software superstructure and infrastructure For use in operational prediction models at the National Centers for Environmental Prediction (NCEP) Support to community through the Developmental Test Center (DTC)

Model Components in NEMS (at least in progress) Atmosphere NMM-B GSM FIM Chemistry GOCART CMAQ Ocean MOM HYCOM POM Sea Ice CICE KISS Wave WaveWatch3 Land/Hydro LIS WRF-Hydro Ionosphere IPE Coupling mediators Ensemble mediator Atmosphere-Ocean-Ice mediator Physics-Chemistry mediator Space Weather mediator

Newer NEMS Coupling standard Newer NEMS Coupling standard* NUOPC (National Unified Operational Prediction Capability) NEMS ESMF Field brokering. Initialize sequence. Run sequence. Compatibility testing. Compliance checker. ** ** ** Driver  - Provides a harness for Models, Mediators, and Connectors, coordinating their initialization and driving them during the application time loop. Model  - Typically implements a specific physical domain, e.g. atmosphere, ocean. Mediator  - Used for custom coupling code (flux calculations, averaging, etc.) between multiple Models. Connector  - Connects pairs of components, e.g. Model to/from Model, or Model to/from Mediator, and executes simple transforms (Regrid or Redist). * Sources of the materials on the slide is a courtesy of NUOPC group ** Will be revised according to dynamic core selection and NGGPS budget 2/2/2016

Another View of NEMS: NGGPS Schematic Image courtesy of the Developmental Testbed Center

NEMS Architecture NUOPC Driver NUOPC Mediator NUOPC Models NUOPC Main Program ESMF Component NUOPC Driver NUOPC Mediator NUOPC Models NUOPC Connector

NEMS Structure (with respect to NMMB) MAIN NEMS All boxes represent ESMF components. EARTH(1:NM) NMMB Overall NEMS superstructure. The atmosphere-ocean mediator is recently included. Solver Write

Could have multiple instantiations for different forecast hours. NEMS Write component Could have multiple instantiations for different forecast hours. Each instantiation runs on the union of model processors and its own quilt processors. Import state is forecast data on forecast processors and forecast decomposition. No export state. Overall NEMS superstructure. The atmosphere-ocean mediator is recently included.

NEMS Write component steps Send model data to quilt processors, independently decomposed on latitude. Return from model processors so model can resume running. Run full UPP post-processor and write GRIB master files (if requested). Write model history files using NEMSIO. Overall NEMS superstructure. The atmosphere-ocean mediator is recently included.

NUOPC Physics Driver Schematic Key Model Standard Model Specific Dynamics Dynamical equations, advection, horizontal mixing, diffusion. Δt, u, v, w, T, θ, p, z, qx, cx, ax staggered Tendencies and Updates Vertical flipping Destaggering (direction check) Vertical flipping Restaggering (direction check) Pre-Physics Interface qx (microphysics species) cx (chemistry species) ax (aerosol species) Post-Physics Interface Δt, u, v, w, T, θ, p, z, qx, cx, ax destaggered Tendencies and Updates Atmospheric Physics Driver (init, run, finalize modes) Initialize Physics Tables and Databases Output Diagnostics fields rates budgets others Modified Kalnay Rules Layer Init Mode Finalize Mode. Radiation Deep and Shallow Cumulus Surface Layer PBL and Vertical Mixing Micro-physics Sat. adjust fluxes, precipitation radiation, stability, exchange coefficients fluxes, SST, coefficients, etc. NUOPC Layer Wave Prep/Post LSM Prep/Post Ocean Prep/Post LSM, Ocean, Wave, Chemistry, Aerosol, Ice Drivers

Summary ● The NOAA Environmental Modeling System is being built to unify operational systems under a single framework in order to more easily share common structures/components and to expedite interoperability. ● The first two systems under NEMS have been implemented into NCEP operations with others to follow in the next few years. ● The NUOPC layer will be used to make collaboration with other groups less difficult when building/coupling modeling systems. ● Incorporation of a NUOPC physics driver can help standardize the often complex connections to physics packages thereby enhancing their portability. ● There are now atmosphere, ocean, sea ice, wave, land, hydro, chemistry, ionosphere, and mediator components within the NEMS framework.