Overview of NEMS infrastructre Mark Iredell NEMS-NMMB tutorial February 18,

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) Eventual support to community through the Developmental Test Center (DTC) What is NEMS? 2

Motivation for NEMS – Develop a common superstructure that can be shared by NCEP models. – Modularize large pieces of the models with ESMF components and interfaces. – Isolate history/restart output in a common Write component. – No intrusion into the science code and parallelization in the respective models. 3

NEMS Developers in-house Nicole McKeedocumentation, web, testing Ratko Vasicupgrades, regression, atmos coupling Jun WangIO, post, configuration, WAM Weiyu Yangensemble, earth coupling, ESMF Patrick TrippNUOPC physics, software support 4

NEMS Developers ESMF group Gerhard TheurichNUOPC layer, HYCOM coupling Fei LiuNUOPC layer, MOM5 coupling Tony CraigNUOPC layer, Mediator 5

NEMS Developers model-specific Tom Black Dusan Jovic Jim Abeles John Michalakes NAM / NMM-B S Moorthi Henry Juang Eugene Mirvis GFS Jun Wang Misha Rancic WAM Sarah Lu Arlindo da Silva NGAC Tom Henderson Jim Rosinski FIM Xingren Wu CFS 6

NEMS Structure MAIN EARTH(1:NM) Ocean AtmIce NMM GSM FIM Solver Domains(1:ND) Wrt Dyn Phy Wrt NEMS Earth Ensemble Mediator Chem All boxes represent ESMF components. Atm-Ocn Mediator

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 model data on model processors, decomposed on latitude. No export state.

NEMS Write component steps 1.Send model data to quilt processors, independently decomposed on latitude. 2.Return from model processors so model can resume running. 3.Run full UPP post-processor and write GRIB master files (if requested). 4.Write model history files using NEMSIO.

NAM/NMM-B 12 km gridpoint spacing Static nests: - -4 km CONUS - -6 km Alaska - -3 km Hawaii - -3 km Puerto Rico Relocatable Fire Wx nest: km inside CONUS km inside Alaska ► One-way ► Boundaries received every parent timestep

Atmosphere Dynamics Physics Dyn-Phy Coupler Spectral Color Key Generic Component Generic Coupler Completed Instance GFS Phy unified atmosphere Including digital filter GOCART Dynamics, physics and chemistry run on the same grid in the same decomposition GOCART does not own aerosol tracers (i.e, do not allocate aerosol tracer fields) PHY2CHEM coupler component transfers/converts data from physics export state to GOCART import state – –Convert units (e.g., precip rate, surface roughness) – –Calculations (e.g., soil wetness, tropopause pressure, relative humidity, air density, geopotential height) – –Flip the vertical index for 3D fields from bottom-up to top-down CHEM2PHY coupler component transfers data from GOCART export state to physics export state – –Flip vertical index back to bottom-up – –Update 2d aerosol diagnostic fields Phy-Chem Coupler NEMS GFS Aerosol Component 11

LSM Prep/Post Pre-PhysicsInterface Dynamics  t, u, v, w, T, , p, z, q x, c x, a x staggered destaggered Post-PhysicsInterface Tendencies and Updates Tendencies Vertical flipping Destaggering (direction check) Vertical flipping Restaggering (direction check) Ocean Prep/Post Wave Prep/Post LSM, Ocean, Wave, Chemistry, Aerosol, Ice Drivers fluxes, SST, coefficients, etc. InitMode Dynamical equations, advection, horizontal mixing, diffusion. Radiation Deep and ShallowCumulus Surface Layer PBL and Vertical Mixing Micro- physics Sat. adjust Modified Kalnay Rules Layer NUOPC Physics Driver Schematic NUOPC Layer fluxes, precipitation radiation, stability, exchange coefficients q x (microphysics species) c x (chemistry species) a x (aerosol species) Output Diagnostic s fieldsfields ratesrates budgetsbudgets othersothers Key Model Standard Model Specific Atmospheric Physics Driver (init, run, finalize modes) Initialize Physics Tables and Databases FinalizeMode. 12

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. ● ● ● ●