Overview of NEMS infrastructure
Jun Wang
Mark Iredell
April 1, 2015
NEMS-NMMB tutorial
1
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)
• Eventual support to community through the
Developmental Test Center (DTC)
2
Model Components in NEMS
as of March 2015
Atmosphere
– NMM-B
– GSM
– FIM
Chemistry
– GOCART
Ocean
– MOM
– HYCOM
Sea Ice
– CICE
Ionosphere
– IPE
Coupling mediators
– Ensemble mediator
– Atmosphere-Ocean-Ice mediator
– Physics-Chemistry mediator
3
NEMS Structure
MAIN
NEMS
All boxes represent
ESMF components.
MOM,HYCOM
Ocean
Earth
Ensemble
Mediator
EARTH(1:NM)
Atm-Ocn-Ice
Mediator
Atm
Ice
GSM
NMM
Wrt
Dyn Phys
Chem
phys-chem
mediator
IPE
FIM
Domains(1:ND)
Solver
CICE
Wrt
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.
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:
► One-way
► Boundaries received
every parent timestep
-
4 km CONUS
6 km Alaska
3 km Hawaii
3 km Puerto Rico
Relocatable Fire Wx nest:
- 1.33 km inside CONUS
- 1.5 km inside Alaska
NEMS GFS Aerosol Component
Generic Component
Atmosphere
Generic Coupler
unified atmosphere
Including digital filter
Dynamics
Spectral
•
•
•
•
Dyn-Phy
Coupler
Color Key
Completed Instance
Physics
GFS Phy
Phy-Chem
Coupler
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
8
– Update 2d aerosol diagnostic fields
NUOPC Physics Driver Schematic
Dynamics
Dynamical equations, advection, horizontal mixing, diffusion.
Key
Model Standard
Model Specific
Dt, u, v, w, T, q, p, z, qx, cx, axTendencies
and Updates
staggered
Vertical flipping
Vertical flipping
species)
Post-Physics
Destaggering Pre-Physics qcxx (microphysics
(chemistry species)
Restaggering
Interface
a
(aerosol
species)
Interface (direction check)
(direction check)
x
Dt, u, v, w, T, q, p, z, qx, cx, ax Tendencies
destaggered
and Updates
Atmospheric Physics Driver
(init, run, finalize modes)
Initialize
Physics
Tables and
Databases
Modified Kalnay Rules Layer
Init
Mode
Radiation Deep and
Shallow
Cumulus
Surface
Layer
radiation, stability,
fluxes,
precipitation exchange coefficients
Micro- Finalize
Mode.
physics
Sat. adjust
PBL
and
Vertical
Mixing
fluxes, SST,
coefficients, etc.
Output
Diagnostic
s
• fields
• rates
• budgets
• others
NUOPC Layer
LSM
Wave
Prep/Post Prep/Post
Ocean
Prep/Post
LSM, Ocean, Wave, Chemistry, Aerosol, Ice Drivers
9
Summary
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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, chemistry, ionosphere,
and mediator components within the NEMS framework.