Glossary

This page collects the acronyms and abbreviations that appear throughout the ERF documentation. Each entry gives the expansion, a one-line description, and – where the documentation discusses the topic in more detail – a link to the relevant section.

ABL: Atmospheric Boundary Layer – the lowest portion of the atmosphere, which is directly influenced by the surface. See ABL Driver and Geostrophic Forcing.
AGL: Above Ground Level – a height measured from the local terrain surface rather than from sea level. See 2D plotfile diagnostic reference.
AMR: Adaptive Mesh Refinement – the use of locally finer grids to resolve selected regions of the domain. See Mesh Refinement.
AMR-Wind: An incompressible wind-energy flow solver, also built on AMReX, that ERF can drive through boundary-plane data exchange. See Coupling To AMR-Wind.
AMReX: The block-structured adaptive mesh refinement (AMR) framework, developed for exascale architectures, on which ERF is built. See AMReX.
API: Application Programming Interface – here, the source-level interface of the ERF classes and functions documented by Doxygen. See Doxygen Documentation.
CCN: Cloud Condensation Nuclei – aerosol particles on which water vapor condenses to form cloud droplets. See Microphysics model.
CFL: Courant-Friedrichs-Lewy – the dimensionless number that limits the stable explicit time step. See Time Step.
CI: Continuous Integration – the automated builds and tests that run on each pull request. See Getting Started with ERF Tests.
CPM: Cell Perturbation Method – a technique that adds temperature perturbations near an inflow boundary to accelerate the development of turbulence. See Inflow Turbulence Generation.
CPU: Central Processing Unit – the conventional processor on which ERF runs when no accelerator backend is enabled. See Build Requirements and Dependencies.
CSV: Comma-Separated Values – the plain-text tabular format used for several ERF sampling and time-series outputs. See Data Sampling Outputs.
CUDA: Compute Unified Device Architecture – NVIDIA’s programming model, used as one of the AMReX GPU backends. See Beyond the Basics: Machines and Libraries.
DNS: Direct Numerical Simulation – a mode in which all dynamically relevant scales of motion are resolved rather than modeled. See Simulation Modes: DNS and LES.
E3SM: Energy Exascale Earth System Model – the DOE Earth system model from which ERF borrows several physics packages. See Library Configuration.
EAMxx: E3SM Atmosphere Model in C++ – the C++ rewrite of the E3SM atmosphere model that supplies the SHOC implementation used by ERF. See Library Configuration.
EB: Embedded Boundary – the cut-cell representation of solid geometry such as buildings. See Embedded Boundary (EB) Tuning.
EDMF: Eddy-Diffusivity Mass-Flux – a boundary-layer closure that combines local diffusion with a nonlocal mass-flux plume contribution. See MYNN-EDMF Level 2.5 PBL Model.
EKAT: E3SM Kokkos Application Toolkit – the utility library, bundled as a submodule, required by the EAMxx-derived physics. See Library Configuration.
EOS: Equation of State – the thermodynamic relation between pressure, density and temperature. See Governing Equations.
ERA5: ECMWF Reanalysis version 5 – the global reanalysis dataset commonly used to drive hindcast simulations. See Hindcasting using weather data.
ERF: Energy Research and Forecasting – the atmospheric model documented here. See Getting Started.
EWP: Explicit Wake Parametrization – a wind-farm parameterization that represents turbine wakes through an analytically prescribed velocity deficit. See Explicit Wake Parametrization (EWP) model.
FFT: Fast Fourier Transform – used by the spectral Poisson solvers available for the anelastic formulation. See Linear Solvers.
GAD: Generalized Actuator Disk – the most detailed of the ERF wind-turbine models, which computes blade-element forces around the rotor disk. See Generalized actuator disk model.
GCM: General Circulation Model – a global climate or weather model; the term appears in the name of the RRTMGP radiation package. See Radiation.
GPU: Graphics Processing Unit – the accelerator hardware targeted through the CUDA, HIP and SYCL backends. See Build Requirements and Dependencies.
HDF5: Hierarchical Data Format version 5 – an optional output format for ERF plotfiles. See Plotfiles.
HIP: Heterogeneous-Compute Interface for Portability – AMD’s programming model, used as one of the AMReX GPU backends. See Beyond the Basics: Machines and Libraries.
HPC: High-Performance Computing – the large parallel machines on which production ERF simulations are run. See Machine Profiles, Cray Detection, Build Scripts, and Workstation Builds.
IF: Immersed Forcing – the representation of terrain or buildings in which large body forces drive the velocity to zero inside solid cells, selected with erf.terrain_type or erf.buildings_type = ImmersedForcing. See Immersed Forcing.
INAS: Ice Nucleation Active Surface site – the density of sites on an insoluble aerosol particle that can trigger freezing. See Super-Droplets.
INP: Ice Nucleating Particle – an aerosol particle capable of initiating ice formation. See Microphysics model.
LAD: Leaf Area Density – the one-sided leaf area per unit volume used by the forest canopy drag model. See Forest Model.
LAI: Leaf Area Index – the one-sided leaf area per unit ground area used by the land surface model. See Simplified Land-surface Model (SLM).
LES: Large-Eddy Simulation – a mode in which the large turbulent eddies are resolved and the smaller ones are modeled. See Simulation Modes: DNS and LES.
LSM: Land Surface Model – the component that evolves soil and surface state and supplies energy and moisture fluxes at a land lower boundary. See Land Surface Model, Simplified Land-surface Model (SLM) and Coupling to Noah-MP.
LW: Longwave – the thermal infrared part of the radiative spectrum. See Radiation.
MOST: Monin-Obukhov Similarity Theory – the surface-layer theory used to relate surface fluxes to the flow in the lowest grid cells. See Surface Layer Boundaries.
MPI: Message Passing Interface – the library used for distributed-memory parallelism. See Build Requirements and Dependencies.
MRF: Medium Range Forecast – a nonlocal PBL scheme that originated in the NCEP MRF model. See MRF PBL Model.
MYJ: Mellor-Yamada-Janjic – a local, TKE-based PBL scheme. See MYJ PBL Model.
MYNN: Mellor-Yamada-Nakanishi-Niino – a family of TKE-based PBL closures, of which Level 2.5 is implemented in ERF. See MYNN Level 2.5 PBL Model.
NERSC: National Energy Research Scientific Computing Center – the DOE facility that hosts Perlmutter. See HPC System Guides.
NetCDF: Network Common Data Form – the self-describing file format used for WRF inputs, boundary files and several ERF outputs. See Initialization Pathways.
Noah-MP: Noah Multi-Parameterization – the community land surface model that ERF can couple to. See Coupling to Noah-MP.
NREL: National Renewable Energy Laboratory – the source of the reference wind turbine specifications used by the wind farm models. See Wind farm models.
OpenMP: Open Multi-Processing – the directive-based interface used for shared-memory threading. See Beyond the Basics: Machines and Libraries.
PBL: Planetary Boundary Layer – the turbulent layer of the atmosphere adjacent to the surface, and by extension the schemes that parameterize it. See PBL Schemes.
PBS: Portable Batch System – one of the job schedulers used on supported HPC systems. See Machine Profiles, Cray Detection, Build Scripts, and Workstation Builds.
RANS: Reynolds-Averaged Navier-Stokes – a modeling mode in which all turbulence is parameterized rather than resolved. See One-equation RANS closure.
RH: Relative Humidity – the ratio of the vapor pressure to its saturation value. See 3D plotfile variable reference.
RHS: Right-Hand Side – the collected source and flux-divergence terms advanced by the time integrator. See Time Advance.
RICO: Rain In Cumulus Over the Ocean – a precipitating shallow-cumulus benchmark case. See Microphysics model.
RK2
RK3: Second- and third-order Runge-Kutta – the explicit multi-stage time integrators used by ERF. See Time Advance.
RRTMGP: Rapid Radiative Transfer Model for GCMs, Parallel – the radiative transfer package used by ERF. See Radiation.
SAD: Simplified Actuator Disk – a wind-turbine model that applies thrust over the rotor disk without resolving the blades. See Simplified actuator disk model.
SAI: Stem Area Index – the one-sided stem area per unit ground area used by the land surface model. See Simplified Land-surface Model (SLM).
SAM: System for Atmospheric Modeling – the cloud-resolving model whose single-moment bulk microphysics scheme is available in ERF. See Microphysics model.
SatAdj: Saturation Adjustment – the simplest ERF moisture model, which condenses or evaporates water to remove supersaturation. See Microphysics model.
SBM: Spectral-Bin Microphysics – a scheme that resolves the hydrometeor size distribution over discrete bins. See Spectral-Bin Microphysics (SBM).
SDM: Super-Droplet Method – a particle-based, probabilistic microphysics model. See Super-Droplets.
SEB: Surface Energy Balance – the budget of radiative, sensible, latent and ground heat fluxes that sets the surface temperature. See Surface energy balance on immersed-boundary faces.
SGS: Sub-Grid Scale – the motions smaller than the mesh spacing, which must be modeled rather than resolved. See Simulation Modes: DNS and LES.
SHOC: Simplified Higher-Order Closure – a unified turbulence and cloud macrophysics parameterization taken from EAMxx. See SHOC PBL Model.
SLM: Simplified Land Model – ERF’s lightweight land surface model. See Simplified Land-surface Model (SLM).
SST: Sea Surface Temperature – the prescribed or coupled temperature of the ocean surface. See Ocean Surface Model.
STF: Smoothed Terrain Following – a terrain-fitted mesh in which small-scale terrain features are progressively damped with height. See Meshing.
STL: Stereolithography – the triangulated-surface file format used to describe building geometry for embedded boundaries. See STL-Based Building Geometry.
SW: Shortwave – the solar part of the radiative spectrum. See Radiation.
SYCL: The Khronos C++ programming model for heterogeneous processors, used as the AMReX backend for Intel GPUs. See Beyond the Basics: Machines and Libraries.
TKE: Turbulent Kinetic Energy – the kinetic energy of the turbulent fluctuations, carried as a prognostic variable by several closures. See Simulation Modes: DNS and LES.
TSK: Skin Temperature – the surface skin temperature field, named after the corresponding WRF variable. See 2D plotfile diagnostic reference.
UPP: Unified Post Processor – the NOAA post-processing package whose sea-level pressure reduction ERF reproduces. See 2D plotfile diagnostic reference.
UTC: Coordinated Universal Time – the time standard used for simulation start times and provenance metadata. See Provenance and Restart Lineage.
UUID: Universally Unique Identifier – the identifier stamped into plotfiles and checkpoints to tie outputs to the run that produced them. See Provenance and Restart Lineage.
WDM6: WRF Double-Moment 6-class – a bulk microphysics scheme that predicts both mass and number concentration for several hydrometeor species. See Microphysics model.
WENO: Weighted Essentially Non-Oscillatory – a family of high-order advection schemes designed to limit spurious oscillations. See Advection Schemes.
WoA: Witch of Agnesi – the analytic hill profile used as a canonical flow-over-terrain test case. See Meshing.
WPS: WRF Preprocessing System – the toolchain that generates the wrfinput and wrfbdy files ERF can be initialized from. See Initialization Pathways.
WRF: Weather Research and Forecasting model – the widely used mesoscale model that ERF is frequently compared to and can be initialized from. See ERF vs WRF.
WSM6: WRF Single-Moment 6-class – a bulk microphysics scheme that predicts the mass of six hydrometeor species. See Microphysics model.
WW3: WAVEWATCH III – the ocean surface wave model that ERF can couple to. See Coupling To WW3.
YSU: Yonsei University – a nonlocal PBL scheme with countergradient mixing. See YSU PBL Model.