13. Glossary


The topic of this technical guide, the Common Community Physics Package (CCPP) is a model-agnostic, well-vetted collection of codes containing atmospheric physical parameterizations and suites for use in NWP along with a framework that connects the physics to a host model

CCPP Framework

The infrastructure that connects physics schemes with a host model; also refers to a software repository of the same name

CCPP Physics

The pool of CCPP-compliant physics schemes; also refers to a software repository of the same name

Fast physics

Physical parameterizations that require tighter coupling with the dynamical core than “slow” physics (due to the approximated processes within the parameterization acting on a shorter timescale) and that benefit from a smaller time step. The distinction is useful for greater accuracy, numerical stability, or both. In the UFS Atmosphere, a saturation adjustment is used in some suites and is called directly from the dynamical core for tighter coupling


A set of physics schemes within a suite definition file (SDF) that are called together without intervening computations from the host application. Groups are described in more detail in Chapter 4.

Group cap

Autogenerated interface between a group of physics schemes and the host model. Caps are described in more detail in Chapter 5.

Host model

A host model (or host application) is an atmospheric model or application that allocates memory, provides metadata for the variables passed into and out of the physics, and controls time-stepping

Interstitial scheme

A modularized piece of code to perform data preparation, diagnostics, or other “glue” functions that allows primary schemes to work together as a suite. They can be categorized as “scheme-specific” or “suite-level”. Scheme-specific interstitial schemes augment a specific primary scheme (to provide additional functionality). Suite-level interstitial schemes provide additional functionality on top of a class of primary schemes, connect two or more schemes together, or provide code for conversions, initializing sums, or applying tendencies, for example. The details of primary vs. interstitial schemes are described in more detail in Chapter 2.


The National Center for Atmospheric Research - a US federally funded research and development center (FFRDC) managed by the University Corporation for Atmospheric Research (UCAR) and funded by the National Science Foundation (NSF).


The NOAA Environmental Modeling System - a software infrastructure that supports NCEP/EMC’s forecast products. The coupling software is based on ESMF and the NUOPC layer.


The representation, in a dynamic model, of physical effects in terms of admittedly oversimplified parameters, rather than realistically requiring such effects to be consequences of the dynamics of the system (from the AMS Glossary)


A CCPP phase is one of five steps that each physics scheme can be broken down into. Phases are described in more detail in Chapter 2.

Physics cap

Generic name to refer to suite and group physics caps.

Physics Suite cap

Autogenerated interface between an entire suite of physics schemes and the host model. It consists of calls to autogenerated physics group caps. It may be used to call an entire suite at once or to call a specific group within a physics suite

Primary scheme

A parameterization, such as PBL, microphysics, convection, and radiation, that fits the traditionally-accepted definition, as opposed to an interstitial scheme


A CCPP-compliant parameterization (primary scheme) or auxiliary code (interstitial scheme)


Suite Definition File (SDF) is an external file containing information about the construction of a physics suite. It describes the schemes that are called, in which order they are called, whether they are subcycled, and whether they are assembled into groups to be called together


A collection of physics schemes that do not share memory (e.g. fast and slow physics)


The CCPP Single Column Model (SCM) is a simple 1D host model designed to be used with the CCPP Physics and Framework as a lightweight alternative to full 3D dynamical models for testing and development of physics schemes and suites. See the SCM User Guide for more information.

Slow physics

Physical parameterizations that can tolerate looser coupling with the dynamical core than “fast” physics (due to the approximated processes within the parameterization acting on a longer timescale) and that often use a longer time step. Such parameterizations are typically grouped and calculated together (through a combination of process- and time-splitting) in a section of an atmospheric model that is distinct from the dynamical core in the code organization

Standard name

Variable names based on CF conventions (http://cfconventions.org) that are uniquely identified by the CCPP-compliant schemes and provided by a host model. See Section 2.3 for more details.


Executing a physics scheme more frequently (with a shorter timestep) than the rest of the model physics or dynamics. See Section 4.1.2 for more details.


A collection of primary physics schemes and interstitial schemes that are known to work well together


A Unified Forecast System (UFS) is a community-based, coupled comprehensive Earth system modeling system. The UFS numerical applications span local to global domains and predictive time scales from sub-hourly analyses to seasonal predictions. It is designed to support the Weather Enterprise and to be the source system for NOAA’s operational numerical weather prediction applications

UFS Atmosphere

The atmospheric model component of the UFS. Its fundamental parts are the dynamical core and the physics

UFS Weather Model

The combined global/regional medium- to short-range weather-prediction model used in the UFS to create forecasts