# SCALE Regional Model (SCALE-RM)

SCALE-RM is a regional atmospheric model using the SCALE library.

## Brief Description

Framework

- The three-dimensional (3D) Cartesian grid system based on actual distance
- 2D domain decomposition by Message Passing Interface (MPI) communication
- Several map projections commonly used
- Domain nesting system ( one-way, i.e., data transfer from parent domain to child domain. )
- On-line nesting: concurrent execution of multiple domains).
- Offline nesting: execution of computation in an inner domain after that in an outer domain.

- Collective execution system of multiple cases, i.e., bulk job system
- netCDF file I/O based on CF (Climate and Forecast) convention
- Selection of netCDF 3 and netCDF 4 formats

- Generation of initial data for an ideal experiment
- Generation of topographical and land-use data, converted from external data
- Generation of initial and boundary data from external data

Dynamical core

- Grid system : Arakawa-C type
- Governing equations: 3D fully compressible non-hydrostatic equations
- Spatial descretization: finite volume method
- 2nd-, 4th-, and 6th-order central differences
- 3rd- and 5th-order upwind differences

- Time integration: selection from the “fully explicit method” or the “horizontally explicit and vertically implicit methods”
- Heun-type 3rd-order Runge–Kutta scheme
- Wicker and Skamarock (2002)’s 3-step Runge–Kutta scheme
- 4th-order Runge–Kutta scheme

- Guarantee of non-negative value:
- Flux corrected transport method (Zalesak, 1979)
- Koren (1993)’s filter: available only with the use of the 3rd-order upwind scheme

- Numerical filter: 4th-order hyper-viscosity and diffusion
- Topography: expressed using terrain-following coordinates

Figure:Schematic illustration of grid system |

Physical processes

- Turbulence process: selectable from among the following
- Smagorinsky (1963) & Lilly (1962)-type sub-grid model corrected by Brown et al. (1994) and Scotti et al. (1993)
- Deardorff (1980) sub-grid model
- MYNN level 2.5 boundary scheme ( Mellor and Yamada (1982); Nakanishi and Niino (2004) )

- Cloud microphysics: selectable from among the following
- 3-class 1 moment bulk scheme (Kessler, 1969)
- 6-class 1 moment bulk scheme (Tomita, 2008)
- 6-class 2 moment bulk scheme (Seiki and Nakajima, 2014)
- spectral bin scheme (Suzuki et al., 2010)

- Radiation process
- a k-distribution-based broadband radiation transfer model ( Sekiguchi and Nakajima (2008) )

- Surface models
- Land model: heat diffusion/bucket model
- Ocean model: selectable from among the following
- fixed to initial condition
- input from external data
- slab model

- Urban model: a single-layer canopy model (Kusaka et al., 2001)
- Heat transfer coefficient at land and in ocean: selectable from among the following
- The bulk method using the universal function (Beljaars and Holtslag, 1991; Wilson, 2001)
- Louis-type bulk method (Uno et al., 1995)

## Documents

The description for SCALE-RM is available at SCALE Document page