WACCMX

The NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) is a self-consistent general circulation model. It fully couples the chemistry and dynamics, while calculating three-dimensional temperature, wind, composition, and ionospheric structures from the surface to the exobase (500-700 km). It is a configuration of the NCAR Community Earth System Model (CESM) and can couple to ocean, land, and/or ice models. WACCM-X incorporates all the features from the CESM and WACCM (the NCAR Whole Atmosphere Community Climate Model), extending the model top boundary of WACCM from the lower thermosphere into the upper thermosphere (4.1E-10 hPa, roughly 500 to 700 km altitude, depending on solar and geomagnetic activities).

WACCM-X is currently based on the Community Atmosphere Model-6 (CAM-6) physics and the three-dimensional chemical transport Model for Ozone and Related chemical Tracers (MOZART) chemistry. The gravity wave parameterization is based on the linear saturation theory. The standard resolution of WACCM-X is 0.9° in latitude x 1.25° in longitude with 130 levels in the vertical direction with a resolution of quarter scale height above 1 hPa, using the log-pressure coordinate system.

The new ionospheric component in WACCM-X v2.0 includes modules of the ionospheric wind dynamo, F-region O+ transport, and electron and ion temperatures, which are used to calculate heating of the neutral atmosphere through collisions with thermal electrons and ions. In addition, two metastable O1 states, O1(2D) and O1(2P), have been added to the chemistry package, which already includes 5 ions (O+,O2+ ,NO+,N+, N2+), electrons, and 74 neutral species. The model has 87 photolysis and photoionization reactions and 202 gas phase and heterogeneous reactions. The specification of solar spectral irradiance at wavelengths from Lyman-⍺ to the near infrared is specified by the empirical model of Lean et al. (2005).

Solar spectral irradiance: solar spectral irradiance at wavelengths from Lyman-⍺ to the near infrared is specified by the empirical model of Lean et al. (2005).

High-Latitude Ionospheric Inputs: Provided by Heelis model and Weimer model.

Inputs for Heelis model: Cross polar cap potential in kV, obtained from 3-hour Kp index Hemispheric Power in GW, obtained from 3-hour Kp index.

Inputs for Weimer model: Interplanetary magnetic field, By and Bz, in nT Solar wind density and speed, ρ and v, in cm-3 and km s-1

Timed-dependent 3-dimensional output fields, specified in latitude, longitude, and pressure level: Geopotential height: Height of pressure surfaces above sea level (m), (Z_geometric = Z_geopotential / (1-Z_geopotential/R_earth)) Temperatures: Neutral, ion, electron (K) Neutral winds: zonal, meridional, (m s-1), vertical (s-1) Ion drift from e-dynamo: zonal meridional, vertical (m s-1) Composition: NO, O, O2, H (volume mixing ratios - dimensionless), (N2_vmr=1-O_vmr-O2_vmr-H_vmr) Electron densities: Ne (cm-3), (electron number Density (sum of O2+,NO+,N2+,O+)) Ion densities:NO+, O+, O2+, H+ (volume mixing ratios - dimensionless) Conductivity: Pederson, Hall (siemens/m)

Timed-dependent 2-dimensional output fields, specified in latitude and longitude: Electron Column Density or TEC: (TECu) HMF2: (km) NMF2: (cm -3)

Other fields are available which can be set as needed.