cesm_hawc.constituents¶

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Build the sasktran2 constituents that represent a WACCM column.

hawcsimulator’s default atmosphere contains Rayleigh scattering, MIPAS climatological ozone, solar irradiance and a Lambertian surface with albedo 0.3. build_waccm_constituents() returns WACCM ozone (replacing the MIPAS ozone), WACCM NO2 and the two MAM4 sulfate modes, to be passed to simulator.run() under the constituents key:

constituents = build_waccm_constituents(profiles, alt_grid_m)
data = simulator.run(products, {**sim_input, "constituents": constituents})

Do not wrap the dict in Atmosphere(constituents=...): that bypasses the simulator’s atmosphere step and the aerosol is silently dropped.

Each sulfate mode is an ExtinctionScatterer backed by its own Mie database, built for a lognormal size distribution with that mode’s width (sigma_g = 1.6 for accumulation, 1.2 for coarse) and the H2SO4 refractive index. sasktran2 integrates over the size distribution, and the same database supplies extinction and phase function at every wavelength. The L2 retrieval separately assumes a single mode with sigma_g = 1.6, via aliprocessing.l2.optical.aerosol_median_radius_db.

Requires the [sim] extra.

get_mode_mie_database¶

def get_mode_mie_database(mode_width: float)

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Return the Mie database for one sulfate mode.

Use this to rebuild an sk.constituent.ExtinctionScatterer yourself from a saved column’s {mode}_reference_extinction_per_m and {mode}_median_radius_nm (see cesm_hawc.save_inputs).

Parameters¶

• mode_width (float) — Geometric standard deviation of the mode: 1.6 for accumulation, 1.2 for coarse.

Returns¶

• sasktran2.database.MieDatabase — The database, built on first use.

warm_mode_databases¶

def warm_mode_databases() -> None

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Build both sulfate-mode Mie databases.

Call this in the main process before starting worker processes, so the databases are built once rather than concurrently by every worker.

build_waccm_constituents¶

def build_waccm_constituents(
    profiles: dict,
    alt_m: np.ndarray,
    return_extinction: bool = False,
    truth_wavelengths_nm=None,
)

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Build the sasktran2 constituents for one WACCM column.

Parameters¶

• profiles (dict) — Result of cesm_hawc.waccm.WACCMAtmosphere.get_column_profiles().

• alt_m (numpy.ndarray) — Altitude grid [m]; must match profiles["altitudes_m"] and the simulator’s altitude_grid.

• return_extinction (bool, optional) — Also return the truth extinction. Default False.

• truth_wavelengths_nm (array-like, optional) — Wavelengths [nm] for the truth extinction; normally the simulated wavelengths. Default [745.0].

Returns¶

• constituents (dict) — o3 and no2 (VMRAltitudeAbsorber) and aerosol_accum and aerosol_coarse (ExtinctionScatterer, from so4_a1 and so4_a3).

• true_extinction (dict) — Only if return_extinction is True. For each mode (aerosol_accum, aerosol_coarse):

  • {mode}_extinction_per_m: truth extinction [m⁻¹], shape (wavelength, altitude), at truth_wavelengths_nm;

  • {mode}_reference_extinction_per_m: extinction at 745 nm [m⁻¹], shape (altitude,);

  • {mode}_median_radius_nm: clipped median radius [nm], shape (altitude,);

  plus extinction_wavelength_nm. The reference extinction and median radius are exactly the arguments used to build that mode’s ExtinctionScatterer, so it can be rebuilt from them with get_mode_mie_database().

Notes¶

Median radii are clipped to the Mie database range (10–590 nm), and extinction is set to zero where the radius is below 10 nm.