Patrick G. Stegmann

Effect of Particle Shape, Density, and Inhomogeneity on the Microwave Optical Properties of Graupel and Hailstones

Atmospheric ice particles can be rimed and contaminated (e.g., by soot attachments). Previous optical property calculations usually assume rimed particles such as graupel and hailstones to be homogeneous spheres with fixed densities. The relevant dielectric constants are estimated with the effective medium approximation (EMA), although such particles are predominately nonspherical, porous, and contain small interior grains. This paper assesses the effects of nonsphericity, density, and inhomogeneity of graupel and hailstones on their optical properties. The bicontinuous medium approximation (BMA) is employed to simulate the particle internal structure. Conical shapes are compared with spherical and spheroidal shapes to assess the effect of nonsphericity. At frequencies lower than 89 GHz, the optical properties are more sensitive to particle’s mass density than to overall particle shape, and the internal structure plays an insignificant role when the particle effective diameter (a quantity involving the particle size distribution) is smaller than approximately 10 mm, and the internal grain size is smaller than 0.2 mm. With a small grain size, the BMA phase function converges to the EMA phase function with an effective refractive index calculated with the Bruggeman formulation. Simulated top of atmosphere radiances at three microwave frequencies, 18.7, 36.5, and 89 GHz, are quite sensitive to ice particle effective diameter between 1 and 5 mm, ice fraction between 0.1 and 0.9, and ice water path between 1 and 5 kg/

Modeling the single and multiple scattering properties of soot-laden mineral dust aerosols

\text{m}^{2}

A Fast Hyperspectral Radiative Transfer Model

. Thus, these frequencies are suitable for retrieving the microphysical properties.

Influence of Low Mass-density Particles and Temperature-dependent Refractive Index on Hyper-spectral Forward Calculations

Fractal particle morphologies are employed to study the light scattering properties of soot-laden mineral dust aerosols. The applicability of these models is assessed in comparison with measurements and other numerical studies. To quantify the dust-soot mixing effects on the single and multiple scattering properties, a parameterization of the effective bulk properties is developed. Based on the parameterized bulk properties, polarized one-dimensional radiative transfer simulations are performed. The results indicate that small uncertainties in conjunction with soot contamination parameters may lead to large uncertainties in both forward and inverse modeling involving mineral dust contaminated with soot.

Development of a Discontinuous Galerkin Time Domain Solver on a staggered grid for pan-spectral single scattering analysis

We develop a fast absorption calculation method used in the hyperspectral radiative transfer model for the PACE mission. The model will serve as a TOA radiance and reflectance simulator for remote sensing applications of PACE.

A regional, size-dependent, and causal effective medium model for Asian and Saharan mineral dust refractive index spectra

The present work uses the Community Radiative Transfer Model to assess the influence of complex particle shapes, including snowflakes, in hyper-spectral calculations. Also considered will be the temperature-dependence of the refractive-index of ice.

A stochastic model for density-dependent microwave Snow- and Graupel scattering coefficients of the NOAA JCSDA community radiative transfer model

The present work discusses the progress made in the development of a Discontinuous Galerkin (DG) solver in the time domain on a staggered grid specifically tailored towards the scattering of electromagnetic radiation by nonspherical particles.