Microwave Radiometry at Frequencies From 500 to 1400 MHz: An Emerging Technology for Earth Observations.

Microwave radiometry has provided valuable spaceborne observations of Earth's geophysical properties for decades. The recent SMOS, Aquarius, and SMAP satellites have demonstrated the value of measurements at 1400 MHz for observing surface soil moisture, sea surface salinity, sea ice thickness, soil freeze/thaw state, and other geophysical variables. However, the information obtained is limited by penetration through the subsurface at 1400 MHz and by a reduced sensitivity to surface salinity in cold or wind-roughened waters.

Band characterization of topological photonic crystals using the broadband Green's function technique.

A novel method is developed in this paper to characterize the band diagram and band modal fields of gyromagnetic photonic crystals that support topological one-way edge states. The proposed method is based on an integral equation formulation that utilizes the broadband Green's function (BBGF). The BBGF is a hybrid representation of the periodic lattice Green's function with imaginary extractions that has accelerated convergence and is suitable for broadband evaluations.

Photon transport model for dense polydisperse colloidal suspensions using the radiative transfer equation combined with the dependent scattering theory.

In near-infrared imaging and spectroscopy, high-fidelity modeling of photon transport for dense polydisperse colloidal suspensions is crucial. We developed photon transport models using the radiative transfer equation (RTE) with the dependent scattering theory (DST) at volume fractions up to 20%. The polydispersity and interference effects strongly influence results of the scattering properties and the RTE in cases of small mean diameter and large variance of the particle size distribution.

Fast and broadband computation of the Green's function in a cavity resonator of irregular shape using an imaginary wave number extraction technique.

A semi-analytical approach for rapid calculation of the Green's function inside a cavity of irregular shape over a broad range of frequency is presented. The method is based on the extraction of the Green's function at an imaginary wave number from itself to obtain a rapidly convergent hybrid spatial-spectral expansion of the Green's function. The method is applied to a V-grooved cavity, and the results are compared with the integral equation method.

Scaling laws for the mechanics of loose and cohesive granular materials based on Baxter's sticky hard spheres.

We have conducted discrete element simulations (pfc3d) of very loose, cohesive, granular assemblies with initial configurations which are drawn from Baxter's sticky hard sphere (SHS) ensemble. The SHS model is employed as a promising auxiliary means to independently control the coordination number z_{c} of cohesive contacts and particle volume fraction ϕ of the initial states. We focus on discerning the role of z_{c} and ϕ for the elastic modulus, failure strength, and the plastic consolidation line under quasistatic, uniaxial compression.

Scattering of waves by a half-space of periodic scatterers using broadband Green's function.

An efficient scatterer-free full-wave solution for plane wave scattering from a half-space of two-dimensional (2D) periodic scatterers is derived using broadband Green's function. The Green's function is constructed using band solutions of the infinite periodic structure, and it satisfies boundary conditions on all the scatterers. A low wavenumber extraction technique is applied to the Green's function to accelerate the convergence of the modal expansion.

Scattering of electromagnetic waves from 3D multilayer random rough surfaces based on the second-order small perturbation method: energy conservation, reflectivity, and emissivity.

A theoretical investigation of energy conservation, reflectivity, and emissivity in the scattering of electromagnetic waves from 3D multilayer media with random rough interfaces using the second-order small perturbation method (SPM2) is presented. The approach is based on the extinction theorem and develops integral equations for surface fields in the spectral domain. Using the SPM2, we calculate the scattered and transmitted coherent fields and incoherent fields.

Surface Soil Moisture Retrieval Using the L-Band Synthetic Aperture Radar Onboard the Soil Moisture Active-Passive Satellite and Evaluation at Core Validation Sites.

This paper evaluates the retrieval of soil moisture in the top 5-cm layer at 3-km spatial resolution using L-band dual-copolarized Soil Moisture Active-Passive (SMAP) synthetic aperture radar (SAR) data that mapped the globe every three days from mid-April to early July, 2015. Surface soil moisture retrievals using radar observations have been challenging in the past due to complicating factors of surface roughness and vegetation scattering. Here, physically based forward models of radar scattering for individual vegetation types are inverted using a time-series approach to retrieve soil moisture while correcting for the effects of static roughness and dynamic vegetation.

Calculations of band diagrams and low frequency dispersion relations of 2D periodic dielectric scatterers using broadband Green's function with low wavenumber extraction (BBGFL).

The broadband Green's function with low wavenumber extraction (BBGFL) is applied to the calculations of band diagrams of two-dimensional (2D) periodic structures with dielectric scatterers. Periodic Green's functions of both the background and the scatterers are used to formulate the dual surface integral equations by approaching the surface of the scatterer from outside and inside the scatterer. The BBGFL are applied to both periodic Green's functions.

Loss and back-coupling effects on subwavelength imaging of three-dimensional superlens.

The loss and back-coupling effects on the subwavelength imaging of three-dimensional superlens are reported in this paper. The loss is added in the image region of a superlens. The back-coupling effects are considered by adding a shielded layer above the object region.

Subwavelength imaging enhancement through a three-dimensional plasmon superlens with rough surface.

In this Letter we investigate the subwavelength imaging of a three-dimensional plasmon superlens based on the full vector wave simulations of optical wave propagation and transmission. The optical transfer functions are computed. Comparisons are made between the results of lenses with flat and periodic/random rough surfaces.

Electromagnetic fields and modal excitations on a thin silver film.

In this paper we extend the fast-all-modes method and the numerical modified steepest-descent-path method to the optical frequency range by finding all modes and solving the total electric field in three dimensions that is due to a point source above a lossy thin metal film with a negative permittivity situated between two dissimilar dielectric materials. We show that up to four proper surface wave modes may propagate on the film surface, including both backward and forward waves. We also solve for the electric field below the lossy thin metal film and verify the existence of superlensing of the electric field, comparing that case to the case of a dielectric film where no superlensing occurs.