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The article presents a study which focuses on the passive method for retrieving the atmospheric pressure profiles based on the measurement of the apparent flattening of the solar disk as observed through the atmosphere by a spaceborne imager. It says that the accurate simulations of the solar occultation and uses the Zernike moments to quantify the flattening is involved in the method. Moreover, the Zernike moments can be a useful tool for identifying the mesospheric and stratospheric clouds.

A numerical method is presented for the computation of reflection, transmission, and mode conversion coefficients, for the scattering of both SH and P-SV waves by a cylindrical obstacle embedded in a multilayered medium. In this method the scatterer and the surrounding medium are modeled by means of finite elements. On the boundary of the finite element mesh an integral representation boundary condition (IRBC) is imposed. This condition is derived from the elastodynamic reciprocity relation and contains the Green's tensor of the undisturbed layered medium. The size of the finite element mesh is limited to roughly that of the cross section of the scatterer. The displacements over the finite element mesh are then obtained using a Galerkin error criterion. Numerical results are presented for geometries occurring in underground seismic surveys of coal layers and in the design of surface acoustic wave devices. [ABSTRACT FROM AUTHOR]

We describe a new spectral imaging instrument using a TeO(2) acousto-optical tunable filter (AOTF) operating in the visible domain (450-900 nm). It allows for fast (~1 second), monochromatic (FWHM ranges from 0.6 nm at 450 nm to 3.5 nm at 800 nm) picture acquisition with good spatial resolution. This instrument was designed as a breadboard of the visible channel of a new satellite-borne atmospheric limb spectral imager, named the Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere (ALTIUS), that is currently being developed. We tested its remote sensing capabilities by observing the dense, turbulent plume exhausted by a waste incinerator stack at two wavelengths sensitive to NO(2). An average value of 6.0±0.4×10(17) molecules cm(-2) has been obtained for the NO(2) slant column density within the plume, close to the stack outlet. Although this result was obtained with a rather low accuracy, it demonstrates the potential of spectral imaging by using AOTFs in remote sensing.

A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz's model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.