Spectral Sciences Incorporated

About: Spectral Sciences Incorporated is a company organization based out in Burlington, Massachusetts, United States. It is known for research contribution in the topics: Hyperspectral imaging & Radiance. The organization has 114 authors who have published 342 publications receiving 10875 citations.

Conductive polymer selective species sensor

Abstract: A selective chemical species detector including a conductive polymer based sensing element having a detectable characteristic, for example, the polymer resistivity, permanently altered on exposure to a first chemical species and not permanently altered on exposure to a second chemical species. The detector then determines a permanent change in the detected characteristic and indicates the presence of a chemical species on detection of a such a permanent characteristic change. Also disclosed is a method of fabricating such a sensing element to achieve the desired selectivity.

MODTRAN2: suitability for remote sensing

Abstract: MODTRAN2 (1992) is the most recent version of MODTRAN, the Moderate Resolution Atmospheric Radiance and Transmittance Model, first released by the Geophysics Directorate, Phillips Laboratory, in 1990. It encompasses all the capabilities of LOWTRAN 7, the historic 20 cm-1 resolution radiance code, but incorporates a much more sensitive molecular band model with 2 cm-1 resolution. For inversion algorithm applications, MODTRAN2 must prove to be sufficiently accurate when calculating layer- specific perturbations. First steps in establishing this capability have recently been accomplished. DREV (Defence Research Establishment Valcartier, Canada), in conjunction with the Geophysics Directorate, has taken measurements with a surface-based Bomem interferometer (approximately 1 cm-1 resolution), with full supporting sonde profiles (z, T, p, and relative humidity). This suggests that the derivative matrices, typically required for inversion algorithms, may be readily (and rapidly) calculated using MODTRAN whenever its spectral resolution is adequate.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Validation of MODTRAN®6 and its line-by-line algorithm

Abstract: A new line-by-line (LBL) algorithm has been developed for use within the MODTRAN ® 6 1 atmospheric radiative transfer model. The model computes both emitted and scattered line-of-sight radiances utilizing a spherical refractive geometry package and the DISORT discrete ordinate model to solve the 1-D scattering problem. The MODTRAN6 LBL method distinguishes itself from most other monochromatic models in that the radiative transfer problem is solved at arbitrarily fine spectral resolution within disjoint and contiguous 0.1 cm -1 steps, marching through the user-specified band pass. The advantage of this approach is that the predominantly Lorentzian, temperature and pressure dependent contributions to each 0.1 cm -1 spectral bin from molecular transitions centered more than 0.05 cm -1 from the bin can be summed off-line and fit to a simple analytic form. The line-shape of each molecular transition is explicitly modeled on-the-fly only over a narrow 0.2 cm -1 sub-region. The challenge of this approach is to ensure that spectral discontinuities do not arise at spectral bin edges, where the method for modeling absorption from individual molecular lines changes abruptly. Interpolations based on the radiative transfer physics of the pre-computed line tail data are introduced to produce a smooth transition across these edges. Spectral validations against LBLRTM verify the fidelity of the approach. The new MODTRAN LBL algorithm is used to quantify the accuracy of the MODTRAN band model and correlated- k statistical approaches under varying conditions. Future upgrades to the MODTRAN band model, correlated- k and LBL methods are also discussed.

0.8-13 micron spectroscopy of v838 monocerotis and a model for its emission

Abstract: : We report on the results of a number of infrared spectra (0.8-2.5, 2.1-4.6, and 3-14 microns) of V838 Monocerotis, taken from a short time after discovery in 2002 January to about 14 months later, in early 2003. The spectrum evolved dramatically, changing from a quasi-photospheric stellar spectrum with weak atomic emission lines (some with P Cygni profiles) to one showing a wide range of deep absorption features indicative of a cool, extended atmosphere with a circumstellar dust shell. The early spectra showed lines of s-process elements, such as Sr II and Ba I. The later spectra showed absorption by gaseous H2O, CO, AlO, TiO, SiO, SO2, OH, VO, and SH, as well as a complex of emission near 10 microns reminiscent of silicate emission, with a central absorbing feature at 10:3 microns. Thus, V838 Mon appears to be oxygen-rich. A simple, spherically symmetric model of the system involving a central star with a two-component expanding circumstellar shell is presented that is able to explain the major molecular features and spectral energy distribution in the object's late stages. The derived shell mass and distance are 0.04 M(circle dot solar) and 9.2 kpc, respectively.

Incursions and radiative impact of Asian dust in northern Alaska

Abstract: [1] The Arctic region is sensitive to incursions of aerosols that affect its radiation balance, directly through interactions with solar and terrestrial radiation and indirectly as cloud condensation nuclei. During spring 2002 dust was transported from the Gobi desert passing over instrumented field sites near Barrow, Alaska, providing the opportunity to measure the dust properties. Empirical determinations of the direct radiative forcing by dust were used to corroborate simulations made using the Moderate Resolution Transmittance radiative transfer code, MODTRAN™5. During sunlit periods, dust cools the surface while warming those layers in which it resides, increasing atmospheric stability. At night, dust layers tend to cool while the surface warms slightly due to infrared emissions from the dust layer.