Joseph H. Pierluissi

New Molecular Transmission Band Models For LOWTRAN

A discussion is presented of a modification to the molecular absorption band models in the LOWTRAN code for the uniformly mixed (N 20, CH4, CO, 02, and CO2) and the trace (NO, NO2, NH3, and SO2) gases. The transmission function adopted for each model consists of a double exponential defined by three absorber parameters and a single spectral parameter. All the parameters were determined optimally through a numerical procedure that incorporates line-by-line and measured transmittance spectra. Vertical concentration profiles are provided for these gases that may be used together with the 33-levels standard atmospheres in the calculation of slant-path transmittances. The present single model for the uniformly mixed gases in LOWTRAN is compared with the combination of the proposed individual models.

Fast calculational algorithm for the Voigt profile

Abstract A fast calculational algorithm is proposed for the evaluation of the Voigt profile of primary use in the line-by-line transmittance computations. It consists of a variation from the method proposed by Drayson, providing comparable accuracy with a simplification of the approximating functions, as well as a reduction of the defining regions and the computational times.

Wavelet Transform-Based ECG Baseline Drift Removal for Body Surface Potential Mapping

This paper gives a new approach for the removal of slow baseline drift components of electrocardiographic (ECG) signals based on the discrete wavelet transform. The baseline drift is efficiently removed by zeroing the scaling coefficients of the discrete wavelet transform. Such approach can easily be combined with other wavelet based approaches for random noise reduction or power line interference reduction. The new pre-processing approach can remove the low-frequency components without introducing distortions in the ECG waveform

New lowtran band model for water vapor

A Transmittance band model for IR water vapor in the atmosphere is determined using line by line generated spectra. The absorberp arameters of the model are tabulated.

New LOWTRAN models for the uniformly mixed gases

Programme FORTRAN des fonctions de transmission atmospherique de CO 2 , CO, CH 4 , N 2 O et O 2

Numerical methods for the generation of empirical and analytical transmittance functions with applications to atmospheric trace gases

A numerical approach is taken in the study of two methods commonly used in the development of band models for the calculation of gaseous molecular transmittance in the IR region. The first method considered is for the determination of a discrete transmittance function without the use of an analytical band model. This method is then modified assuming a piecewise continuous function to provide for interpolation between the discrete points. The second method relaxes restrictions inherent to the first and assumes an analytical function over the entire range of transmittance values. Although the theory is generally applicable to other gaseous absorbers, it is specifically applied to 20-cm(-1) resolution data for the major bands of the atmospheric trace gases SO(2), NH(3), NO, and NO(2). The spectral parameters are listed for the convenience of model users at 5-cm(-1) intervals throughout the bands.

Analysis of the Lowtran transmission functions

The empirical transmission functions for molecular absorption in the widely used computer code called Lowtran are analyzed from a computerized numerical approach. Continuous functions are first adapted to the empirical functions, and then the absorber and spectral parameters are determined simultaneously for transmittance data in the major absorption bands of H(2)O, O(3), and the uniformly mixed gases. The analysis indicates that the transmission function parameters for Lowtran may be easily, and accurately, redetermined using numerical methods. This opens the possibility for code extensions to other absorbers, frequencies, spectral resolutions, absorber concentrations, as well as to recent transmittance measurements on the major absorbers.

Numerical methods of band modeling and their application to atmospheric nitrous oxide

Four numerical methods useful for determining the band parameters of infrared transmittance models are presented. A double exponential function described by three absorber parameters and one spectral parameter is adopted as the transmittance model. The methods are compared for accuracy and convenience through an application to line-by-line and measured data for nitrous oxide (N2O) of 20-cm−1 resolution over a wide range of atmospheric conditions. Sufficient mathematical details are provided so that the methods may be easily adapted to other transmittance functions. One of these—the weighted average method—is shown to be clearly superior to the others.

Experimental Study of the Relationship Between Radiosonde Temperatures and Satellite-Derived Temperatures

Abstract A large sample of temperature observations was statistically analyzed to estimate horizontal temperature variability as a function of distance. These estimates were determined at several altitudes from the surface to 15 km and are applicable to horizontal distances up to 175 km, from a data set collected at White Sands Missile Range,. N. M. The results were used to assess the amount of disagreement one should expect when comparing radiosonde temperature measurements with corresponding measurements derived from satellite radiometric observations. The conclusion was that horizontal temperature variations over the radiometrically observed area contribute approximately 1 K rms disagreement between such comparisons. When the separation distance between the radiosonde and satellite observation approaches 200 km, rms differences of greater than 2 K are to be expected at this location.

Accurate Formula for Gaseous Transmittance in the Infrared

By considering the infrared transmittance model of Zachor as the equation for an elliptic cone, a quadratic generalization is proposed that yields significantly greater computational accuracy. The strong-band parameters are obtained by iterative nonlinear, curve-fitting methods using a digital computer. The remaining parameters are determined with a linear least-squares technique and a weighting function that yields better results than the one adopted by Zachor. The model is applied to CO(2) over intervals of 50 cm(-1) between 550 cm(-1) and 9150 cm(-1) and to water vapor over similar intervals between 1050 cm(-1) and 9950 cm(-1), with mean rms deviations from the original data being 2.30 x 10(-3) and 1.83 x 10(-3), respectively.