Validation of fascod3 and modtran3: comparison of model calculations with ground-based and airborne interferometer observations under clear-sky conditions

Abstract

The validation of fascod3 and modtran3 against ground-based and airborne high-resolution Michelson interferometer measurements under clear-sky conditions is presented. Important considerations including water vapor continuum, frequency-dependent sea surface emissivity in the IR window region, and spectral resolution of modtran3 in the comparison of model calculations with high-resolution interferometer measurements are discussed. Our results indicate that it is not adequate to assume sea surface emissivity of 1.0 [?(ν) = 1.0] or a constant in the simulation of upwelling radiance observed by the airborne Michelson interferometer. The use of spectral emissivity (frequency-dependent emissivity) leads to much better agreement between model calculations and interferometer measurements in the IR window region from 750.0 to 1050.0 cm(-1). This could have important implications for the retrieval of sea surface temperature, thin cirrus properties, and aerosol parameters because of the sea surface emissivity of 1.0 assumption commonly used by many researchers. Comparisons of modtran3 calculations with interferometer measurements show that the agreement might not be adequate at the nominal resolution of 2.0 cm(-1), and further spectral degradation might be necessary to improve the agreement between measurements and modtran3 calculations. modtran should be used with caution for relatively high spectral resolution remote-sensing applications.

Simultaneous retrieval of middle atmospheric temperature and trace gas species volume mixing ratios from Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS 1A)

“…As a part of this study, we have developed a nonlinear least squares code for retrieving atmospheric parameters from the CIRRIS measurements. This retrieval package, consisting of a forward model derived from the Fast Atmospheric Signature Code 3 (FASCODE3) [Smith et al, 1978;Wang et al, 1996] coupled with an inversion module based on the optimal estimation method of Rodgers [1976], provides the error analysis tools necessary to determine the information content of the retrievals. In this context the absence of sufficient information to retrieve certain species is also discussed.…”

A comparison of NO2 absorption measurements from an FTIR spectrometer and the OSIRIS spectrograph

“…Also shown in Fig. 5 are simulations of NO 2 absorption calculated with the MODTRAN3 transmission code [10][11][12]. The MODTRAN3 model incorporated NO 2 cross sections based on the work by Schneider et al [13].…”

Models and methods for automated material identification in hyperspectral imagery acquired under unknown illumination and atmospheric conditions

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