Introduction to the ringing effect in satellite hyperspectral atmospheric spectrometry

Atmospheric remote spectrometry from space has become in the last 20 years a key component of the Earth monitoring system: their large coverage and deci-kelvin stability have demonstrated their usefulness for weather prediction, atmospheric composition monitoring as well as climate monitoring. It is thus critical to investigate the possible sources of errors associated to this technique. One of them is the so-called "ringing error" that appears in Fourier transform spectrometers when the instrument transmission varies at the scale of the spectral resolution. This paper exposes the theoretical basis of this particular type of radiometric uncertainty. Its sensitivity to instrumental parameters as well as the impact on the radiometrically calibrated measurements is assessed in the context of atmospheric infrared sounding using Fourier transform spectrometers. It is shown that this error is an intrinsic feature of such instruments that could safely be ignored in early-generation instruments but will have to be taken into account in the new generation ones as it can yield a significant degradation of the radiometric error budget.

New possibilities of remote spectrometry of surface water bodies

Article presents a new approach to the analysis of spectrometric data obtained by modern spectrometers in the visible range of wavelengths for surveys of surface water bodies. The efficiency of the new approach in the interpretation of spectrometric data in the visible range is shown with the use, proposed by us, of the space of optical images (SOI) formed by a combination of experimental and model ranges of the remote sensing reflectance (RS). The RS ranges calculated parallel to measuring the absorbance indexes in particular hydrological seasons with a known structural composition of phytoplankton permit us to gradate the SOI with respect to the structural composition of phytoplankton. The curve of the status of the ecosystem of the Don River constructed by the data of remote spectrometry shows changes in the structure of phytoplankton during the observation period.

Possible Extensions of XIA'S Digital Spectrometer Technology to Portable and Remote Monitoring Instrumentation

The XIA DXP-4C is a 4 channel, CAMAC based, x-ray spectrometer which digitally processes directly digitized preamplifier signals. The DXP-4C was designed for instrumenting multi-detector arrays for synchrotron radiation applications, and optimized for very high count rates at a low cost per detector channel. This produced a very compact and low power (3.4 W/channel) instrument for its count rate and MCA capabilities, which thus provides a strong basis for portable applications. Because all functions are digitally controlled, it can be readily adapted to various user interfaces, including remote access interfaces. Here we describe the design and examine approaches to lowering its power to 50 mW/channel. We then consider the issues in applying it to three typical portable or remote spectrometry applications.