The Geostationary Atmospheric Sounder (GAS)

Abstract

Millimeter and Sub-mm-wave imagers/sounders are considered for future meteorological geostationary satellite missions. A novel interferometric Geostationary Atmospheric Sounder (GAS) has been developed and a concept demonstrator is under construction. The concept is a response to the requirements of observations for nowcasting and short range forecasting in 2015-2025, as determined by EUMETSAT for post-MSG operational satellites observations. Prioritized parameters include vertical profiles of temperature and humidity with high temporal and horizontal resolution (15 min and 30 km) under all weather conditions. Frequency bands around 53GHz, 118GHz, 183GHz, 380GHz have the highest user priority and are all supported by GAS. The instrument relies on an innovative configuration of interferometer elements which enables the use of a sparse array and simplifies calibration.

Analysis and design of synthetic radiometers: Some tools and comparisons

“…Both because of the difficulty of managing (4)(5)(6)(7)(8), and because of the fact three identical arms necessarily worsen the sidelobe level with respect to the first term of (4), it makes sense to consider the case where both the angles and the (different) positions along each of the different arms are contemporarily optimized to achieve a beam efficiency as large as possible while satisfying given upper bounds on the pattern behavior.…”

“…In a number of applications of actual interest (see for instance [4]), by taking profit from the fact the scenery under observation is slowly varying in time, these instruments exploiting interferometric principles also take profit from a rotation in time of the structure. Roughly speaking, this allows to deal with a number of 'additional' baselines, which allow a better sensing of the quantity of interest.…”

“…In several ongoing projects [4,5], the exploited architecture consists in planar array antennas with a Y-shaped geometry [6,7,8]. In these cases, the instrument is an array made up by several receivers located along three directions which are usually at a 120° angular distance each from the other.…”

Image Retrieval Simulations for the GEO Atmospheric Sounder (GAS)

“…The GEO Atmospheric Sounder (GAS) [1], is a mm-wave imaging sounder considered for future meteorological and climate observation satellites. Frequency bands around 53 GHz, 118 GHz, 183 GHz, and 380 GHz are included to satisfy the user requirements for vertical profiles of temperature and humidity under all weather conditions.…”

A High-Resolution Full-Earth Disk Model for Evaluating Synthetic Aperture Passive Microwave Observations From GEO

“…The model would be beneficial to similar microwave instruments being developed internationally, including the Geostationary Atmospheric Sounder [7] in Sweden and the clock scanning interferometric radiometer [8] in China.…”