HR: 09:15h
AN: G11A-06 INVITED    [Abstracts]
TI: Opportunities in Atmosphere Monitoring Offered by Modernized/New Global Navigation Satellite Systems
AU: * Skone, S
EM: sskone@geomatics.ucalgary.ca
AF: University of Calgary, Department of Geomatics Engineering 2500 University Dr. N.W., Calgary, AB T2N 1N4, Canada
AB: L-band RF signals experience propagation delays dependent on pressure, temperature and humidity in the neutral atmosphere. This effect can be measured using GNSS receivers, and information extracted about atmospheric properties, particularly water vapour. Over the past decade, meteorologists have exploited GNSS as an atmospheric remote sensing tool, with applications in weather forecasting and climate change. The availability of Galileo signals, when combined with those from the modernized GPS (and/or GLONASS), will enable more accurate estimates of water vapour using ground-based receivers, with higher temporal and spatial resolution. By deploying modernized/new GNSS receivers onboard low-Earth orbiters, vertical profiles of atmospheric temperature and humidity may be derived with improved accuracy over current GPS-based methods. A GPS/Galileo approach would effectively double the number of observations available at a given epoch, allowing reliable precipitable water vapour estimation (PWV) over a shorter batch processing interval (e.g. ten minutes or less) than currently used for ground-based GPS networks. Increased redundancy will allow improved detection of outliers, particularly orbit errors, which are currently a limiting factor in near real-time processing. This resolution would allow new opportunities for detecting and monitoring severe weather such as hail storms, thunderstorms and tornados. Additional observations in a GPS/Galileo approach could be used to resolve azimuthal asymmetries and higher- order spatial variations. The availability of triple-frequency observations for Galileo and modernized GPS can be used to eliminate residual higher order ionospheric effects and provide more accurate input observables for PWV estimation. Overall, the availability of modernized/new GNSS signals for atmosphere monitoring will improve accuracies of ground-based moisture estimates by as much as 50 percent – through improved observation accuracy, better geometry, and higher temporal and spatial resolution. For radio occultation applications using low-Earth orbiters, vertical profiles may be obtained at higher altitudes through elimination of higher order ionosphere residual errors using triple-frequency observations. The availability of multiple-frequency signals from new/modernized GNSS will also improve observation quality and humidity profiling at lower altitudes (atmospheric boundary layer) where current methods based on GPS are limited by atmospheric attenuation of the L2 signal.
DE: 1200 GEODESY AND GRAVITY
SC: Geodesy [G]
MN: 2007 Fall Meeting