Controls of the sounding points in space-based GPS=LEO meteorology

GPS radio occultation technique has been developed resulting from remote sensing applications in planetary atmospheric limb sounding pioneered by JPL and Stanford University in 1960s. Since the launch of the experimental satellite MicroLab1 on April 3 1995, the primary results from this Low Earth orbiter (LEO) satellite demonstrated potential scienti:c values and practical signi:cance of this innovation in GPS meteorology. For MicroLab1, the sounding locations on the Earth’s surface were globally pseudo-randomly distributed, which is good for data assimilation in atmospheric and ionospheric research. As another strategy, as similar to mountain-based or airborne GPS receiver, sequential occultation footprints falling within adjacent regions of some speci:c points on the Earth’s surface are expected in the following possible cases: comparing and cross-calibrating radio occultation data with other techniques, such as ground-based GPS, radiosonde and lindar; continuous monitoring of local atmospheric refractivity :eld and local hazardous weather within a speci:c time period. In this paper, we discuss a possibility to get sequential atmospheric pro:les near a speci:c ground location by optimally designing a LEO satellite orbit. This may have potential bene:ts in the applications of GPS=LEO occultation technique to atmospheric science, improving numerical weather prediction with data assimilation, and the monitoring of hazardous weather and atmospheric refractivity :eld. Such an orbit design of LEO satellite would in?uence future GPS launch plan, and would in?uence the design of new generation of LEO satellite. c © 2001 Elsevier Science Ltd. All rights reserved.