The Multi-Instrument Data Analysis System (MIDAS) algorithm is a spatial and temporal imaging program for the atmosphere and ionosphere. This analysis algorithm can routinely use dual-frequency ground-based observations from the GPS satellites to produce four-dimensional images of electron concentration over very large geographical regions (potentially globally). MIDAS also has the facility to ...

[1] A new type of radio occultation (RO) data, recorded in open-loop (OL) mode from the SAC-C satellite, has been tested for monitoring refractivity in the Atmospheric Boundary Layer (ABL). Previously available RO signals, recorded in phase-locked loop mode were often unusable for sensing the lower troposphere (LT) or resulted in significant inversion errors, especially in the tropics. The OL R...

[1] We introduce new vector diffractive integrals, which can be used for the radio holographic remote sensing of the atmosphere and terrestrial surfaces. These integrals are exact relationships connecting the electromagnetic fields known at some interface or curve in space with radio fields on the terrestrial surface or inside the atmosphere. They allow one to restore the radio image of the atm...

[1] Radio bursts from Saturn lightning have been observed by the Cassini Radio and Plasma Wave Science instrument at frequencies of a few megahertz during several month‐long storms since 2004. As the radio waves traverse Saturn’s ionosphere on their way to the spacecraft, one can determine the peak electron density from the measurement of the low‐frequency cutoff below which the radio bursts ar...

A wide variety of radio propagation and scattering phenomena observed when a radio source is occulted by the solar corona has formed the basis for probing the solar corona for over four decades. The purpose of this paper is to review the subject of transients — variations in the radio occultation measurements that appear different from those of the background solar wind. A major surprise in the...

The navigation by the stellar refraction is important for a LEO (Low-Earth-Orbit) satellite, especially in GNSS (Global Navigation Satellite System)-denied environment, since it totally autonomous. However, biggest barrier to accurate lies stratospheric density. Therefore, retrieval of density star occultation proposed this paper acquire globally with high accuracy. Compared GPS Positioning Sys...

High resolution observations over data-sparse oceanic regions are critical if the trend towards higher resolution global numerical weather prediction (NWP) models is to be converted into tangible improvements in weather forecasting success. GPS radio occultation sounding of the atmosphere from airborne platforms has the potential to fill this unique niche in the global meteorological observing ...

A GPS Radio Occultation occurs when a transmitting GPS satellite, setting or rising behind the Earth limb, is viewed by a LEO satellite that carries on board a space-qualified GPS receiver. In this way, it is provided a vertical sounding of the atmosphere exploiting the relative motion between the GPS and the LEO satellites. The technique proved to be particularly precise in retrieving temperat...

GPS radio occultation events observed between 24 July and 17 November 2008 by the IGOR occultation receiver aboard the TerraSAR-X satellite are processed and analyzed. The comparison of 15 327 refractivity profiles with collocated ECMWF data yield a mean bias between zero and −0.30 % at altitudes between 5 and 30 km. Standard deviations decrease from about 1.4 % at 5 km to about 0.6 % at 10 km ...

In the height range 10-30 km atmospheric gravity waves lead to periodic perturbations of the background temperature field in the order of 2-3 K, which can be resolved in temperature profiles derived from radio occultation measurements. Due to the spherical symmetry assumption in the retrieval algorithm and the low horizontal resolution of the measurement weakening in the amplitude and phase shi...