Simultaneous observation of the vertical gradients of refractivity in the atmosphere and electron density in the lower ionosphere by radio occultation amplitude method

Abstract

It is shown that the refractivity and temperature vertical gradients may be retrieved using radio occultation (RO) amplitude data only. For the considered RO events the vertical gradient of refractivity found from the amplitude data shows good correspondence at two frequencies and changes in interval ±2–±5 N‐units/km (between heights 5–10 km) up to ±1–±2 N‐units/km (between heights 12–21 km). The corresponding magnitudes of temperature gradient change from negative values 4– 9°K/km at the height 8–14 km to positive 1–3 °K/km above 20.5 km. Sharp changes of temperature gradient ±6–±9 °K/km are found in the tropopause at the heights between 14–20 km. The height of the equatorial tropopause is found to be equal 16.8 km in correspondence with UCAR data. The vertical gradient of electron density in the sporadic E‐layer of the ionosphere has been retrieved from the same RO event. Two maximum values of the positive gradient of about 29·109 and 28·109 [m−3km−1] are located at heights 93.5 and 99 km. Simultaneous observations of the vertical gradients of refractivity in the atmosphere and ionosphere would be useful to investigate connections between meteorological and space weather phenomena.

Identification and localization of layers in the ionosphere using the eikonal and amplitude of radio occultation signals

“…High-stability radio signals transmitted at two GPS (Global Positioning navigational System) frequencies f 1 = 1575.42 MHz and f 2 = 1227.60 MHz from a GPS satellite and received at a GPS receiver aboard a low Earth orbit (LEO) small/micro satellite have been used in radio occultation (RO) investigations of the atmosphere (Melbourne et al, 1994;Ware et al, 1996;Kursinki et al, 1997;Hajj and Romans, 1998;Steiner et al, 1999;Wickert et al, 2001Wickert et al, , 2004Gorbunov et al, 2002Gorbunov et al, , 2010Yakovlev, 2003;Jensen et al, 2003, Melbourne, 2004Gorbunov and Lauritsen, 2004;Gorbunov and Kirchengast, 2005;Pavelyev et al, 2002Pavelyev et al, , 2004Pavelyev et al, , 2009Liou and Pavelyev, 2006;Liou et al, 2002Liou et al, , 2003Liou et al, , 2005Liou et al, , 2007Liou et al, , 2010. When applied to ionospheric investigations, the RO method may be considered as a global tool and can be compared with the global ground-and spacebased radio tomography (e.g.…”

Radio Wave Propagation Phenomena from GPS Occultation Data Analysis

“…The radio occultation (RO) method employs the highly-stable radio waves transmitted at two GPS frequencies 1 f  1575.42 MHz and 2 f  1227.60 MHz by the GPS satellites and recorded at a GPS receiver onboard low Earth orbiting (LEO) satellite to remote sense the Earth's ionosphere and neutral atmosphere [4,5,10,11,17,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]46,47,[52][53][54][55][56][59][60][61]. When applied to ionospheric investigations the RO method may be considered as a global tool and can be compared with the global Earth-and space-based radio tomography [42,43].…”

Global GNSS Radio Occultation Mission for Meteorology, Ionosphere & Climate

“…The space-based GNSS atmospheric limb sounding offers a complementary solution to these issues (Yunck et al, 2003). The space-based GNSS RO atmospheric remote sensing technique, which makes use of the L-band radio signals transmitted by the GNSS satellites, has emerged as a powerful approach for sounding the global atmosphere in all weather over both lands and oceans (Yunck et al, 1990(Yunck et al, & 2003Wu et al, 1993;& Liou et al, 2002). Figure 1 shows a schematic diagram illustrating radio occultation of GNSS signals received by a low-earth-orbit satellite.…”