The effect of residual ionospheric errors on GPS radio occultation temperature

In order to investigate the effects of residual ionospheric errors (RIEs) on radio occultation (RO) temperature profiles due to solar activity, local time and azimuth of occultation plane, two simulation schemes have been conducted using the models of MSIS90 for atmosphere and 3D NeUoG for ionosphere, and a 3D ray tracing approach. The results show that during solar active periods mean temperature errors mainly resulted from RIEs. In the upper stratosphere (35~50 km) and lower mesosphere (50~70 km) the statistical errors could reach about 1.8 K and 7 K, respectively, and global mean temperature errors could reach about -0.6 K at the stratopause and about 1.2 K at 70 km altitude. These results suggest that the RIE is a major temperature error at the altitude of 35~70 km. Hence, developing more effective ionospheric correction approaches is significant for improving the accuracy of RO retrievals and global climate monitoring.