Comparison of GPS AND Incoherent Scatter Measurements of the Total Electron Content.

摘要

GPS and incoherent scatter (IS) measurements of the total electron content (TEC) taken during 1-3 March 1989 are compared. During this period, four different GPS satellites, SV nos. 6, 9, 11, and 12, were observed. The T14100 GPS receiver at Millstone monitored these satellites continuously while they were in view. At the same time, the Millstone UHF radar was sequentially pointed in the direction of several of these satellites taking incoherent scatter measurements. The incoherent scatter measurements produce profiles of the electron density distribution. The IS profiles are then integrated to produce TEC measurements up to 800 km. The combined pseudo-range and phase data of the GPS system measure the group delay at both the L1 (1575.42 MHz) and L2 (1227.6 MHz) frequencies. This information is converted to TEC measurements along the line of sight to the satellite at 19000 km. The comparison of the GPS and incoherent scatter data gives us a new technique for estimating the number of electrons above 800 km. Our results were surprising. The 1-3 March time period was associated with interesting geophysical conditions. The experiment began during quiet geomagnetic conditions and at a time when the daily 10.7 cm solar flux values were moderate (162).