Modeling, tracking and inverting the tropospheric radio occultation signals

Radio occulation signals propagating through the moist lower troposphere are subjected to strong fluctuation due to the multipath. This causes problems for tracking such signals by means of routine phase-locked loop technique, as well as for their inversions into refractivity by means of routine calculation of the bending angles from Doppler. In this paper we discuss: 1) modeling of realistic radio occultation signals with the use of high resolution tropical radiosondes; 2) open-loop tracking technique capable of capturing the complicated structure of such signals; 3) radio holographic inversion technique capable of solving for the multipath propagation.