Effects of CICERO Receiver Characteristics on the Quality of Radio Occultation Data

Abstract:

Community Initiative for Cellular Earth Remote Observation (CICERO) is a recent constellation of 6U cubeSats developed by GeoOptics. Unlike the early high-end receivers in COSMIC (e.g., BlackJack, TriG), each CICERO cubeSat carries the relatively low mass receiver called CION with a phased array of GPS antenna. The development of CICERO promises to provide massive occultation data inexpensively while improving the weather prediction capability.

The performance assessment is necessary before using the CICERO data for reliable weather forecasting which requires high quality of RO measurements. In this study, we assess the performance of CICERO in terms of the RO receiver and antenna characteristics and their impacts on the quality of RO measurements. The signal-to-noise ratio (SNR) was used to indicate the quality of received signals at the RO receiver/antenna. The SNR values from CICERO were compared with those from other GNSS RO missions to identify the CICERO receiver performance. The impacts of SNR on the retrieval process were analyzed by investigating the error statistics of RO measurements (e.g., excess phase, bending angle, refractivity) in relation to SNR.

The performance results show that even though CICERO has the miniature version of RO receiver, it can achieve high SNR compared to those values from other RO missions. In terms of the SNR impacts on the refractivity (one of the major atmospheric parameters from RO measurements), the results show, within a certain range of SNR, the refractivity measurements from CICERO have high levels of accuracy.

This research demonstrates the potential benefits of using CICERO for the observation of radio occultations with the high quality in received signals and RO measurements. With the advantage of miniaturized RO receiver, we can obtain high quality of RO data for weather prediction while reducing the time and cost for system development.