![]() ![]() Withers ( 2014) developed software tools to derive vertical profiles of ionospheric electron density and neutral atmospheric density, pressure, and temperature from the frequency residuals of radio occultation investigations. This article builds upon the earlier work of Withers ( 2014). Although radio occultation observations have been conducted throughout the solar system for over 50 years (e.g., Kliore et al., 1965 Withers, 2010), the expertise necessary to derive useful scientific products from raw measurements is not widespread. Furthermore, a detailed description of this data processing method may be useful to scientists and engineers interested in processing radio occultation observations from other missions. For instance, users may be prompted to develop and implement alternative processing methods if they are dissatisfied with those reported here. We anticipate that a detailed description of the data processing method used to generate MAVEN ROSE ionospheric electron density profiles will be useful to users of these profiles. The current focus of the MAVEN ROSE investigation is the ionosphere (Withers et al., 2018). Although neutral atmospheric profiles can be derived from MAVEN ROSE and other two-way, single-frequency observations (e.g., Jenkins et al., 1994), the MAVEN ROSE team has not yet done so. Here we report the theoretical development of the processing methods used to generate these ionospheric electron density profiles. Vertical profiles of electron density in the ionosphere of Mars have been derived from time series of the frequency of the radio signal received on Earth during these observations (Crismani et al., 2019 Mendillo et al., 2018 Withers et al., 2018 Yao, 2019). The Radio Occultation Science Experiment (ROSE) on the MAVEN spacecraft has conducted a series of two-way, single-frequency radio occultation observations of Mars (Withers et al., 2018, 2020). ![]() Errors are found to be on the order of a few percent. These methods have been validated using a simulated occultation representative for the ionosphere of Mars. We also present forms of these methods appropriate to one-way radio occultation experiments. Four angles, each being the angle between the asymptote of a portion of a refracted ray path and the corresponding idealized unrefracted ray path, provide a natural framework for development of these methods. This is consistent with the dispersion relation for radio waves in plasma. We show that the relevant set of equations can be closed for ionospheric observations if the uplink bending angle is equal to the product of the downlink bending angle and the square of the turn-around ratio. Here we develop methods for generating vertical profiles of ionospheric electron density from frequency residuals obtained from such observations. The MAVEN Radio Occultation Science Experiment (ROSE) generates vertical profiles of electron density in the ionosphere of Mars from two-way, single-frequency radio occultation observations. ![]()
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