MEX-M-MRS-5-OCC-9101

Data Set Overview This data set contains neutral atmosphere temperaturepressure profiles and ionospheric electron density profiles derived from 12 Mars Express radio occultations spread over the first three years of orbital operations (20042007). The data set was created as a prototype for future data sets containing a larger number of profiles. PARAMETERS The neutral atmosphere profiles are ASCII tables containing values of pressure, temperature, and number density (with uncertainties) as a function of radius from the Mars center of mass, geopotential height relative to a reference model, latitude, longitude, and time. Pressure and temperature are derived using an inversion procedure; the results for three starting conditions are included. The ionospheric profiles are ASCII tables giving electron number density (and uncertainty), refractivity, and signal level as a function of radius, latitude, longitude, and time. PROCESSING Measurements of radio signal frequency/phase collected during an occultation were corrected for known Doppler effects such as motion of the spacecraft and ground receiving station, for drift of the frequency reference, and for effects of the intervening medium (such as Earth?s atmosphere and ionosphere). The residual frequency shifts are presumed to result from refractive bending by the atmosphere of Mars. Variation of the bending angle, ray asymptote, and refractivity of the neutral atmosphere are related by an Abel transform, which can be inverted FJELDBOETAL1971 using knowledge of the spacecraft trajectory. If hydrostatic equilibrium and a mean molecular weight for the atmosphere (primarily CO2) are assumed, number density, pressure, and temperature can be derived from the refractivity profile of the neutral atmosphere. For the ionosphere, the procedures are similar but assumptions such as hydrostatic equilibrium do not apply, so the details are more truncated!, Please see actual data fo [truncated!, Please see actual data for full text]