Observations of Turbulence in the Atmosphere of Venus using Mariner 10 Radio Occultation Measurements

Abstract

In this paper we develop a technique for estimating the outer scale of turbulence in a planetary atmosphere using dual-frequency radio occultation measurements. This technique is based on the frequency dependence of the temporal frequency spectra for the log-amplitude fluctuations, and is particularly useful when probing the upper atmosphere where the transverse velocity of the line-of-sight path is decelerating very rapidly. We apply this technique to the region of strong turbulence located in the vicinity of 60 km (?180 mb) on the dayside of the atmosphere of Venus using the Mariner 10 S/X radio occultation measurements. We find that, contrary to earlier findings from Mariner 5, the outer scale of turbulence is at least 5 km. It appears, therefore, that the outer scale of turbulence is as large as the vertical extent of the region of strong turbulence. Estimates of the structure constants for refractive index and temperature fluctuations indicate that the turbulence is stronger than that measured near the earth's tropopause.