The occulation of β Scorpii by Jupiter. IV. Diurnal temperature variations and the methane mixing ratio in the Jovian upper atmosphere

The nightime cooling of the Jovian atmosphere near the occulation level of 10¹⁴cm^?3 is calculated using the models of Strobel (1973) and Strobel and Smith (1973). The amount of cooling is found to depend on χ, the methane mixing ratio; μ the mean molecular weight; and the sunrise temperature. Using the range of sunrise (emersion) temperatures observed by Veverka et al. (1974), the overnight cooling is calculated to be 1.5–5.5°K, if reasonable assumptions are made for χ and μ. The argument may be reversed to show that the agreement in measured sunrise and sunset temperatures obtained by other observers of the β Sco occulation implies that χ cannot be significantly greater than the generally accepted value of 7 ×10^?4.