9:15 AM - 9:30 AM
[PPS11-14] Diversity of atmospheric circulations of tidally locked gas giant planets -- dependence on the incident radiation strength
Keywords:Hot Jupiter, Equatorial jets, Equatorial superrotation
The atmospheric model used for numerical experiments is "DCPAM5" developed by GFD Dennou Club (http://www.gfd-dennou.org/library/dcpam/), which is a three-dimensional primitive model assuming hydrostatic balance in the radial direction. Dual band radiative transfer is adopted to express incident short wave radiation and outgoing long wave radiation. The incident radiation from the central star illuminates only the same hemisphere of the planet at all times. There is no heat flow through the bottom boundary. The parameters characterizing the planetary atmosphere in the model are based on those of the exoplanet HD209458b. Incident radiation strength is varied around the value of HD209458b. Time integrations are performed for various strength of incident radiation. When the incident radiation is as strong as that of the original HD209458b (106 W/m2), strong equatorial prograde jet emerges which penetrates to about 1bar level. The equatorial jet is weakened and becomes shallow as the incident radiation is decreased. Finally, when the incident radiation is as weak as 103 W/m2, equatorial zonal flows tend to retrograde and prograde high latitude jets become dominant. The newly found equatorial retrograde regime of tidally locked gas giants contrasts with that of equatorial prograde flow proposed so far.