We use the Massachusetts Institute of Technology general circulation model ( GCM ) dynamical core , in conjunction with a Newtonian relaxation scheme that relaxes to a gray , analytical solution of the radiative transfer equation , to simulate a tidally locked , synchronously orbiting super-Earth exoplanet .
This hypothetical exoplanet is simulated under the following main assumptions : ( 1 ) the size , mass , and orbital characteristics of GJÂ 1214b ( Charbonneau et al. , 2009 ) , ( 2 ) a greenhouse-gas dominated atmosphere , ( 3 ) , the gas properties of water vapor , and ( 4 ) a surface .
We have performed a parameter sweep over global mean surface pressure ( 0.1 , 1 , 10 , and 100 bar ) and global mean surface albedo ( 0.1 , 0.4 , and 0.7 ) .
Given assumption ( 1 ) above , the period of rotation of this exoplanet is 1.58 Earth-days , which we classify as the rapidly rotating regime .
Our parameter sweep differs from Heng and Vogt ( 2011 ) , who performed their study in the slowly rotating regime and using Held and Suarez ( 1994 ) thermal forcing .
This type of thermal forcing is a prescribed function , not related to any radiative transfer , used to benchmark Earth ’ s atmosphere .
An equatorial , westerly , superrotating jet is a robust feature in our GCM results .
This equatorial jet is westerly at all longitudes .
At high latitudes , the flow is easterly .
The zonal winds do show a change with global mean surface pressure .
As global mean surface pressure increases , the speed of the equatorial jet decreases between 9 and 15 hours local time ( substellar point is located at 12 hours local time ) .
The latitudinal extent of the equatorial jet increases on the nightside .
For the two greatest initial surface pressure cases , an increasingly westerly component of flow develops at middle to high latitudes between 11 and 18 hours local time .
On the nightside , the easterly flow in the midlatitudes also increases in speed as global mean surface pressure increases .
Furthermore , the zonal wind speed in the equatorial and midlatitude jets decreases with increasing surface albedo .
Also , the latitudinal width of the equatorial jet decreases as surface albedo increases .