Numerical Simulations of the Evolution of Neptune’s Spot NDS-2018

In support of new HST observations of Neptune’s dark spot called NDS-2018, we used the EPIC model to perform numerical simulations of spots in Neptune’s atmosphere to investigate what conditions would lead to the observed behavior of NDS-2018. In particular, we focused on determining the parameters that control the observed drift in latitude and longitude of the spot with the goal of forecasting its fate. We present the results of these simulations and show that some of the parameters defining the spot are key in determining its behavior. For example, the magnitude of the maximum tangential velocity emerges as a key parameter determining if a spot would oscillate latitudinally or not, with stronger spots being more prone to show oscillatory behavior than weaker spots. These preliminary simulations also show that the rate at which spots drift in latitude and longitude is strongly influenced by the vertical placement and extension of the spot in the background atmosphere. Finally, we also explore the effect that the jet curvature at low latitudes has on the equatorial drift of the spots.