Skip to Content

Investigations into the transient response of the polar mid-troposphere to mid-latitude surface heating

On short time scales, atmospheric motions can be considered to moist-adiabatic. The moist-isentropic surfaces connect the mid-latitudes surface with the polar mid-troposphere, suggesting that surface perturbations in the mid-latitudes should effect the polar mid-tropsphere by transport along the moist-isentropic surfaces. Although there is observational evidence which suggests that these processes can be very important for understanding both temperature trends and intra-seasonal variability in the Arctic mid-troposphere, this connection can be obscured by the nature of the dynamic turbulence which accomplishes this transport as well as the complex diabatic processes in the atmosphere.

In order to study this relationship in a simpler context, this study uses an idealized auqaplanet general circulation model. Using such a simplified model has two major advantages for our study; firstly the model can be run many more times than an more complicated GCM could be, allowing us to run very large ensembles, and secondly it allows for the dynamics to become somewhat uncoupled from the diabatic processes, which allow for the dynamics to be studied in a more independent setting. Large initial condition ensembles are done for a variety of surface perturbations in order to study the transient response to this warming. These initial condition ensembles show that the transient response is dominated by the changes in the mean temperature, while the dynamics take longer to respond. The size are location of the perturbation are also found to be important in the response of the mid-troposphere, and it is shown that mid-latitude perturbations are more effective at warming the polar-mid-troposphere than polar temperature perturbations.