The Key Factors Controlling the Seasonality of Planetary Climate

TL;DR

This paper investigates how various planetary parameters, especially rotation rate, influence seasonal climate patterns using climate models, revealing complex dependencies beyond simple expectations.

Contribution

It identifies the key factors controlling planetary seasonality, highlighting the nontrivial effects of rotation rate on seasonal amplitude and latitudinal temperature shifts.

Findings

Seasonal amplitude decreases with slower rotation rates.

Latitudinal shift of maximum temperature moves poleward as rotation slows.

Rotation rate influences atmospheric heat transport affecting seasonality.

Abstract

Several different factors influence the seasonal cycle of a planet. This study uses a general circulation model and an energy balance model (EBM) to assess the parameters that govern the seasonal cycle. We define two metrics to describe the seasonal cycle, $\phi_s$, the latitudinal shift of the maximum temperature, and $\Delta T$, the maximum seasonal temperature variation amplitude. We show that alongside the expected dependence on the obliquity and orbital period, where seasonality generally strengthens with an increase in these parameters, the seasonality depends in a nontrivial way on the rotation rate. While the seasonal amplitude decreases as the rotation rate slows down, the latitudinal shift, $\phi_s$, shifts poleward. A similar result occurs in a diffusive EBM with increasing diffusivity. These results suggest that the influence of the rotation rate on the seasonal cycle stems from the effect of the rotation rate on the atmospheric heat transport.