Ponds in melting ice: bistability in radiatively heating

The interplay between convective and radiation-driven processes driving the dynamics of surface ice melting plays a fundamental role in geophysical contexts.

In particular, understanding the formation of melt ponds, initiated by solar radiation has great implications as the total albedo is significantly lowered thus further increasing the overall melting rate. Through direct numerical simulations and theoretical analysis, we unveil a bistability phenomenon in melt pond dynamics. As solar radiation intensity and initial pond depth vary, an abrupt transition occurs (also referred to as a tipping point) transforming the system from a fully frozen to an equilibrium state characterized by a distinct melt pond depth.

We elucidate the mechanism of this transition by the heat flux mismatch between ice and water and propose a theoretical model based on heat flux balance, which shows excellent agreement with our numerical results. Moreover, we employ our model to predict the bulk temperature and flow strength within melt ponds, offering insights into the coupling of phase transitions with convective flows.