Reconstructing full temperature field in co-evolving ice-water bodies

Experimental studies are of great importance amid the urgent need to understand thermo-fluid dynamics and energy exchanges in rapidly changing ice-bounded water bodies. However, such systems raise a technical challenge: How can the temperature field in these two-phase coupled systems be measured? Although various methods have been proposed to characterize fine temperature fields in fluid phases, such as the laser-induced fluorescent method and the liquid crystal thermometry, simultaneous two-phase temperature field measurements are beyond their applications. There are two primary technical challenges in the ice-bounded water bodies: Difficulty embedding temperature probes in ice and the irregular co-evolving ice-water interface. To tackle this challenge, we first employ particle tracking velocimetry to well-resolve the flow fields along the interface. We then assimilate this velocity data with well-constrained boundary conditions and the advection-diffusion heat transport equation to reconstruct temperature fields while fulfilling the system's heat budget. Local thermistor temperature measurements are used to validate the reconstructed thermo field. We demonstrate this methodology through laboratory experiments that quantify and link the evolving ice-water interface, buoyancy-driven flows, and interfacial heat exchange. This framework not only captures the coupled evolution of ice-bounded freshwater systems: the reconstructed temperature field, with further quantification, shall offer critical insights into the fundamental physics of ice-bounded water bodies characteristic of cryosphere-hydrosphere interactions in a warming climate.